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1

U-series disequilibria in suspended river sediments and implication for sediment transfer time in alluvial plains: The case of the Himalayan rivers  

Microsoft Academic Search

238U–234U–230Th radioactive disequilibria were analyzed in suspended sediments (collected at different depths) from the Ganges River and one of its main tributaries: the Narayani–Gandak River. Results associated with bedload sediment data suggest that uranium-series (U-series) disequilibria in river sediments of the Ganges basin vary with grain size and sampling location. The range of observed U-series disequilibria is explained by a

M. Granet; F. Chabaux; P. Stille; A. Dosseto; E. Blaes

2010-01-01

2

The relationship between riverine U-series disequilibria and erosion rates in a basaltic terrain  

NASA Astrophysics Data System (ADS)

U-series isotopes have been measured in the dissolved phase, suspended load and bedload of the main rivers draining basaltic catchments in Iceland. For the dissolved phase, ( 234U/ 238U) and ( 238U/ 230Th) range between 1.08 and 2.2, and 7.4 and 516, respectively. For the suspended load and bedload, ( 234U/ 238U) and ( 238U/ 230Th) range from 0.97 to 1.09 and from 0.93 to 1.05, respectively. Chemical erosion rates, calculated from dissolved major elements, range between 13 and 333 t km - 2 yr - 1 . Physical erosion rates have also been estimated, from existing data, and range between 21 and 4864 t/km 2/yr, with an average of 519 t km - 2 yr - 1 . U-series disequilibria indicate that weathering in Iceland operates at close to steady-state conditions. A model of continuous weathering indicates a maximum weathering timescale of 10 kyr, with an average rate of uranium release into water of 1.6 · 10 - 4 yr - 1 , which is significant when compared to granitic terrains located at similar latitudes and to tropical basaltic terrains. All river waters display ( 234U/ 238U) greater than secular equilibrium, consistent with the effects of alpha-recoil. The same dissolved phase ( 234U/ 238U) exhibit a negative trend with physical erosion rates, explained by the dominant effect of close-to-congruent chemical weathering of hyaloclastites in the younger basaltic terrains. Therefore, chemical erosion rate and mineral weathering susceptibility play a major role in determining 234U- 238U disequilibria in basaltic river waters. Comparison of global data for river basins in which weathering was recently strongly limited indicates a negative correlation between silicate weathering rates estimated with major elements and the age of weathering estimated with U-series disequilibria. This strongly suggests a key role of time and soil thickness on the chemical erosion of silicates.

Vigier, N.; Burton, K. W.; Gislason, S. R.; Rogers, N. W.; Duchene, S.; Thomas, L.; Hodge, E.; Schaefer, B.

2006-09-01

3

Mantle Melting Processes Beneath Iceland, Assessment from U-series Disequilibria: Implication for Mantle Plume Dynamics  

NASA Astrophysics Data System (ADS)

The existence of mantle plumes has recently been questioned on the basis of geophysical, petrological and geochemical arguments (e.g., Meibom, et al., 2003), although there is a long-standing concession that hotspot volcanoes such as Hawaii or Iceland represent the surface expression of mantle plumes which is hot, buoyant upwelling regions beneath the Earth's lithosphere. In addition to that, the physical structures of plumes are still a subject of questions. For instance, there are models which advocate a relatively cool and broad plume beneath Iceland (Ribe, et al, 1995; Ito, et al., 1996), while others proposed hot and narrow plume beneath central Iceland (Mckenzie, 1984; White, et al., 1995; Wolf et al., 1997). Recently, it has been shown that U-series disequilibria in young hotspot lavas (e.g. Sims, et al., 1999; Kokfelt, et al., 2003; Bourdon, et al., 2005) provide a relative measure of mantle upwelling velocity beneath ocean islands. U and Th fractionation produced during melting is a function of the melting rate. In turn, this parameter should scale with mantle upwelling velocities. Simply stated, a larger melting rate (larger mantle upwelling velocity) yields smaller Th excess relative to the parent nuclide. Using our new data together with previous works we modeled U-series disequilibria measured in recent lavas of Iceland volcanoes. For a reasonable range of mantle porosities (0.01-0.5 %) in a dynamic melting model the upwelling rates show sharp radial increase from 3 to12 cm per year towards the presumed center of Iceland plume (i.e., from Krafla and Eldija to Hekla, Örfæjökull, Tunguhran and Askja), but after about 135 km from the center of the plume the upwelling rates remain constant (2-3 cm per year) in Heimaey, Reykjanes Peninsula and Snæfelsness Peninsula as away from the plume center. We suggest that the incremental upwelling rates towards the center must indeed associated with hot and buoyant upwelling that characterized by higher excess temperature than the surrounding mantle. Our observation is consistent with Wolf et al. (1997) seismic study that shows about 150 km radius of the low velocity anomaly beneath central Iceland, and it gives a strong supporting evidence for models of hot and narrow plume beneath central Iceland. Thus, geochemical data (U series disequilibrium) provide important complementary information that is not available from geophysical and petrological data alone in constraining the physical structure of mantle plumes.

Akalu, T. C.; Kobayashi, K.; Yokoyama, T.; Nakamura, E.

2008-12-01

4

U-series disequilibria in suspended river sediments and implication for sediment transfer time in alluvial plains: The case of the Himalayan rivers  

NASA Astrophysics Data System (ADS)

238U- 234U- 230Th radioactive disequilibria were analyzed in suspended sediments (collected at different depths) from the Ganges River and one of its main tributaries: the Narayani-Gandak River. Results associated with bedload sediment data suggest that uranium-series (U-series) disequilibria in river sediments of the Ganges basin vary with grain size and sampling location. The range of observed U-series disequilibria is explained by a mixing model between a coarse-grained sediment end-member, represented by bedload and bank sediments, and a fine-grained end-member that both originate from Himalaya but undergo different transfer histories within the plain. The coarse-grained sediment end-member transits slowly (i.e. >several 100's ky) in the plain whereas the fine-grained sediment end-member is transferred much faster (<20-25 ky), as indicated by the absence of significant variations in Th isotope composition of the fine-grained sediment end-members. These results show that U-series isotopes can be used to quantify the various transfer times of river sediments of different sizes and infer that there can be an order of magnitude of difference, or more, between the transfer time of suspended and bedload sediments. This underlines that a good knowledge of the proportion of suspended vs. bedload sediments transported in the river is required to accurately assess how fast erosion products are transferred in a catchment and how fast a catchment is likely to respond to external forcing factors.

Granet, M.; Chabaux, F.; Stille, P.; Dosseto, A.; France-Lanord, C.; Blaes, E.

2010-05-01

5

Evaluation of Mantle Upwelling Beneath Iceland from U-series Disequilibria: Implication for Icelandic Mantle Plume Dynamics  

NASA Astrophysics Data System (ADS)

The existence of mantle plumes has recently been questioned on the basis of geophysical, petrological and geochemical arguments (e.g., Meibom, et al., 2003), although there is a long-standing concession that hotspot volcanoes such as Hawaii or Iceland represent the surface expression of mantle plumes which is hot, buoyant upwelling regions beneath the Earth's lithosphere. In addition to that, the physical structures of plumes are still a subject of questions. For instance, there are models which advocate a relatively cool and broad plume beneath Iceland (Ribe, et al, 1995; Ito, et al., 1996), while others proposed hot and narrow plume beneath central Iceland (Mckenzie, 1984; White, et al., 1995; Wolf et al., 1997). Recently, it has been shown that U- series disequilibria in young hotspot lavas provide a relative measure of mantle upwelling velocity beneath ocean islands(e.g. Sims, et al., 1999; Kokfelt, et al., 2003; Bourdon, et al., 2005). U and Th fractionation produced during melting is a function of the melting rate. In turn, this parameter should scale with mantle upwelling velocities. Simply stated, a larger melting rate (larger mantle upwelling velocity) yields smaller Th excess relative to the parent nuclide. Using our new data together with previous works we modeled U-series disequilibria measured in recent lavas of Iceland volcanoes. For a reasonable range of mantle porosities (0.01-0.5 %) in a dynamic melting model the upwelling rates show sharp radial increase from 3 to 12 cm per year towards the presumed center of Iceland plume, but after about 135 km from the center of the plume the upwelling rates remain constant (2-3 cm per year). We suggest that the incremental upwelling rates towards the center can be associated with hot and buoyant upwelling that characterized by higher excess temperature than the surrounding mantle. Our observation is consistent with Wolf et al. (1997) seismic study that shows about 150 km radius of the low velocity anomaly beneath central Iceland, and it gives a strong supporting evidence for models of hot and narrow plume beneath central Iceland. Thus, geochemical data (U series disequilibrium) provide important complementary information that is not available from geophysical and petrological data alone in constraining the physical structure of mantle plumes.

Chekol, T. A.; Kobayashi, K.; Nakamura, E.

2009-05-01

6

CHARACTERIZATION OF CONTAMINANT TRANSPORT USING NATURALLY-OCCURRING U-SERIES DISEQUILIBRIA  

EPA Science Inventory

The interactions of mixed wastes containing radionuclides with solid rock surface and the mobility of the radionuclides in aquifer systems depend not only on the chemistry of the nuclides and the physico-chemical effects of radioactive decay, but also on the site-specific hydroge...

7

Characterization of Contaminant Transport using Naturally-Occurring U-Series Disequilibria - Final Report - 05/01/1997 - 04/30/2001  

SciTech Connect

The interactions of mixed wastes containing radionuclides with solid rock surface and the mobility of the radionuclides in aquifer systems depend not only on the chemistry of the nuclides and the physico-chemical effects of radioactive decay, but also on the site-specific hydrogeology. Thus, to characterize contaminant transport, it is best to cross-check figures derived from any small-scale laboratory experiments over limited times with that obtained from field-oriented, natural analog studies. We propose such a study using the naturally-occurring U and Th decay-series disequilibria. The work of ours and other researchers have shown that the parent/daughter disequilibrium patterns existing in groundwater systems can be modeled in terms of local nuclide mass balance to arrive at such information as the rock-water contact time (fluid flow) and rates of contaminant transport, taking into account the retardation effect due to nuclide/rock interaction contaminants at INEL by grouping them into three categories, represented by isotopes of (1) Th and Pa, (2) U and (3) Ra. Mass spectrometric measurements of these elements will be emphasized in order to minimize sample size requirements and to maximize precision. Results will form the data base for a model code for computing: (1) Fluid residence time (transport rates) in the basalt aquifers at various locations, (2) The in-situ adsorption and desorption rate constants, as well as the retardation factors, of various radionuclide wastes, and (3) Rock dissolution rate and its relation to preferential flow and contamination transport in the fractured rock.

Murrell, Michael T.; Ku, Teh-Lung

2001-04-30

8

Recycling of crystal mush-derived melts and short magma residence times revealed by U-series disequilibria at Stromboli volcano  

NASA Astrophysics Data System (ADS)

The presence of crystal mushes in the feeding system of active volcanoes is generally revealed by antecrysts, representing the crystalline portion of old magmas recycled in the juvenile material, but very little is known about the fate of interstitial liquid hosted within the crystal-rich mush (i.e. antemelt). U-series disequilibria measured in magmas erupted in the past 18 years at Stromboli volcano provide the first geochemical evidence of the involvement of antemelt and help constraining the timescales of the processes occurring in the plumbing system of the volcano. Despite almost constant major and trace element composition, significant variations in isotope ratios are observed. (230Th/232Th) decreases with time, whilst (238U/232Th), (226Ra/230Th) and 87Sr/86Sr are different in the two types of magma erupted. Magma with low phenocryst content (lp) is erupted as pumices during paroxysm and is thought to belong to a deep reservoir. Highly porphyritic magma (hp) is erupted during the normal “Strombolian” activity as scoria and during the effusive events as lavas, and it is considered to derive from the former one within a shallow reservoir through degassing-driven crystallisation, mixing and incorporation of antecrysts. The distinct (238U/232Th) of lp and hp magma requires the involvement of a component with high 87Sr/86Sr and (238U/232Th) deriving from older magmas erupted earlier in the volcano history (up to 2.5 ka). The incompatibility of U and Th in major mineral phases limits the possible effect of antecrysts, hence requiring the involvement of a U- and Th-rich antemelt. The decrease of 226Ra-excess from lp to hp magmas provides further and independent evidence for the involvement of a few thousands years old antemelt. The variation with time of (230Th/232Th) within lp and hp magmas is exploited to constrain the residence time of magmas in the deep and shallow reservoir of the volcano to <55 yrs (inferred reservoir volume <0.5 km) and 2-10 yrs (inferred reservoir volume 0.02-0.09 km), respectively. Our results show the occurrence of magmatic processes operating at different timescale within the feeding system of a so-called steady state volcano, such as Stromboli. We show that, while most of the magma is erupted within few years, a portion of it, made of both crystals (antecrysts) and residual liquid (antemelt), can be stored in the plumbing system for thousands of years to be eventually rejuvenated and mixed back into the shallow reservoir. The presence of antemelts may also affect the eruptive mechanism by promoting heat transfer in locked crystal mushes, hence favouring their remobilisation.

Bragagni, Alessandro; Avanzinelli, Riccardo; Freymuth, Heye; Francalanci, Lorella

2014-10-01

9

Radioactive disequilibria in mineralised fracture samples from two uranium occurrences in northern Sweden  

USGS Publications Warehouse

Mineralised fractures from two uranium occurrences in northern Sweden were examined mineralogically and isotopically to establish the presence or absence of radioactive equilibrium that may indicate recent rock-water interaction processes based on the natural mobility of uranium (i.e.; during the last 0.5 Ma). The results show evidence of radioactive disequilibrium in six of the nine samples investigated. Disequilibria are attributable to solution to solid 234U recoil gain (weakly mineralised zones adjacent to the main mineralisation) and solid to solution 234U recoil loss (moderate to highly mineralised zones). The absence of significant 238U loss in the samples emphasises the reducing conditions at the sampled depths. ?? 1984.

Smellie, J.A.T.; Rosholt, J.N.

1984-01-01

10

From mantle to ash cloud: quantifying magma generation, ascent, and degassing rates at Kilauea during short-lived explosive episodes using short-lived U-series radionuclide disequilibria  

NASA Astrophysics Data System (ADS)

We analyzed for 238U-series isotopes lava, scoria and ash samples erupted from Kilauea volcano, Hawai'i between 1982 and 2008, in order to investigate processes and timescales of magma generation in the mantle, magma ascent through the crust, and eruption. Timescales of degassing during steady-state lava flow activity occurring in Kilauea East Rift Zone and short-lived explosive episodes that occurred in both the East Rift Zone (Pu'u 'O'o vent opening in 1983 and episode 54 at N?pau crater in January 1997) and on the summit (Halema'uma'u crater eruptions in March 2008) are compared and contrasted. All samples were found to have small but variable 230Th and 226Ra activity excesses over 238U and 230Th, respectively, with (230Th/238U) ratios ranging from 1.00 to 1.13 and (226Ra/230Th) ratios ranging from 1.03 to 1.17. These two variable isotopic disequilibria may reflect local heterogeneities in the mantle underneath Kilauea, with sources in relatively primitive mantle with (238U)-(230Th)-(226Ra) in secular equilibrium and in recently (< 8000 years) depleted mantle with (230Th) and (226Ra) deficits over parent nuclides. In this model, both types of mantle melt to generate Kilauea magmas and subsequently mix in variable proportions. Samples from the brief explosive episodes span the entire composition range, suggesting that they were fed by heterogeneous magma batches which did not homogenize during ascent from the mantle. (210Pb/226Ra) ratios range from 0.75 to 1.00. The lack of correlation between (210Pb/226Ra) and (226Ra/230Th) or (230Th/238U), and the rapid return to secular equilibrium of 210Pb (< 100 years) suggest a fractionation process distinct from and subsequent to the Ra-Th-U fractionation inherited from mantle melting. We hypothesize that 210Pb deficits originate from 222Rn degassing during magma ascent, and estimate magma ascent from lower crust to surface to take place in a maximum of ~ 7 years for the lava flow samples. Products from the explosive episodes have ratios from ~ 0.75 to near equilibrium, suggesting that they comprise of a mix of young melts and degassed magmas which were stored in the shallow volcanic edifice for a few decades, in agreement with existing petrologic models.

Girard, G.; Reagan, M. K.; Sims, K. W.; Garcia, M. O.; Pietruszka, A. J.; Thornber, C. R.

2012-12-01

11

Constraining Rates of Chemical and Physical Erosion Using U-Series Radionuclides  

Microsoft Academic Search

\\u000a This chapter relates recent developments concerning the use of several U-series nuclides, in particular 234U-238U and 230Th-238U disequilibria, for constraining physical and chemical erosion rates and sediment age. Indeed, the ability to measure these\\u000a disequilibria with an extremely high precision, even in samples with low concentrations such as natural waters, has opened\\u000a new avenues for investigating erosional processes. This chapter

Nathalie Vigier; Bernard Bourdon

12

Origin of 226Ra- 230Th disequilibria in arc lavas from southern Chile and implications for magma transfer time  

NASA Astrophysics Data System (ADS)

Improved understanding of mantle melting processes and melt transport requires knowledge of how fast magma is generated and transferred from source region to surface. The rate of magma transfer can in favorable cases be estimated from radioactive disequilibria between nuclides of the 238U series. Young lavas from southern Chile, in which 238U- 230Th disequilibria have been measured [Sigmarsson et al., Nature 346 (1990) 163-165; Sigmarsson et al., Nature 394 (1998) 566-569], were analyzed for 226Ra abundances. The disequilibrium between 226Ra and 230Th in these lavas is found to correlate with 238U- 230Th disequilibria and 10Be/Be [Morris et al., Nature 344 (1990) 31-36]. These correlations strongly suggest that the excess of 226Ra over 230Th is due to the addition of a slab-derived fluid to the magma source, since Ra and U are fluid-mobile elements and the cosmogenic 10Be is most likely derived from the subducting Nazca plate beneath the Andes. The largest slab signature is observed in the lavas of Villarrica volcano, which is the most active volcano in South America. A model for subduction fluxing is discussed, in which the U series disequilibria in arc lavas will reflect the integrated dehydration process during metamorphism of the subducting plate and the metasomatized mantle, but be principally controlled by the latest hydrous mineral breakdown in the mantle wedge. Repeated precipitation and dehydration mineral reactions of the hydrated mantle could be the homogenization process of the slab input needed to explain the 10Be/Be-B/Be correlation for different arcs [Morris et al., Nature 344 (1990) 31-36]. The fact that excesses of 226Ra and 238U over 230Th are correlated indicates that linear arrays on the ( 230Th/ 232Th)-( 238U/ 232Th) diagram are not isochrons reflecting time elapsed since a fluid addition but rather mixing lines between a fluid phase and melts. The 226Ra- 230Th disequilibrium in arc lavas suggests significantly shorter timescales for magma transfer, or less than 8000 years. This disequilibrium is consistent with minimum magma transfer rate through the mantle wedge on the order of 10 m/year. Finally, the correlations of ( 226Ra /230Th) with ( 238U/ 232Th) and 10Be/Be in Andean magmas imply that magma chamber residence time is of the same order of magnitude beneath the stratovolcanoes studied.

Sigmarsson, O.; Chmeleff, J.; Morris, J.; Lopez-Escobar, L.

2002-03-01

13

On the quantitative interpretation of uranium series disequilibria  

NASA Astrophysics Data System (ADS)

The quantitative interpretation of radioactive disequilibria developed between radionuclides in natural decay chains is discussed. Due to the wide spectrum of radioactive half lives of the member nuclides, uranium series can retain information long times (350,000 years) about changes in the bedrock. Radioactive disequilibrium is the result of different physico-chemical behavior of nuclides under natural conditions. The geochemical behavior of important nuclides is known rather well, which provides a sound basis for using Uranium Series Disequilibrium (USD) method. A mathematical model was developed to simulate inventories of a four member (or shorter) radioactive decay chain in simplified systems. The systems can be periodically opening or continuously open in thermodynamical sense, which means that outside mass flows are periodical or continuous in nature, respectively. Both types of mass flow can be combined into continuous scenarios. The computer code URSE (URanium SEries disequilibria) was developed from the mathematical model. URSE was tested extensively by reference calculations with another code and by calculating relevant cases presented in the literature. The interpretation of uranium series disequilibria is based on the natural trend of decay chains to develop towards radioactive equilibrium. This equilibration process is disturbed by outside mass flows; the nature and time scale of the disturbance can be assessed from the degree of radioactive equilibrium of the system. The quantitative interpretation of uranium series disequilibria is a demanding task, because the system under study must be known theoretically first. On the other hand, using USD method, conceptual models of the system in situ can be validated over time scales of hundreds of thousands of years that cannot be achieved in laboratory or field experiments.

Rasilainen, Kari; Suksi, Juhani

1992-10-01

14

U-series disequilibria in early diagenetic minerals from Lake Magadi sediments, Kenya: Dating potential  

NASA Astrophysics Data System (ADS)

At the southern end of the Gregory Rift Valley, Lake Magadi occupies the bottom of a relatively large drainage basin. It is presently covered by a thick trona crust, which overlies two silty-clay units deposited during Late Pleistocene high lake stands. These units consist of a mixture of detrital grains (anorthoclase, amphiboles, quartz), clays (illite, authigenic zeolites), phosphates, and sedimentary sodium silicates and cherts. A late diagenetic calcite is occasionally observed. The authigenic and/or diagenetic mineralogical phases were extracted and analyzed for their uranium and thorium isotope contents. All yielded highly correlated ( 234U /232Th vs. 238U /232Th ) and ( 230Th /232Th vs. 234U /232Th ) isochrons defining two-component mixing systems (detrital and authigenic phases). The detrital component is characterized by large excesses of 230Th (over 234U) and by 230Th /232Th ratios carrying an imprint of the source rocks (e.g., Precambrian basement vs. volcanics) and indicating efficient uranium-leaching processes during the previous pedologic cycle. The slope of the isochrons defines the 234U /238U and 230Th /234U ratios of the authigenic component, i.e., the age of the uranium-uptake episode. Zeolites yield an age of 10.4 ± 0.6 ka. This age is in agreement with the 14C chronology already established for the most recent high lake level episode in the basin (10,000-12,000 yr Bp). Sodium-silicates and cherts yield distinct ages of 98.5 ± 20 and 6 ± 3 ka, respectively, for the lower and upper lacustrine units. These ages allow the conclusion that (1) sedimentary silicates are of late diagenetic origin, and (2) that the lower lacustrine unit was deposited during a former high Lake Magadi level, possibly during the lacustrine episode dated at 135 ± 10 ka from uranium-series measurements on littoral stromatolites. Finally, the late diagenetic calcite, which yields an age of about 5 ka, indicates a significant change in the sediment interstitial water chemistry. This is also shown by the occurrence of calcitic oncolites in flat deposits assigned to a mid-Holocene minor oscillation of Lake Magadi level on the basis of their 14C ages. It is concluded that uranium-series measurements in diagenetic minerals may give access to the age of their formation. Dr. Christian Goetz passed away in May 1991, a few weeks after we received comments on the original version of our manuscript from its handling editor, Henry Schwarcz. Data and interpretations put forth in this paper are principally from one chapter of Christian's doctoral dissertation (Université Aix-Marseille II). Formerly at the Laboratoire de Géologie du Quaternaire of the CNRS, at Marseille (France), Christian Goetz was about to occupy a research position at the Institut de Physique du Globe, in Paris. He was 31 years old.

Goetz, Christian; Hillaire-Marcel, Claude

1992-03-01

15

Characterization of U-series disequilibria at the Pena Blanca natural analogue site, Chihuahua, Mexico  

SciTech Connect

The purpose of this study was to evaluate radionuclide migration from a uranium-mineralized breccia pipe. The site provides an excellent opportunity to evaluate radionuclide mobility in a geochemical environment similar to that around the proposed high-level waste repository at Yucca Mountain, Nevada. Samples represent fracture-infillings from both within and outside the breccia pipe. Mineral assemblages within the fractures include (1) pure kaolinite, (2) a mixture of iron-oxyhydroxides (goethite and hematite) with associated alunite and jarosite, which the authors refer to as the Fe-mineral assemblage, and (3) carbonates. Uranophane, weeksite, soddyite, and boltwoodite are associated with samples from within the breccia zone. The authors obtain radionuclide activities from gamma-ray rather than alpha spectroscopy, and the methodology for these measurements is presented in detail. Plots of {sup 230}Th/{sup 238}U vs. {sup 226}Ra/{sup 230}Th show three distinct mobility trends. (1) The majority of the Fe-mineral samples from within the breccia pipe yield values between 1.0 and 1.1 for both ratios, (2) Fe-mineral samples from outside the ore zone and a kaolinite from within the ore zone have {sup 230}Th/{sup 238}U of 0.58 to 0.83 and {sup 226}Ra/{sup 230}Th of 1.09 to 1.42, and (3) some Fe-mineral samples from within the breccia pipe have values of 1.2 and 0.9 respectively. These data, combined with those from other studies at Pena Blanca suggest that U and Ra are sometimes mobile in the near-surface environment and that multiple episodes of enrichment and leaching are required to explain the trends.

Wong, V.; Goodell, P.C.; Anthony, E.Y.

1999-07-01

16

Investigation of 238U- 230Th- 226Ra and 232Th- 228Ra- 228Th radioactive disequilibria in volcanic rocks from Trindade and Martin Vaz Islands (Brazil; Southern Atlantic Ocean)  

NASA Astrophysics Data System (ADS)

This paper presents the first results of 238U- 230Th- 226Ra and 232Th- 228Ra- 228Th radioactive disequilibria of alkaline volcanic rocks from Trindade and Martin Vaz islands (Southern Atlantic Ocean — Brazil). Th and U concentrations reinforce the role of fractional crystallization in the genesis of Trindade volcanics and allow dividing the rocks in three groups: Group I is characterized by phonolites depleted in U in relation to Th, whose genesis can be explained by mineral assemblage fractionation with high uranium partition coefficients (magnetite, apatite and/or titanite); Group II is composed of ultrabasic, basic and intermediate rocks, with relatively high U contents in respect to Th, whose enrichment is probably caused by the presence of small comagmatic xenoliths containing accumulation of those fractionated mineral phases; Group III is composed of remaining rocks, which tend to present despite of some variation homogeneous Th/U ratios (average = 4.6 ± 0.8). Very low degrees (1-2%) of partial melting generated ultrabasic rocks of the last group, which are highly SiO 2 undersaturated, and together with Ascension volcanics have the highest Th/U ratios of all OIB from Southern Atlantic Ocean. Activity ratios of ( 234U/ 238U), ( 230Th/ 238U), ( 226Ra/ 238U), ( 226Ra/ 230Th), ( 228Ra/ 232Th), and ( 228Th/ 232Th) are equal to unity in all phonolites and some basic and ultrabasic rocks belonging to Trindade Complex and Desejado Sequence, agreeing with ages more than 300 ky. Martin Vaz peralkaline phonolite also presents activity ratios indicating radioactive equilibrium, except for ( 226Ra/ 238U), which is significantly smaller than unity as the result of 226Ra steady mobilization. Rocks from the three youngest volcanic episodes of Trindade (Morro Vermelho Formation, Valado Formation, and Vulcão do Paredão) present ( 230Th/ 238U) and ( 226Ra/ 238U) ratios distinct from unity, showing also a significant 230Th enrichment, and all pairs of activity ratios indicate system closure between 8 and 300 ky ago. ( 230Th/ 232Th) and ( 238U/ 232Th) data of Morro Vermelho rocks allowed determining an age of 111 ± 20 ky. Radioactive disequilibrium between 238U and 226Ra of Valado Formation rocks, associated with literature information constrain the system was closed between 8 and 11 ky. For ultrabasic rocks, calculated 230Th 0 excesses, along with Th/U ratios do not show significant correlations with K 2O contents, therefore if phlogopite remained as a residual phase during K-poor magma generation, this mineral did not fractionate Th because of its very small partition coefficient. The relatively low ( 230Th/ 232Th) 0 in comparison with measured 87Sr/ 86Sr, plotting slightly below the mantle array, may be explained either by a relatively long time (maximum of about 110 ky for Morro Vermelho Formation) of magma transfer towards surface or, more probably, by melting of heterogeneous mantle due to a metasomatic event occurred between 111 and 300 ky, followed by a very short magma transfer time (hundreds of years).

Santos, Rosana N.; Marques, Leila S.

2007-03-01

17

Time-scales of sedimentary transfer and weathering processes from U-series nuclides: Clues from the Himalayan rivers  

NASA Astrophysics Data System (ADS)

In order to define time-scales of erosion and sedimentary transfer in the Himalaya, 238U- 234U- 230Th disequilibria have been analysed in river bank sediments and in bedloads collected along the Kali Gandaki river, one of the main Nepalese rivers, and in the Ghaghara and Gandak rivers, two major plain tributaries of the Ganges. The Th activity ratios and U/Th ratios in river sediments of the two Ganges tributaries constantly decrease from upstream to downstream. This is related to the maturation of sediments by weathering during their transfer to the plain. The U-series data allow to calculate a transfer time for the sediments in the alluvial Gangetic plain from the chain front to the confluence with the Ganges of about 100 kyr for both rivers. The Kali Gandaki river sediment data highlight a decrease of both the Th isotopic and U/Th ratios which is explained by a mixing between two sources with similar U/Th ratios but having suffered a different U-Th fractionation history. Interpretation of the U-series data in the frame of this scenario gives long time-scales of weathering of several 100's kyr for the Himalayan terranes. The results imply that Himalayan bedrocks are submitted to a long in situ stage of weathering before their erosion and transfer into the rivers. In addition, occurrence of similar U-Sr signatures in dissolved (i.e. < 0.1-0.2 ?m) and sediment phases of the Kali Gandaki river suggests that "dissolved" uranium could be carried by colloids constituted by sedimentary microparticles. This precludes the use of U-series disequilibria in this river to calculate weathering budgets and to assess whether the erosion is working at steady-state or not.

Granet, M.; Chabaux, F.; Stille, P.; France-Lanord, C.; Pelt, E.

2007-09-01

18

U-Series Dating of Tropical Stalagmites  

NASA Astrophysics Data System (ADS)

Stalagmites are often seen as one of the ideal phases for U-series disequilibrium dating. Typically closed systems with high 234/238 ratios and little initial Th-230, these samples have yielded some of the most precise and accurate ages of the climate system over the last half million years. However, conditions in tropical cave systems can fail on all of these criteria, many times all of them at once. We use our set of over 400 U-series analyses in stalagmites and dozens of others from host rocks and drip waters from the karst region in Northern Borneo to show how problems with low uranium content, very depleted 234/238 ratios, and high ';detrital' thorium can be overcome to yield quality dates. Isochrons are an important tool, and we explore their advantages and weaknesses, but understanding the location and signature of hiatuses is also important. We have developed several geochemical lines of evidence for how to identify these pauses in stalagmite growth. In addition we explore how many of these conditions might come about and how they may be ubiquitous to tropical systems worldwide. The most puzzling observation is low 234/238 ratios. Ranging from near secular equilibrium to values below -600 permil, the missing U-234 requires some specific weathering scenarios to explain the complementary suite of rocks, waters, and stalagmites. Other Me/Ca data helps understand the degree that prior precipitation affects the range U-series data. Some simple numerical models of water moving through karst help us to understand the implications of these extensive data sets.

Adkins, J. F.; Carolin, S. A.; Cobb, K.; Subhas, A. V.; Rider, A.; Meckler, N.

2013-12-01

19

Using U-series and beryllium isotopes to reveal the occurrence and relative timing of crustal and mantle processes in the Southern Volcanic Zone of Chile  

NASA Astrophysics Data System (ADS)

Magmas erupted from subduction zone volcanoes represent the end products of multiple magmatic processes occurring in the asthenospheric mantle wedge and overlying lithosphere (i.e., fluid addition, melting, assimilation, and crystal fractionation). To resolve the contributions of diverse processes and components, and the relative timing of these events, we have determined U-series activities (U-Th-Ra-Pa) for 60 and 10Be compositions for 20 historic or very young lavas carefully chosen on the basis of major and trace element analyses of 625 samples from six volcanoes in the Andean Southern Volcanic Zone of Chile (37.6-41.1°S: Nevados de Chillán, Antuco, Llaima, Lonquimay, Villarrica, and Osorno). Our dataset demonstrates that each of these volcanoes reflects a unique combination and sequence of magmatic processes that are only revealed through analysis of multiple samples spanning the extent of intra-volcano and intra-eruption chemical variation. Sigmarsson et al. (1990; 2002) identified a regional trend using U-series and Be from mostly single samples, which they interpreted to represent along-strike variations in the flux of slab-derived fluids into the wedge [from 230Th-excess plus 226Ra-deficit plus low 10Be/9Be at Chillán towards progressively higher 238U- and Ra-excesses and 10Be/9Be at Villarrica and Osorno]. These data fall within the much broader array defined by our results, but we infer the operation of assimilation (e.g., Llaima; Reubi et al., 2011) and aging of subduction zone components of variable compositions and proportions in the mantle prior to partial melting as important factors in generating the highly individualized and complex U-series systematics observed at each of these six volcanoes. All of the volcanoes exhibit evidence of assimilation, with the exception of Lonquimay which has undergone mostly closed-system fractional crystallization. At Llaima and Chillán the assimilant is crustal. At Villarica, flux-related melts that dominate in the main edifice have been mixed with magma compositions similar to those at surrounding minor eruptive centers (Hickey-Vargas et al., 2002). The latter appear to be decompression melts of enriched mantle which manifest moderate U-Th-Ra disequilibrium and substantial 231Pa-excesses, whereas melts from Villarrica have substantial U- and Ra-excesses. Magmas from Osorno reflect a greater influence of sediments originating from the incoming slab. After discounting assimilated samples, all primary melts have uniformly high Pa-excesses (1.7-2.2) coincident with large variations in 238U-230Th disequilibria. Fluid addition-aging-melting successions at Antuco and Chillán may have led to compositions near U-Th equilibrium or with Th-excesses, respectively. Primary Ra-deficits at Chillán, Lonquimay, and Osorno are under investigation and potentially reflect melting of a cumulate body. Forthcoming 10Be data for select U-series samples will enable further clarification of the regional trend. Preliminary analyses of nine Llaima samples erupted between 1850 and 2009 confirm the successful elimination of a meteoric 10Be component and produce a data array consistent with assimilation. The invocation of radioactive decay to produce U-Th equilibrium (duration of at least 380 ky) could also explain the low 10Be/9Be compositions (half-life of 10Be=1,390 ky). Our comprehensive dataset may shed new light on melting processes in subduction zone systems.

Cooper, L. B.; Reubi, O.; Dungan, M. A.; Bourdon, B.; Langmuir, C. H.; Turner, S. J.; Schaefer, J. M.

2012-12-01

20

Subduction and melting processes inferred from U-Series, Sr Nd Pb isotope, and trace element data, Bicol and Bataan arcs, Philippines  

NASA Astrophysics Data System (ADS)

We present U-series, Sr-Nd-Pb isotope, and trace element data from the two principal volcanic chains on Luzon Island, developed over oppositely dipping subduction zones, to explore melting and mass transfer processes beneath arcs. The Bataan (western) and Bicol (eastern) arcs are currently subducting terrigenous and pelagic sediments, respectively, which have different trace element and isotopic compositions. The range of ( 230Th/ 238U) disequilibria for both arcs is 0.85-1.15; only lavas from Mt. Mayon (Bicol arc) have 230Th activity excesses. Bataan lavas have higher 87Sr/ 86Sr and lower 143Nd/ 144Nd than Bicol lavas ( 87Sr/ 86Sr = 0.7042-0.7046, 143Nd/ 144Nd = 0.51281-0.51290 vs. 87Sr/ 86Sr = 0.70371-0.70391, 143Nd/ 144Nd = 0.51295-0.51301) and both arcs show steep linear arrays towards sediment values on 207Pb/ 204Pb vs. 206Pb/ 204Pb diagrams. Analysis of incompatible element and isotopic data allows identification of a sediment component that, at least in part, was transferred as a partial melt to the mantle wedge peridotite. Between 1% and 5% sediment melt addition can explain the isotopic and trace element variability in the rocks from both arcs despite the differences in sediment supply. We therefore propose that sediment transfer to the mantle wedge is likely mechanically or thermally limited. It follows that most sediments are either accreted, reside in the sub-arc lithosphere, or are recycled into the convecting mantle. However, whole-sale sediment recycling into the upper mantle is unlikely in light of the global mid-ocean ridge basalt data. Fluid involvement is more difficult to characterize, but overall the Bicol arc appears to have more fluid influence than the Bataan arc. Rock suites from each arc can be related by a dynamic melting process that allows for 230Th ingrowth, either by dynamic or continuous flux melting, provided the initial ( 230Th/ 232Th) of the source is ˜0.6-0.7. The implication of either model is that inclined arrays on the U-Th equiline diagram may not have chronologic significance. Modeling also suggests that U-series disequilibria are influenced by the tectonic convergence rate, which dictates mantle matrix flow. Thus with slower matrix flow there is a greater degree of 230Th ingrowth. While other factors such as prior mantle depletion and addition of a subducted component may explain some aspects of U-series data, an overall global correlation between tectonic convergence rate and the extent of U-Th disequilibria may originate from melting processes.

DuFrane, S. Andrew; Asmerom, Yemane; Mukasa, Samuel B.; Morris, Julie D.; Dreyer, Brian M.

2006-07-01

21

How precise are U-series coral ages?  

Microsoft Academic Search

U-series dating of fossil reef corals is a well established and widely applied technique in paleoclimate research. Many fossil corals, however, show evidence for post-depositional diagenetic alteration, and it is generally accepted that the accuracy of U-series coral ages is more limited due to coral diagenesis than analytical precision. In recent years, three models have been published that try to

Denis Scholz; Augusto Mangini

2007-01-01

22

Determination of sedimentary transfer time from U-series nuclides:implications from the study of the Gandak river sediments  

NASA Astrophysics Data System (ADS)

In previous studies, it was proposed to constrain sediments transfer time in alluvial plains by analyzing the variations of the U-series disequilibria in river sediments along the stream. This approach was illustrated in the case of the Ganges-Brahmaputra basin and it allowed defining a sediment transfer scenario that includes significantly different transfer times within the alluvial plain. These studies suggest that the transfer times depend on the sediment grain size: short transfer times for fine-grained sediments (a few ky or less) and much longer ones for coarse-grained sediments (100 ky or more - [1-4]). However, those estimations can be questioned in the light of recent studies based on the analysis of cosmonuclides [5] and Sr et Nd isotopes [6] , that suggest shorter transfer times (respectively 1-2 ky and less for the second study) for coarse-grained sediments in Himalayan streams. In order to better constrain the origin of the U-series disequilibria variations in river sediments, we performed a detailed study of the U-series nuclides in the sediments of the Gandak River, one of the main Ganges tributaries. This study involves the sampling during monsoon period of suspended sediments, collected at different depths of the water column in the downstream and upstream river sections. At the same time, a regular upstream-downstream sampling of riverbank sediments during non-monsoon period was conducted, with sediments collection on both riversides of a same sampling station. U-Th data obtained on whole rock samples outline the occurrence of significant 238U-230Th-226Ra disequilibria in river sediments, with however no simple upstream-downstream variation. The correlations observed between (238U/232Th) activity ratios and Ti/Th ratios as well as between (230Th/238U) ratios and (Nd, Ce, La, Sm)/Th ratios suggest that minor mineral phases, such as Ti-bearing minerals, monazite, zircon or xenotime, are likely to control a significant part of the U-Th-Ra budget in the Gandak sediments. U-isotopes fractionation could therefore not only depend on the chemical evolution of the sediments during its transfer within the plain and on the time evolution, but also on the mechanical transformation of the sediments mineralogical composition. This last aspect can be significantly influenced by local hydraulic conditions, inducing important sorting effects in river sediments. These results illustrate the interest to investigate separated mineral phases of river sediments. Indeed, we need to clarify the role of the mineral composition in the control of U-Th-Ra isotopic fractionation in river sediments. This is a key point to achieve more reliable transfer times, avoiding problems linked to environmental bias. [1] Chabaux et al., 2012, C. R. Geoscience, 344 (11-12): 688-703; [2] Chabaux et al., 2006, J. Geochem. Exploration, 88: 373-375 ; [3] Granet et al., 2010, Geochim. et Cosmoch. Acta, 74 (10): 2851-2865 ; [4] Granet et al., 2007, Earth and Planet. Sci. Lett., 261 (3-4): 389-406 ; [5] Lupker et al., 2012, Earth and Planet. Sci. Lett., 333-334: 146-156; [6] Rahaman et al., 2009, Geology, 37 (6): 559-562.

Bosia, Clio; Chabaux, Francois; France-Lanord, Christian; Deloule, Etienne; Pelt, Eric

2014-05-01

23

Quantifying trace element disequilibria in mantle xenoliths and abyssal peridotites  

E-print Network

Quantifying trace element disequilibria in mantle xenoliths and abyssal peridotites Arnaud Agranier in mantle xenoliths and abyssal peridotites using in situ analytical tools. Even when only mineral cores in mantle xenoliths are closer to equilibrium than those in abyssal peridotites even though mantle xenoliths

Lee, Cin-Ty Aeolus

24

238U-Series in Fe Oxy/Hydroxides by LA-MC-ICP-MS, New Insights Into Weathering Geochronology  

NASA Astrophysics Data System (ADS)

The establishment of a geochronological framework for weathering processes is essential for an understanding of the evolution of the regolith and its dynamics. However, there are few robust answers regarding the absolute age of weathering and its rates. Nowadays, 40Ar/39Ar analysis of Mn-Oxides (cryptomelane) and K-bearing secondary sulphates have provided one of the few generally reliable chronometers (e.g. 1), but is restricted to high-K secondary phases. This work presents a different approach to obtain geochronological information from weathering minerals, namely measurement of 238U-series disequilibria in authigenic Fe oxy/hydroxides. These may be potentially useful recorders of weathering processes as they commonly occur as weathering products and have high affinity towards dissolved uranyl complexes. Furthermore, U-Th fractionation during weathering has been extensively reported [2], effectively resetting the U/230Th geochronometer. LA-MC-ICP-MS facilitates in situ measurement of 238U-series disequilibria in authigenic microcrystalline iron oxy/hydroxides (precipitated between cracks and veins in partially and heavily weathered chlorite-muscovite schist) and pisoliths (ferruginous concretions). Contrary to previous studies [e.g. 3], in situ measurement of 238U-nuclides enables selective analysis or iron oxy/hydroxides phases, minimizes contributions from allogenic phases and, reduces the need of mathematical corrections to obtain the activity ratios for the authigenic phase [4, 5]. The results suggest that supergene iron oxy/hydroxides are good recorders of weathering processes; they precipitate during the early stages of weathering, reflect the U-isotopic composition of the groundwater, appear to act as closed-systems in weathering conservative environments, and behave in a predictable fashion when subjected to intense weathering and leaching conditions. The 230Th-ages of the iron oxy/hydroxides indicate that the timing and intensity of weathering appears to be largely controlled by global climatic changes, suggesting that weathering rates have not been constant during the last 300 ka in Northern Australia. References: 1 P.M. Vasconcelos. Annual Review in Earth and Planetary Sciences 27(1), 183-229, (1999) 2 M. Ivanovich and R.S. Harmon, Uranium-series disequilibrium : applications to earth, marine, and environmental science, xxxiv, 910 pp., Oxford University Press, Oxford, (1992) 3 S.A. Short, R.T. Lowson, J. Ellis and D.M. Price. Geochimica et Cosmochimica Acta 53, 1379-1389, (1989) 4 K.R. Ludwig and D.M. Titterington. Geochimica et Cosmochimica Acta 58(22), 5031-5042, (1994) 5 Luo, S. and T. L. Ku. Geochimica et Cosmochimica Acta 55(2): 555-564. (1991)

Bernal, J.; McCulloch, M.; Eggins, S.; Grun, R.; Eggleton, R.

2003-12-01

25

234Th:238U disequilibria within the California Current  

Microsoft Academic Search

Profiles of dissolved and particulate 234Th were determined at several stations within the Cali- fornia Current. Modeling of the disequilibria between the 234Th and 23aU within the surface waters provides for estimates of the residence time of dissolved thorium with respect to particle scavenging (TP varies from 6 to 50 days), the particle residence time (TP varies from 2 to

KENNETH H. COALE; KENNETH W. BRULAND

1985-01-01

26

How precise are U-series coral ages?  

NASA Astrophysics Data System (ADS)

U-series dating of fossil reef corals is a well established and widely applied technique in paleoclimate research. Many fossil corals, however, show evidence for post-depositional diagenetic alteration, and it is generally accepted that the accuracy of U-series coral ages is more limited due to coral diagenesis than analytical precision. In recent years, three models have been published that try to correct the effects of diagenesis and allow the calculation of model ages [Thompson W. G., Spiegelmann M. W., Goldstein S. L., and Speed R. C. (2003) An open-system model for U-series age determinations of fossil corals. Earth and Planetary Science Letters210, 365-381; Villemant B., and Feuillet N. (2003) Dating open systems by the 238U- 234U- 230Th method: application to Quaternary reef terraces. Earth and Planetary Science Letters210, 105-118; Scholz D., Mangini A., and Felis T. (2004) U-series dating of diagenetically altered fossil reef corals. Earth and Planetary Science Letters218, 163-178]. Here, we assess the age variability of both conventional 230Th/U-dating and the three models by application to different sub-samples of individual coral specimens. The age variability, estimated as the 2 ?-standard deviation on the individual ages, is compared with the errors quoted by the different methods. Our results show that the errors of conventional 230Th/U-dating as well as those of the method of Thompson et al. (2003) do not account for the true age variability. The age variability of both methods is in the range of the errors given by the models of Villemant and Feuillet (2003) and Scholz et al. (2004). Furthermore, we show that the widely used reliability criteria are not sufficient to identify all diagenetically altered corals. In contrast, analysis of different sub-samples of one coral specimen allows (i) to estimate the real age variability, (ii) to test if the assumptions of the models are fulfilled, and (iii) to investigate the diagenetic processes in more detail. Thus, this method should generally be applied to obtain more reliable U-series coral ages and errors.

Scholz, Denis; Mangini, Augusto

2007-04-01

27

Methods for obtaining sorption data from uranium-series disequilibria  

SciTech Connect

Two possible methods have been identified for obtaining in situ retardation factors from measurements of uranium-series disequilibria at Yucca Mountain. The first method would make use of the enhanced {sup 234}U/{sup 238}U ratio in groundwater to derive a signature for exchangeable uranium sorbed on the rock; the exchangeable uranium would be leached and assayed. The second method would use the ratio of {sup 222}Rn to {sup 234}U in solution, corrected for weathering, to infer the retardation factor for uranium. Similar methods could be applied to thorium and radium.

Finnegan, D.L.; Bryant, E.A.

1987-12-01

28

Chemical Disequilibria and Sources of Gibbs Free Energy Inside Enceladus  

NASA Astrophysics Data System (ADS)

Non-photosynthetic organisms use chemical disequilibria in the environment to gain metabolic energy from enzyme catalyzed oxidation-reduction (redox) reactions. The presence of carbon dioxide, ammonia, formaldehyde, methanol, methane and other hydrocarbons in the eruptive plume of Enceladus [1] implies diverse redox disequilibria in the interior. In the history of the moon, redox disequilibria could have been activated through melting of a volatile-rich ice and following water-rock-organic interactions. Previous and/or present aqueous processes are consistent with the detection of NaCl and Na2CO3/NaHCO3-bearing grains emitted from Enceladus [2]. A low K/Na ratio in the grains [2] and a low upper limit for N2 in the plume [3] indicate low temperature (possibly < 273 K) of aqueous processes. Although many of the energetically favorable redox reactions are sluggish at low temperature, they could be catalyzed by enzymes if organisms were (are) present. The redox conditions in aqueous systems and amounts of available Gibbs free energy should have been affected by the production, consumption and escape of hydrogen. Aqueous oxidation of minerals (Fe-Ni metal, Fe-Ni phosphides, etc.) accreted on Enceladus should have led to H2 production, which is consistent with H2 detection in the plume [1]. Numerical evaluations based on concentrations of plume gases [1] reveal sufficient energy sources available to support metabolically diverse life at a wide range of activities (a) of dissolved H2 (log aH2 from 0 to -10). Formaldehyde, carbon dioxide [c.f. 4], HCN (if it is present), methanol, acetylene and other hydrocarbons have the potential to react with H2 to form methane. Aqueous hydrogenations of acetylene, HCN and formaldehyde to produce methanol are energetically favorable as well. Both favorable hydrogenation and hydration of HCN lead to formation of ammonia. Condensed organic species could also participate in redox reactions. Methane and ammonia are the final products of these putative redox transformations. Sulfates may have not formed in cold and/or short-term aqueous environments with a limited H2 escape. In contrast to Earth, Mars and Europa, the moon may have no (or very limited [4]) potential for sulfate reduction. Despite nutrient (C, N, P and S) and metal (e.g. Fe, Ni) rich environments and multiple sources of Gibbs free energy during aqueous episode(s), putative life on Enceladus [4] would have adapted to survive in low water activity alkaline brines rich in ammonia, methanol and organic liquids at temperature >150-170 K. The comet-like abundances of major plume gases and apparent redox disequilibria in aquatic systems are consistent with a minimal influence of aqueous processes on endogenic chemical reactions and may indicate abiotic interior. Alternatively, plume gases may represent never melted primordial parcels of the icy shell, while the deeper interior could contain altered species transformed in abiotic and/or biological processes. Refs: [1] Waite J. et al. (2009) Nature 460, 487-490. [2] Postberg F. et al. (2009) Nature 459, 1098-1101. [3] Hansen C. et al. (2010) 38th COSPAR Sci. Assembly. [4] McKay C. et al. (2008) Astrobiology 8, 909-919.

Zolotov, M. Y.

2010-12-01

29

Dispersion of U-series natural radionuclides in stream sediments from Edale, UK.  

PubMed

The spatial distribution of (238)U-series radionuclides, specifically 238U, 234U, 230Th and 226Ra, has been determined in stream sediments from Edale, Derbyshire, United Kingdom, to explore the behaviour of U-series radionuclides during weathering. For uranium and thorium, two different extraction methods were used, total dissolution with HNO3/HF in a microwave and leaching with aqua regia. This was followed by radiochemical separation using extraction chromatography, then alpha spectrometry measurement. The total radium contents in the sediments were measured using gamma spectrometry, while the leached fraction was measured in the same way as for uranium and thorium. The total sediment content of uranium and thorium ranges from ?10 up to ?200 Bq kg(-1), while the radium specific activity lies between ?15 and 180 Bq kg(-1). In the aqua regia extractions, the uranium and thorium contents are in the range of ?5 to ?100 Bq kg(-1), while the radium specific activities are similar to those measured by total dissolution. All the radionuclides show no correlation with organic matter content. The activity ratios 234U/238U, 230Th/238U and 226Ra/238U were used to determine the degree of radioactive disequilibrium. The data show disequilibrium in most of the sediments, with activity ratios of 234U/238U, 230Th/238U and 226Ra/238U>1, inconsistent with evolution through straightforward weathering processes. Multivariate cluster analysis based on five variables, the specific activities of 238U, 234U, 230Th, 226Ra and loss on ignition, was employed to group the data and identify five distinct clusters. There seems to be a link between high radionuclide concentrations and proximity to landslips. PMID:24562972

Siddeeg, Saifeldin M; Bryan, Nicholas D; Livens, Francis R

2014-05-01

30

Modeling U-Series Concordia/Discordia Using STELLA  

NSDL National Science Digital Library

U-Series dating techniques are widely used to determine the absolute ages of some of Earth's oldest rocks, but the concordia/discordia diagram can be quite difficult for students to grasp. In particular, the fact that differing amounts of lead and uranium loss from minerals such as zircon can be used to determine not only the original formation age, but also the time of metamorphism of a rock like granite, is a challenging concept. Making use of previous workers' web-published excercises on radiometric decay, I have produced a STELLA-based lab exercise to develop students' understanding of this important chronologic technique. Students create models of the two isotopic decay systems, 238U --> 206Pb and 235U --> 207Pb, and run these models for 4.5 billion years to create the concordia diagram. They then carry out experiments in which they "add" or "remove" varying amounts of lead or uranium in simulation of metamorphism. The uranium-lead ratios at the end of the simulation allow the discordia line to be plotted on top of the concordia diagram and the ages of original crystallization and metamorphism to be determined from the points of intersection of the two lines. In the course of the lab, students are introduced to the concepts of exponential decay and secular equilibrium as well as modeling concepts such as the creation of if-then statements.

Kirsten Menking

31

U-series dating of diagenetically altered fossil reef corals  

NASA Astrophysics Data System (ADS)

Initial ( 234U/ 238U) activity ratios higher than those expected from closed system evolution of seawater are an outstanding problem in U-series dating of fossil reef corals. The increased activity ratios are ascribed to post-depositional diagenesis. We analysed six Last Interglacial and one Holocene coral of the genus Porites collected near the northern end of the Gulf of Aqaba (northern Red Sea) together with three recent corals from this location as a modern reference. While the values measured on the recent samples show no deviation from expected values, the Holocene and Last Interglacial corals display highly elevated ( 234U/ 238U) activity ratios as well as increased 238U and 232Th concentrations. ( 234U/ 238U) activity ratios are strongly correlated with ( 230Th/ 238U) and total uranium content. A model assuming different degrees of uranium addition and subsequent loss in different sub-samples of one coral produces straight lines (isochrons) on a ( 234U/ 238U)-( 230Th/ 238U) plot and predicts that the true age of the coral can be calculated by intersecting this isochron with the seawater evolution curve. We used the strong correlation detected in the Aqaba corals to calculate isochron ages. The isochron age of the Holocene coral (3116 +167 -156 yr) is concordant with its calibrated 14C age (2963 +92 -103 yr). The ages of the Last Interglacial corals are between 121 (+6.7 -5.3) and 121.9 (+7.0 -6.3) kyr for a higher terrace (7-10 m asl) and 106.4 (+8.9 -8.1) and 117.1 (+19.7 -15.3) kyr for a lower terrace (4-5 m asl). One Last Interglacial coral with an aragonite content of ˜85% could not be dated. The elevation and ages of the fossil terraces are consistent with existing sea level reconstructions from the Red Sea.

Scholz, Denis; Mangini, Augusto; Felis, Thomas

2004-01-01

32

Evaluation of Pleistocene groundwater flow through fractured tuffs using a U-series disequilibrium approach, Pahute Mesa, Nevada, USA  

USGS Publications Warehouse

Groundwater flow through fractured felsic tuffs and lavas at the Nevada National Security Site represents the most likely mechanism for transport of radionuclides away from underground nuclear tests at Pahute Mesa. To help evaluate fracture flow and matrix–water exchange, we have determined U-series isotopic compositions on more than 40 drill core samples from 5 boreholes that represent discrete fracture surfaces, breccia zones, and interiors of unfractured core. The U-series approach relies on the disruption of radioactive secular equilibrium between isotopes in the uranium-series decay chain due to preferential mobilization of 234U relative to 238U, and U relative to Th. Samples from discrete fractures were obtained by milling fracture surfaces containing thin secondary mineral coatings of clays, silica, Fe–Mn oxyhydroxides, and zeolite. Intact core interiors and breccia fragments were sampled in bulk. In addition, profiles of rock matrix extending 15 to 44 mm away from several fractures that show evidence of recent flow were analyzed to investigate the extent of fracture/matrix water exchange. Samples of rock matrix have 234U/238U and 230Th/238U activity ratios (AR) closest to radioactive secular equilibrium indicating only small amounts of groundwater penetrated unfractured matrix. Greater U mobility was observed in welded-tuff matrix with elevated porosity and in zeolitized bedded tuff. Samples of brecciated core were also in secular equilibrium implying a lack of long-range hydraulic connectivity in these cases. Samples of discrete fracture surfaces typically, but not always, were in radioactive disequilibrium. Many fractures had isotopic compositions plotting near the 230Th-234U 1:1 line indicating a steady-state balance between U input and removal along with radioactive decay. Numerical simulations of U-series isotope evolution indicate that 0.5 to 1 million years are required to reach steady-state compositions. Once attained, disequilibrium 234U/238U and 230Th/238U AR values can be maintained indefinitely as long as hydrological and geochemical processes remain stable. Therefore, many Pahute Mesa fractures represent stable hydrologic pathways over million-year timescales. A smaller number of samples have non-steady-state compositions indicating transient conditions in the last several hundred thousand years. In these cases, U mobility is dominated by overall gains rather than losses of U.

Paces, James B.; Nichols, Paul J.; Neymark, Leonid A.; Rajaram, Harihar

2013-01-01

33

Oceanic stratified euphotic zone as elucidated by 234Th : 238U disequilibria  

Microsoft Academic Search

Profiles of dissolved and particulate 234Th were determined at the VERTEX 2 and 3 stations off Manzanillo, Mexico, and at the VERTEX 4 station about 900 km north of Hawaii. By modeling the disequilibria between 234Th and 238U in the dissolved and particulate form, estimates of scav- enging rates for Th from the dissolved to particulate phases, particle residence times,

KENNETH H. COALE; KENNETH W. BRULAND

1987-01-01

34

Disequilibrium of the 238U series in basalt  

USGS Publications Warehouse

Radioisotope analyses of basalt samples from Hawaii, Japan, and Iwo Jima show that: (1) 234U and 238U are virtually in radioactive equilibrium, (2) 230Th exceeds equilibrium values in all these samples, (3) 210Pb concentrations range from 10-200% of the equilibrium values and average 30% deficient, and (4) 226Ra is probably not in equilibrium with 234U. The source regions of the basalts or magma forming processes are open systems, chemically. The enrichment of some of the uranium-daughter nuclides is insufficient to account for the excess 206Pb in volcanic rocks. The isotopic composition of lead and specific activity of 210Pb in sublimates from Showa-shinzan, Japan are also reported. ?? 1966.

Somayajulu, B.L.K.; Tatsumoto, M.; Rosholt, J.N.; Knight, R.J.

1966-01-01

35

Constraining the timescales of sediment transport in lowland regions using U-series isotopes and morphometric analysis  

NASA Astrophysics Data System (ADS)

The uranium-series (U-series) isotopes are fractionated by chemical and physical weathering, and undergo radioactive decay on timescales relevant to Earth-surface processes (103-106 a). The comminution age technique is based on the disequilibrium between 234U and 238U due to the effects of alpha-decay in fine-grained (< 63 µm) sediment [1]. The calculated comminution age represents the sediment residence time i.e. the time elapsed since a sediment grain was formed by weathering from bedrock, until its eventual deposition. When applied to fluvial systems, this integrates storage in the weathering profile, transit time in the catchment and any temporary storage in alluvial deposits. Despite the majority of global sediment flux to the oceans being derived from slowly eroding lowland regions, still little is known with regard to the dominant controls of erosion in these areas [2]. Here we apply the comminution age technique to the six major catchments in the Gulf of Carpentaria basin (GOC) in northern Australia to investigate the temporal dynamics of erosion in lowland regions. In addition, the geomorphometric properties of the catchments were measured using Geographic Information System techniques (GIS) in order to disentangle topographic vs. climatic controls on the sediment residence time. The sediment residence times calculated from U-series isotopes do not increase linearly downstream which reflects the complicated nature of sediment transport in lowland regions. The sediment residence time appears to be broadly correlated with mean annual precipitation but this relationship is less clear following consideration of the geomorphometric properties of each sub-catchment. This highlights the tendency of geochronological approaches to oversimplify the mechanisms of sediment transport in fluvial systems. Understanding what controls the temporal dynamics of erosion in fluvial system on millennial timescales requires the combination of the hitherto commonly separate approaches of geochronology and geomorphometrics. [1] DePaolo et al. (2006), Earth and Planetary Science Letters, 248, 394-410. [2] Willenbring et al. (2013), Geology 41, 343.

Martin, Ashley; Dosseto, Anthony; Chivas, Allan; May, Jan-Hendrik

2014-05-01

36

U-Th-Ra in Amazon rivers: New insights on U-series fractionation during chemical weathering  

Microsoft Academic Search

Seawater ({ 234} U\\/{ 238} U) has been proposed as a proxy for understanding past continental weathering conditions. Thus, it is crucial to constrain the parameters that control U-series fractionation during present day weathering in order to understand what they have recorded in the past. Additionally, U-series provide useful constraints for understanding chemical weathering as a function of environmental variables.

A. Dosseto; B. Bourdon; J. Gaillardet; C. J. Allegre

2002-01-01

37

IXth millenium B.C. ceramics from Niger: detection of a U-series disequilibrium and TL dating  

NASA Astrophysics Data System (ADS)

A set of pottery sherds collected from two ancient neolithic sites in Niger (Tagalagal and Adrar Bous 10) has been dated by thermoluminescence. The natural radioactivity of these ceramics and of their surrounding sediments was measured using low background gamma spectrometry and atomic emission plasma spectrometry. With gamma spectrometry, the comparison between the activity of 238U (deduced from the 235U and 234Th gamma emissions) and that of 226Ra (deduced from 214Pb and 214Bi ? emissions in equilibrium with 222Rn) shows a significant disequilibrium of the U-series. The activity ratio {38U}/{226Ra}, which is greater than unity in this case, is interpreted as a result of either uranium enrichment ( 234U, 235U, 238U) or radium impoverishment that has been occurring since the burying of the archaeological artefacts. The effects of the changes in radiochemical composition on the annual dose are discussed and various determinations of the annual dose are analysed according to different hypotheses of disequilibrium (either permanent state or recent occurrence). The TL results: Tagalagal — 9820±780-10, 180±780 years/1993, Adrar Bous 10 — 9530±750-10,500±730 years/1993, are consistent with the radiocarbon dates obtained from charcoals collected at the same locations (the uncalibrated 14C dates belong to the 9100-9370 BP range). These results are of fundamental interest for the chronology of early neolithic cultures.

Guibert, P.; Schvoerer, M.; Etcheverry, M. P.; Szepertyski, B.; Ney, C.

38

U-series dating of bone using the diffusion-adsorption model  

NASA Astrophysics Data System (ADS)

U-series dating of bone has suffered problems of reliability since its inception because bone remains an open system with respect to uranium. Commonly applied a priori assumptions of U uptake, such as early uptake or linear uptake, are inadequate because they have no physical or chemical bases, no means of demonstrating which model is suitable for a particular bone, and no intrinsic tests of reliability. Despite this and numerous examples of anomalous U-series dates, such assumptions are still routinely applied. We address this problem using the diffusion-adsorption (D-A) model of U uptake (Millard and Hedges, 1996), which incorporates a physicochemical description of U uptake. Using this model, we show how the U uptake of a bone responds to geochemical changes in the burial environment, which can lead to phenomena such as the removal of U from bones ("leaching") or U uptake late in their burial history ("recent uptake"), and we show how the overall uptake history is reflected in distributions (profiles) of U and U-series isotopes across a bone section. We present measurements of U concentration profiles, and 230Th/ 234U profiles on archeological bone from a number of different sites and burial environments and compare the results to profiles predicted by the D-A model. Bones that have undergone complex uptake histories (which include U leaching or recent uptake) are identified on the basis of these profiles and rejected as unsuitable for dating. For bones that appear to have undergone uptake under constant geochemical conditions, the D-A model is applied to calculate U-series dates, with much improved reliability.

Pike, A. W. G.; Hedges, R. E. M.; Van calsteren, P.

2002-12-01

39

Symbiont survival and host-symbiont disequilibria under differential vertical transmission.  

PubMed Central

Interspecific genetic interactions in host-symbiont systems raise intriguing coevolutionary questions and may influence the effectiveness of public health and management policies. Here we present an analytical and numerical investigation of the effects of host genetic heterogeneity in the rate of vertical transmission of a symbiont. We consider the baseline case with a monomorphic symbiont and a single diallelic locus in its diploid host, where vertical transmission is the sole force. Our analysis introduces interspecific disequilibria to quantify nonrandom associations between host genotypes and alleles and symbiont presence/absence. The transient and equilibrium behavior is examined in simulations with randomly generated initial conditions and transmission parameters. Compared to the case where vertical transmission rates are uniform across host genotypes, differential transmission (i) increases average symbiont survival from 50% to almost 60%, (ii) dramatically reduces the minimum average transmission rate for symbiont survival from 0.5 to 0.008, and (iii) readily creates permanent host-symbiont disequilibria de novo, whereas uniform transmission can neither create nor maintain such associations. On average, heterozygotes are slightly more likely to carry and maintain the symbiont in the population and are more randomly associated with the symbiont. Results show that simple evolutionary forces can create substantial nonrandom associations between two species. PMID:10757775

Sánchez, M S; Arnold, J; Asmussen, M A

2000-01-01

40

Evaluation of New Geological Reference Materials for U-Series Measurements  

NASA Astrophysics Data System (ADS)

Uranium-series analytical measurements are widely used in geochemistry, geochronology, paleoclimatology, volcanology, environmental risk assessment and other fields. Recent advances in high-resolution, rapid, in situ microanalytical techniques e.g. LA-ICP-MS and SIMS present numerous opportunities for the geoanalytical community. As with other analytical techniques, the quality of the elemental concentration and isotopic data obtained through microanalytical techniques is dependent on the accurate characterization of suitable reference materials. Even for the case of fs-laser ablation applications, a range of well-characterized standards are required for high precision U-series work. Advances have been made in evaluating existing standard reference materials for U-series isotopic analysis, but this work is ongoing as more reference materials become available. In this study we present MC-TIMS and MC-ICP-MS results for uranium and thorium isotopic ratios and elemental concentrations measured in a suite of newly available Chinese Geological Standard Glasses (CGSG) designed for microanalysis. These glasses exhibit a range of chemical compositions including basalt, syenite, andesite and a soil. U concentrations for these glasses range from ?2 to 14 ?g/g and [Th]/[U] ratios range from ?4 to 6. Uranium and thorium concentration and isotopic data will also be presented for rhyolitic obsidian from Macusani, SE Peru, which can be used as a rhyolitic reference material. These high-precision and high-accuracy ratios, from a suite of standards that exhibit a range of natural, non-basaltic compositions, will complement data from existing standards and expand the catalogue of reference materials that are appropriate for in situ U-series work. These results can be used to assess the performance of microanalytical techniques and will facilitate inter-laboratory comparison of data within the broader geoscience community.

Denton, J. S.; Goldstein, S. J.; Nunn, A. J.; Ui Chearnaigh, K.; Amato, R.; Murrell, M. T.

2012-12-01

41

U-series and radiocarbon analyses of human and faunal remains from Wajak, Indonesia.  

PubMed

Laser ablation U-series dating results on human and faunal bone fragments from Wajak, Indonesia, indicate a minimum age of between 37.4 and 28.5 ka (thousands of years ago) for the whole assemblage. These are significantly older than previously published radiocarbon estimates on bone carbonate, which suggested a Holocene age for a human bone fragment and a late Pleistocene age for a faunal bone. The analysis of the organic components in the faunal material show severe degradation and a positive ?(13)C ratio indicate a high degree of secondary carbonatisation. This may explain why the thermal release method used for the original age assessments yielded such young ages. While the older U-series ages are not in contradiction with the morphology of the Wajak human fossils or Javanese biostratigraphy, they will require a reassessment of the evolutionary relationships of modern human remains in Southeast Asia and Oceania. It can be expected that systematic direct dating of human fossils from this area will lead to further revisions of our understanding of modern human evolution. PMID:23465338

Storm, Paul; Wood, Rachel; Stringer, Chris; Bartsiokas, Antonis; de Vos, John; Aubert, Maxime; Kinsley, Les; Grün, Rainer

2013-05-01

42

Determination of transfer time for sediments in alluvial plains using 238U-234U-230Th disequilibria: The case of the Ganges river system  

NASA Astrophysics Data System (ADS)

An approach to deriving the transfer time of sediments within alluvial plains by using the variation of the U-series nuclides in sediments collected along rivers is presented in this article and discussed in the light of new data from samples from different locations within the Ganges watershed and its outlet. These data indicate that the upstream-downstream variation of 238U-234U-230Th disequilibria in the sediments, with different variation trends for suspended and coarse-grained sediments, is probably a general feature of all Himalayan rivers flowing across the Indo-Gangetic plain. The data therefore confirm the occurrence of very different transfer times within the plain, depending on the sediments granulometry, with much shorter transfer time for the fine-grained (a few ky or less) than for the coarse-grained sediments (100 ky or more). A new solving approach, using a parallel stochastic Quantum-behaved Particle Swarm Optimization (p-QPSO), has been developed for identifying the unknown parameters of the model necessary for the determination of the transfer time. The data of sediments collected at the Ganges outlet show significant variations of the 234U/230Th activity ratios for the fine-grained sediment end-member collected in 2004 and 2008. Such variations indicate that the fine-grained sediments transit quickly (a year or less) within the plain. The highly variable activity ratios might be the result of quickly changing weathering intensities. Conversely, the U-Th variations observed for the 2004 and 2008 bedload from the Ganges basin cannot result from a short sedimentary transfer time. They probably result from the dredge sampling procedure, which might be influenced by local placer effects controlling the abundance of U and Th carrying minerals. Dredging may not allow the sampling of a representative bedload, hence it may cause an artificial mineralogical and, therefore, an U-Th variability for bedload sediments collected at different periods. At this stage, the transfer time uncertainty induced by this variability is difficult to assess.

Chabaux, François; Blaes, Estelle; Granet, Mathieu; Roupert, Raphaël di Chiara; Stille, Peter

2012-11-01

43

U Th Ra disequilibria and the time scale of fluid transfer and andesite differentiation at Arenal volcano, Costa Rica (1968 2003)  

NASA Astrophysics Data System (ADS)

To evaluate the time scale of fluid transfer and andesite differentiation at Arenal volcano in Costa Rica, we have measured trace-element concentrations and U-series disequilibria in whole rocks and mineral separates (pyroxene, plagioclase, magnetite) from lavas of the current eruption (1968 to 2003) by HR-ICP-MS, TIMS and PIMMS techniques. Whole rock and mineral separate analyses show a small but measurable variation in ( 230Th)/( 232Th) (1.10 to 1.18). In contrast, ( 230Th)/( 238U) range from 0.91 to 1.04 reflecting the moderate spread in Th/U. Stage 1 (1968-1971) whole rocks and mineral separates have both higher ( 230Th)/( 232Th) and ( 238U)/( 232Th) than to younger stage 2 lavas (1971 to present), which have lower, nearly constant ( 230Th)/( 232Th) and lower, slightly variable ( 238U)/( 232Th). 226Ra excesses exist in both whole rocks and mineral separates with ( 226Ra)/( 230Th) ranging between 0.94 and 4.8. Whole rock ( 226Ra)/( 230Th) are largest early in the eruption and decrease in the later lavas, which are influenced by newer recharge material. 238U- 230Th whole rock and mineral data produce an inclined array on an equiline diagram, which we interpret to represent progressive melting of a variably fluxed mantle wedge and a Nicaraguan sediment component, and subsequent mixing. 238U- 230Th internal isochrons suggest that minerals grew instantaneously with respect to the half-life of 230Th. Whole rock and mineral separate ( 226Ra)/( 230Th) data indicate that melts were produced, transported, differentiated and erupted in < 8 kyr. Mineral ( 226Ra)/Ba-( 230Th)/Ba model ages are calculated and corrected for melt inclusions and glass adherents in the mineral fractions, and for the differential partitioning of Ra and Ba. Plagioclase model ages and 238U- 230Th isochron ages suggest that plagioclase could be as young as a few years or as old as several centuries upon eruption.

Tepley, Frank J.; Lundstrom, Craig C.; Gill, James B.; Williams, Ross W.

2006-09-01

44

An open-system model for U-series age determinations of fossil corals  

NASA Astrophysics Data System (ADS)

The source of excess 234U in fossil corals and its relationship to U-series age determinations has been an outstanding problem in geochronology for more than 20 years. With increasing numbers of U-series isotope measurements in corals, and significant improvements in analytical precision through mass spectrometry, it is increasingly apparent that a substantial fraction of observed isotope ratios cannot be reasonably explained by closed-system decay. Moreover, observations of a positive correlation between 234U/ 238U and 230Th/ 238U ratios in corals from the same terrace are difficult to explain. However, the decay of dissolved uranium and ?-recoil mobilization of uranium daughters produce particle-reactive 234Th and 230Th, and the coupled addition of these Th isotopes could simultaneously increase coral 234U/ 238U and 230Th/ 238U. Here we present a quantitative model, based on decay-dependent redistribution of 234Th and 230Th, permitting calculation of open-system coral ages. These equations provide a general solution to the ?-recoil redistribution problem, applicable to any alpha decay series. While measured isotope ratios of corals from the three youngest stratigraphically defined Barbados terraces are inconsistent with closed-system decay, they fall in broadly linear arrays agreeing with model predictions. Isotopic arrays of older Barbados corals, and corals from terraces around the world, are also consistent with model predictions suggesting the open-system model is generally applicable. Corals with extreme isotopic compositions that are impossible to produce by closed-system decay are consistent with the limited range of isotopic compositions predicted by the model at ages older than 600 ka. For corals from a single terrace, 234Th and 230Th redistribution appears to be a source of systematic conventional age error, even for corals with slightly elevated 234U. However, open-system ages are consistent, even for corals with extremely elevated 234U. For the youngest three Barbados terraces, mean open-system terrace ages are consistent with mean conventional terrace ages calculated from pristine samples. If the most accurate conventional ages are from corals with an initial 234U/ 238U identical to modern seawater, then the open-system model will improve the accuracy of coral U-series age determinations and dramatically increase the number of reliable ages.

Thompson, William G.; Spiegelman, Marc W.; Goldstein, Steven L.; Speed, Robert C.

2003-05-01

45

U-series dating of the Late Pleistocene mammalian fauna from Wood Quarry (Steetley), Nottinghamshire, UK  

NASA Astrophysics Data System (ADS)

We present the U-series dating of bones from Wood Quarry (Steetley Quarry Cave) using the diffusion-adsorption model to account for uranium uptake. The results give a weighted mean date of 66.8 ± 3.0 kyr, placing this assemblage within or just before Marine Oxygen Isotope Stage 4. The fauna is thought to correlate with the Banwell Bone Cave mammal assemblage-zone of the Early Devensian in Britain. Our results support the idea that this assemblage-zone immediately precedes the assemblage represented nearby at Pin Hole in Creswell Crags which is contemporary with the Mid-Devensian and correlates with MIS 3. Our dates, and dates for the Banwell Bone Cave mammal assemblage-zone from Stump Cross Cavern and evidence from other sites may indicate a longevity for this fauna.

Pike, A. W. G.; Eggins, S.; Grün, R.; Hedges, R. E. M.; Jacobi, R. M.

2005-01-01

46

U-series dating of impure carbonates: An isochron technique using total-sample dissolution  

USGS Publications Warehouse

U-series dating is a well-established technique for age determination of Late Quaternary carbonates. Materials of sufficient purity for nominal dating, however, are not as common as materials with mechanically inseparable aluminosilicate detritus. Detritus contaminates the sample with extraneous Th. We propose that correction for contamination is best accomplished with the isochron technique using total sample dissolution (TSD). Experiments were conducted on artificial mixtures of natural detritus and carbonate and on an impure carbonate of known age. Results show that significant and unpredictable transfer of radionuclides occur from the detritus to the leachate in commonly used selective leaching procedures. The effects of correcting via leachate-residue pairs and isochron plots were assessed. Isochrons using TSD gave best results, followed by isochron plots of leachates only. ?? 1991.

Bischoff, J.L.; Fitzpatrick, J.A.

1991-01-01

47

U-series disequilibrium constraints on magma generation at the Jan Mayen hotspot  

NASA Astrophysics Data System (ADS)

The incompatible element-enriched magma source beneath the Jan Mayen Island hotspot influences melt generation on the adjacent northern Mid-Atlantic Ridge system and likely derives from either a small, local mantle plume, ancient Icelandic plume material emplaced in the mantle source, and/or sub-continental lithospheric mantle remnants emplaced locally by rifting of Greenland. The slow spreading Northern Kolbeinsey and Southern Mohns Ridges are immediately adjacent to Jan Mayen Island. Both have relatively shallow ridge axes, particularly the extremely shallow Eggvin Bank region of the Northern Kolbeinsey Ridge, which host anomalously large central volcanic edifices. We are currently collecting U-series disequilibrium and long-lived radiogenic isotope data for fresh, glassy mid-ocean ridge basalts from the Northern Kolbeinsey and Southern Mohns Ridge segments to better constrain source composition, depth of melting in the garnet peridotite stability field, solid mantle upwelling rates, and the nature of melt extraction beneath those segments. In particular, we are measuring isotopic data for geographically well-located samples collected from hummocky pillow basalt flows within the axial valley of the Northern Kolbeinsey Ridge segment as well as from the large volcanoes on both ridge segments, to further determine the role of the Jan Mayen hotspot in crustal construction on the Mid-Atlantic Ridge. Recently collected data show particularly high strontium isotope ratios consistent with trace element patterns that suggest a distinct local plume located beneath the Jan Mayen hotspot. A plume model for Jan Mayen is supported by new bathymetric imaging of adjacent ridge segments that reveals excess volcanism beneath the large axial volcanoes and a radial distribution of enrichment surrounding Jan Mayen Island. We predict that age-constrained U-series disequilibrium measurements will support active mantle upwelling focused beneath both Jan Mayen Island and the large axial volcanoes.

Rivers, E. R.; Chernow, R.; Elkins, L. J.; Sims, K. W.; Blichert-Toft, J.; Devey, C. W.

2013-12-01

48

Initial and Diagenetic Behaviour of U Isotopes in Corals: Implications for U-series Dating  

NASA Astrophysics Data System (ADS)

U-series isotopes in corals are one of the most powerful tools for chronometry in Quaternary Paleoceanography. Modern mass spectrometric techniques routinely reach 1 permil precision for the isotopic ratios of uranium and thorium. However, the corals themselves are often found to be open systems for U-series dating. The most widely used metric for diagenetic alteration of the age is the deviation of the ?234U ratio from the seawater value of 146‰. In this study we use deep-sea corals that live and are preserved in a constant seawater environment to investigate the causes of this diagenetic alteration. Coral thin-sections display complex visible banding patterns based on the crystal morphology. Fission track maps and MC-ICP-MS measurements performed on micro-milled sub-samples reveal a primary [U]-variability that has a spatial distribution closely related to the visible banding. Sub-samples from fossil corals, ranging in age from 11 ka to 218 ka, have variable ?234Uinitial with the highest ?234Uinitial values in areas of low [U]. A model shows that most of the variability can be explained by two simple processes, direct transfer of alpha recoil 230Th and 234Th and, more importantly, preferential movement of alpha-decay mobilised 234U. Coupling this preferential movement with a high [U] coating such as an organic film provides a source of 234U to the coral lattice that can account for large ?234Uinitial elevations, with little change to the final age. As surface corals also have large initial [U] gradients, our results demonstrate that many elevated ?234Uinitial values are a natural consequence of the coral's initial [U] gradient. These gradients are biologically induced at the time of calcification and are an example of how better understanding the effects of biomineralization can improve our interpretation of paleotracers.

Robinson, L. F.; Adkins, J. F.; Fernandez, D.; Burnett, D.; Gagnon, A.; Krakauer, N.; Wang, S.

2005-12-01

49

A diffusion-decay model for steady-state U-series disequilibrium in the mantle with implications for island arc lavas  

NASA Astrophysics Data System (ADS)

Mantle equilibrium has long been considered the de facto starting point for U-series modeling. The half-lives of most U-series elements are considerably shorter than the timescales for major mantle differentiation processes (e.g. 75 Ka for 230Th, 1622 a for 226Ra), so it seems logical that any disruption in the U-series decay chain should correct itself relatively quickly. We have developed a model whereby 226Ra/230Th disequilibrium can be maintained indefinitely between coexisting clinopyroxene and phlogopite. The steady-state 226Ra/230Th ratio is determined by competing effects of diffusion and radioactive decay. Partition coefficients have been calculated (Ra) or experimentally determined (Th) for diopside and phlogopite. The cpx/phlogopite distribution coefficient for Ra is very low (~10-5), while that for Th is neutral (~1). Therefore, when 230Th in cpx decays to 226Ra, the incompatible Ra tends to diffuse out of the cpx and into neighboring phlogopite, while the Th remains in place. The result is a steady-state 230Th excess in cpx, with a complementary steady-state 226Ra excess in phlogopite. The extent of the disequilibrium is determined by the rate of diffusion (a function of temperature), the size of the grains, and the ratio of phlogopite to cpx. In order for disequilibrium to develop, the Ra must diffuse out of the cpx grain faster than it decays. The lengthscale for 226Ra loss is given by (DRa/? Ra)1/2. At 1000°C, Ra is lost from only the outer 35 ?m of the cpx grain, whereas at 1300°C, loss occurs from the outer 1.7 mm of the grain, effectively draining it of Ra. Preferential sampling of phlogopite during melting leads to 226Ra excess in the melt itself, with the extent of the 226Ra excess dependent on the degree of partial melting. Small degree melts of metasomatised mantle can develop very high 226Ra excesses (226Ra/230Th > 60 in a 0.1% melt), consistent with observations of high activity ratios in island arc lavas. Furthermore, the high 226Ra/230Th in island arc lavas is correlated with high Ba/Th, also consistent with a preferential phlogopite contribution. Phlogopite "contamination" of the melt is possible in the source region, by incipient melting of conduit walls during transport, or from the partial re-melting of cumulates in the magma chamber. Therefore, 226Ra/230Th may not be a reliable tracer of source-to-surface magma travel time at island arcs.

Feineman, M. D.; Depaolo, D. J.

2002-12-01

50

Travertine in western Grand Canyon: paleoclimatically driven aggradation and incision directly dated by U-Series  

NASA Astrophysics Data System (ADS)

Quaternary travertines of the Grand Canyon region provide a rich rock record for understanding interactions between canyon incision, geomorphology, paleohydrology, and paleoclimate. Travertine Grotto (TG) displays a long history of travertine deposition recorded by travertine-cemented alluvial terraces and spring mounds derived from a fault-controlled, CO2-rich spring, and exposed along a deeply incised, modern inner gorge carved by TG Creek (TGC). U-Series geochronology has been effective at dating travertine deposition and hence limits the timing of stream aggradation and incision. The oldest dated travertine (354 +/- 15 ka, 2 sigma) is a flowstone remnant on bedrock within a few meters of the present bedrock channel of TGC; this sample indicates that at this location there has been little net bedrock incision in the last 350 ka. The highest and oldest dated terrace remnant (T5- 70 m above TGC) is 243+/- 4 ka . An extensive fill terrace topped by a travertine dam (T4-60-66 m above TGC) yields a 137+/- 10 ka age . The most prominent fill terrace (T3 - 22-25 m) yields ages of 53.9 +/- 1 and 52.8 +/- 1 ka along its base, 31.4 +- 8 ka by optically stimulated luminescence (OSL) to 22.5 +/- 1 ka half way up, and 11.3 +/- 0.2 ka at its top. T3 is interpreted to represent semi continuous alluviation from ca. 50 to 11 ka; incision of the modern TGC inner gorge began after 11.5 ka. OSL dates broadly agree with U-Series dates. Fill terraces T3 and T4 show upward change from cemented alluvium to flowstone, interpreted to reflect climatic-paleohydrologic cycles as follows. Approaching terminations of glacial cycles, colluvial loads delivered to streams apparently decreased, perhaps due to dense vegetation related to high effective moisture levels. Concurrent high spring discharges deposited the relatively pure capping flowstones. Incision ensued during interglacial and early glacial times, possibly characterized by lower effective moisture levels, hence reduced vegetation and enhanced bedloads, and reduced spring discharges. Stable isotope analysis of nine dated travertines involved subsampling of as many as 10 individual laminations, as well as analyses of modern travertine and water. These data indicate that C-13 isotopic variations may reflect depositional environment (i.e., rate of degassing), whereas O-isotopic variation may reflect paleoclimate/paleohydrology. O-isotopic values vary by 1-2 permil across cm-scale laminations reflecting seasonal to decadal changes. Isotopically distinct results are obtained for modern, 11, 47-100, 136 and 354 ka samples.

Karlstrom, K. E.; Crossey, L. J.; Sharp, W. D.; Lyons, A.; Rittenour, T.

2005-12-01

51

Carbonate mound evolution and coral diagenesis viewed by U-series dating of deep water corals  

NASA Astrophysics Data System (ADS)

U-series dating of constructional deep sea corals is a powerful tool to reconstruct the evolution of carbonate mound sediments driven by coral growth, sediment trapping and diagenesis. Here we have investigated in great detail the time framework of constructional corals such as L. pertusa and M. oculata on 5 different mounds of the eastern North Atlantic (on Rockall Bank and in Porcupine Seabight) taken at variable depth and location (610 to 880m water depth). Periods favorable for coral growth are the Holocene and prior interglacials such as marine isotope stage 5 and 7, while glacial coral growth seems inhibited or extremely reduced. Coral development is almost continuous throughout the Holocene since mound re-colonization about 10,500 years ago. Mound accumulation rates vary between 20 and 220 cm/kyr determined from the coral age - depth relationship in each core. Those changes are most likely driven by changes between horizontal and vertical mound accumulation, food supply and ocean circulation. In addition, coral dating allowed to identify an important erosional event recorded in core MD01-2455G from Rockall Bank. Here a 1m thick sediment layer containing ancient corals likely from the start of Holocene re-colonization was displaced (collapsed) from further upslope on top of younger corals of ~2500 to 3000 years age. Prior to the initiation of coral growth diagenesis occurred frequently resulting in (1) the construction of so called carbonate hardgrounds and/or (2) the dissolution of the pre-Holocene coral framework. Solely, the deepest selected core in Porcupine Seabight (MD01-2463G at 880m depth) reveals coral re-colonization on an undisturbed ancient reef structure that dates back to 250,000 years. Diagenesis of earlier coral reef generations leading to coral dissolution leads to a loss of magnetic susceptibility and open system behavior of the coral skeletons with respect to U-series dating. While the processes causing such diagenetic layers are barely understood the disappearance of the magnetic susceptibility can be used to trace such phenomena and a conserved magnetic susceptibility allows sampling of well preserved corals.

Frank, N.; Ricard, E.; Blamart, D.; van der Land, C.; Colin, C.; Foubert, A.; van Rooij, D.; van Weering, T.

2007-12-01

52

U-series ages of solitary corals from the California coast by mass spectrometry  

SciTech Connect

The purpose of this study is to evaluate the feasibility of dating fossil solitary corals from Pleistocene marine strandlines outside tropical latitudes using the recently developed high sensitivity, high-precision U-series technique based on thermal-ionization mass-spectrometry (TIMS). The TIMS technique is much more efficient than conventional {alpha} spectrometry and, as a result, multiple samples of an individual coral skeleton, or different specimens from the same bed can be analyzed. Detached and well-rounded fossil specimens of the solitary coral Balanophyllia elegans were collected from relict littoral deposits on emergent marine terraces along the California coast at Cayucos terrace, Shell Beach terrace, Nestor terrace, San Diego, Bird Rock terrace, San Diego. Attached living specimens were collected from the intertidal zone on the modern terrace at Moss Beach. The calculated initial {sup 234}U activities in the fossil specimens of Balanophyllia elegans are higher than the {sup 234}U activity in modern seawater or in the modern specimen. The higher initial activities could possibly reflect the influx of {sup 234}U-enriched continental water into Pleistocene coastal waters, or it could reflect the influx of {sup 234}U-enriched continental water into Pleistocene coastal waters, or it could reflect minor diagenetic alteration, a persistent and fundamental problem in dating all corals.

Stein, M.; Wasserburg, G.J.; Chen, J.H. (California Inst. of Tech., Pasadena (United States)); Lajoie, K.R. (Geological Survey, Menlo Park, CA (United States))

1991-12-01

53

The U-series ages of carnotites and implications regarding their formation  

NASA Astrophysics Data System (ADS)

The U-series nuclides, 230Th, 234U, 238U, 227Ac, 231Pa and 210Pb, were analyzed in up to 75 carnotites from a group of trenches in southwestern Israel. Though 230Th/234U had the large range of 0.14 to 0.99, its spatial distribution was not random and the ratio never exceeded unity. 231Pa/230Th was at least 91% concordant with 230Th/234U in four of five cases. These facts, together with the details of the 230Th/234U distribution, especially among ten samples from one small block of rock, indicate that 230Th/234U ages of carnotites are at least a reasonable approximation of true ages. The unexpectedly widespread deficiencies in both 227Ac and 210Pb indicate that although carnotites are nearly closed to the migration of uranium, they are open to those of actinium and to lead, radon or radium. A model of carnotite precipitation is presented which attributes the large range in 230Th/234U to a continual shift in the site of carnotite precipitation, in keeping with a continual change in the geometry of joints. This model may apply to other minerals as well.

Kaufman, Aaron; Ku, Teh-Lung

1989-10-01

54

Speleothem U-series dating of semi-synchronous climate oscillations during the last deglaciation  

NASA Astrophysics Data System (ADS)

Evidence for nearly synchronous climate oscillations during the last deglaciation has been found throughout the Northern Hemisphere but few records are based on independent time scales of calendar years. We present a rare uranium-series dated oxygen-carbon isotope record for a speleothem from Tangshan Cave, China, which demonstrates that abrupt deglacial climatic oscillations from 16?800 to 10?500 yr BP are semi-synchronous with those found in Greenland ice core records. Relatively rapid shifts in speleothem oxygen isotope ratios demonstrate that the intensity of the East Asian monsoon switched in parallel with the abrupt transitions separating the Bølling-Allerød, Younger Dryas, and pre-Boreal climatic reversals. However, the dated isotopic transitions appear to have lasted longer. Our results demonstrate the dominant role of atmospheric teleconnections in the rapid propagation of deglacial climatic signals on a hemispheric scale, and highlight the importance of U-series dated speleothems in the timing and characterization of abrupt climate change.

Zhao, Jian-xin; Wang, Yong-jin; Collerson, Kenneth D.; Gagan, Michael K.

2003-11-01

55

ESR, U-series and paleomagnetic dating of Gigantopithecus fauna from Chuifeng Cave, Guangxi, southern China  

NASA Astrophysics Data System (ADS)

Several Gigantopithecus faunas associated with taxonomically undetermined hominoid fossils and/or stone artifacts are known from southern China. These faunas are particularly important for the study of the evolution of humans and other mammals in Asia. However, the geochronology of the Gigantopithecus faunas remains uncertain. In order to solve this problem, a program of geochronological studies of Gigantopithecus faunas in Guangxi Province was recently initiated. Chuifeng Cave is the first studied site, which yielded 92 Gigantopithecus blacki teeth associated with numerous other mammalian fossils. We carried out combined ESR/U-series dating of fossil teeth and sediment paleomagnetic studies. Our ESR results suggest that the lower layers at this cave can be dated to 1.92 ± 0.14 Ma and the upper layers can be dated to older than 1.38 ± 0.17 Ma. Correlation of the recognized magnetozones to the geomagnetic polarity timescale was achieved by combining magnetostratigraphic, biostratigraphic and ESR data. The combined chronologies establish an Olduvai subchron (1.945-1.778 Ma) for the lowermost Chuifeng Cave sediments. We also analyzed the enamel ?13C values of the Gigantopithecus faunas. Our results show that southern China was dominated by C3 plants during the early Pleistocene and that the Gigantopithecus faunas lived in a woodland-forest ecosystem.

Shao, Qingfeng; Wang, Wei; Deng, Chenglong; Voinchet, Pierre; Lin, Min; Zazzo, Antoine; Douville, Eric; Dolo, Jean-Michel; Falguères, Christophe; Bahain, Jean-Jacques

2014-07-01

56

Systematics of U-series nuclides in primitive lavas from the 1730-36 eruption on Lanzarote, Canary Islands, and implications for the role of garnet pyroxenites during oceanic basalt formations  

NASA Astrophysics Data System (ADS)

Inferences on mantle melting and related parameters are often derived from U-series results on oceanic basalts. However, most of these basalts come from magma chambers in which magma mixing amongst other processes is likely to have reduced the true compositional spread created during partial melting. Here are presented U-Th-Ra disequilibrium results on historical lavas of near-primary composition from Lanzarote, Canary Islands, where magma chambers have not been detected. During the 1730-36 fissure eruption, the magma composition varied with time from basanites through alkali basalts to tholeiites. Approximately 3-5 km 3 of primitive and often ultramafic xenolith-bearing lavas were produced. Abundances of Ba, Th and U generally decreased towards the end of the eruption, and show more than four-fold variations (e.g. Th = 5.75-1.55 ppm). Ba/Th and Ba/U vary by more than 75%, whereas Th/U vary by less than 10%. Excesses of 230Th over 238U range from 18% to 33% and generally increase with alkalinity. ( 230Th/ 232Th) decreased significantly from 1.02 to 0.94 with time and is positively correlated with the alkalinity of the lavas. Isotope ratios of Sr and ( 226Ra/ 230Th) also correlate with SiO 2. ( 226Ra/ 230Th) increased with time from 1.10 to 1.56. The correlations between ( 230Th/ 232Th), 87Sr/ 86Sr and SiO 2 suggest that the lava compositions represent nearly unmodified primary melts from a lithologically and compositionally heterogeneous mantle source. Decreasing ( 230Th/ 238U) and increasing ( 226Ra/ 230Th) in basanites to tholeiites can be explained by partial melting of a mixed garnet pyroxenite-lherzolite source, during which the proportion of pyroxenite and extent of melting diminished. Alternatively, the large variations of excess 226Ra and Ba/Th may reflect fluid addition to such a heterogeneous mantle source. In order to conserve the systematic variations of ( 226Ra/ 230Th) with other geochemical variables, transfer time through the lithosphere is likely to have been short relative to the half-life of 226Ra. A magma velocity through the lithosphere on the order of 10 -5 m/s (0.5 km/year) is compatible with the data. Both the Th-U disequilibria and the Th-isotope ratios of the Lanzarote lavas appear to be related to the mantle source lithology and composition, where garnet pyroxenite melting produced the early alkaline basalts and increasing melting of garnet lherzolite produced the tholeiites. Furthermore, correlations between ( 230Th/ 238U) and ( 232Th/ 238U) for different volcanic provinces worldwide, strongly suggest that Th-U disequilibria in oceanic basalts are principally caused by partial melting of garnet pyroxenites.

Sigmarsson, Olgeir; Carn, Simon; Carracedo, Juan Carlos

1998-10-01

57

Mantle melting in within-plate continental settings: Sr-Nd-Pb and U-series isotope constraints in alkali basalts from the Sicily Channel (Pantelleria and Linosa Islands, Southern Italy)  

NASA Astrophysics Data System (ADS)

The origin of the mantle sources of the Na-alkaline magmas erupted within the continental rift of the Sicily Channel and their melting behaviour are here investigated through the determination of Sr, Nd and Pb isotope ratios and U-series disequilibria on basaltic volcanic rocks from Linosa and Pantelleria. The isotope data, along with trace element ratios are used to assess the possible role of the interaction with the continental crust and/or the Sub-Continental Lithospheric Mantle (SCLM). The data show little variation in Sr and Nd isotopes and a continuous trend toward more radiogenic Pb isotope composition from Linosa to the oldest mafic activity of Pantelleria (i.e. Paleo-Pantelleria), with intermediate values measured in the youngest Pantelleria lavas (Neo-Pantelleria). Pantelleria basalts have ubiquitous 230Th-excess ranging from 7% to 20%. These data suggest the magmas are originated within the asthenospheric mantle, with little or no interaction with either the continental crust or the SCLM. The increasing FOZO-like character of the studied magmas and the variation of some key trace element ratios (e.g. Rb/La) argue for an increasing role of recycled oceanic material in the form of eclogite/pyroxenite dispersed within the mantle sources of these magmas. A completely distinct isotope composition is recorded in Neo-Pantelleria hawaiites from Khartibucale, which show significantly higher 87Sr/86Sr and lower 143Nd/144Nd, 206Pb/204Pb, (238U/232Th) and (230Th/232Th), but comparable (230Th/238U) with respect to all the other rocks studied. These rocks cannot be considered co-genetic with other Pantelleria basalts and are interpreted either as related to interaction with partial melts of the SCLM or to be originated from a mantle source enriched by recycled crustal material (EM-like). 235U-231Pa disequilibria were also measured in one Neo-Pantelleria hawaiite and one Neo-Pantelleria basalt. The coupled (230Th/238U) = 1.20 and (231Pa/235U) = 1.39 of the latter were used to perform quantitative dynamic melting models in order to constrain physical parameters of mantle melting in the Sicily Channel. The combined modelling yielded positive solutions only for high DU/DTh (? 2.5) and low melting rates (? < 1 × 10- 4 kg/m3/a). These data argue against any important role for amphibole in the genesis of these magmas and are consistent with a peridotite source possibly well mixed with recycled components. The modelled values of ? can also be converted into estimates of the upwelling rate of the mantle that are compatible with slow passive upwelling along the Sicily Channel rift.

Avanzinelli, Riccardo; Braschi, Eleonora; Marchionni, Sara; Bindi, Luca

2014-02-01

58

Radioactive Waste Radioactive Waste  

E-print Network

#12;Radioactive Waste at UF Bldg 831 392-8400 #12;Radioactive Waste · Program is designed to;Radioactive Waste · Program requires · Generator support · Proper segregation · Packaging · labeling #12;Radioactive Waste · What is radioactive waste? · Anything that · Contains · or is contaminated

Slatton, Clint

59

U-series constraints on the Holocene human presence in the Cuatro Cienegas basin, Mexico  

NASA Astrophysics Data System (ADS)

U-series tufa ages dating a human trackway have been obtained, part of a larger Late Pleistocene - Recent palaeoclimate and human occupation study of the Cuatro Cienegas basin, NE Mexico. Our analytical approach, including tracer calibration, couples aspects of what we consider best practice in the U-series community with our U-Pb experiences which includes the EarthTime U-Pb tracer calibration exercise. The recently discovered trackway is near a small hydrothermal pool within the basin [1], an ecologically highly significant oasis in the Chihuahuan desert. The oasis comprises >200 freshwater hydrothermal pools and a river system, and the related ecosystem hosts >70 endemic species[2]. Pools are fed by waters that circulate a deep karstic system and that originate in the surrounding upper Jurassic-lower Cretaceous Sierra Madre Oriental mountains (>3000m) [3]. The area hosted nomadic hunter-gatherers during the Holocene, and possibly as early as Late Pleistocene (~12 ka BP). Despite the basin's ecological significance, only three palaeoenvironmental studies have been published to date, and limited geochronological constraints are available. A pollen study of drill core through peats and tufas proximal to the pools suggested a long period of climatic stability and biogeographic isolation[4], a notion supported by the large number of endemic species, but other palynological and plant macrofossil data suggest that large climatic changes occurred post Late Pleistocene [5]. The 10 m long in situ trackway is preserved in tufa and five samples from the uppermost surfaces were analysed to date the footprints. The tufas comprise clean carbonate with no petrographic evidence of replacement and little contaminant detrital material (on some exposed upper surfaces). Powdered tufa was processed following [6-8], and analysed by TIMS (Triton, U) and MC-ICP-MS (Th, Nu HR), although our future analyses will primarily be obtained on a Neptune. Samples were spiked with a 229Th/236U tracer calibrated against gravimetric solutions prepared from Ames high-purity Th metal crystal and CRM 112a U metal ingot rather than natural materials of assumed secular equilibrium. ICP-MS mass bias and Faraday-SEM gain was monitored using CRM 112a and an in-house 229Th-230Th-232Th solution. Most samples have relatively high U contents (~2 ppm U), moderate [230Th/232Th] = 29-44, and initial [234U/238U] ~ 1.92. We obtain an age of 7.24 ± 0.13 ka BP for this trackway based on an average of two samples of the uppermost tufa surface. Depth profiling of one sample shows consistently increasing age downwards (~370 a/cm). [1] Gonzalez, A.H.G. et al., 2006, Ichnos 16, 12-24;[2] Souza, V. et al., 2006, PNAS 103, 6565-6570; [3] Johannesson, K.H. et al., 2004, J.S.Am.Earth Sci. 17, 171-180; [4] Meyer, E. 1973, Ecology 54, 982-995; [5] Minckley, T.A. & Jackson, S. 2008. J. Biogeography 35, 188-190; [6] Edwards, R.L. et al., 1987, EPSL 81, 175-192; [8] Cheng, H. et al., 2000, Chem. Geol. 169, 17-33; [8] Potter, E.K. et al., 2005, EPSL 247, 10-17.

Noble, S. R.; Felstead, N.; Gonzalez, S.; Leng, M. J.; Metcalfe, S. E.; Patchett, P. J.

2010-12-01

60

U-series constraints on sediment residence timescales in semi-arid Australia  

NASA Astrophysics Data System (ADS)

Fractionation of uranium isotopes (234U and 238U) in fine-grained sediment (< 50 ?m) can be used to quantify timescales of sediment residence i.e. storage in soils and associated transport in fluvial or aeolian systems. This information is invaluable for understanding the relationships between climate, tectonics and landscape evolution. In particular, how sediment transport and the landscape have responded to climate change over the past 100,000 yrs. (234U/238U) activity ratios have been measured in the fine fraction (2-50 ?m) of palaeochannel sediments from the Katipiri Formation of the Cooper Creek in the Strzelecki Desert (south Australia). Cooper Creek is one of three major rivers feeding the Lake Eyre Basin, one of the largest internally-drained catchments in the world. Sediments were collected from six palaeochannels with depositional ages ranging from 119±11 to 22± ka (optically-stimulated luminescence (OSL) dating). U-series and OSL data are combined in order to constrain the time elapsed between production by physical weathering of the source bedrock (comminution age) and the deposition age, to give an average residence time of the sediment in the catchment. Preliminary work yields sediment residence timescales between 66±10 to 107±17 ka. The inferred residence timescales for Cooper Creek sediments, in what today is a semi-arid environment, are comparable to sediment residence timescales (of similar depositional age) in temperate Australia. This suggests that the strong links observed between climate change and sediment transport during the last glacial cycle in temperate Australia maybe be witnessed Australia-wide. Future research is required to assess the contribution of wind-blown dust and its effect on calculated sediment residence timescales.

Handley, Heather; Dosseto, Anthony; Suresh, P. O.; Cohen, Tim; Turner, Simon

2010-05-01

61

U-Series Dating of Carbonates by Mass Spectrometry With Examples of Speleothem Coral and Shell  

Microsoft Academic Search

Uranium series dating is a well established technique for dating carbonate deposits of the last 350,000 years. The most common carbonates which have been dated are cave calcites (speleothem) and corals. The technique relies on the buildup of ²³?Th over time by radioactive decay of ²³?U and ²³?U, in materials which were initially free of ²³?Th. The ratios of the

Joyce Lundberg

1990-01-01

62

Middle Palaeolithic refugium, or archaeological misconception? A new U-Series and radiocarbon chronology of Abric Agut (Capellades, Spain)  

USGS Publications Warehouse

New U-Series and C14 (AMS) dates are provided for the Abric Agut (Capellades, Barcelona, Spain). This site was previously considered to be of Middle Palaeolithic age according to the characteristics of the lithic assemblage. In addition, human teeth were uncovered and attributed to neandertals. However, radiometric dating clearly indicates a Late Pleistocene-Early Holocene age. ?? 2002 Elsevier Science Ltd. All rights reserved.

Vaquero, M.; Esteban, M.; Allue, E.; Vallverdu, J.; Carbonell, E.; Bischoff, J.L.

2002-01-01

63

High-precision U-series measurements of more than 500,000 year old fossil corals  

Microsoft Academic Search

Robust, independent age constraints on the absolute timing of climate events based on the U-series dating of fossil coral are sparse before the last glacial cycle. Using multiple-collector inductively coupled plasma mass spectrometry with multiple-Faraday protocols, we are able to date ?600 ka samples with an uncertainty of better than ±15 ka (2?), representing a three-fold improvement in precision compared with previous

Morten B. Andersen; Claudine H. Stirling; Emma-Kate Potter; Alex N. Halliday; Steven G. Blake; Malcolm T. McCulloch; Bridget F. Ayling; Michael O'Leary

2008-01-01

64

238U, 232Th profiling and U-series isotope analysis of fossil teeth by laser ablation-ICPMS  

NASA Astrophysics Data System (ADS)

U and Th concentration profiles in fossil hominid and faunal teeth have been measured by laser ablation ICPMS. These profiles record diverse modes of U and Th uptake, particularly within enamel, that can be broadly related to the state of sample preservation. Observed U profiles are in general inconsistent with existing diffusion-adsorption models developed for U-uptake in bone and teeth. Where the models appear applicable, calculated diffusion rates are several orders of magnitude smaller than previous estimates. Laser ablation ICPMS offers a means of rapidly characterizing U and Th distributions in the enamel and dentine components of teeth as a precursor to ESR and U-series dating. In particular, it should allow the identification of teeth (and also bone) samples that have simple U-uptake histories and are amenable to precise dating by time-consuming and expensive Th-U and Pa-U TIMS techniques. We also demonstrated the use of laser ablation ICPMS to measure U-series isotopes in dentine and enamel samples with relatively high U concentrations (>20 ppm). These results, obtained using a quadrupole ICPMS, illustrate significant promise for in situ U-series isotope analysis, particularly when combined with the greater sensitivity and multi-collection capabilities of new sector ICPMS instrumentation. The latter may permit precise isotope ratio measurements on samples containing only a few ppm of U.

Eggins, Stephen; Grün, Rainer; Pike, Alistair W. G.; Shelley, Michael; Taylor, Lois

2003-05-01

65

U-series Chronology of volcanoes in the Central Kenya Peralkaline Province, East African Rift  

NASA Astrophysics Data System (ADS)

We are studying the East African Rift System (EARS) in the Central Kenya Peralkaline Province (CKPP), and specifically the young volcanoes Mt. Suswa, Longonot, and Menengai. Ar dates by Al Deino on K-feldspar phenocrysts show a strong correlation between older Ar ages and decreasing 230Th/232Th, which we interpret to reflect the age of eruption. This system has been the subject of recent research done by several UTEP alumni including Antony Wamalwa using potential field and magnetotelluric (MT) data to identify and characterize fractures and hydrothermal fluids. Also research on geochemical modeling done by John White, Vanessa Espejel and Peter Omenda led to the hypothesis of possible disequilibrium in these young, mainly obsidian samples in their post eruptive history. A pilot study of 8 samples, (also including W-2a USGS standard and a blank) establish the correlation that was seen between the ages found by Deino along with the 230/232Th ratios. All 8 samples from Mt. Suswa showed a 234U/238U ratio of (1) which indicates secular equilibrium or unity and that these are very fresh samples with no post-eruptive decay or leaching of U isotopes. The pilot set was comprised of four samples from the ring-trench group (RTG) with ages ranging from 7ka-present, two samples from the post-caldera stage ranging from 31-10ka, one sample from the syn-caldera stage dated at 41ka, and one sample from the pre-caldera stage dated at 112ka. The young RTG had a 230/232Th fractionation ratio of 0.8 ranging to the older pre-caldera stage with a 230/232Th ratio of 0.6. From this current data and research of 14C ages by Nick Rogers, the data from Longonot volcano was also similar to the 230/232Th ratio we found. Rogers' data places Longonot volcano ages to be no more than 20ka with the youngest samples also roughly around 0.8 disequilibrium. These strong correlations between the pilot study done for Mt. Suswa, 40Ar ages by Deino, along with 14C ages from Rogers have led to the exploration of present U-series data set of the youngest samples from the rest of the CKPP volcanoes including: Menengai, more from Longonot, and Olkaria. And since it is observed that there is the presence of lateral migration along an axial dike swarm that has operated in other parts of the EARS, we have chosen to run samples from the adjacent mafic fields of Elmenteita, Tandamara, and Ndabibi to see if there is a trend in the correlation of the 230/232Th ratios at the time of eruption as well as observing how close these samples get to unity. This would answer questions as to whether similar 230/232Th ratios imply that the mafic fields feed the calderas.

Negron, L. M.; Ma, L.; Deino, A.; Anthony, E. Y.

2012-12-01

66

U-series dating of pillow rim glass from recent volcanism at an Axial Volcanic Ridge  

NASA Astrophysics Data System (ADS)

Visual observations using camera systems on the tethered ROV Isis deployed during the 2008 JC024 cruise to the Mid Atlantic Ridge at 45°N showed1 numerous monogenetic volcanoes that are essentially piles of lava pillows. The pillows are usually ˜1m diameter and >2m long and form mounds with average dimensions around 300m diameter, ˜150m altitude, and 0.005km3 volume. Small protrusions, 10-50cm long, which are numerous on pillows appear to be the youngest regions, were sampled using the pincers on the hydraulic arms of Isis, and returned to the surface. On the surface, any glass crust on the pillow protrusions was chiselled off using clean tools and double bagged in polythene. In the laboratory a portion of the glass was crushed in a jeweller’s roller mill and sieved using stainless steel sieves to obtain a sufficient amount of the fraction 0.125-0.250mm for hand picking, using a binocular microscope with the glass submerged in a mix of water and iso-propyl alcohol. The samples were subsequently leached using the procedure of Standish & Sims2. Samples were spiked with a mixed 229Th-236U spike and the U, Th and Ra fractions were separated and purified using standard chemistry methods. U and Th isotope ratios were determined using a Nu Instruments MC-ICPMS and Ra isotope ratios were determined using a MAT-262-RPQII TIMS instrument. The U-series data were evaluated using a MathCad program based on published4,5,6 equations. The data can be successfully modelled by assuming the ‘accepted’ mantle upwelling rate for the region of 11mm.y-1. The U-Th characteristics are mostly derived during ‘porous flow’ magma upwelling in the garnet stability zone, ranging to a depth of 60km with incipient melting starting at 70km. Above 60km depth the melt fraction will be >3% and the mantle mineralogy devoid of phases that fractionate U-Th significantly. Moreover, at melt fractions >3%, channel flow will be dominant and magma will transit to eruption on time-scales that are short enough to retain the U-Th characteristics from the garnet zone. The rheology of the deep mantle is such that melt generation should be in ‘steady state’ and U-Th characteristics should be constant. On that assumption, measured differences in collected samples can be used to calculate model ages relative to the ‘youngest’ sample, thus allowing the construction of a relative eruption timescale. However, significant fractional crystallisation is taking place in the oceanic crust, as testified by the frequent presence of plagioclase crystals up to mm-size in the glass samples. A ‘magma chamber’ on a scale larger than the magma channels is not required and we aim to assess the rate of plagioclase crystal growth using a 226Ra chronometer. This chronometer requires the assumption that Ba-Ra fractionation is constant and can then also be used to calculate a relative model age timescale, provided that not all samples are >8000 y old, which we consider unlikely. 1Searle, RC et al, EPSL in press, 2010 2Standish, JJ & Sims, KWW. Nature Geoscience V3, 2010 3Murton, BJ et al, in prep, 2010 4Williams, RW and Gill, JB, GCA 53, 1989 5Spiegelman, M and Elliott, T, EPSL 118, 1993 6Richardson, C and McKenzie, D, EPSL 128, 1994

Thomas, L. E.; van Calsteren, P. W.; Jc024 Shipboard Party

2010-12-01

67

U-series data of recent volcanism at an Axial Volcanic Ridge (Invited)  

NASA Astrophysics Data System (ADS)

The spreading rate of the Mid Atlantic Ridge, at the area around 45°N is 11mm/y. This is appropriate scaling for mantle horizontal flow and vertical upwelling. However, the accretion of oceanic crust within the median valley graben (MVG), occurs episodically on timescales much longer than years. During the 2008 JC024 cruise various geophysical and bathymetry datasets were collected as well as photographic and video evidence and some 270 rock samples, using ship-borne instruments, a deep-towed platform TOBI and a tethered ROV Isis both in demersal mode and 'flying' at 100m above the seafloor. We1 could identify the overall 'hour-glass' shape of the MVG, the location of the AVR, 'flat-top' features and some smooth areas on either side. Overall we1 counted some 8000 conical or dome-shaped hummocks, which are arranged in lineaments, mostly parallel to the spreading axis. We1 deduced that each hummock is an individual monogenetic volcano. Smooth areas between the AVR and the median valley boundary faults may indicate sheet flows which are probably burying the subsiding hummocks. For Dive 91, we1 used a MS2000 high-resolution multi-beam bathymetry echo-sounder on Isis flying at an altitude of 100m above the seafloor; to construct a bathymetry map with a vertical resolution of 20cm and a horizontal precision of 5m over an area of ˜3km2. The high-resolution bathymetry allows us to deduce that volcano dimensions average around 300m diameter, ˜150m altitude, and 0.005km3 volume and to count ˜100 volcanoes. Visual observations using the camera systems on Isis showed that individual volcanoes are essentially piles of pillow lavas, usually ˜1m diameter and >2m long of various types, sometimes leaving >10% gaps between pillows, sometimes interlocking somewhat deformed pillows. Small protrusions, 10-50cm long, which are numerous on some pillows, could be fairly easily broken off using the pincers on the hydraulic arms of Isis, and returned to the surface. Uncertainty remains over the age of the AVR, or probably more appropriately, the time-span between to youngest and the oldest exposed rocks. Many indirect dating methods have been applied with inferred ages ranging from ˜10ky to 200ky. We1 applied the magnetic paleo-intensity method to infer an age of ˜12ky for the 45°N AVR. We will report U-series based age calculations for samples from the Dive 91 area. The samples were taken from a number of individual volcanoes and the simplest expectation would be that the youngest samples are from the AVR crest with older ages down the flanks. However, crustal magnetisation intensity can be taken as a proxy for age and this1,3 indicates a more complex pattern of young ages in the volcanic lineaments away from the crest. Indeed, visual observations of rocks at up to 1km from the crest would indicate that those are equally fresh. Indeed, Standish and Sims2 have shown that young eruption ages are broadly dispersed throughout the rift valley of the ultra-slow spreading Southwest Indian Ridge at a range much wider than covered by the area of Dive 91. Construction of new volcanic crust solely at the crest of the AVR may well be too simplistic.

van Calsteren, P. W.; Thomas, L. E.; Jc024 Shipboard Party

2010-12-01

68

Preliminary U-series disequilibrium and thermoluminescence ages of surficial deposits and paleosols associated with Quaternary fault, Eastern Yucca Mountain  

SciTech Connect

Geochronological control is an essential component of paleoseismic evaluation of faults in the Yucca Mountain region. New U-series disequilibrium and thermoluminescence age estimates for pedogenic deposits that bracket surface-rupture events are presented from four sites exposing the Paintbrush Canyon, Bow Ridge and Stagecoach Road faults. Ages show an internal consistency with stratigraphic relationships as well as an overall concordancy between the two independent geochronometers. Age estimates are therefore interpreted to date depositional events or episodes of pedogenic carbonate mobility that can be used to establish a paleoseismic fault chronology. Ultimately, this type of chronological information will be used to evaluate seismic hazards at Yucca Mountain.

Paces, J.B.; Menges, C.M.; Bush, C.A.; Futa, K.; Millard, H.T.; Maat, P.B.; Whitney, J.W. [Geological Survey, Denver, CO (United States); Widmann, B. [Science Applications International Corp., Golden, CO (United States); Wesling, J.R. [Geomatrix Consultants, Inc., San Francisco, CA (United States)

1994-12-31

69

Preliminary U-series disequilibrium and thermoluminescence ages of surficial deposits and paleosols associated with Quaternary faults, eastern Yucca Mountain  

SciTech Connect

Geochronological control is an essential component of paleoseismic evaluation of faults in the Yucca Mountain region. New U-series disequilibrium and thermoluminescence age estimates for pedogenic deposits that bracket surface-rupture events are presented from four sites exposing the Paintbrush Canyon, Bow Ridge and Stagecoach Road faults. Ages show an internal consistency with stratigraphic relationships as well as an overall concordancy between the two independent geochronometers. Age estimates are therefore interpreted to date depositional events or episodes of pedogenic carbonate mobility that can be used to establish a paleoseismic fault chronology. Ultimately, this type of chronological information will be used to evaluate seismic hazards at Yucca Mountain.

Paces, J.B.; Menges, C.M.; Bush, C.A.; Futa, K.; Millard, H.T.; Maat, P.B.; Whitney, J.W. [Geological Survey, Denver, CO (United States); Widmann, B. [Science Applications International Corp., Golden, CO (United States); Wesling, J.R. [Geomatrix Consultants, Inc., San Francisco, CA (United States)

1994-12-31

70

A new explanation for extreme 234U/238U disequilibria in a dolomitic aquifer  

NASA Astrophysics Data System (ADS)

High 234U/238U activity ratios are found in the shallow groundwater of the phreatic Transvaal Dolomite Aquifer. The aquifer is uranium poor, while the waters are oxygen rich and young. Tritium and 14C are used to show that the disequilibrium increases the longer the water resides in contact with the dolomite host. The 228Ra and 222Rn isotopes were used as supporting evidence that ion exchange between the 238U series nuclides in the water and the carbonate wall rock is necessary in assisting in the fractionation process. The Wolkberg cave speleothems preserve a record of the uranium isotopic fractionations that evolved as water flowed through the aquifer. Extremely variable and elevated 234U/238U ratios (of 2-12) are characteristic. Individual caverns may exhibit very large 234U/238U variability in their drip water and in derivative carbonate precipitates (speleothems). Deeper chambers, where water has spent a longer time in contact with the aquifer, tend to exhibit a greater degree of uranium isotopic fractionation in their speleothems. The recorded fractionation process has been an ongoing one from at least the middle-late Pleistocene to the present. The speleothem study supports the contention that ion exchange processes that produce sufficient enrichment of uranium on carbonate can provide ideal conditions for generating uranium isotopic fractionation in the water of carbonate aquifers (in the absence of redox changes and within a uranium-poor environment).

Kronfeld, J.; Vogel, J. C.; Talma, A. S.

1994-05-01

71

Linkage disequilibria between mtDNA haplotypes and chromosomal arrangements in a natural population of Drosophila subobscura.  

PubMed

The association between mtDNA haplotypes and chromosomal arrangements in a natural population of Drosophila subobscura from Calvia (Balearic Islands, Spain) was studied in order to search for linkage disequilibria, in an attempt to explain the populational dynamics of the mtDNA haplotypes of this species in nature. The presence of Wolbachia was not detected. Two main haplotypes (I and II) were found, as well as a series of less common ones. The Tajima D-test seemed to indicate some kind of seasonal population bottleneck. An analysis of linkage disequilibrium and factorial analysis of correspondences detected an association between haplotype I and the J(ST) inversion and haplotype II and the J(1) inversion. PMID:12136416

Oliver, P; Castro, J A; Picornell, A; Ramon, M M; Solé, E; Balanyà, J; Serra, L; Latorre, A; Moya, A

2002-08-01

72

Internal [sup 238]U-series systematics of pumice from the November 13, 1985, eruption of Nevado de Ruiz, Colombia  

SciTech Connect

High-precision mass spectrometer and alpha scintillation measurements of [sup 238]U-series nuclides were obtained for whole-rock pumice and constituent mineral and glass separates to help interpret the timing and nature of magmatic processes that led up to the 1985 eruption of Nevado de Ruiz volcano. Internal isochron diagrams for [sup 226]Ra/Ba vs. [sup 230]Th/Ba and [sup 230]Th/[sup 232]Th vs. [sup 238]U/[sup 232]Th show that data define linear arrays, indicating an average crystallization age of 6.1 [+-] 0.5 ka (Ra-Th isochron) and 7 [+-] 6 ka (Th-U isochron). Stratigraphic, petrographic geochemical, repose time, and eruption volume data for the Holocene eruptive sequence of Nevado del Ruiz indicate that significant changes occurred in the subvolcanic magma chamber between eruptions R9 ([approx]8.6 ka) and R8 ([approx]3.0 ka). This coincides with the average crystallization age derived from the U-series data and may represent the injection of a new batch (or batches) of mantle-derived magma into the subvolcanic magma chamber. 26 refs., 4 figs., 2 tabs.

Schaefer, S.J.; Williams, S.N. (Arizona State Univ., Tempe (United States)); Sturchio, N.C. (Argonne National Lab., IL (United States)); Murrell, M.T. (Los Almos National Lab., NM (United States))

1993-03-01

73

U-series concentration in surface and ground water resources of Ardabil province.  

PubMed

Hundred and sixteen water resources including springs, wells, rivers and lakes in Ardabil province, northwest of Iran, were sampled and analyzed. The analysis included chemical analyses, (222)Rn and (226)Ra levels as well as total Uranium contents. (222)Rn levels were determined only for hot springs. The concentrations of Radium and Uranium in all water resources of Ardabil province were determined by the collector chamber and fluorimetric methods, respectively. The Radium and Uranium concentrations ranged from 2.0 to 300 mBq L(-1) and from 1.4 to 280 ppb, respectively. Furthermore, the annual effective dose varied between 8 and 47 microS y(-1). The reason for variations of Radium and Uranium concentration is the diverse geological structures in Ardabil province. The aim of this study was to determine the level of natural radioactivity in all water resources of the Ardabil province and whether this radiation causes any danger to health. The hot springs were found to have high level of activities and some water resources in Meshkin-Shahr city had the highest activities among other cities in Ardabil province. PMID:18310614

Hadad, Kamal; Doulatdar, Reza

2008-01-01

74

U-series dating of co-seismic gypsum and submarine paleoseismology of active faults in Northern Chile (23°S)  

NASA Astrophysics Data System (ADS)

The convergence of the Nazca and South American plates along the subduction margin of the central Andes results in large subduction earthquakes and tectonic activity along major fault systems. Despite its relevance, the paleoseismic record of this region is scarce, hampering our understanding about the relationship between the Andes building and earthquake occurrence. In this study, we used the U-series disequilibrium method to obtain absolute ages of paleoearthquake events associated with normal displacements along the active Mejillones and Salar del Carmen faults in the Coastal Range of the Atacama Desert of northern Chile. The 230Th- 234U disequilibrium ages in co-seismic gypsum salts sampled along the fault traces together with marine evidences indicate that earthquakes occurred at ca. 29.7 ± 1.7 ka, 11 ± 4 ka and 2.4 ± 0.8 ka. When coupled with paleoseismic marine and radiocarbon ( 14C) records in the nearby Mejillones Bay evidencing large dislocations along the Mejillones Fault, the geochronological dataset presented here is consistent with the notion that gypsum salts formed during large earthquakes as a result of co-seismic dilatancy pumping of saline waters along the major faults. Based on maximum observed cumulative vertical offsets in the studied faults, this phenomena could have occurred episodically at a rate in the order of 1:40 to 1:50 with respect to the very large subduction earthquakes during the latest Pleistocene-Holocene period. The results presented here reveal that the U-series disequilibrium method can be successfully applied to date the gypsum salts deposited along faults during seismic events, and therefore directly constrain the age of large paleoearthquakes in hyperarid and seismically active zones.

Vargas, Gabriel; Palacios, Carlos; Reich, Martin; Luo, Shangde; Shen, Chuan-Chou; González, Gabriel; Wu, Yi-Chen

2011-01-01

75

Combined ESR/U-series chronology of Acheulian hominid-bearing layers at Trinchera Galería site, Atapuerca, Spain  

USGS Publications Warehouse

The Sierra de Atapuerca, northern Spain, is known from many prehistoric and palaeontological sites documenting human prehistory in Europe. Three major sites, Gran Dolina, Galería and Sima del Elefante, range in age from the oldest hominin of Western Europe dated to 1.1 to 1.3 Ma (millions of years ago) at Sima del Elefante to c.a. 0.2 Ma on the top of the Galería archaeological sequence. Recently, a chronology based on luminescence methods (Thermoluminescence [TL] and Infrared Stimulated Luminescence [IRSL]) applied to cave sediments was published for the Gran Dolina and Galería sites. The authors proposed for Galería an age of 450 ka (thousands of years ago) for the units lower GIII and GII, suggesting that the human occupation there is younger than the hominid remains of Sima de los Huesos (>530 ka) around 1 km away. In this paper, we present new results obtained by combined Electron Spin Resonance/Uranium-series (ESR/U-series) dating on 20 herbivorous teeth from different levels at the Galería site. They are in agreement with the TL results for the upper part of the stratigraphic sequence (GIV and GIIIb), in the range of between 200 and 250 ka. But for the GIIIa to GIIb levels, the TL ages become abruptly older by 200 ka while ESR ages remain relatively constant. Finally, the TL and ESR data agree in the lowest part of the section (GIIa); both fall in the range of around 350–450 ka. Our results suggest a different interpretation for the GII, GIII and GIV units of Galería and the upper part of Gran Dolina (TD10 and TD11) than obtained by TL. The ESR/U-series results are supported by a Bayesian analysis, which allows a better integration between stratigraphic information and radiometric data.

Falguères, Christophe; Bahain, Jean-Jacques; Bischoff, James L.; Pérez-González, Alfredo; Ortega, Ana Isabel; Ollé, Andreu; Quilles, Anita; Ghaleb, Bassam; Moreno, Davinia; Dolo, Jean-Michel; Shao, Qingfeng; Vallverdú, Josep; Carbonell, Eudald; María Bermúdez de Castro, Jose; Arsuaga, Juan Luis

2013-01-01

76

Improving the accuracy and precision of TIMS U-series ages of modern corals from the Great Barrier Reef, Australia  

NASA Astrophysics Data System (ADS)

The main limiting factor in obtaining precise and accurate Uranium-series ages of modern corals (e.g. since European settlement of northern Australia around 1850 AD), is the ability to constrain and correct for initial or non-radiogenic 230Th. This is becoming particularly important in paleoecological research where accurate chronologies are required to pinpoint changes in community structure and the timing of mortality events in order to identify possible drivers. In this study, thermal ionisation mass spectrometry (TIMS) Uranium-series dating of 61 samples collected from living and non-living Porites spp. from the near shore region of the GBR was performed to spatially constrain initial 230Th/232Th (230Th/232Th0) variability. In the living Porites corals, the majority of 230Th/232Th0 values were higher than the bulk-Earth value (~4.4×10-6) generally assumed for non-radiogenic 230Th corrections where the primary source of initial thorium is terrestrially derived. Despite samples being taken from regions adjacent to contrasting levels of land modification, no apparent difference was found in 230Th/232Th0 between regions exposed to varying levels of sedimentation during runoff events. However, 230Th/232Th0 variability is evident between reefs within each region. Overall, most samples across the entire region give 230Th/232Th0 values in the range of 6±1×10-6. An examination of 232Th/238U versus 230Th/238U from living and non-living corals revealed mainly two components contributing to initial 230Th in the non-living coral samples. High 232Th concentrations found in the majority of non-living coral samples suggest that a significant amount of Th may have been incorporated into the coral skeleton through post-mortem non-carbonate sediment infiltration. The results of this study demonstrate that accurate U-series ages cannot be achieved where single non-radiogenic thorium correction values are used interchangeably for samples taken from different hydrological settings and for both living and dead Porites. For non-living corals, we propose the use of a specific correction value calculated based on 232Th levels for individual samples to account for both terrestrially-derived detrital and hydrogenous Th. Furthermore, we have also developed a vigorous cleaning procedure to reduce the level of infiltrated sediment adhering to the non-living coral skeleton. Using both methods we are able to achieve precise and accurate U-series ages (up to ±1 year) for corals less than 200 years old.

Clark, Tara; Zhao, Jian-Xin; Feng, Yuexing; Done, Terry; Jupiter, Stacy; Lough, Janice; Matson, Eric; Pandolfi, John; Roff, George

2010-05-01

77

High-precision U-series dating of corals from Western Australia and implications for the timing and duration of the Last Interglacial  

Microsoft Academic Search

U-series ages using methods of thermal ionisation mass spectrometry (TIMS) are reported for Last Interglacial fossil reefs along the stable coastal margin of Western Australia. Thorium isotope ratios were measured with superior precision using methods of charge collection. High levels of precision in the measurement of both uranium and thorium isotopes has reduced the age uncertainty due to analytical errors,

C. H. Stirling; T. M. Esat; M. T. McCulloch; K. Lambeck

1995-01-01

78

Rapid Climate Oscillations During the Last Deglaciation Synchronised by TIMS U-series Dating of a Stalagmite in East China  

NASA Astrophysics Data System (ADS)

Evidence for nearly synchronous climate oscillations during the last deglaciation has been found throughout the Northern Hemisphere but few records are based on independent time-scales of calendar years. We present the first U-series dated oxygen-carbon isotope record for a speleothem from Tangshan Cave, east China, which demonstrates unambiguously that abrupt deglacial climatic oscillations from 16,800 to 10,500 years BP are synchronous with those found in Greenland ice core records. Rapid shifts in speleothem \\delta18O, interpreted as reflecting changes in the amount of monsoon precipitation, demonstrate that the intensity of the East Asian monsoon switched within decades, in parallel with the abrupt transitions separating the B? lling-Aller? d (BA), Younger Dryas (YD), and pre-Boreal (PB) climatic reversals. \\delta13C values also change systematically, reflecting biomass response to changes in monsoon precipitation. The Tangshan record shows that the transitions to BA, YD and PB climatic conditions occurred at 14.62+/-0.10, 12.47+/-0.10 and 11.54+/-0.10 thousand years BP, respectively, which, considering different age errors, are in very good agreement with GRIP, GISP2 and Lake Gosciaz records. Our results suggest that the amount of monsoonal rainfall changes rapidly in parallel with deglacial temperature changes in the north Atlantic region, which is consistent with long-term histories of monsoon moisture documented using the loess, lake and marine sediment records in China. East Asian monsoon circulation is controlled by seasonal changes in the land-sea thermal gradient between the East Asian continent and the Pacific Ocean. During glacial (or stadial) periods, the winter monsoon strengthens as a result of intensified outflow of cold and dry air from the Siberian/Mongolian High, which was driven by westerly wind transport of cold air from the North Atlantic. In contrast, the summer monsoon weakens because of the reduced sea-land thermal gradient, coupled with reduced sea-surface temperature and moisture level above the western Pacific. During interglacial (or interstadial) periods, changes in the monsoon system tend to be the reverse. Thus changes in air temperature in the north Atlantic appear to be capable of reorganising the large-scale atmospheric circulation in the northern hemisphere with profound implications for monsoonal rainfall in East Asia. The Tangshan speleothem records provide the first unambiguous evidence for synchronised, abrupt climatic changes in the North Atlantic and East Asia regions. Such rapid hemispheric synchronicity strongly supports the role of atmospheric teleconnections in controlling global climate change during the last glaciation. The study shows that C-O isotope records extracted from climatically sensitive U-series-dated speleothems, like Devils Hole calcite vein, should play an important role in future investigations of the timing and duration of global climatic events.

Zhao, J.; Wang, Y.; Collerson, K. D.; Gagan, M. K.

2001-12-01

79

Uranium-series disequilibria of inflated sections of the Juan de Fuca Ridge: Implications for mantle melting  

NASA Astrophysics Data System (ADS)

U-Th disequilibria are reported for the two inflated portions (defined by bathymetric highs) of the Juan de Fuca Ridge (JdFR): Axial Seamount and the northern Endeavour segment. Both have broad axis-centered bathymetric plateaus, commonly attributed to the influence of the adjacent Heckle and Cobb melt anomalies, respectively. We explore structural and geochemical contrasts between them that imply fundamental differences in magma plumbing and/or transport processes. The depth to the axial magma chamber (AMC) within the JdFR crust is shallowest beneath Axial Seamount and deepest and most variable beneath Endeavour. Lavas from Endeavour include the most enriched and diverse compositions of the JdFR. Endeavour N-MORBs are most similar to Axial basalts in K2O/TiO2, La/Yb, Na8, and Fe8 although most Axial basalts have lower MgO. Major element trends suggest clinopyroxene saturation at higher MgO at Endeavour. Additional basalt types from Endeavour (i.e., those with K2O/TiO2 >0.15), the West Valley segment to the north, and Southwest Seamount to the west share similar enrichments in incompatible trace elements (Th, Nb) and radiogenic-Pb. Similar characteristics are absent from basalts from the adjacent Heck and Heckle seamount chains, which are highly-depleted N-MORBs, precluding the hypothesis that thickened and inflated crust at Endeavour is associated with increased melt supply due to transit over the seamount source. In contrast, Axial basalts are more chemically homogeneous, and share selected geochemical characteristics with the adjacent Cobb seamount chain. New uranium-series data suggest fundamental differences in melting parameters between inflated and non-inflated portions of the JdFR. Average Th/U at Endeavour (3.03 ± 6, n=10) is nearly indistinguishable from Axial (2.83 ± 9, n=17), but both are distinct from elsewhere on the JdFR (~2.1-2.5). That is, basalts erupted from regions of inflated crust have higher Th/U. Despite high overall compositional diversity in Endeavour basalts, Th/U variance is low, as in Axial basalts. However, there are differences in (230Th)/(232Th). Seventeen samples from Axial Seamount have (230Th)/(232Th) <1.22, the lowest on the JdFR axis. The range at Endeavour is 1.26-1.35, and highest in N-MORB. (230Th)-excesses [(230Th)/(238U) >1] are much higher at Endeavour (20-30%) than Axial Seamount (5-20%) and the rest of the JdFR (8-14%) but more similar to values of the adjacent Gorda Ridge to the south (up to ~25%). If differences in melt column characteristics (i.e., porosity, lithology, potential temperature) are similar along the JdFR, then ingrowth melt models predict slower upwelling of mantle-derived melts (e.g., longer residence time in the melt column) at Endeavour. Alternatively, Endeavour lavas may be generated from a more pyroxenitic (lherzolite) mantle where large degrees of disequilibria can be generated.

Dreyer, B. M.; Gill, J. B.; Ramos, F. C.; Clague, D. A.; Scott, S. R.

2010-12-01

80

Transport and exchange of U-series nuclides between suspended material, dissolved load and colloids in rivers draining basaltic terrains  

NASA Astrophysics Data System (ADS)

This study presents uranium and thorium concentrations and activity ratios for all riverine phases (bedload, suspended load, dissolved load and colloids) from basaltic terrains in Iceland and the Azores. Small basaltic islands, such as these, are thought to account for ~ 25% of CO2 consumed by global silicate weathering, and for ~ 45% of the flux of suspended material to the oceans. These data indicate that [U] and [Th] in the dissolved and colloidal fractions are strongly controlled by pH, and to a much lesser extent by levels of dissolved organic carbon (which are low in these environments). At high pH, basalt glass dissolution is enhanced, and secondary mineral formation (e.g. Fe-oxyhydroxides and allophane) is suppressed, resulting in high dissolved [U], and low colloidal [U] and [Th], indicating a direct chemical weathering control on elemental abundances. When the dissolved (234U/238U) activity ratio is >~1.3 (i.e. when physical weathering, groundwater contribution or soil formation are high), there is little isotope exchange between dissolved and colloidal fractions. At lower activity ratios, the dissolved load and colloids have indistinguishable activity ratios, suggesting that when chemical weathering rates are high, secondary clay formation is also high, and colloids rapidly adsorb dissolved U. Many of the suspended sediment samples have (234U/238U) activity ratios of > 1, which suggests that uptake of U onto the suspended load is important. Identical (230Th/232Th) in suspended, dissolved and colloidal samples suggests that Th, like U, is exchanged or sorbed rapidly between all riverine phases. This particle-reactivity, combined with poorly constrained contributions from groundwater and hydrothermal water, and short-term variations in input to soils (volcanic and glacial), suggests that U-series nuclides in riverine material from such basaltic terrains are unlikely to reflect steady state erosion processes.

Pogge von Strandmann, Philip A. E.; Burton, Kevin W.; Porcelli, Don; James, Rachael H.; van Calsteren, Peter; Gislason, Sigurður R.

2011-01-01

81

Using U-series isotopes to quantify regolith formation and chemical weathering rates along a climosequence associated with the Susquehanna Shale Hills Critical Zone Observatory  

NASA Astrophysics Data System (ADS)

Regolith formation and chemical weathering are important Critical Zone processes and are responsible for soil development. Despite their fundamental importance, we still lack effective tools to quantify these processes. U-series isotopes offer a powerful geochronometer to quantify regolith production rates and weathering duration. This is largely due to improvements in analytical methods and mathematical approaches made over the last decade in measuring U-series isotopes and interpreting their fractionation during chemical weathering. Here, we present a systematic study of U-series isotopes (238U, 234U and 230Th) in shale-derived soils from five small watersheds in the eastern USA to understand the rates of regolith formation as a function of climate. The selected watersheds in Pennsylvania, Virginia, Tennessee, Alabama, and Puerto Rico are part of the shale transect established as part of the Susquehanna Shale Hills Critical Zone Observatory. We first measured U-series isotopes in six regolith profiles from two planar hill-slopes (north vs. south) within the Shale Hills CZO in central PA to evaluate the role of aspect on regolith formation in the small watershed. All regolith samples display significant U-series disequilibrium. These U-series disequilibrium values are explained by two processes acting on U-series isotopes during weathering: a loss of 234U, 238U, and 230Th during water-rock interactions and a gain from circulating soil water and/or downslope particle transport. Regolith production rates and weathering durations were calculated with a U-series isotope mass balance model. On the southern (shaded) slope, regolith production rates decrease systematically with increasing soil thickness and distance from the ridge: from ~44.5 m/Myr at the ridge top to ~15.0 m/Myr at the valley floor. Durations of chemical weathering within these profiles range from 6.7 kyr to 44.7 kyr, increasing from the ridge to the valley floor. The regolith profiles on the northern (sun-facing) slope are characterized by faster regolith production rates (~40-52 m/Myr) and shorter durations of chemical weathering in the regolith zone (~12-16 kyr). These results reveal the important control of hill-slope aspect on the rate of regolith formation at Shale Hills: we hypothesize that aspect creates microclimates that in turn affect slope stability and erosion, and set different regolith residence times. The difference in microclimate is inferred to have been important before and during the periglacial period that occurred at Shale Hills ~15 ka. Our ongoing investigation of the four additional gray shale watersheds in VA, TN, AL, and PR provides information on shale weathering along a climosequence at a much larger continental scale. Only ridge top sites were selected to limit the aspect effect. This systematic study will enable us to quantitatively model regolith formation and landscape development on gray shales and to consider the effects of ongoing climate change.

Ma, L.; Chabaux, F. J.; Dere, A. L.; White, T.; Jin, L.; Brantley, S. L.

2012-12-01

82

TIMS U-series dating and stable isotopes of the last interglacial event in Papua New Guinea  

NASA Astrophysics Data System (ADS)

The extensive flight of uplifted reef terraces which occurs along the Vitiaz strait on the northern flank of the Huon Peninsula in PNG (Papua New Guinea) contains a particularly good record of sea level changes in the last 250 ky. The Huon terraces were the target of an international expedition which took place in July-August 1988. In particular, we searched for suitable samples for U-series dating in a reef complex designated as VII, which is correlated with the last interglacial episode and high sea level stand. This complex is composed of a barrier reef (VIIb), a lagoon, and a fringing reef (VIIa). Twelve corals from these terraces and two corals from the older reef complex VIII were selected for analysis. The petrography, oxygen and carbon isotope compositions, and magnesium and strontium concentrations were determined along with the concentrations and isotopic compositions of uranium and thorium. 230Th- 234U ages of the corals with > 99% aragonite, having primary textures, and which show U/Sr ratios around 0.4 × 10 -3 and initial ? 234U values close to that of present seawater, appear to be reliable. The "most reliable" ages from complex VII corals fall in two tight groups centered at 118 ky and 134 ky. Corals with ?234U( T) values higher than 160 and U/Sr ratios substantially lower than seawater are assumed to have undergone diagenetic alteration, which appears to be common in this area. The simplest model for sea level height for terrace VII is a continuous rise between 134 and 118 ky. Alternatively, there may have been two periods of rapid sea level rise. In contrast, in the Bahamas, there is evidence that sea level remained rather constant over the time interval 132 to 120 ky. The absence of ages between 132 and 120 ky in PNG could be the result of changes in the local tectonic uplift rates during that time, or erosion that disrupted the continuous record. In any event, we find no basis for accepting a single brief time for the age of the last interglacial and applying this age as a precise chronometer for worldwide correlation, or as a test of climatic models. The older ages reported here precede the Milankovitch solar insolation peak at 128 ky, and the younger ages are ~ 10 ky after this peak. If the present high-precision data are correct, then it will be necessary to reassess the validity of the Milankovitch theory of climatic changes. The fundamental issue which must now be resolved is a means of identifying coral samples that have not been disturbed by diagenetic processes.

Stein, M.; Wasserburg, G. J.; Aharon, P.; Chen, J. H.; Zhu, Z. R.; Bloom, A.; Chappell, J.

1993-06-01

83

Enhanced particle scavenging in deep water of the Aleutian Basin revealed by 210Po-210Pb disequilibria  

NASA Astrophysics Data System (ADS)

high sedimentation rate but low primary production in surface ocean raised a question whether particles from local upper water column could support high deposition in the Aleutian Basin. Here we first present large 210Po-210Pb disequilibria in deep water of the Aleutian Basin. Dissolved 210Po and 210Pb were depleted relative to 210Pb and 226Ra, respectively, in deep water below 1000 m, as well as decreased with depth, suggesting enhanced particle scavenging in the deep water. The 210Po residence times (1-2 a) in deep water were comparable to those in the upper water column, indicating that 210Po scavenging rates were high in deep water of the Aleutian Basin. The export fluxes of 210Po from the upper 100 m were estimated to be 0.2-0.8 Bq/m2/d, much lower than those in the deep water (7-8 Bq/m2/d). Similarly, POC export fluxes in deep water (24-80 mmolC/m2/d) were higher than those in the upper 100 m (˜1 mmolC/m2/d). Such a large discrepancy between the upper and deep water suggested that particles from local upper water column could not totally meet the enhanced scavenging in the deep water. Based on mass balance calculations, the extra fluxes of 210Pb and POC imported to deep water were estimated to be 8-12 Bq/m2/d and 22-79 mmolC/m2/d, respectively. The ratio of POC to particulate 210Pb (i.e., POC/PPb) in the extra source was estimated to be 6.5 mmol/Bq, which was lower than that in the Bering Shelf with a mean POC/PPb ratio of 10.9 mmol/Bq, implying that particles in the Bering Shelf could be a potential source for the enhanced particle scavenging in deep water of the Aleutian Basin. However, quantitative and detailed role of ridges and manganese from sediments in particle scavenging in the deep water was unclear, and further studies are necessary.

Hu, Wangjiang; Chen, Min; Yang, Weifeng; Zhang, Run; Qiu, Yusheng; Zheng, Minfang

2014-06-01

84

Measurement of radioactivity levels and assessment of radioactivity hazards of soil samples in Karaman, Turkey.  

PubMed

In this study, the levels of the natural and artificial radioactivity in soil samples collected from surrounding of Karaman in Turkey were measured. Activity concentrations of the concerned radionuclides were determined by gamma-ray spectrometry using a high-purity germanium detector with a relative efficiency of 40 % at 1.332 MeV. The results obtained for the (238)U series ((226)Ra, (214)Pb and (214)Bi), (232)Th series ((228)Ac), (40)K and fission product (137)Cs are discussed. To evaluate the radiological hazard of radioactivity in samples, the radium equivalent activity (Raeq), the absorbed dose rate (D), the annual effective dose and the external (Hex) and internal hazard index (Hin) were calculated and presented in comparison with the data collected from different areas in the world and Turkey. PMID:24587487

Agar, O; Boztosun, I; Korkmaz, M E; Özmen, S F

2014-12-01

85

Linkage disequilibria among (CA){sub n} polymorphisms in the human dystrophin gene and their implications in carrier detection and prenatal diagnosis in Duchenne and Becker musclar dystrophies  

SciTech Connect

Four short tandem repeat loci, characterized by length polymorphisms of (CA){sub n} repeats, have been detected within introns 44, 45, 49, and 50 of the human dystrophin gene. The predicted heterozygosites for these loci range from 72 to 93%, and observed allele numbers range from 6 to 19 in 57 normal chromosomes, revealing their high degree of polymorphism. Evidence for significant disequilibria between the loci within introns 49 and 50 is found. These data appear to be consistent with observations of recombination frequencies between these markers and the length of the intron 44 in relation to the entire region. In addition, these four loci are collectively found to be 100% informative in carrier detection/prenatal diagnosis of Becker and Duchenne muscular dystrophies (B/DMD), whereas scoring the (CA){sub n} markers within introns 45 and 49 alone gives a 99.6% success rate. 13 refs., 4 tabs.

Chakraborty, R.; Zhong, Y.; Andrade, M. de [Univ. of Texas Graduate School of Biomedical Sciences, Houston, TX (United States)] [and others] [Univ. of Texas Graduate School of Biomedical Sciences, Houston, TX (United States); and others

1994-06-01

86

Radioactivity Environmental Protection Course  

E-print Network

D1 D4 D5 D1 Radioactivity Environmental Protection Course Radioactivity Environmental Protection Course Radioactivity Social Recovery Course protect the environment from radioactivity protect human lives from radiation disasters protect the human society from radioactivity Development of Phoenix

Ishii, Hitoshi

87

Radioactive Iodine  

MedlinePLUS

... form of iodide, is made into two radioactive isotopes that are commonly used in patients with thyroid ... the best results? I-123 is the usual isotope used to take pictures and determine the activity ...

88

Radioactivity Calculations  

ERIC Educational Resources Information Center

Three problems in radioactive buildup and decay are presented and solved. Matrix algebra is used to solve the second problem. The third problem deals with flux depression and is solved by the use of differential equations. (LC)

Onega, Ronald J.

1969-01-01

89

Concentrating Radioactivity  

ERIC Educational Resources Information Center

By concentrating radioactivity contained on luminous dials, a teacher can make a high reading source for classroom experiments on radiation. The preparation of the source and its uses are described. (DT)

Herrmann, Richard A.

1974-01-01

90

Simulated Radioactivity  

ERIC Educational Resources Information Center

Describes the errors in the sugar-cube experiment related to radioactivity as described in Project Physics course. The discussion considers some of the steps overlooked in the experiment and generalizes the theory beyond the sugar-cube stage. (PS)

Boettler, James L.

1972-01-01

91

Investigation of aerial dispersion of radioactive dust from an open-pit uranium mine by passive vinyl collectors  

Microsoft Academic Search

Detailed investigations of the aerial dispersion of radioactive dust from the biggest open-pit U mining and milling operation in Australia were carried out. Spatial distributions of the long-lived radionuclides of ²³⁸U series and their origin, i.e., mining and milling operations vs. natural background radiation, have been studied. Horizontal flux, dry deposition, and ground resuspension of the radionuclides were investigated along

H. B. L. Pettersson; J. Koperski

1991-01-01

92

Radioactive Wastes  

NSDL National Science Digital Library

Created by David Smith for the Connected Curriculum Project, this module develops multiple representations for decay of radioactive substances, in the context of environmental policies on a university campus, and discusses storage times for wastes to decay to safe levels for disposal. This is one of a much larger set of learning modules hosted by Duke University.

Smith, David

2010-04-29

93

Radioactive Decay  

NSDL National Science Digital Library

Created by William Barker and David Smith for the Connected Curriculum Project, this module develops a mathematical model for decay of radioactive substances, and a technique for deciding whether quantitative data fits the model or not. This is one within a much larger set of learning modules hosted by Duke University.

Barker, William

94

Radioactive fallout  

Microsoft Academic Search

Radioactive fallout from the Nevada tests does not provide a great danger to any inhabitants of the US or to the world in general, for the AEC has not been indiscrete in its testing of nuclear weapons. The data presented to the public in this discussion provides the first reliable and realistic estimate of the hazards associated with nuclear warfare.

Libby

1955-01-01

95

Radioactive Waste.  

ERIC Educational Resources Information Center

Presents a literature review of radioactive waste disposal, covering publications of 1976-77. Some of the studies included are: (1) high-level and long-lived wastes, and (2) release and burial of low-level wastes. A list of 42 references is also presented. (HM)

Blaylock, B. G.

1978-01-01

96

Radioactive Wastes  

NSDL National Science Digital Library

Using Mathcad, Maple, Mathmatica, or MatLab, the user should be able to develop multiple representations for decay of radioactive substances, in the context of environmental policies on a university campus, and to determine storage times for wastes to decay to safe levels for disposal.

Smith, David

2001-01-22

97

Using U-series Isotopes To Determine Sources Of Pedogenic Carbonates: Comparison Of Natural And Agricultural Soils In The Semi-arid Southern New Mexico And Western Texas  

NASA Astrophysics Data System (ADS)

Pedogenic carbonates commonly precipitate from infiltrating soil water in arid and semi-arid lands and are observed in soils of southern New Mexico and western Texas. These carbonates could form an impermeable layer in the soil horizons impairing water infiltration, thus affecting crop growth and yield. It is important to determine the source of C and Ca in these carbonates and to understand conditions favoring their formation, kinetics and precipitation rates. In this study, major elements and U-series isotopes in bulk calcic soils, and weak acid leachates and residues were measured from one irrigated alfalfa site in the Hueco basin near El Paso, TX and one natural shrubland site on the USDA Jornada experimental range in southern NM. The combined geochemical and isotopic results allow us to determine the formation ages of the carbonates; investigate the mobility of U, Th, and major elements in these soils; and infer for the effects of irrigation on carbonate formation in agricultural soils. Our results show distinctive U and Th isotope systems in the two soil profiles analyzed. For example, (234U/238U) ratios in the Jornada bulk soils decrease from ~1.01 to 0.96 towards the surface, consistent with a preferential loss of 234U over 238U during chemical weathering. At the Jornada site, (238U/232Th) ratios decrease while (230Th/238U) increase towards the surface, consistent with a general depletion of U and the immobility of Th in the natural soils. By contrast at the Alfalfa site, (234U/238U) ratios of bulk soils increase from ~ 0.97 to 1.02 towards the surface, suggesting an additional source of external uranium, most likely the irrigation water from Rio Grande which has a (234U/238U) ratio of ~ 1.5 near El Paso. The (238U/232Th) and (230Th/238U) ratios also imply leaching of U from shallower soils but precipitation in greater depths at Alfalfa site; suggests that partial dissolution and re-precipitation of younger carbonates occur. Calculated carbonate ages from U-series isotopes at the natural Jornada site range from 15.7±0.1 to 36.9±0.1kyrs. Near the surface these carbonates are older but at depth, relatively young carbonates indicate partial weathering and overprinting over older carbonates. However, much younger carbonate ages (2.1±0.2 to 21±0.1kyrs) are observed at the Alfalfa site. These ages generally decrease with increasing depth with the youngest carbonate ages (2.1±0.2 kyrs) at ~52 cm. The trend depicted represents a mixture of newly-formed carbonates due to irrigation and pre-existing much older natural carbonates in soils. Evidently young carbonates in the agricultural soils indicate that calcite precipitates out of saline irrigation water. An additional profile is noted with MgO at the Alfalfa site and suggests that Mg2+ is added onto these soils probably from irrigation waters. However at the Jornada site, low MgO contents near the surface indicate loss of Mg most likely by leaching and plant uptake. Our case study highlights the use of U-series and major elements to understand the formation processes of carbonates in both agricultural and natural soils. Clearly, the high salinity of Rio Grande water contributes to elevated amounts of carbonates in agricultural farms and this flux might be important for the overall global mass balance of carbon.

Nyachoti, S. K.; Ma, L.; Borrok, D. M.; Jin, L.; Tweedie, C. E.

2012-12-01

98

Differential incision of the Grand Canyon related to Quaternary faulting—Constraints from U-series and Ar/Ar dating  

NASA Astrophysics Data System (ADS)

Incision of the Colorado River in the Grand Canyon, widely thought to have happened between ca. 6 and 1.2 Ma, has continued at variable rates along the canyon over the past ˜500 k.y., based on measurements of bedrock incision combined with U-series and 40Ar/39Ar ages. River incision rates downstream of the Toroweap fault in the western Grand Canyon are about half the ˜140 m/m.y. incision rate calculated for a distance of at least 200 km upstream of the fault. We hypothesize that this differential incision is due to west-down slip on the Toroweap fault of 94 ± 6 m/m.y. based on measured offset of the newly dated Upper Prospect basalt flow, which is the major middle-late Quaternary slip evident along the river. Regional incision has been driven mostly by base-level fall related to drainage reversal off the Colorado Plateau ca. 6 Ma. Because local normal faulting is lower in rate than this regional incision and is likely an expression of Basin and Range extension and subsidence rather than uplift, this is a case where active faulting diminishes, but does not drive, incision. Quaternary incision rates are insufficient to have carved the Grand Canyon in 6 m.y., suggesting either that rates have decreased through time as the original base-level signal has attenuated, or that some component of the canyon relief we see today existed prior to Colorado River integration.

Pederson, Joel; Karlstrom, Karl; Sharp, Warren; McIntosh, William

2002-08-01

99

Timing and intensity of groundwater movement during Egyptian Sahara pluvial periods by U-series analysis of secondary U in ores and carbonates  

NASA Astrophysics Data System (ADS)

Wet climatic episodes are known to have prevailed in the Egyptian Sahara several times during the late Quaternary, most recently during the Holocene 8000 yr ago. Earlier wet episodes have been recognized as having occurred during the past 300,000 yr and have been dated by U-series methods in speleothems and in lake travertines. We show here that the times of enhanced groundwater movement can also be determined by 230Th/ 234U dating of secondary U in ores of uranium, iron, and phosphate. We also present evidence that such acceleration of groundwater movements is indicated by relatively low 234U/ 238U activity ratios in the secondary uranium. Our new data show that pluvial periods in Egypt occurred during marine oxygen isotope stages 4, 5, 6, and 7 and therefore are consistent with the view that the wet episodes are the results of migration of the tropical monsoonal belt driven primarily by the 23,000-yr precession cycle of the Milankovich curve, modulated by the 100,000-yr eccentricity cycle.

Osmond, J. K.; Dabous, Adel A.

2004-01-01

100

Radioactive Wastes  

NSDL National Science Digital Library

Created by Lang Moore and David Smith for the Connected Curriculum Project, the purposes of this module are to develop multiple representations for decay of radioactive substances, in the context of environmental policies on a university campus, and to determine storage times for wastes to decay to safe levels for disposal. This is one lesson within a larger set of learning modules hosted by Duke University.

Moore, Lang; Smith, David

2010-07-06

101

Sea-level history of the past two interglacial periods: New evidence from U-series dating of reef corals from south Florida  

USGS Publications Warehouse

As a future warm-climate analog, much attention has been directed to studies of the Last Interglacial period or marine isotope substage (MIS) 5.5, which occurred ???120,000 years ago. Nevertheless, there are still uncertainties with respect to its duration, warmth and magnitude of sea-level rise. Here we present new data from tectonically stable peninsular Florida and the Florida Keys that provide estimates of the timing and magnitude of sea-level rise during the Last Interglacial period. The Last Interglacial high sea stand in south Florida is recorded by the Key Largo Limestone, a fossil reef complex, and the Miami Limestone, an oolitic marine sediment. Thirty-five new, high-precision, uranium-series ages of fossil corals from the Key Largo Limestone indicate that sea level was significantly above present for at least 9000 years during the Last Interglacial period, and possibly longer. Ooids from the Miami Limestone show open-system histories with respect to U-series dating, but show a clear linear trend toward an age of ???120 ka, correlating this unit with the Last Interglacial corals of the Key Largo Limestone. Older fossil reefs at three localities in the Florida Keys have ages of ???200 ka and probably correlate to MIS 7. These reefs imply sea level near or slightly above present during the penultimate interglacial period. Elevation measurements of both the Key Largo Limestone and the Miami Limestone indicate that local (relative) sea level was at least 6.6 m, and possibly as much as 8.3 m higher than present during the Last Interglacial period. ?? 2010.

Muhs, D.R.; Simmons, K.R.; Schumann, R.R.; Halley, R.B.

2011-01-01

102

High-precision U-series dating of corals from Western Australia and implications for the timing and duration of the Last Interglacial  

NASA Astrophysics Data System (ADS)

U-series ages using methods of thermal ionisation mass spectrometry (TIMS) are reported for Last Interglacial fossil reefs along the stable coastal margin of Western Australia. Thorium isotope ratios were measured with superior precision using methods of charge collection. High levels of precision in the measurement of both uranium and thorium isotopes has reduced the age uncertainty due to analytical errors, excluding the uncertainty in the decay constants, by a factor of four over the precisions reported by many earlier TIMS workers. Uncertainties in ?234U(T), determined from both 230Th/ 238U and 234U/ 238U, are also significantly smaller than previously reported, allowing samples which have undergone diagenetic exchange of uranium and thorium to be more easily identified. Strict criteria were adopted to screen the new Western Australian data. Reliable ages range from 127 to 122 ka. Published TIMS observations from other localities have been assessed using the same strict criteria. When these are combined with glacio-hydro isostatic sea-level models they indicate that the Last Interglacial period occurred from at least 130 to 117 ka. However, these age constraints are largely determined from single data points and need to be verified with additional ages before considering them to be robust estimates for the timing of onset and termination of the Last Interglacial. Globally, the main episode of reef growth appears to be confined to a narrow interval occurring from 127 to 122 ka, in direct agreement with the narrow range in ages obtained from the Western Australian sites. This may indicate that the Last Interglacial was of short duration, extending from 127 to 122 ka only. Alternatively, this interval may reflect a major reef-building event in the middle of a longer duration (130-117 ka) interglacial interval.

Stirling, C. H.; Esat, T. M.; McCulloch, M. T.; Lambeck, K.

1995-10-01

103

Na, K, Ca, Mg, and U-series in fossil bone and the proposal of a radial diffusion-adsorption model of uranium uptake.  

PubMed

Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion-adsorption (RDA) model is described. Unlike the classic diffusion-adsorption (D-A) model, RDA uses a cylindrical geometry to describe the U uptake in fossil bones. The model was applied across a transverse section of a tibia of an extinct megamammal Macrauchenia patachonica from the La Paz Local Fauna, Montevideo State, Uruguay. Measurements of spatial distribution of Na, K, Ca, and Mg were also performed by neutron activation analysis (NAA). Gamma-ray spectrometric U-series dating was applied to determine the age of the bone sample. From U concentration profile, it was possible to observe the occurrence of a relatively slow and continuous uranium uptake under constant conditions that had not yet reached equilibrium, since the uranium distribution is a ?-shaped closed-system. Predictions of the RDA model were obtained for a specific geochemical scenario, indicating that the effective diffusion coefficient D/R in this fossil bone is (2.4 ± 0.6)10(-12) cm(2)s(-1). Mean values of Na, K, Ca, and Mg contents along the radial line of the fossil tibia are consistent with the expected behavior for spatial distributions of these mineral elements across a modern bone section. This result indicates that the fossil tibia may have its mineral structure preserved. PMID:24953228

Cid, A S; Anjos, R M; Zamboni, C B; Cardoso, R; Muniz, M; Corona, A; Valladares, D L; Kovacs, L; Macario, K; Perea, D; Goso, C; Velasco, H

2014-10-01

104

Origins of large-volume, compositionally zoned volcanic eruptions: New constraints from U-series isotopes and numerical thermal modeling for the 1912 Katmai-Novarupta eruption  

USGS Publications Warehouse

We present the results of a combined U-series isotope and numerical modeling study of the 1912 Katmai-Novarupta eruption in Alaska. A stratigraphically constrained set of samples have compositions that range from basalt through basaltic andesite, andesite, dacite, and rhyolite. The major and trace element range can be modeled by 80–90% closed-system crystal fractionation over a temperature interval from 1279°C to 719°C at 100 MPa, with an implied volume of parental basalt of ?65 km3. Numerical models suggest, for wall rock temperatures appropriate to this depth, that 90% of this volume of magma would cool and crystallize over this temperature interval within a few tens of kiloyears. However, the range in 87Sr/86Sr, (230Th/238U), and (226Ra/230Th) requires open-system processes. Assimilation of the host sediments can replicate the range of Sr isotopes. The variation of (226Ra/230Th) ratios in the basalt to andesite compositional range requires that these were generated less than several thousand years before eruption. Residence times for dacites are close to 8000 years, whereas the rhyolites appear to be 50–200 kyr old. Thus, the magmas that erupted within only 60 h had a wide range of crustal residence times. Nevertheless, they were emplaced in the same thermal regime and evolved along similar liquid lines of descent from parental magmas with similar compositions. The system was built progressively with multiple inputs providing both mass and heat, some of which led to thawing of older silicic material that provided much of the rhyolite.

Turner, Simon; Sandiford, Mike; Reagan, Mark; Hawkesworth, Chris; Hildreth, Wes

2010-01-01

105

ESR and U-series analyses of faunal material from Cuddie Springs, NSW, Australia: implications for the timing of the extinction of the Australian megafauna  

NASA Astrophysics Data System (ADS)

The timing and cause of late Pleistocene faunal extinctions in Australia are subjects of a debate that has become polarised by two vigorously defended views. One contends that the late Pleistocene extinction was a short event caused by humans colonising the Australian continent, whereas the other promotes a gradual demise of the fauna, over a period of at least 10-20 ka, due to a combination of climatic changes and ecological pressures by humans. Cuddie Springs is central to this debate as it is the only site known in continental Australia where archaeological and megafauna remains co-occur. We have analysed more than 60 bones and teeth from the site by laser ablation ICP-MS to determine U, and Th concentrations and distributions, and those with sufficiently high U concentrations were analysed for U-series isotopes. Twenty-nine teeth were analysed by ESR. These new results, as well as previously published geochronological data, contradict the hypothesis that the clastic sediments of Stratigraphic Unit 6 (SU6) are in primary context with the faunal, archaeological and other materials found in SU6, and that all have ages consistent with the optically stimulated luminescence (OSL) estimates of 30-36 ka. These young OSL results were used to argue for a relatively recent age of the extinct fauna. Our results imply that SU6 is either significantly older than the OSL results, or that a large fraction of the faunal material and the charcoal found in SU6 was derived from older, lateral deposits. Our U and Th laser ablation ICPMS results as well as the REE profiles reported by Trueman et al. [2008. Comparing rates of recystallisation and the potential for preservation of biomolecules from the distribution of trace elements in fossil bones. C.R. Palevol. General Paleontology (Taphonomy and Fossilization) 7, 145-158] contradict the interpretation of previously reported rare earth element compositions of bones, and the argument based thereon for the primary context of faunal material and clastic sediments in SU6 layers.

Grün, Rainer; Eggins, Stephen; Aubert, Maxime; Spooner, Nigel; Pike, Alistair W. G.; Müller, Wolfgang

2010-03-01

106

U-Th-Ra and U-Pa disequilibria in Izu-arc basalts: the interplay of depleted mantle wedge and sediment poor slab fluid  

NASA Astrophysics Data System (ADS)

The Izu arc, south of Honshu, Japan, appears to be an end member in the spectrum of island arcs in having most of its slab component dominated by basalt-derived fluid. Three islands, Oshima, Miyakejima and Torishima, at its volcanic front have produced lavas during historical time. Lavas from all of them were analyzed for 238U-230Th-226Ra and 231Pa-235U disequilibria, showing decreasing (230Th/232Th) from north to south along the arc. The highest 238U and 231Pa excesses are found in lavas from Oshima that also record the highest fluid signal (Ba/Th, Pb/Ce) and the highest sediment signal (Th/La, 10Be/Be). Large 226Ra excesses correlate positively with Ba/Th apart from Oshima and imply rapid ascent and differentiation of the magmas. Unlike other oceanic arcs, there is no correlation between (230Th/232Th) and (238U/232Th). Four models are explored to explain the observations: two in which sediment- and basalt-derived slab components are added to the mantle separately, and two in which they are added together and recently. A version of the latter is preferred for Izu in which a homogeneous mostly basalt-derived fluid causes flux melting of a heterogeneous mantle. The variable (230Th/232Th) is unlikely to reflect in-growth of 230Th from old addition of sediment from the slab and is more likely to reflect an increasingly depleted mantle towards the south, as a result of back-arc basalt production. Relatively modest 238U-excesses over 230Th in the Izu arc lavas suggest that this fluid is not Th-free and is less U-enriched than observed elsewhere. The association of high Ba/Th, Th/La, (238U/230Th), and (231Pa/235U) suggests that Pa also can be carried in the slab component. These characteristics may apply widely to recent arc fluids. Evidence for sediment melt in the slab component of arcs may integrate effects of prior sediment addition with recent flux melting. In the absence of such melts, Th is the isotope tracer most sensitive to recent source depletions.

Sigmarsson, O.; Gill, J.; Holden, P.

2006-12-01

107

New Constraints on Fluid Addition Beneath the Tonga Arc: Reconciliation of U-Th-Ra Disequilibria in a Single-Stage Fluid Addition Model  

NASA Astrophysics Data System (ADS)

Previous U-series isotope studies of Tongan lavas yielded inclined arrays on a U-Th equiline diagram. Taken together, these along-arc data were inferred to record timescales of ~ 50 kyr since fluid addition of U and large Ra excesses were reconciled using second-stage (or continuous) fluid addition models. However, Ata island displayed a clear horizontal trend on the U-Th equiline diagram suggesting that here, addition of U could have occurred only a few kyr ago. New high precision U-Th disequilibrium data have been obtained by solution MC-ICP-MS analysis for a new suite of Tongan rocks. Samples from the islands of Tofua, Kao and Late all form horizontal arrays on the U-Th equiline diagram. Thus is appears that the 50 kyr array in earlier studies actually represents a series of horizontal en-echelon island trends, each recording recent addition of slab derived fluid to the mantle wedge. Thus, the need for Th addition via the fluid is negated, in good agreement with its fluid immobile character. Moreover, this new insight enables reconciliation of the observed positive correlation between (238U/230Th) and (226Ra/230Th) that, until now, required a two-stage (or continuous) fluid addition model in order to account for the persistence of both U and Ra excesses in the same samples. The very large (up to 600%) Ra excesses in many rocks cannot be produced by in-growth melting models. Identification of positive correlations between (226Ra/230Th) and widely accepted indices of fluid addition (e.g. Ba/Th, Sr/Th) support the conclusion that metasomatism of the Tongan sub-arc mantle wedge was brought about by rapid single-stage fluid addition from the down-going subducted Pacific plate.

Caulfield, J. T.; Turner, S. P.; Dosseto, A.; Beier, C.

2008-12-01

108

Improved spatial resolution for U-series dating of opal at Yucca Mountain, Nevada, USA, using ion-microprobe and microdigestion methods  

USGS Publications Warehouse

Two novel methods of in situ isotope analysis, ion microprobe and microdigestion, were used for 230Th/U and 234U/238U dating of finely laminated opal hemispheres formed in unsaturated felsic tuff at Yucca Mountain, Nevada, proposed site for a high-level radioactive waste repository. Both methods allow analysis of layers as many as several orders of magnitude thinner than standard methods using total hemisphere digestion that were reported previously. Average growth rates calculated from data at this improved spatial resolution verified that opal grew at extremely slow rates over the last million years. Growth rates of 0.58 and 0.69 mm/m.y. were obtained for the outer 305 and 740 ??m of two opal hemispheres analyzed by ion microprobe, and 0.68 mm/m.y. for the outer 22 ??m of one of these same hemispheres analyzed by sequential microdigestion. These Pleistocene growth rates are 2 to 10 times slower than those calculated for older secondary calcite and silica mineral coatings deposited over the last 5 to 10 m.y. dated by the U-Pb method and may reflect differences between Miocene and Pleistocene seepage flux. The microdigestion data also imply that opal growth rates may have varied over the last 40 k.y. These data are the first indication that growth rates and associated seepage in the proposed repository horizon may correlate with changes in late Pleistocene climate, involving faster growth during wetter, cooler climates (glacial maximum), slower growth during transition climates, and no growth during the most arid climate (modern). Data collected at this refined spatial scale may lead to a better understanding of the hydrologic variability expected within the thick unsaturated zone at Yucca Mountain over the time scale of interest for radioactive waste isolation. ?? 2004 Elsevier Ltd.

Paces, J.B.; Neymark, L.A.; Wooden, J.L.; Persing, H.M.

2004-01-01

109

Radioactive iodine uptake  

MedlinePLUS

... the testing center so that the amount of radioactivity in the thyroid gland can be measured. This ... The amount of radioactivity is very small, and there have been no documented side effects. The amount of iodine used is less than ...

110

Radioactive Decay 1. Background  

E-print Network

Radioactive Decay 1. Background It is well known that many nuclei are unstable and are transformed into other nuclear species by means of either alpha decay or beta decay. The rate at which those radioactive on the number N of radioactive nuclei in the sample and also on the probability for each nucleus to decay

Elster, Charlotte

111

Procedures for radioactive I-131  

SciTech Connect

Details of the radioactive I-131 administration and radiation safety considerations are presented. Topics covered include patient survey, radioactive labelling, levels in patients containing radioactivity, hospital discharge of radioactive patients, and nursing procedures.

Sharma, S.C. (Univ. of Louisville, KY (USA))

1988-12-01

112

Radioactivity and food  

SciTech Connect

Two topics relating to radioactivity and food are discussed: food irradiation for preservation purposes, and food contamination from radioactive substances. Food irradiation involves the use of electromagnetic energy (x and gamma rays) emitted by radioactive substances or produced by machine in order to destroy the insects and microorganisms present and prevent germination. The sanitary and economic advantages of treating food in this way are discussed. Numerous studies have confirmed that under strictly controlled conditions no undesirable changes take place in food that has been irradiated nor is radioactivity induced. Reference is made to the accident at the Chernobyl nuclear power station, which aroused public concern about irradiated food. The events surrounding the accident are reviewed, and its consequences with regard to contamination of different foods with radioactive substances, particularly iodine-131 and cesium-137, are described. Also discussed are the steps that have been taken by different international organizations to set limits on acceptable radioactivity in food.15 references.

Olszyna-Marzys, A.E. (Laboratorio Unificado de Control de Alimentos y Medicamentos (LUCAM) (Guatemala))

1990-03-01

113

Radioactive Waste: 1. Radioactive waste from your lab is  

E-print Network

Radioactive Waste: 1. Radioactive waste from your lab is collected by the RSO. 2. Dry radioactive waste must be segregated by isotope. 3. Liquid radioactive waste must be separated by isotope. 4. Liquid frequently and change them if contaminated. 5. Use radioactive waste container to collect the waste. 6. Check

Jia, Songtao

114

Radioactive Waste Management Basis  

SciTech Connect

The purpose of this Radioactive Waste Management Basis is to describe the systematic approach for planning, executing, and evaluating the management of radioactive waste at LLNL. The implementation of this document will ensure that waste management activities at LLNL are conducted in compliance with the requirements of DOE Order 435.1, Radioactive Waste Management, and the Implementation Guide for DOE Manual 435.1-1, Radioactive Waste Management Manual. Technical justification is provided where methods for meeting the requirements of DOE Order 435.1 deviate from the DOE Manual 435.1-1 and Implementation Guide.

Perkins, B K

2009-06-03

115

Radioactivity in Food and the Environment, 2005  

E-print Network

........................................................................................................................... 9 . Disposals of radioactive waste .............................................................................................. 0 .. Radioactive waste disposal from nuclear sites............................................ .. Radioactive waste disposal at sea

116

Porosity of the melting zone and variations in the solid mantle upwelling rate beneath Hawaii: Inferences from {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria  

SciTech Connect

Measurements of {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria in a suite of tholeiitic-to-basanitic lavas provide estimates of porosity, solid mantle upwelling rate and melt transport times beneath Hawaii. The observation that ({sup 230}Th/{sup 238}U) {gt} 1 indicates that garnet is required as a residual phase in the magma sources for all of the lavas. Both chromatographic porous flow and dynamic melting of a garnet peridotite source can adequately explain the combined U-Th-Ra and U-Pa data for these Hawaiian basalts. For chromatographic porous flow, the calculated maximum porosity in the melting zone ranges from 0.3--3% for tholeiites and 0.1--1% for alkali basalts and basanites, and solid mantle upwelling rates range from 40 to 100 cm/yr for tholeiites and from 1 to 3 cm/yr for basanites. For dynamic melting, the escape or threshold porosity is 0.5--2% for tholeiites and 0.1--0.8% for alkali basalts and basanites, and solid mantle upwelling rates range from 10 to 30 cm/yr for tholeiites and from 0.1 to 1 cm/yr for basanites. Assuming a constant melt productivity, calculated total melt fractions range from 15% for the tholeiitic basalts to 3% for alkali basalts and basanites.

Sims, K.W.W.; DePaolo, D.J.; Murrell, M.T.; Baldridge, W.S.; Goldstein, S.; Clague, D.; Jull, M.

1999-12-01

117

Radioactive waste management  

Microsoft Academic Search

The management of radioactive waste is a very important part of the nuclear industry. The future of the nuclear power industry depends to a large extent on the successful solution of the perceived or real problems associated with the disposal of both low-level waste (LLW) and high-level waste (HLW). All the activities surrounding the management of radioactive waste are reviewed.

N. Tsoulfanidis; R. G. Cochran

1991-01-01

118

Radioactive Wastes. Revised.  

ERIC Educational Resources Information Center

This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. This booklet deals with the handling, processing and disposal of radioactive wastes. Among the topics discussed are: The Nature of Radioactive Wastes; Waste Management; and Research and Development. There are…

Fox, Charles H.

119

Radioactive waste disposal package  

DOEpatents

A radioactive waste disposal package comprising a canister for containing vitrified radioactive waste material and a sealed outer shell encapsulating the canister. A solid block of filler material is supported in said shell and convertible into a liquid state for flow into the space between the canister and outer shell and subsequently hardened to form a solid, impervious layer occupying such space.

Lampe, Robert F. (Bethel Park, PA)

1986-01-01

120

Radioactivity in PffP Radioactivity  

E-print Network

-"heavy water", which can be used in nuclear reactors. #12;Physics review (cont'd) Even less common and Pierre Curie: discover many properties of uranium, new elements and coin the term "radioactivity." #12 at a distance of 100 meters. · Tokyo water at one plant in April 2011 had an activity of ~200 Bq/liter warnings

Browder, Tom

121

Natural and man-made radioactivity in soils and plants around the research reactor of Inshass.  

PubMed

The specific radioactivities of the U-series, 232Th, 137Cs and 40K were measured in soil samples around the Inshass reactor in Cairo, using a gamma-ray spectrometer with a HpGe detector. The alpha activity of 238U, 234U and 235U was measured in the same soil samples by surface barrier detectors after radiochemical separation and the obtained results were compared with the specific activities determined by gamma-measurements. The alpha-activity of 238Pu, 239+240Pu, 241Am, 242Cm and 244Cm was measured after radiochemical separation by surface barrier detectors for both soil and plant samples. Then beta-activity of 241Pu was measured using liquid scintillation spectrometry. PMID:9776618

Higgy, R H; Pimpl, M

1998-12-01

122

Dynamic radioactive particle source  

DOEpatents

A method and apparatus for providing a timed, synchronized dynamic alpha or beta particle source for testing the response of continuous air monitors (CAMs) for airborne alpha or beta emitters is provided. The method includes providing a radioactive source; placing the radioactive source inside the detection volume of a CAM; and introducing an alpha or beta-emitting isotope while the CAM is in a normal functioning mode.

Moore, Murray E.; Gauss, Adam Benjamin; Justus, Alan Lawrence

2012-06-26

123

(Revised May 25, 2012) Radioactivity  

E-print Network

(Revised May 25, 2012) Radioactivity GOALS (1) To gain a better understanding of naturally and/or energy in the process. This process is called radioactive decay or, simply, radioactivity be dangerous if the radioactive material is ingested into the body. Beta particles are simply electrons. Gamma

Collins, Gary S.

124

238U-230Th-226Ra disequilibria in dacite and plagioclase from the 2004-2005 eruption of Mount St. Helens: Chapter 36 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006  

USGS Publications Warehouse

230Th)/(232Th) measured for the 1980s reference suite. However, (230Th)/(232Th) for plagioclase separates for dome samples erupted during October and November 2004 are significantly different from corresponding whole-rock values, which suggests that a large fraction (>30 percent) of crystals in each sample are foreign to the host liquid. Furthermore, plagioclase in the two 2004 samples have U-series characteristics distinct from each other and from plagioclase in dacite erupted in 1982, indicating that (1) the current eruption must include a component of crystals (and potentially associated magma) that were not sampled by the 1980-86 eruption, and (2) dacite magmas erupted only a month apart in 2004 contain different populations of crystals, indicating that this foreign component is highly heterogeneous within the 2004-5 magma reservoir.

Cooper, Kari M.; Donnelly, Carrie T.

2008-01-01

125

Biodegradation of radioactive animals  

SciTech Connect

The two most common disposal alternatives for animals contaminated with radioactive materials are incineration and burial. For most of the country burial has entailed shipping the carcasses to a commercial disposal facility at Barnwell, South Carolina, where it was landfilled along with other solid radioactive waste. Unfortunately, since 30 June 1994, this facility accepts waste generated by the states of the Southeast Compact only. Therefore, burial is no longer an option for most of the country`s generators and incineration is an option only for those institutions which have, or have access to, an incinerator that is permitted to burn radioactive materials and that accepts animal carcasses with de minimis levels of radioactive contaminants. Many institutions, especially those in congested urban areas where the public does not support incineration, do not have viable outlets for radioactive animal carcasses. Interim, on-site storage poses problems of its own. Biodegradation of animal carcasses with dermestid beetles is an inexpensive approach to this waste management problem. 7 refs., 3 figs., 1 tab.

Party, N.; Party, E.; Wilkerson, A. [Rockefeller Univ., NY (United States)] [and others

1995-06-01

126

Radioactivity in food crops  

SciTech Connect

Published levels of radioactivity in food crops from 21 countries and 4 island chains of Oceania are listed. The tabulation includes more than 3000 examples of 100 different crops. Data are arranged alphabetically by food crop and geographical origin. The sampling date, nuclide measured, mean radioactivity, range of radioactivities, sample basis, number of samples analyzed, and bibliographic citation are given for each entry, when available. Analyses were reported most frequently for /sup 137/Cs, /sup 40/K, /sup 90/Sr, /sup 226/Ra, /sup 228/Ra, plutonium, uranium, total alpha, and total beta, but a few authors also reported data for /sup 241/Am, /sup 7/Be, /sup 60/Co, /sup 55/Fe, /sup 3/H, /sup 131/I, /sup 54/Mn, /sup 95/Nb, /sup 210/Pb, /sup 210/Po, /sup 106/Ru, /sup 125/Sb, /sup 228/Th, /sup 232/Th, and /sup 95/Zr. Based on the reported data it appears that radioactivity from alpha emitters in food crops is usually low, on the order of 0.1 Bq.g/sup -1/ (wet weight) or less. Reported values of beta radiation in a given crop generally appear to be several orders of magnitude greater than those of alpha emitters. The most striking aspect of the data is the great range of radioactivity reported for a given nuclide in similar food crops with different geographical origins.

Drury, J.S.; Baldauf, M.F.; Daniel, E.W.; Fore, C.S.; Uziel, M.S.

1983-05-01

127

Radioactive mixed waste disposal  

SciTech Connect

Various types of waste have been generated during the 50-year history of the Hanford Site. Regulatory changes in the last 20 years have provided the emphasis for better management of these wastes. Interpretations of the Atomic Energy Act of 1954 (AEA), the Resource Conservation and Recovery Act of 1976 (RCRA), and the Hazardous and Solid Waste Amendments (HSWA) have led to the definition of radioactive mixed wastes (RMW). The radioactive and hazardous properties of these wastes have resulted in the initiation of special projects for the management of these wastes. Other solid wastes at the Hanford Site include low-level wastes, transuranic (TRU), and nonradioactive hazardous wastes. This paper describes a system for the treatment, storage, and disposal (TSD) of solid radioactive waste.

Jasen, W.G.; Erpenbeck, E.G.

1993-02-01

128

Viewer Makes Radioactivity "Visible"  

NASA Technical Reports Server (NTRS)

Battery operated viewer demonstrates feasibility of generating threedimensional visible light simulations of objects that emit X-ray or gamma rays. Ray paths are traced for two pinhold positions to show location of reconstructed image. Images formed by pinholes are converted to intensified visible-light images. Applications range from radioactivity contamination surveys to monitoring radioisotope absorption in tumors.

Yin, L. I.

1983-01-01

129

Radioactivity: A Natural Phenomenon.  

ERIC Educational Resources Information Center

Discussed is misinformation people have on the subject of radiation. The importance of comparing artificial source levels of radiation to natural levels is emphasized. Measurements of radioactivity, its consequences, and comparisons between the risks induced by radiation in the environment and from artificial sources are included. (KR)

Ronneau, C.

1990-01-01

130

TABLE OF RADIOACTIVE ELEMENTS.  

SciTech Connect

For those chemical elements which have no stable nuclides with a terrestrial isotopic composition, the data on radioactive half-lives and relative atomic masses for the nuclides of interest and importance have been evaluated and the recommended values and uncertainties are listed.

HOLDEN,N.E.

2001-06-29

131

Teaching ``radioactivity'' through research  

Microsoft Academic Search

We have supervised a variety of undergraduates (primarily first year students in engineering or physical science) in explorations of the radioactive decay of actinides. Perhaps it is surprising that, by combining radiochemical techniques and physical measurements (radiation detection and spectroscopy), most of the students have discovered new information about the nuclides they have studied. For example, one of the projects

Henry Griffin; Krish Rengan

2004-01-01

132

Environmental Radioactivity, Temperature, and Precipitation.  

ERIC Educational Resources Information Center

Reports that environmental radioactivity levels vary with temperature and precipitation and these effects are due to radon. Discusses the measurement of this environmental radioactivity and the theory behind it. (JRH)

Riland, Carson A.

1996-01-01

133

Environmental Radioactivity in the Faroes  

E-print Network

I Radioactivity in the Faroes in 1979 A. Aarkrog and J. Lippeit Risø National Laboratory, DK-4000 Roskilde, Denmark July 1980 #12;Risø-R-422 ENVIRONMENTAL RADIOACTIVITY IN THE FAROES IN 1979 A. Aarkroo and J. Lippert Abstract. Measurements of fallout radioactivity in the Faroes

134

Process for treating radioactive waste  

Microsoft Academic Search

A process for treating radioactive sludge waste wasted in a nuclear power plant comprises the steps of pulverizing the radioactive sludge waste into dry powder which is combustible, burning the powder into ashes, and pelletizing the ashes. The radioactive sludge waste including granular ion-exchange resins, powder resins, filter sludge, etc. is reduced in volume by subjecting to combustion.

M. Hirano; S. Horiuchi

1985-01-01

135

Teaching ``radioactivity'' through research  

NASA Astrophysics Data System (ADS)

We have supervised a variety of undergraduates (primarily first year students in engineering or physical science) in explorations of the radioactive decay of actinides. Perhaps it is surprising that, by combining radiochemical techniques and physical measurements (radiation detection and spectroscopy), most of the students have discovered new information about the nuclides they have studied. For example, one of the projects involved study of ^239U (the gateway to the heavy elements); many of its prior ? ray assignments are incorrect. This work required a source of neutrons (a reactor) and high resolution spectrometers as well as radiochemical skills and an understanding of fission vs. neutron capture. Other studies can be done with readily available natural radioactive materials. We will summarize a variety of projects, including ones that do not require specialized resources, albeit with lower probability of new results.

Griffin, Henry; Rengan, Krish

2004-10-01

136

Disposal of radioactive waste  

SciTech Connect

A method and apparatus for charging radioactive waste into a disposable steel drum having a plug type lid. The drum is sealed to a waste dispenser and the dispenser closure and lid are withdrawn into the dispenser in back-to-back manner. Before reclosing the dispenser the drum is urged closer to it so that on restoring the dispenser closure to the closed position the lid is pressed into the drum opening.

Critchley, R.J.; Swindells, R.J.

1984-05-01

137

Radioactivity in interplanetary dust  

Microsoft Academic Search

Most of the radioactivity in interplanetary dust in the region of the Earth's orbit results from interactions with solar protons. The most abundant nuclides having half-lives longer than a few hours in a dust of chondritic composition are Co56, Fe55, Al26, Mn53, Co55, C14, Na22, and Co57. The measurement of ratios of dust radionuclides can provide a means of measuring

John T. Wasson

1963-01-01

138

Table of radioactive elements  

SciTech Connect

As has been the custom in the past, the Commission publishes a table of relative atomic masses and halflives of selected radionuclides. The information contained in this table will enable the user to calculate the atomic weight for radioactive materials with a variety of isotopic compositions. The atomic masses have been taken from the 1984 Atomic Mass Table. Some of the halflives have already been documented.

Holden, N.E.

1985-01-01

139

Natural radioactivity and radiological hazards assessment of bone-coal from a vanadium mine in central China  

NASA Astrophysics Data System (ADS)

A comprehensive utilization project of bone-coal in a vanadium mine was proposing in recent years in central China. Based on the analysis of 31 representative bone-coal samples from 9 boreholes at various depth drilled in planning initial minery, the average activity concentrations of 238U, 226Ra, 232Th and 40K were determined in the range of 196.4-653.3 Bq/kg, 200.2-564.4 Bq/kg, 9.4-64.6 Bq/kg and 71.5-345.4 Bq/kg, respectively. The major natural radionuclides were identified as U-series nuclides with the activity concentrations obviously higher than common coal. The estimated absorbed dose rates in the air varied between 107.1 and 310.5 nGy/h. The averaged external annual effective dose due to the radioactivity in the bone-coal was predicted as 0.37 mSv/a, and the main contribution is 87.5% for U-series. The radium equivalent activity, the external and internal indices of most of the samples were shown with high values of an unacceptable level, which indicated the bone-coal would carry a considerable radiation hazard to the workers and the local individuals. The hazard of radon inhalation should be focused during mining and following processes. Further radiological assessment should be carried out as the natural radioactivity in the bone-coal would be technically enriched during the combustion process of the bone-coal and utilization of the byproducts.

Huang, Yan-Jun; Chen, Chao-Feng; Huang, Yi-Chao; Yue, Qi-Jian; Zhong, Chun-Ming; Tan, Cheng-Jun

2015-02-01

140

ASSESSMENT OF RADIOACTIVE AND NON-RADIOACTIVE CONTAMINANTS FOUND IN LOW LEVEL RADIOACTIVE WASTE STREAMS  

SciTech Connect

This paper describes and presents the findings from two studies undertaken for the European Commission to assess the long-term impact upon the environment and human health of non-radioactive contaminants found in various low level radioactive waste streams. The initial study investigated the application of safety assessment approaches developed for radioactive contaminants to the assessment of nonradioactive contaminants in low level radioactive waste. It demonstrated how disposal limits could be derived for a range of non-radioactive contaminants and generic disposal facilities. The follow-up study used the same approach but undertook more detailed, disposal system specific calculations, assessing the impacts of both the non-radioactive and radioactive contaminants. The calculations undertaken indicated that it is prudent to consider non-radioactive, as well as radioactive contaminants, when assessing the impacts of low level radioactive waste disposal. For some waste streams with relatively low concentrations of radionuclides, the potential post-closure disposal impacts from non-radioactive contaminants can be comparable with the potential radiological impacts. For such waste streams there is therefore an added incentive to explore options for recycling the materials involved wherever possible.

R.H. Little, P.R. Maul, J.S.S. Penfoldag

2003-02-27

141

PERSPECTIVE: Fireworks and radioactivity  

NASA Astrophysics Data System (ADS)

Katharina Breitenecker Fireworks, the one and only amongst all other pyrotechnic applications, have pleased the hearts and minds of billions of people all over the world for almost 1000 years. Even though pyrotechnics were originally developed in order to fulfil the needs of military purposes, fireworks began to form a unique part of the cultural heritage of many countries, presumably starting in ancient China during the Song Dynasty (960-1280 AD). Festivities like New Year's Eve, national holidays or activities like music festivals and parish fairs are crowned by a firework display. Fireworks have traditionally been associated with Independence Day celebrations, like 4 July in the United States, Guy Fawkes' Night (5 November) in Britain, or Bastille Day (14 July) in France. Much of Chinese culture is associated with the use of firecrackers to celebrate the New Year and other important occasions. The fascination of fireworks and firecrackers is due to the brilliant colours and booming noises, which have a universal appeal to our basic senses [1]. The basic components of any traditional civil firework is black powder, a mixture of about 75% potassium nitrate, 15% charcoal, and about 10% sulfur [2]. Without the addition of a colouring agent, the fuel would provide an almost white light. Therefore, several metal salts can be added to cause colourful luminescence upon combustion. In general barium is used to obtain a green coloured flame, strontium for red, copper for blue and sodium for yellow [2, 3]. The use of pyrotechnics has raised issues pertaining to health concerns. The health aspects are not only restricted to injuries by accidental ignition of certain devices. Moreover, several recent works identified fireworks and pyrotechnics as causing environmental pollution, which might result in a potential hazard concerning health aspects. The fundamental problem in this respect is that all chemicals used are dispersed in the environment by combustion. This includes both reaction products and unburnt constituents of a pyrotechnic mixture. One major environmental concern in pyrotechnics focuses on the emission of heavy metals. This is the topic discussed in the article by Georg Steinhauser and Andreas Musilek in this issue [4]. A possible interrelationship between respiratory effects and fireworks emissions of barium-rich aerosols was also raised last year [5]. In recent years the potential hazard of naturally occurring radioactive material has become of importance to the scientific community. Naturally occurring radionuclides can be of terrestrial or cosmological origin. Terrestrial radionuclides were present in the presolar cloud that later contracted in order to build our solar system. These radionuclides—mainly heavy metals—and their non-radioactive isotopes are nowadays fixed in the matrix of the Earth's structure. Usually, their percentage is quite small compared to their respective stable isotopes—though there are exceptions like in the case of radium. The problem with environmental pollution due to naturally occurring radioactive material begins when this material is concentrated due to mining and milling, and later further processed [6]. Environmental pollution due to radioactive material goes back as far as the Copper and Iron Ages, when the first mines were erected in order to mine ores (gold, silver, copper, iron, etc), resulting in naturally occurring radioactive material being set free with other dusts into the atmosphere. So where is the link between pyrotechnics and radioactivity? In this article presented by Georg Steinhauser and Andreas Musilek [4], the pyrotechnic ingredients barium nitrate and strontium nitrate are explored with respect to their chemical similarities to radium. The fundamental question, therefore, was whether radium can be processed together with barium and strontium. If so, the production and ignition of these pyrotechnic ingredients could cause atmospheric pollution with radium aerosols, resulting in potential negative health effects, unless an extensive purification of the ores is

Breitenecker, Katharina

2009-09-01

142

Radioactivity distribution at MAFF  

NASA Astrophysics Data System (ADS)

A detailed account on the distribution of radioactive nuclei in the vacuum system of the planned Munich Accelerator for Fission Fragments (MAFF) located at the FRM-II research reactor is presented. Tools used for the simulation of spacial and temporal distribution of radionuclides are explained. The latter allows for a detailed activity budget as well as estimates for the mass-separated ion yields at MAFF. Additionally, a concept to reduce the activity release from the MAFF slit system due to surface sputtering is presented. It is shown, that the use of low-density carbon foam, as a surface coating, reduces sputtering by orders of magnitude.

Nebel, F.; Szerypo, J.; Zech, E.; Faestermann, T.; Groetzschel, R.; Groß, M.; Habs, D.; Krücken, R.; Maier-Komor, P.; Thirolf, P. G.; Yakushev, A.

2006-09-01

143

Simpler radioactive wastewater processing.  

PubMed

José Canga Rodríguez, key account manager, Pharmaceutical and Life Sciences, EnviroChemie, and Volker Luh, CEO of EnviroDTS, describe the development, and recent successful application, of a new technology for dealing safely and effectively with the radioactive "wastewater" generated by patients who have undergone radiotherapy in nuclear medicine facilities. The BioChroma process provides what is reportedly not only a more flexible means than traditional "delay and decay" systems of dealing with this "by-product" of medical treatment, but also one that requires less plant space, affords less risk of leakage or cross-contamination, and is easier to install. PMID:22368885

Rodríguez, José Canga; Luh, Volker

2011-11-01

144

Radioactive waste material disposal  

DOEpatents

The invention is a process for direct conversion of solid radioactive waste, particularly spent nuclear fuel and its cladding, if any, into a solidified waste glass. A sacrificial metal oxide, dissolved in a glass bath, is used to oxidize elemental metal and any carbon values present in the waste as they are fed to the bath. Two different modes of operation are possible, depending on the sacrificial metal oxide employed. In the first mode, a regenerable sacrificial oxide, e.g., PbO, is employed, while the second mode features use of disposable oxides such as ferric oxide. 3 figs.

Forsberg, C.W.; Beahm, E.C.; Parker, G.W.

1995-10-24

145

Radioactive Decay of Candium  

NSDL National Science Digital Library

In this simulation, learners use M&M™ candy to explore radioactive isotope decay. Learners pour out a bag of candy and count and record the number of candy pieces that have "decayed" or show the print side up. Learners get to consume the "decayed atoms." Then, they will shake the bag again and recount the decay. Learners will continue shaking, counting and consuming until all the atoms have decayed, and then graph the results. This activity is a great introduction to half-life and nuclear decay.

The Science House

2014-01-28

146

Radioactive waste material disposal  

DOEpatents

The invention is a process for direct conversion of solid radioactive waste, particularly spent nuclear fuel and its cladding, if any, into a solidified waste glass. A sacrificial metal oxide, dissolved in a glass bath, is used to oxidize elemental metal and any carbon values present in the waste as they are fed to the bath. Two different modes of operation are possible, depending on the sacrificial metal oxide employed. In the first mode, a regenerable sacrificial oxide, e.g., PbO, is employed, while the second mode features use of disposable oxides such as ferric oxide.

Forsberg, Charles W. (155 Newport Dr., Oak Ridge, TN 37830); Beahm, Edward C. (106 Cooper Cir., Oak Ridge, TN 37830); Parker, George W. (321 Dominion Cir., Knoxville, TN 37922)

1995-01-01

147

Radioactively labelled porphyrin derivatives  

NASA Astrophysics Data System (ADS)

Radioactive labelling of guanidine-bearing tetraphenylporphyrin and Dy—texaphyrin with selected radionuclides (166Ho and 90Y) is described. A basic characterisation of studied porphyrin and texaphyrin, including their behaviour in a wide range of pH values and data on holmium and yttrium complexation with these compounds was probed using UV-VIS absorption spectrometry. The labelling yield of these macrocyclic molecules depends on the pH of the reaction mixture, metal: ligand ratio and time of incubation. Optimal reaction conditions for formation of porphyrin and texaphyrin radioactive complexes were determined by thin layer chromatography with the detection of ?- activity. The ability of porphyrin derivatives to bind anions was examined as well. Our experiments were focused on perrhenate ion (ReO4 -) because radiopharmaceuticals labelled with isotopes 186Re and 188Re play an important role in therapy of numerous tumour diseases. The possibility of applying ReO4 - anion directly for labelling purposes, without the necessity of its reduction to lower oxidation state, was not proved.

Koní?ová, R.; Ernestová, M.; Jedináková-K?ížová, V.; Král, V.

2003-01-01

148

Radioactive waste processing apparatus  

DOEpatents

Apparatus for use in processing radioactive waste materials for shipment and storage in solid form in a container is disclosed. The container includes a top, and an opening in the top which is smaller than the outer circumference of the container. The apparatus includes an enclosure into which the container is placed, solution feed apparatus for adding a solution containing radioactive waste materials into the container through the container opening, and at least one rotatable blade for blending the solution with a fixing agent such as cement or the like as the solution is added into the container. The blade is constructed so that it can pass through the opening in the top of the container. The rotational axis of the blade is displaced from the center of the blade so that after the blade passes through the opening, the blade and container can be adjusted so that one edge of the blade is adjacent the cylindrical wall of the container, to insure thorough mixing. When the blade is inside the container, a substantially sealed chamber is formed to contain vapors created by the chemical action of the waste solution and fixant, and vapors emanating through the opening in the container.

Nelson, Robert E. (Lombard, IL); Ziegler, Anton A. (Darien, IL); Serino, David F. (Maplewood, MN); Basnar, Paul J. (Western Springs, IL)

1987-01-01

149

Process and apparatus for treating radioactive waste  

Microsoft Academic Search

This patent describes a process for treating radioactive waste. This process consists of: 1.) providing radioactive waste comprising at least one of radioactive liquid waste and radioactive waste slurry each of solid matter and water; 2.) conducting the radioactive waste to a first waste feed tank; 3.) Evaporating a portion of the water in an evaporator; 4.) withdrawing the evaporated

S. Horiuchi; M. Hirano; T. Saito

1986-01-01

150

RSSC RADIOACTIVE WASTE DISPOSAL 08/2011 7-1 RADIOACTIVE WASTE DISPOSAL  

E-print Network

RSSC RADIOACTIVE WASTE DISPOSAL 08/2011 7-1 CHAPTER 7 RADIOACTIVE WASTE DISPOSAL PAGE I. Radioactive Waste Disposal ............................................................................................ 7-2 II. Radiation Control Technique #2 Instructions for Preparation of Radioactive Waste

Slatton, Clint

151

CHERNOBYL DATA BASE ENVIRONMENTAL RADIOACTIVITY  

E-print Network

MAY 1990 THE NORDIC CHERNOBYL DATA BASE ENVIRONMENTAL RADIOACTIVITY MEASUREMENTS Nordic liaison CHERNOBYL DATA BASE ENVIRONMENTAL RADIOACTIVITY MEASUREMENTS Final Report of the NKA Project AKT 242 Edited the members of the working group. Graphic Systems AB, Malmo 1990 #12;111 ABSTRACT. The NORDIC CHERNOBYL DATA

152

Induced radioactivity in LDEF components  

Microsoft Academic Search

A systematic study of the induced radioactivity of the Long Duration Exposure Facility (LDEF) is being carried out in order to gather information about the low earth orbit radiation environment and its effects on materials. The large mass of the LDEF spacecraft, its stabilized configuration, and long mission duration have presented an opportunity to determine space radiation-induced radioactivities with a

B. A. Harmon; G. J. Fishman; T. A. Parnell; C. E. Laird

1992-01-01

153

Radioactive Sources in Chemical Laboratories  

Microsoft Academic Search

Radioactive sources including all radioactive materials exceeding exemption levels have to be registered in national databases according to international standards based on the recommendations ICRP 60 and a proper licensing should take place as described for example in the 96\\/29\\/EURATOM. In spite of that, unregistered sources could be found, usually due to the fact that the owner is not aware

Helena Jan

154

Low Radioactivity in CANDLES  

SciTech Connect

CANDLES is the project to search for double beta decay of 48Ca by using CaF2 crystals. Double beta decay of 48Ca has the highest Q value among all nuclei whose double beta decay is energetically allowed. This feature makes the study almost background free and becomes important once the study is limited by the backgrounds. We studied double beta decays of 48Ca by using ELEGANTS VI detector system which features CaF2(Eu) crystals. We gave the best limit on the lifetime of neutrino-less double beta decay of 48Ca although further development is vital to reach the neutrino mass of current interest for which CANDLES is designed. In this article we present how CANDLES can achieve low radioactivity, which is the key for the future double beta decay experiment.

Kishimoto, T.; Ogawa, I.; Hazama, R.; Yoshida, S.; Umehara, S.; Matsuoka, K.; Sakai, H.; Yokoyama, D.; Mukaida, K.; Ichihara, K.; Tatewaki, Y.; Kishimoto, K.; Hirano, Y.; Yanagisawa, A.; Ajimura, S. [Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 (Japan)

2005-09-08

155

Radioactivity in Food and the Environment, 1995  

E-print Network

.................................................................................................................................................. 11 2. Disposals of radioactive waste...................................................................................................................... 11 2.1 Radioactive waste disposal from, and in, sites on land ........................................................................ 11 2.2 Solid radioactive waste disposal at sea

156

Radioactivity in Food and the Environment, 2006  

E-print Network

.............................................................................................................................22 1.2 Disposals of radioactive waste ................................................................................................................22 1.2.1 Radioactive waste disposal from nuclear sites.......................................................................................................25 1.2.5 Solid radioactive waste disposal at sea

157

Radioactivity in Food and the Environment, 2009  

E-print Network

............................................................................................................................22 1.2 Disposals of radioactive waste ................................................................................................................22 1.2.1 Radioactive waste disposal from nuclear sites ..............................................................................................................27 1.2.5 Solid radioactive waste disposal at sea

158

Radioactivity in Food and the Environment, 1998  

E-print Network

.................................................................................................................15 1.2 Disposals of radioactive waste ......................................................................................17 1.2.1 Radioactive waste disposal from nuclear sites.......................................................17 1.2.2 Solid radioactive waste disposal at sea

159

Radioactivity in Food and the Environment, 1999  

E-print Network

........................................................................................................................... 15 1.2 Disposals of radioactive waste.............................................................................................. 15 1.2.1 Radioactive waste disposal from nuclear sites ........................................................... 15 1.2.2 Past disposals of solid radioactive waste at sea

160

Radioactive waste processing apparatus  

DOEpatents

Apparatus for use in processing radioactive waste materials for shipment and storage in solid form in a container is disclosed. The container includes a top, and an opening in the top which is smaller than the outer circumference of the container. The apparatus includes an enclosure into which the container is placed, solution feed apparatus for adding a solution containing radioactive waste materials into the container through the container opening, and at least one rotatable blade for blending the solution with a fixing agent such as cement or the like as the solution is added into the container. The blade is constructed so that it can pass through the opening in the top of the container. The rotational axis of the blade is displaced from the center of the blade so that after the blade passes through the opening, the blade and container can be adjusted so that one edge of the blade is adjacent the cylindrical wall of the container, to insure thorough mixing. When the blade is inside the container, a substantially sealed chamber is formed to contain vapors created by the chemical action of the waste solution and fixant, and vapors emanating through the opening in the container. The chamber may be formed by placing a removable extension over the top of the container. The extension communicates with the apparatus so that such vapors are contained within the container, extension and solution feed apparatus. A portion of the chamber includes coolant which condenses the vapors. The resulting condensate is returned to the container by the force of gravity.

Nelson, R.E.; Ziegler, A.A.; Serino, D.F.; Basnar, P.J.

1985-08-30

161

"LOW-LEVEL " RADIOACTIVE WASTE  

E-print Network

Internationally, nuclear power waste is categorized as high, intermediate, or low-level waste. In the U.S. nuclear power waste is either high or so-called “low-level, ” with what other nations consider “intermediate ” included in the “low–level ” category. In the US, “low-level ” radioactive waste is defined in the Low Level Radioactive Waste Policy Act of 1980 and its 1985 amendments (P.L. 99-240) as radioactive material that is: • not high-level radioactive waste or irradiated nuclear fuel • not uranium, thorium or other ore tailings or waste from extraction and concentration for source material content • classified as “low-level ” radioactive waste by the US Nuclear Regulatory Commission. “Low-level ” radioactive waste is divided into four classes—A, B, C and Greater Than Class C (GTCC) —with A being the least concentrated and C being more concentrated and requiring longer institutional controls (10 CFR 61.55). Classes A, B and C are utility liabilities but states were intended to provide disposal. 1 As of the 1985 Low Level Radioactive Amendments Act, Greater Than Class C waste was designated a Department of Energy responsibility, and that waste is often stored with the high level irradiated fuel at nuclear power reactors, both awaiting a final repository.

Is Not; Low Risk

162

Star formation and extinct radioactivities  

NASA Technical Reports Server (NTRS)

An assessment is made of the evidence for the existence of now-extinct radioactivities in primitive solar system material, giving attention to implications for the early stages of sun and solar system formation. The characteristics of possible disturbances in dense molecular clouds which can initiate the formation of cloud cores is discussed, with emphasis on these disturbances able to generate fresh radioactivities. A one-solar mass red giant star on the asymptotic giant branch appears to have been the best candidate to account for the short-lived extinct radioactivities in the early solar system.

Cameron, A. G. W.

1984-01-01

163

Star formation and extinct radioactivities  

SciTech Connect

An assessment is made of the evidence for the existence of now-extinct radioactivities in primitive solar system material, giving attention to implications for the early stages of sun and solar system formation. The characteristics of possible disturbances in dense molecular clouds which can initiate the formation of cloud cores is discussed, with emphasis on these disturbances able to generate fresh radioactivities. A one-solar mass red giant star on the asymptotic giant branch appears to have been the best candidate to account for the short-lived extinct radioactivities in the early solar system. 36 references.

Cameron, A.G.W.

1984-11-01

164

Final disposal of radioactive waste  

NASA Astrophysics Data System (ADS)

In this paper the origin and properties of radioactive waste as well as its classification scheme (low-level waste - LLW, intermediate-level waste - ILW, high-level waste - HLW) are presented. The various options for conditioning of waste of different levels of radioactivity are reviewed. The composition, radiotoxicity and reprocessing of spent fuel and their effect on storage and options for final disposal are discussed. The current situation of final waste disposal in a selected number of countries is mentioned. Also, the role of the International Atomic Energy Agency with regard to the development and monitoring of international safety standards for both spent nuclear fuel and radioactive waste management is described.

Freiesleben, H.

2013-06-01

165

Numerical dating of a Late Quaternary spit-shoreline complex at the northern end of Silver Lake playa, Mojave Desert, California: A comparison of the applicability of radiocarbon, luminescence, terrestrial cosmogenic nuclide, electron spin resonance, U-series and amino acid racemization methods  

USGS Publications Warehouse

A Late Quaternary spit-shoreline complex on the northern shore of Pleistocene Lake Mojave of southeastern California, USA was studied with the goal of comparing accelerator mass spectrometry (AMS) radiocarbon, luminescence, electron spin resonance (ESR), terrestrial cosmogenic radionuclide (TCN) surface exposure, amino acid racemization (AAR) and U-series dating methods. The pattern of ages obtained by the different methods illustrates the complexity of processes acting in the lakeshore environment and highlights the utility of a multi-method approach. TCN surface exposure ages (mostly ???20-30 ka) record the initial erosion of shoreline benches, whereas radiocarbon ages on shells (determined in this and previous studies) within the spit, supported by AAR data, record its construction at fluctuating lake levels from ???16 to 10 ka. Luminescence ages on spit sediment (???6-7 ka) and ESR ages on spit shells (???4 ka) are anomalously young relative to radiocarbon ages of shells within the same deposits. The significance of the surprisingly young luminescence ages is not clear. The younger ESR ages could be a consequence of post-mortem enrichment of U in the shells. High concentrations of detrital thorium in tufa coating spit gravels inhibited the use of single-sample U-series dating. Detailed comparisons such as this provide one of the few means of assessing the accuracy of Quaternary dating techniques. More such comparisons are needed. ?? 2007 Elsevier Ltd and INQUA.

Owen, L.A.; Bright, Jordon; Finkel, R.C.; Jaiswal, M.K.; Kaufman, D.S.; Mahan, S.; Radtke, U.; Schneider, J.S.; Sharp, W.; Singhvi, A.K.; Warren, C.N.

2007-01-01

166

Radioactive decay data tables  

SciTech Connect

The estimation of radiation dose to man from either external or internal exposure to radionuclides requires a knowledge of the energies and intensities of the atomic and nuclear radiations emitted during the radioactive decay process. The availability of evaluated decay data for the large number of radionuclides of interest is thus of fundamental importance for radiation dosimetry. This handbook contains a compilation of decay data for approximately 500 radionuclides. These data constitute an evaluated data file constructed for use in the radiological assessment activities of the Technology Assessments Section of the Health and Safety Research Division at Oak Ridge National Laboratory. The radionuclides selected for this handbook include those occurring naturally in the environment, those of potential importance in routine or accidental releases from the nuclear fuel cycle, those of current interest in nuclear medicine and fusion reactor technology, and some of those of interest to Committee 2 of the International Commission on Radiological Protection for the estimation of annual limits on intake via inhalation and ingestion for occupationally exposed individuals.

Kocher, D.C.

1981-01-01

167

Radioactive Waste Management  

NASA Astrophysics Data System (ADS)

Issues related to the management of radioactive wastes are presented with specific emphasis on high-level wastes generated as a result of energy and materials production using nuclear reactors. The final disposition of these high-level wastes depends on which nuclear fuel cycle is pursued, and range from once-through burning of fuel in a light water reactor followed by direct disposal in a geologic repository to more advanced fuel cycles (AFCs) where the spent fuel is reprocessed or partitioned to recover the fissile material (primarily 235U and 239Pu) as well as the minor actinides (MAs) (neptunium, americium, and curium) and some long-lived fission products (e.g., 99Tc and 129I). In the latter fuel cycle, the fissile materials are recycled through a reactor to produce more energy, the short-lived fission products are vitrified and disposed of in a geologic repository, and the minor actinides and long-lived fission products are converted to less radiotoxic or otherwise stable nuclides by a process called transmutation. The advantages and disadvantages of the various fuel cycle options and the challenges to the management of nuclear wastes they represent are discussed.

Baisden, P. A.; Atkins-Duffin, C. E.

168

Consumer Products Containing Radioactive Materials  

MedlinePLUS

... require that these devices be registered or licensed. Granite Countertops Granite can release the radioactive gas radon into the ... released can vary considerably from one type of granite to another, the radon concentrations in most kitchens ...

169

Radioactive waste material melter apparatus  

DOEpatents

An apparatus for preparing metallic radioactive waste material for storage is disclosed. The radioactive waste material is placed in a radiation shielded enclosure. The waste material is then melted with a plasma torch and cast into a plurality of successive horizontal layers in a mold to form a radioactive ingot in the shape of a spent nuclear fuel rod storage canister. The apparatus comprises a radiation shielded enclosure having an opening adapted for receiving a conventional transfer cask within which radioactive waste material is transferred to the apparatus. A plasma torch is mounted within the enclosure. A mold is also received within the enclosure for receiving the melted waste material and cooling it to form an ingot. The enclosure is preferably constructed in at least two parts to enable easy transport of the apparatus from one nuclear site to another. 8 figs.

Newman, D.F.; Ross, W.A.

1990-04-24

170

Analysis methods for airborne radioactivity.  

E-print Network

??High-resolution gamma-ray spectrometry is an analysis method well suitable for monitoring airborne radioactivity. Many of the natural radionuclides and a majority of anthropogenic nuclides are… (more)

Ala-Heikkilä, Jarmo J

2008-01-01

171

Radioactive waste material melter apparatus  

DOEpatents

An apparatus for preparing metallic radioactive waste material for storage is disclosed. The radioactive waste material is placed in a radiation shielded enclosure. The waste material is then melted with a plasma torch and cast into a plurality of successive horizontal layers in a mold to form a radioactive ingot in the shape of a spent nuclear fuel rod storage canister. The apparatus comprises a radiation shielded enclosure having an opening adapted for receiving a conventional transfer cask within which radioactive waste material is transferred to the apparatus. A plasma torch is mounted within the enclosure. A mold is also received within the enclosure for receiving the melted waste material and cooling it to form an ingot. The enclosure is preferably constructed in at least two parts to enable easy transport of the apparatus from one nuclear site to another.

Newman, Darrell F. (Richland, WA); Ross, Wayne A. (Richland, WA)

1990-01-01

172

Radioactive stilbene derivatives in radioimmunoassay  

SciTech Connect

Novel radioactive stilbene derivatives marked with iodine 125 or 131 possessing an iodine acceptor group and marked with iodine 125 or 131 and their preparation and antigens obtained therefrom and a process for preparing said antigens.

Jouquey, A.; Touyer, G.

1985-07-16

173

Radioactive waste disposal and geology  

Microsoft Academic Search

This book is an excellent, well-presented treatise on the nature and types of radioactive wastes, disposal alternatives and strategies, radionuclide release and disposal models, geologic repositories, natural analogues, subsea-bed options, and low-level wastes. The authors provide national and international perspectives on radioactive waste disposal problems. They carefully dissected each issue, treating its pros and cons equally. Moreover, they is careful

K. B. Krauskopf

1988-01-01

174

Environmental Radioactivity in the North Atlantic Region.  

E-print Network

Environmental Radioactivity in the North Atlantic Region. The Faroe Islands and Greenland included ENVIRONMENTAL RADIOACTIVITY IN THE NORTH ATLANTIC REGION. THE FAROE ISLANDS AND GREENLAND INCLUDED. 1984 A Radioactivity, Monaco Abstract. Measurements of fallout radioactivity in the North Atlantic region including

175

A literature Review on Radioactivity Transfer to  

E-print Network

Ã? *ISE Rise-R-450 A literature Review on Radioactivity Transfer to Plants and Soil Ole John Nielsen ON RADIOACTIVITY TRANSFER TO PLANTS AND SOIL Ole John Nielsen Abstract. The literature on transfer of radioactivity SYMBOLS 99 #12;- 5 - 1. PREFACE The report reviews literature on radioactivity transfer to plants and soil

176

Storage depot for radioactive material  

DOEpatents

Vertical drilling of cylindrical holes in the soil, and the lining of such holes, provides storage vaults called caissons. A guarded depot is provided with a plurality of such caissons covered by shielded closures preventing radiation from penetrating through any linear gap to the atmosphere. The heat generated by the radioactive material is dissipated through the vertical liner of the well into the adjacent soil and thus to the ground surface so that most of the heat from the radioactive material is dissipated into the atmosphere in a manner involving no significant amount of biologically harmful radiation. The passive cooling of the radioactive material without reliance upon pumps, personnel, or other factor which might fail, constitutes one of the most advantageous features of this system. Moreover this system is resistant to damage from tornadoes or earthquakes. Hermetically sealed containers of radioactive material may be positioned in the caissons. Loading vehicles can travel throughout the depot to permit great flexibility of loading and unloading radioactive materials. Radioactive material can be shifted to a more closely spaced caisson after ageing sufficiently to generate much less heat. The quantity of material stored in a caisson is restricted by the average capacity for heat dissipation of the soil adjacent such caisson.

Szulinski, Milton J. (Richland, WA)

1983-01-01

177

Distribution of low-level natural radioactivity in a populated marine region of the Eastern Mediterranean Sea.  

PubMed

The levels of natural radioactivity have been evaluated in the water column of an eastern Mediterranean region (Saronikos Gulf), with respect to the relevant environmental parameters. A novel methodology was used for the determination of natural radionuclides, which substitutes the time-consuming radiochemical analysis, based on an in situ sample preconcentration using ion-selective manganese fibres placed on pumping systems. With regard to the results obtained, (238)U-series radionuclides were found at the same level or lower than those observed previously in Mediterranean regions indicating the absence of technologically enhanced naturally occurring radioactive material (TENORM) activities in the area. Similar results were observed for the (232)Th-series radionuclides and (40)K in the water column in comparison with the relevant literature on the Mediterranean Sea. The calculated ratios of (238)U-(232)Th and (40)K-(232)Th verified the lack of TENORM contribution in the Saronikos Gulf. Finally, a rough estimation was attempted concerning the residence times of fresh water inputs from a treatment plant of domestic wastes (Waste Water Treatment Plant of Psitalia) showing that fresh waters need a maximum of 15.7±7.6 d to be mixed with the open sea water. PMID:22539533

Evangeliou, Nikolaos; Florou, Heleny; Kritidis, Panayotis

2012-12-01

178

Activity concentration of natural radioactive nuclides in nonmetallic industrial raw materials in Japan.  

PubMed

Natural materials such as rock, ore, and clay, containing natural radioactive nuclides are widely used as industrial raw materials in Japan. If these are high concentrations, the workers who handle the material can be unknowingly exposed to radiation at a high level. In this study, about 80 nonmetallic natural materials frequently used as industrial raw materials in Japan were comprehensively collected from several industrial companies, and the activity concentrations of (238)U series, (232)Th series and (40)K in the materials was determined by ICP-MS (inductively-coupled plasma mass spectrometer) and gamma ray spectrum analyses. Effective doses to workers handling them were estimated by using methods for dose estimation given in the RP 122. We found the activity concentrations to be lower than the critical values defined by regulatory requirements as described in the IAEA Safety Guide. The maximum estimated effective dose to workers handling these materials was 0.16 mSv y(-1), which was lower than the reference level (1-20 mSv y(-1)) for existing situation given in the ICRP Publ.103. PMID:25046866

Iwaoka, Kazuki; Tabe, Hiroyuki; Yonehara, Hidenori

2014-11-01

179

Process for treating radioactive waste  

Microsoft Academic Search

N-beta-(Aminoethyl)-gamma-aminopropyltrimethoxysilane (NH2(CH2)2NH(CH2)3SI(OCH3)3) as a silane coupling agent and SiO(2 -x)(ONa)x\\/2(OH)x\\/2 as colloidal silica are mixed into a radioactive liquid waste containing sodium sulfate as a main component, coming from a boiling water-type, nuclear power plant as an effluent. The resulting mixed radioactive liquid waste is supplied into a vessel provided with a rotating shaft with blades. The rotating shaft is

K. Chino; F. Kawamura; M. Kikuchi; H. Yusa

1982-01-01

180

Induced radioactivity in LDEF components  

NASA Technical Reports Server (NTRS)

A systematic study of the induced radioactivity of the Long Duration Exposure Facility (LDEF) is being carried out in order to gather information about the low earth orbit radiation environment and its effects on materials. The large mass of the LDEF spacecraft, its stabilized configuration, and long mission duration have presented an opportunity to determine space radiation-induced radioactivities with a precision not possible before. Data presented include preliminary activities for steel and aluminum structural samples, and activation subexperiment foils. Effects seen in the data show a clear indication of the trapped proton anisotropy in the South Atlantic Anomaly and suggest contributions from different sources of external radiation fluxes.

Harmon, B. A.; Fishman, G. J.; Parnell, T. A.; Laird, C. E.

1992-01-01

181

Radioactive waste problems in Russia  

Microsoft Academic Search

The collapse of the former Soviet Union, with the consequent shift to a market driven economy and demilitarisation, has had a profound effect on the nuclear and associated industries. The introduction of tighter legislation to control the disposal of radioactive wastes has been delayed and the power and willingness of the various governmental bodies responsible for its regulation is in

O. Bridges; J. W. Bridges

1995-01-01

182

Radioactivity and the Biology Teacher  

ERIC Educational Resources Information Center

Discusses minimum necessary nuclear fundamentals of radioactive isotopes such as levels of activity, specific activity and the use of carrier materials. Corrections that need to be taken into account in using an isotope to obtain a valid result are also described and statistics for a valid result are included. (BR)

Hornsey, D. J.

1974-01-01

183

Process for treating radioactive wastes  

Microsoft Academic Search

An aqueous solution containing granular ion exchange resin and filter aid as a radioactive waste generated from a nuclear power plant is supplied to the casing of a centrifugal film dryer. The dryer comprises a casing, a rotating shaft inserted in the casing , rotating blades fixed to the rotating shaft within the casing, and a heating means for heating

K. Chino; E. Ga; S. Horiuchi; M. Kikuchi; A. Oda

1981-01-01

184

Radioactivity in bottled mineral waters  

Microsoft Academic Search

Consumption of bottled mineral water is a growing practice and is sometimes a necessity rather than a choice. In this work, a study of the radioactive content of a wide selection of commercial bottled mineral waters for human intake was carried out. The origins of the analyzed waters were very different, coming from various locations in France, Portugal and Spain.

A Mart??n Sánchez; M. P Rubio Montero; V Gómez Escobar; M Jurado Vargas

1999-01-01

185

RadioActive101 Practices  

ERIC Educational Resources Information Center

In keeping with the overarching RadioActive101 (RA101) spirit and ethos, this report is the product of collaborative and joined-up thinking from within the European consortium spread across five countries. As such, it is not simply a single voice reporting on the experiences and knowledge gained during the project. Rather it is a range of…

Brites, Maria José; Ravenscroft, Andrew; Dellow, James; Rainey, Colin; Jorge, Ana; Santos, Sílvio Correia; Rees, Angela; Auwärter, Andreas; Catalão, Daniel; Balica, Magda; Camilleri, Anthony F.

2014-01-01

186

Radioactivity and nuclear waste disposal  

SciTech Connect

The nature and consequences of ionising radiation are examined at the physical, biological and medical level. Accounts are given of the origins of radioactive waste in various countries around the world. Also investigated are the present policies adopted by various nations in their processing, storage and disposal practices. The presentation of the scientific basis allows discussion of the options for methods of disposal.

Lau, F.

1987-01-01

187

Undiagnosed Illnesses and Radioactive Warfare  

Microsoft Academic Search

The internal contamination with depleted uranium (DU) isotopes was detected in British, Canadian, and United States Gulf War veterans as late as nine years after inhalational exposure to radioactive dust in the Persian Gulf War I. DU iso- topes were also identified in a Canadian veteran's autopsy samples of lung, liver, kidney, and bone. In soil samples from Kosovo, hundreds

Asaf Durakoviæ

188

High-Level Radioactive Waste.  

ERIC Educational Resources Information Center

Presents a method to calculate the amount of high-level radioactive waste by taking into consideration the following factors: the fission process that yields the waste, identification of the waste, the energy required to run a 1-GWe plant for one year, and the uranium mass required to produce that energy. Briefly discusses waste disposal and…

Hayden, Howard C.

1995-01-01

189

Radioactivity in Food and the Environment, 1997  

E-print Network

Radioactivity in Food and the Environment, 1997 RIFE - 3 1998 SCOTTISH ENVIRONMENT PROTECTION SCOTTISH ENVIRONMENT PROTECTION AGENCY Radioactivity in Food and the Environment, 1997 September 1998 #12;2 Preface This report presents the results of surveillance programmes for radioactivity carried out

190

Ris-R-571(EX) Environmental Radioactivity  

E-print Network

Risø-R-571(EX) Environmental Radioactivity in the North Atlantic Region Including the Faroe Islands Radioactivity RisoR5; in the North Atlantic Region Including the Faroe Islands and Greenland. 1988 and 1989 A;Abstract Measurements of fallout radioactivity in the North Atlantic region including Faroe Islands

191

I>KO>OOOO2& Environmental Radioactivity  

E-print Network

I>KO>OOOO2& Risø-R-564 IKJJj Environmental Radioactivity in the North Atlantic Region Including;Environmental Radioactivity *** in the North Atlantic Region Including the Faroe Islands and Greenland. 1987 A, Norway ** International Laboratory of Marine Radioactivity, Monaco Risø National Laboratory, DK-4000

192

Radioactive Target Detection Using Wireless Sensor Network  

E-print Network

Chapter 31 Radioactive Target Detection Using Wireless Sensor Network Tonglin Zhang Abstract The detection of radioactive target is becoming more important recently in public safety and national security can simultaneously detect and locate the radioactive target in the area. Our simulation results have

Zhang, Tonglin

193

Environmental Radioactivity in Denmark in 1983  

E-print Network

Dh?5ooobl Risø-Rr509 Environmental Radioactivity in Denmark in 1983 A. Aarkrog, S. Boelskifte, L, Denmark June 1984 #12;ERRATA to RIS�-R-509 Environmental Radioactivity in Denmark in 1983. p 16 Table 3,4.3., and 4.4.5. show the tritium content in sea water. #12;Risø-R-509 ENVIRONMENTAL RADIOACTIVITY IN DENMARK

194

Riso-R-489LK Environmental Radioactivity  

E-print Network

E ~ ~, ~ Riso-R-489·LK Environmental Radioactivity in Greenland in 1982 A. Aarkrog, Henning Roskilde, Denmark July 1963 #12;Risø-R-489 ENVIRONMENTAL RADIOACTIVITY IN GREENLAND IN 1982 A. Aarkrog Abstract. Measurements of fallout radioactivity in Greenland in 1982 are reported. Strontium-90 (and Cesium

195

Natural and Artificial Radioactivity of Potassium  

Microsoft Academic Search

THE question of the origin of the radioactivity of potassium has been much discussed in recent years1. The possibility, however, of producing new radioactive isotopes artificially has opened up a new line of attack on this problem. Quite recently Amaldi, D'Agostino, Fermi, Pontecorvo, Rasetti and Segrè2 have found that, by bombardment of potassium with neutrons, a new radioactive isotope of

G. Hevesy

1935-01-01

196

Laboratory Surveys when Working with Radioactive Materials  

E-print Network

Laboratory Surveys when Working with Radioactive Materials Procedure: 7.546 Created: 9/25/14 Version: 1.0 Revised: Environmental Health & Safety Page 1 of 6 A. Purpose Radioactive contamination and be surveyed every month in which radioactive materials in unsealed for are used. B. Applicability

Jia, Songtao

197

Radioactive Waste Management BasisApril 2006  

SciTech Connect

This Radioactive Waste Management Basis (RWMB) documents radioactive waste management practices adopted at Lawrence Livermore National Laboratory (LLNL) pursuant to Department of Energy (DOE) Order 435.1, Radioactive Waste Management. The purpose of this Radioactive Waste Management Basis is to describe the systematic approach for planning, executing, and evaluating the management of radioactive waste at LLNL. The implementation of this document will ensure that waste management activities at LLNL are conducted in compliance with the requirements of DOE Order 435.1, Radioactive Waste Management, and the Implementation Guide for DOE Manual 435.1-1, Radioactive Waste Management Manual. Technical justification is provided where methods for meeting the requirements of DOE Order 435.1 deviate from the DOE Manual 435.1-1 and Implementation Guide.

Perkins, B K

2011-08-31

198

Transmutation of radioactive nuclear waste  

Microsoft Academic Search

Lack of a safe disposal method for radioactive nuclear waste (RNW) is a problem of staggering proportion and impact. A typical LWR fission reactor will produce the following RNW in one year: minor actinides (i.e. ²³Np, ²²²³Am, ²³²Cm) 40 kg, long-lived fission products (i.e, Tc, ³Zr, ¹²I, ¹³Cs) 80 kg, short lived fission products (e.g. ¹³Cs, °Sr) 50kg and plutonium

A Toor; R Buck

2000-01-01

199

Measurement of natural radioactive nuclide concentrations in various metal ores used as industrial raw materials in Japan and estimation of dose received by workers handling them.  

PubMed

Natural resources such as ores and rocks contain natural radioactive nuclides at various concentrations. If these resources contain high concentrations of natural radioactive nuclides, workers handling them might be exposed to significant levels of radiation. Therefore, it is important to investigate the radioactive activity in these resources. In this study, concentrations of radioactive nuclides in Th, Zr, Ti, Mo, Mn, Al, W, Zn, V, and Cr ores used as industrial raw materials in Japan were investigated. The concentrations of (238)U and (232)Th were determined by inductively coupled plasma mass spectrometry (ICP-MS), while those of (226)Ra, (228)Ra, and (40)K were determined by gamma-ray spectrum. We found the concentrations of (238)U series, (232)Th series, and (40)K in Ti, Mo, Mn, Al, W, Zn, V, and Cr ores to be lower than the critical values defined by regulatory requirements as described in the International Atomic Energy Agency (IAEA) Safety Guide. The doses received by workers handling these materials were estimated by using methods for dose assessment given in a report by the European Commission. In transport, indoor storage, and outdoor storage scenarios, an effective dose due to the use of Th ore was above 4.3 x 10(-2)Sv y(-1), which was higher than that of the other ores. The maximum value of effective doses for other ores was estimated to be about 4.5 x 10(-4)Sv y(-1), which was lower than intervention exemption levels (1.0 x 10(-3)Sv y(-1)) given in International Commission of Radiological Protection (ICRP) Publication 82. PMID:19703725

Iwaoka, Kazuki; Tagami, Keiko; Yonehara, Hidenori

2009-11-01

200

Processes and timescales in the evolution of a chemically zoned trachyte: Fogo A, Sao Miguel, Azores  

Microsoft Academic Search

U-series disequilibria analyses have been combined with chemical and petrographic analyses in order to assess both the timescales and processes involved in the formation of the chemically zoned Fogo A trachytes. Least squares major element modelling demonstrates that the mafic trachytes could have evolved from a parental alkali basalt via trachybasalt with ~70% fractionation of augite (35–36%), plagioclase (23%), magnetite

E. Widom; H.-U. Schmincke; J. B. Gill

1992-01-01

201

Radioactive characterization of the main materials involved in the titanium dioxide production process and their environmental radiological impact.  

PubMed

A study about the distribution of several radionuclides from the uranium and the thorium series radionuclides along the production process of a typical NORM industry devoted to the production of titanium dioxide has been performed. With this end the activity concentrations in raw materials, final product, co-products, and wastes of the production process have been determined by both gamma-ray and alpha-particle spectrometry. The main raw material used in the studied process (ilmenite) presents activity concentrations of around 300 Bq kg(-1) for Th-series radionuclides and 100 Bq kg(-1) for the U-series ones. These radionuclides in the industrial process are distributed in the different steps of the production process according mostly to the chemical behaviour of each radioelement, following different routes. As an example, most of the radium remains associated with the un-dissolved material waste, with activity concentrations around 3 kBq kg(-1) of (228)Ra and around 1 kBq kg(-1) of (226)Ra, while the final commercial products (TiO2 pigments and co-products) contain negligible amounts of radioactivity. The obtained results have allowed assessing the possible public radiological impact associated with the use of the products and co-products obtained in this type of industry, as well as the environmental radiological impact associated with the solid residues and liquid generated discharges. PMID:23416226

Mantero, J; Gazquez, M J; Bolivar, J P; Garcia-Tenorio, R; Vaca, F

2013-06-01

202

Radioactivity levels in aerosol particles surrounding a large TENORM waste repository after application of preliminary restoration work.  

PubMed

In this paper, (238)U-series radionuclides have been analysed in particulate matter samples collected at a phosphogypsum stack system located near the city of Huelva (SW Spain) during the course of 1 year. The results have been compared to those collected at a reference (background) site located a few km away, in order to establish if the stack system provokes an increase in radionuclide exposure due to inhalation with particulate matter. The (222)Rn progeny, which is considered a very important contributor to the internal dose rate received by the population, was collected for 6 months. The results indicate that for several types of radionuclides there is a significant increase in the radioactivity adsorbed by the aerosol particles collected at phosphogypsum stacks. The isotope analysis indicates that this increment could be affected by the water vapour emissions from the factory, which contain high concentrations of these radionuclides. However, the majority of these radionuclides could not be detected at the background location. The corresponding dose increment estimated at the sampling point is, however, negligible. This fact is a consequence of the very small radionuclide concentration increment, together with relatively conservative nature of the occupational factor applied. Regarding the Rn progeny, no significant differences between either the collecting sites has been registered due to of the dominant wind regime at the sampling locations. PMID:17343897

Borrego, E; Mas, J L; Martín, J E; Bolívar, J P; Vaca, F; Aguado, J L

2007-05-01

203

Student Understanding of Ionizing Radiation and Radioactivity  

NSDL National Science Digital Library

This article describes how researchers identified specific difficulties students had with ionizing radiation and radioactivity using interviews. They also explore students' pre-instruction thoughts on these topics.

Prather, Edward E.; Harrington, Randal R.

2006-06-19

204

Radioactive Material Declaration Form Exhibit to the Radioactive Waste Manual (RWM)  

E-print Network

Radioactive Material Declaration Form Exhibit to the Radioactive Waste Manual (RWM) 12/5/2013 (form Declaration Form Exhibit to the Radioactive Waste Manual (RWM) 12/5/2013 (form date) SLAC-I-760-2A08Z-001 (RWM date) SLAC-I-760-2A08Z-001 (RWM number) Page 1 of 2 RADIOACTIVE MATERIAL DECLARATION FORM For RP use

Wechsler, Risa H.

205

Charge Breeding of Radioactive Ions  

E-print Network

Charge breeding is a technique to increase the charge state of ions, in many cases radioactive ions. The singly charged radioactive ions, produced in an isotope separator on-line facility, and extracted with a low kinetic energy of some tens of keV, are injected into a charge breeder, where the charge state is increased to Q. The transformed ions are either directed towards a dedicated experiment requiring highly charged ions, or post-accelerated to higher beam energies. In this paper the physics processes involved in the production of highly charged ions will be introduced, and the injection and extraction beam parameters of the charge breeder defined. A description of the three main charge-breeding methods is given, namely: electron stripping in gas jet or foil; external ion injection into an electron-beam ion source/trap (EBIS/T); and external ion injection into an electron cyclotron resonance ion source (ECRIS). In addition, some preparatory devices for charge breeding and practical beam delivery aspects ...

Wenander, F J C

2013-01-01

206

Radioactivity in the galactic plane  

NASA Technical Reports Server (NTRS)

The paper reports the detection of a large concentration of interstellar radioactivity during balloon-altitude measurements of gamma-ray energy spectra in the band between 0.02 and 12.27 MeV from galactic and extragalactic sources. Enhanced counting rates were observed in three directions towards the plane of the Galaxy; a power-law energy spectrum is computed for one of these directions (designated B 10). A large statistical deviation from the power law in a 1.0-FWHM interval centered near 1.16 MeV is discussed, and the existence of a nuclear gamma-ray line at 1.15 MeV in B 10 is postulated. It is suggested that Ca-44, which emits gamma radiation at 1.156 MeV following the decay of radioactive Sc-44, is a likely candidate for this line, noting that Sc-44 arises from Ti-44 according to explosive models of supernova nucleosynthesis. The 1.16-MeV line flux inferred from the present data is shown to equal the predicted flux for a supernova at a distance of approximately 3 kpc and an age not exceeding about 100 years.

Walraven, G. D.; Haymes, R. C.

1976-01-01

207

Induced radioactivity in LDEF components  

NASA Technical Reports Server (NTRS)

The systematics of induced radioactivity on the Long Duration Exposure Facility (LDEF) were studied in a wide range of materials using low level background facilities for detection of gamma rays. Approx. 400 samples of materials processed from structural parts of the spacecraft, as well as materials from onboard experiments, were analyzed at national facilities. These measurements show the variety of radioisotopes that are produced with half-lives greater than 2 wks, most of which are characteristic of proton induced reactions above 20 MeV. For the higher activity, long lived isotopes, it was possible to map the depth and directional dependences of the activity. Due to the stabilized configuration of the LDEF, the induced radioactivity data clearly show contributions from the anisotropic trapped proton flux in the South Atlantic Anomaly. This effect is discussed, along with evidence for activation by galactic protons and thermal neutrons. The discovery of Be-7 was made on leading side parts of the spacecraft, although this was though not to be related to the in situ production of radioisotopes from external particle fluxes.

Harmon, B. A.; Fishman, G. J.; Parnell, T. A.; Laird, C. E.

1991-01-01

208

Cosmic radioactivity and INTEGRAL results  

SciTech Connect

Gamma-ray lines from radioactive decay of unstable isotopes co-produced by nucleosynthesis in massive stars and supernova have been measured since more than thirty years. Over the past ten years, INTEGRAL complemented the first sky survey made by COMPTEL. The {sup 26}A1 isotope with 1 My decay time had been first direct proof of currently-ongoing nucleosynthesis in our Galaxy. This has now become a tool to study the ?My history of specific source regions, such as massive-star groups and associations in nearby regions which can be discriminated from the galactic-plane background, and the inner Galaxy, where Doppler shifted lines add to the astronomical information about bar and spiral structure. Recent findings suggest that superbubbles show a remarkable asymmetry, on average, in the spiral arms of our galaxy. {sup 60}Fe is co-produced by the sources of {sup 26}A1, and the isotopic ratio from their nucleosynthesis encodes stellar-structure information. Annihilation gamma-rays from positrons in interstellar space show a puzzling bright and extended source region central to our Galaxy, but also may be partly related to nucleosynthesis. {sup 56}Ni and {sup 44}Ti isotope gamma-rays have been used to constrain supernova explosion mechanisms. Here we report latest results using the accumulated multi-year database of INTEGRAL observations, and discuss their astrophysical interpretations, connecting to other traces of cosmic radioactivity and to other cosmic messengers.

Diehl, Roland [Max Planck Institut für Extraterrestrische Physik, D-85748 Garching, Germany and Excellence Cluster Origin and Evolution of the Universe', D-85748 Garching (Germany)

2014-05-02

209

Magic radioactivity of 252Cf  

E-print Network

We show that the sharp maximum corresponding to 107Mo in the fragment distribution of the 252Cf cold fission is actually a Sn-like radioactivity, similar to other decay processes in which magic nuclei are involved, namely alpha-decay and heavy cluster emission, also called Pb-like radioactivity. It turns out that the mass asymmetry degree of freedom has a key role in connecting initial Sn with the final Mo isotopes along the fission path. We suppose the cold rearrangement of nucleons within the framework of the two center shell model, in order to compute the cold valleys in the charge equilibrated fragmentation potential. The fission yields are estimated by using the semiclassical penetration approach. We consider five degrees of freedom, namely the inter-fragment distance, the shapes of fragments, the neck parameter and mass asymmetry. We found an isomeric minimum between the internal and external barriers. It turns out that the inner cold valley of the total potential energy is connected to the double magic isotope 132Sn

M. Mirea; D. S. Delion; A. Sandulescu

2010-03-31

210

Identifying Mixed Chemical and Radioactive Waste Mixed waste is: any waste material containing both radioactive materials  

E-print Network

Identifying Mixed Chemical and Radioactive Waste Mixed waste is: any waste material containing both as noted on the list, you do not have a mixed waste and it may be managed as a normal radioactive waste radioactive waste after initially dating the container, the hold for decay time is extended, but you cannot

Straight, Aaron

211

33. Radioactivity and radiation protection 1 33. RADIOACTIVITY AND RADIATION PROTECTION  

E-print Network

://pdg.lbl.gov) June 18, 2012 16:20 #12;2 33. Radioactivity and radiation protection tissue caused by different33. Radioactivity and radiation protection 1 33. RADIOACTIVITY AND RADIATION PROTECTION Revised radiation in a volume element of a specified material divided by the mass of this volume element. · Kerma, K

212

30. Radioactivity and radiation protection 1 30. RADIOACTIVITY AND RADIATION PROTECTION  

E-print Network

;2 30. Radioactivity and radiation protection caused by different radiation types R weighted with so30. Radioactivity and radiation protection 1 30. RADIOACTIVITY AND RADIATION PROTECTION Revised radiation in a volume element of a specified material divided by the mass of this volume element. · Kerma, K

213

30. Radioactivity and radiation protection 1 30. RADIOACTIVITY AND RADIATION PROTECTION  

E-print Network

30. Radioactivity and radiation protection 1 30. RADIOACTIVITY AND RADIATION PROTECTION Revised for the 2012 edition (pdg.lbl.gov) February 16, 2012 14:08 #12;2 30. Radioactivity and radiation protection tissue caused by different radiation types R weighted with so-called radiation weighting factors wR: HT

214

MARSAME Appendix B B. SOURCES OF BACKGROUND RADIOACTIVITY  

E-print Network

MARSAME Appendix B B. SOURCES OF BACKGROUND RADIOACTIVITY B.1 Introduction Background radioactivity can complicate the disposition decision for M&E. Background radioactivity may be the result of environmental radioactivity, inherent radioactivity, instrument noise, or some combination of the three. Special

215

Natural radioactivity in Italian ceramic tiles  

Microsoft Academic Search

and, therefore, reference is often made to radium instead of uranium (EC, 1999). The knowledge of the natural radioactivity of building materials is important for the determination of population exposure to radiations, as most of the people spend ~80% of their time indoors (UNSCEAR, 1993). High levels of radioactivity in construction materials can increase external and internal indoor exposure. Currently,

S. Righi; A. Albertazzi; R. Guerra; M. Jeyapandian; S. Verità

2009-01-01

216

Bioindicators for Monitoring Radioactive Pollution of the  

E-print Network

* IK s Dfc2looX|o Risø-R-443 Bioindicators for Monitoring Radioactive Pollution of the Marine-R-443 BIOINDICATORS FOR MONITORING RADIOACTIVE POLLUTION OF THE MARINE ENVIRONMENT Experiments Dahlgaard Abstract. Mussels (Mytilus edulis) are globally used as bio- indicators for pollution of coastal

217

Process for solidifying radioactive waste pellets  

Microsoft Academic Search

In storing of radioactive wastes by drying, pulverization and pelletizing, radioactive waste pellets are solidified with an alkali silicate solution as a filler, a substance having an action to harden the alkali silicate solution, and a substance having an action to absorb the water formed by the hardening reaction of the alkali silicate solution, or a substance having both actions

K. Funabashi; F. Kawamura; M. Kikuchi; H. Yusa

1985-01-01

218

Computed tomography of radioactive objects and materials  

Microsoft Academic Search

Computed tomography (CT) has been performed on a number of radioactive objects and materials. Several unique technical problems are associated with CT of radioactive specimens. These include general safety considerations, techniques to reduce background-radiation effects on CT images and selection criteria for the CT source to permit object penetration and to reveal accurate values of material density. In the present

B. D. Sawicka; R. V. Murphy; G. Tosello; P. W. Reynolds; T. Romaniszyn

1990-01-01

219

Pb-Radioactivity in superheavy elements  

E-print Network

The Pb-radioactivity in the superheavy mass region is studied within the frame work of PCM model,the calculation of Pb-Radioactivity looks favorably for the cluster decay studies in superheavy mass region as in the heavy mass region.

Sushil Kumar

2011-10-24

220

RADIOACTIVE WASTES--ORIGIN, HAZARDS AND TREATMENT  

Microsoft Academic Search

When energy is produced by nuclear fission, radioactive wastes also are ; obtained. These are formed in all steps from the mining of uranium ore to the ; operation of reactors. They also arise from the application of radioactive ; nuclides in industry and research. Due to the action of the radiation on the ; different organs in the human

Kinell

1962-01-01

221

Natural radioactivity in the Syrian environment  

Microsoft Academic Search

This study shows some results of the environmental monitoring program for assessment of radiation and background radioactivity in Syria. The average external gamma radiation exposure was found to be ? 94 ± 8 nGy h?1, changing slightly from one district to another. Measurements of natural radioactivity in different types of soil showed a correlation between the ambient gamma exposure levels

I. Othman; T. Yassine

1995-01-01

222

[Examination of radioactive contamination in foods].  

PubMed

Following the Fukushima nuclear plant accident in Mar. 2011, the examination of radioactive contamination in foods is being carried out in Nagoya. During the period between 30 Mar. 2011 and 31 Oct. 2012, a total of 300 food samples were collected and the concentrations of radioactive nuclides were determined by means of ?-ray spectrometry using a high-purity germanium semiconductor detector. The results of analysis indicate that the concentrations of radioactive iodine (I) and cesium (Cs) were below the regulatory limits. Radioactive I ((131)I) was detected in 7 samples which belonged to the categories of green and yellow vegetables and other vegetables. Radioactive Cs ((134)Cs and (137)Cs) was detected in 60 samples which belonged to the categories of rice and its processed products, potatoes and its processed products, nuts and seeds, green and yellow vegetables, other vegetables, fruits, mushrooms, fishes and shellfishes, processed sea foods, meat, milk and dairy products and other beverages. PMID:23676695

Miyazaki, Hitoshi; Tsuchiyama, Tomoyuki; Terada, Hisaya

2013-01-01

223

The safe disposal of radioactive wastes  

PubMed Central

A comprehensive review is given of the principles and problems involved in the safe disposal of radioactive wastes. The first part is devoted to a study of the basic facts of radioactivity and of nuclear fission, the characteristics of radioisotopes, the effects of ionizing radiations, and the maximum permissible levels of radioactivity for workers and for the general public. In the second part, the author describes the different types of radioactive waste—reactor wastes and wastes arising from the use of radioisotopes in hospitals and in industry—and discusses the application of the maximum permissible levels of radioactivity to their disposal and treatment, illustrating his discussion with an account of the methods practised at the principal atomic energy establishments. PMID:13374534

Kenny, A. W.

1956-01-01

224

Diverter assembly for radioactive material  

DOEpatents

A diverter assembly for diverting a pneumatically conveyed holder for a radioactive material between a central conveying tube and one of a plurality of radially offset conveying tubes includes an airtight container. A diverter tube having an offset end is suitably mounted in the container for rotation. A rotary seal seals one end of the diverter tube during and after rotation of the diverter tube while a spring biased seal seals the other end of the diverter tube which moves between various offset conveying tubes. An indexing device rotatably indexes the diverter tube and this indexing device is driven by a suitable drive. The indexing mechanism is preferably a geneva-type mechanism to provide a locking of the diverter tube in place. 3 figs.

Andrews, K.M.; Starenchak, R.W.

1988-04-11

225

Method for immobilizing radioactive iodine  

DOEpatents

Radioactive iodine, present as alkali metal iodides or iodates in an aqueous solution, is incorporated into an inert solid material for long-term storage by adding to the solution a stoichiometric amount with respect to the formation of a sodalite (3M.sub.2 O.3Al.sub.2 O.sub.3. 6SiO.sub.2.2MX, where M=alkali metal; X=I.sup.- or IO.sub.3.sup.-) of an alkali metal, alumina and silica, stirring the solution to form a homogeneous mixture, drying the mixture to form a powder, compacting and sintering the compacted powder at 1073 to 1373 K (800.degree. to 1100.degree. C.) for a time sufficient to form sodalite.

Babad, Harry (Richland, WA); Strachan, Denis M. (Richland, WA)

1980-01-01

226

40 CFR 227.30 - High-level radioactive waste.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false High-level radioactive waste. 227.30 Section 227.30 Protection... Definitions § 227.30 High-level radioactive waste. High-level radioactive waste means the aqueous waste resulting...

2010-07-01

227

40 CFR 147.3005 - Radioactive waste injection wells.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Radioactive waste injection wells. 147.3005...Mexico Tribes § 147.3005 Radioactive waste injection wells. Notwithstanding...of wells used to dispose of radioactive waste (as defined in 10 CFR...

2012-07-01

228

Rev August 2006 Radiation Safety Manual Section 14 Radioactive Waste  

E-print Network

Rev August 2006 Radiation Safety Manual Section 14 ­ Radioactive Waste Page 14-1 Section 14 Radioactive Waste Contents A. Proper Collection, Disposal, and Packaging and Putrescible Animal Waste.........................14-8 a. Non-Radioactive Animal Waste

Wilcock, William

229

40 CFR 147.3005 - Radioactive waste injection wells.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Radioactive waste injection wells. 147.3005...Mexico Tribes § 147.3005 Radioactive waste injection wells. Notwithstanding...of wells used to dispose of radioactive waste (as defined in 10 CFR...

2010-07-01

230

40 CFR 147.3005 - Radioactive waste injection wells.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Radioactive waste injection wells. 147.3005...Mexico Tribes § 147.3005 Radioactive waste injection wells. Notwithstanding...of wells used to dispose of radioactive waste (as defined in 10 CFR...

2013-07-01

231

40 CFR 227.30 - High-level radioactive waste.  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false High-level radioactive waste. 227.30 Section 227.30 Protection... Definitions § 227.30 High-level radioactive waste. High-level radioactive waste means the aqueous waste resulting...

2011-07-01

232

40 CFR 227.30 - High-level radioactive waste.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false High-level radioactive waste. 227.30 Section 227.30 Protection... Definitions § 227.30 High-level radioactive waste. High-level radioactive waste means the aqueous waste resulting...

2013-07-01

233

40 CFR 227.30 - High-level radioactive waste.  

Code of Federal Regulations, 2014 CFR

... 2014-07-01 false High-level radioactive waste. 227.30 Section 227.30 Protection... Definitions § 227.30 High-level radioactive waste. High-level radioactive waste means the aqueous waste resulting...

2014-07-01

234

40 CFR 147.3005 - Radioactive waste injection wells.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Radioactive waste injection wells. 147.3005...Mexico Tribes § 147.3005 Radioactive waste injection wells. Notwithstanding...of wells used to dispose of radioactive waste (as defined in 10 CFR...

2011-07-01

235

Science with radioactive beams: the alchemist's dream  

NASA Astrophysics Data System (ADS)

Nuclear science is being transformed by a new capacity to create beams of radioactive nuclei. Until now all of our knowledge of nuclear physics and the applications which flow from it has been derived from studies of radioactive decay and nuclear reactions induced by beams of the 283 stable or long-lived nuclear species we can find on Earth. Here we describe first how beams of radioactive nuclei can be created. The present status of nuclear physics is then reviewed before potential applications to nuclear physics, nuclear astrophysics, materials science, bio-medical, and environmental studies are described.

Gelletly, W.

2001-05-01

236

Antiprotonic Radioactive Atom for Nuclear Structure Studies  

NASA Astrophysics Data System (ADS)

A future experiment to synthesize antiprotonic radioactive nuclear ions is proposed for nuclear structure studies. Antiprotonic radioactive nuclear atom can be synthesized in a nested Penning trap where a cloud of antiprotons is prestored and slow radioactive nuclear ions are bunch-injected into the trap. By observing of the ratio of ?+ and ?- produced in the annihilation process, we can deduce the different abundance of protons and neutrons at the surface of the nuclei. The proposed method would provide a unique probe for investigating the nuclear structure of unstable nuclei.

Wada, M.; Yamazaki, Y.

2005-10-01

237

Radioactive anomaly discrimination from spectral ratios  

DOEpatents

A method for discriminating a radioactive anomaly from naturally occurring radioactive materials includes detecting a first number of gamma photons having energies in a first range of energy values within a predetermined period of time and detecting a second number of gamma photons having energies in a second range of energy values within the predetermined period of time. The method further includes determining, in a controller, a ratio of the first number of gamma photons having energies in the first range and the second number of gamma photons having energies in the second range, and determining that a radioactive anomaly is present when the ratio exceeds a threshold value.

Maniscalco, James; Sjoden, Glenn; Chapman, Mac Clements

2013-08-20

238

The Discovery of Artificial Radioactivity  

NASA Astrophysics Data System (ADS)

We reconstruct Frédéric Joliot and Irène Curie's discovery of artificial radioactivity in January 1934 based in part on documents preserved in the Joliot-Curie Archives in Paris, France. We argue that their discovery followed from the convergence of two parallel lines of research, on the neutron and on the positron, that were focused on a well-defined experimental problem, the nuclear transmutation of aluminum and other light elements. We suggest that a key role was played by a suggestion that Francis Perrin made at the seventh Solvay Conference at the end of October 1933, that the alpha-particle bombardment of aluminum produces an intermediate unstable isotope of phosphorus, which then decays by positron emission. We also suggest that a further idea that Perrin published in December 1933, and the pioneering theory of beta decay that Enrico Fermi also first published in December 1933, established a new theoretical framework that stimulated Joliot to resume the researches that he and Curie had interrupted after the Solvay Conference, now for the first time using a Geiger-Müller counter to detect the positrons emitted when he bombarded aluminum with polonium alpha particles.

Guerra, Francesco; Leone, Matteo; Robotti, Nadia

2012-03-01

239

Is radioactive decay really exponential?  

NASA Astrophysics Data System (ADS)

Radioactive decay of an unstable isotope is widely believed to be exponential. This view is supported by experiments on rapidly decaying isotopes but is more difficult to verify for slowly decaying isotopes. The decay of 14C can be calibrated over a period of 12550 years by comparing radiocarbon dates with dates obtained from dendrochronology. It is well known that this approach shows that radiocarbon dates of over 3000 years are in error, which is generally attributed to past variation in atmospheric levels of 14C. We note that predicted atmospheric variation (assuming exponential decay) does not agree with results from modelling, and that theoretical quantum mechanics does not predict exact exponential decay. We give mathematical arguments that non-exponential decay should be expected for slowly decaying isotopes and explore the consequences of non-exponential decay. We propose an experimental test of this prediction of non-exponential decay for 14C. If confirmed, a foundation stone of current dating methods will have been removed, requiring a radical reappraisal both of radioisotope dating methods and of currently predicted dates obtained using these methods.

Aston, P. J.

2012-03-01

240

Radioactive isotopes in solid state physics  

NASA Astrophysics Data System (ADS)

A wide range of solid state physics techniques is using radioactive ion beams, both from on-line and off-line separators. The different techniques can be roughly subdivided into two classes: one, including the hyperfine techniques like Mößbauer spectroscopy (MS), Perturbed Angular Correlation (PAC) spectroscopy, ?-NMR and the ion-beam technique of Emission Channeling (EC). They all crucially depend on the availability of radioactive isotopes with very specific decay properties. The second group comprises radio-tracer techniques which combine radioactive probe atoms with conventional semiconductor physics methods like Deep Level Transient Spectroscopy (DLTS), Capacitance Voltage measurements (CV), Hall-effect measurements or Photoluminescence Spectroscopy (PL). They are perfectly feasible without any radioactive probe atom, however, using such isotopes enables the unambiguous chemical identification of impurities. The present paper gives an overview on the potential of nuclear techniques by describing some typical experiments.

Forkel-Wirth, D.

1996-04-01

241

RADIOACTIVITY STANDARDS DISTRIBUTION PROGRAM FY 1977  

EPA Science Inventory

A program is described for the distribution of calibrated radioactive samples, as one function of EPA's quality assurance program for environmental radiation measurements. Included is a discussion of the objectives of the distribution program and a description of the preparation,...

242

RADIOACTIVITY STANDARDS DISTRIBUTION PROGRAM, 1978-1979  

EPA Science Inventory

A program for the distribution of calibrated radioactive samples, as one function of EPA's quality assurance program for environmental radiation measurements, is described. Included is a discussion of the objectives of the distribution program and a description of the preparation...

243

Radioactive isotopes in solid-state physics  

Microsoft Academic Search

Radioactive atoms have been used in solid-state physics and in material science for many decades. Besides their classical application as tracer for diffusion studies, nuclear techniques such as M\\\\\\

Manfred Deicher

2002-01-01

244

Principles for Sampling Airborne Radioactivity from Stacks  

SciTech Connect

This book chapter describes the special processes involved in sampling the airborne effluents from nuclear faciities. The title of the book is Radioactive Air Sampling Methods. The abstract for this chapter was cleared as PNNL-SA-45941.

Glissmeyer, John A.

2010-10-18

245

Overflow of Radioactive Water from K Basins  

SciTech Connect

This report documents the dose calculations for the postulated K Basin overflow accident using current methods to model the environmental doses for radioactive releases into the Columbia River and the air.

RITTMANN, P.D.

1999-10-06

246

Radioactive materials shipping cask anticontamination enclosure  

DOEpatents

An anticontamination device for use in storing shipping casks for radioactive materials comprising (1) a seal plate assembly; (2) a double-layer plastic bag; and (3) a water management system or means for water management.

Belmonte, Mark S. (Irwin, PA); Davis, James H. (Pittsburgh, PA); Williams, David A. (Pittsburgh, PA)

1982-01-01

247

The Current Radioactive Waste Management In Romania  

E-print Network

In 1957, Romania commissioned a Russian-designed VVR-S research reactor used for scientific activities and radioisotope production. This reactor is now planned for decommissioning. An American TRIGA-type research reactor has been in use since 1978. The first Canadian CANDU-6 type power reactor was commissioned in December 1996 and is in commercial operation. The radioactive waste management in Romania followed decentralized on-site strategies and implementation programs in different stages. The issue of a national policy and adequate integrated strategies becomes more and more a necessity in order to assure the safe management of all radioactive waste and provide public and environment protection at the levels recommended by international standards. A national organization, responsible for radioactive waste management, is a possible option in the future. The current radioactive waste management practices on the nuclear sites in Romania, and the projects for the fuel cycle waste m...

V. Andrei; F. Glodeanu; I. Rotaru; T. Chirica

2000-01-01

248

Radioactivity on the Montenegrin Coast, Yugoslavia  

Microsoft Academic Search

Environmental radioactivity has been investigated on the Montenegrin Coast (Yugoslavia). Radioactivity was measured on 14\\u000a beaches and 5 hinterland localities by a method of in situ gamma-spectrometry. At each measuring site two photon countings\\u000a were performed — in ground and above it. Specific activities of40K,232Th,238U,137Cs and corresponding exposure rates were then obtained from gamma-spectra and appropriate radiation field models. The

P. Vukoti?; G. I. Borisov; V. V. Kuzmi?; N. Antovi?; S. Dap?evi?; V. V. Uvarov; V. M. Kulakov

1998-01-01

249

Vitrification of hazardous and radioactive wastes  

SciTech Connect

Vitrification offers many attractive waste stabilization options. Versatility of waste compositions, as well as the inherent durability of a glass waste form, have made vitrification the treatment of choice for high-level radioactive wastes. Adapting the technology to other hazardous and radioactive waste streams will provide an environmentally acceptable solution to many of the waste challenges that face the public today. This document reviews various types and technologies involved in vitrification.

Bickford, D.F.; Schumacher, R.

1995-12-31

250

Transport of Radioactive Material by Alpha Recoil  

SciTech Connect

The movement of high-specific-activity radioactive particles (i.e., alpha recoil) has been observed and studied since the early 1900s. These studies have been motivated by concerns about containment of radioactivity and the protection of human health. Additionally, studies have investigated the potential advantage of alpha recoil to effect separations of various isotopes. This report provides a review of the observations and results of a number of the studies.

Icenhour, A.S.

2005-05-19

251

Radioactivity and X-rays Applications and health effects  

E-print Network

Radioactivity and X-rays Applications and health effects by Thormod Henriksen #12;Preface as the release of radioactivity from reactor accidents and fallout from nuclear explosions in the atmosphere ­ 7 Chapter 2. What is radioactivity page 8 ­ 27 Chapter 3. Radioactive decay laws page 28 ­ 35

Sahay, Sundeep

252

Sorting and disposal of hazardous laboratory Radioactive waste  

E-print Network

Sorting and disposal of hazardous laboratory waste Radioactive waste Solid radioactive waste or in a Perspex box. Liquid radioactive waste collect in a screw-cap plastic bottle, ½ or 1 L size. Place bottles in a tray to avoid spill Final disposal of both solid and radioactive waste into the yellow barrel

Maoz, Shahar

253

s.haszeldine@ed.ac.uk Radioactive waste Cumbria 6, 7 Sept 2012 1 Geological disposal of radioactive  

E-print Network

s.haszeldine@ed.ac.uk Radioactive waste Cumbria 6, 7 Sept 2012 1 Geological disposal of radioactive_and_Copeland.html #12;Nuclear power s.haszeldine@ed.ac.uk Radioactive waste Cumbria 6, 7 Sept 2012 2 First civil nuclear #12;Keeping hot fuel on the surface for 50-150 years s.haszeldine@ed.ac.uk Radioactive waste Cumbria 6

254

CHAPTER 5-RADIOACTIVE WASTE MANAGEMENT  

SciTech Connect

The ore pitchblende was discovered in the 1750's near Joachimstal in what is now the Czech Republic. Used as a colorant in glazes, uranium was identified in 1789 as the active ingredient by chemist Martin Klaproth. In 1896, French physicist Henri Becquerel studied uranium minerals as part of his investigations into the phenomenon of fluorescence. He discovered a strange energy emanating from the material which he dubbed 'rayons uranique.' Unable to explain the origins of this energy, he set the problem aside. About two years later, a young Polish graduate student was looking for a project for her dissertation. Marie Sklodowska Curie, working with her husband Pierre, picked up on Becquerel's work and, in the course of seeking out more information on uranium, discovered two new elements (polonium and radium) which exhibited the same phenomenon, but were even more powerful. The Curies recognized the energy, which they now called 'radioactivity,' as something very new, requiring a new interpretation, new science. This discovery led to what some view as the 'golden age of nuclear science' (1895-1945) when countries throughout Europe devoted large resources to understand the properties and potential of this material. By World War II, the potential to harness this energy for a destructive device had been recognized and by 1939, Otto Hahn and Fritz Strassman showed that fission not only released a lot of energy but that it also released additional neutrons which could cause fission in other uranium nuclei leading to a self-sustaining chain reaction and an enormous release of energy. This suggestion was soon confirmed experimentally by other scientists and the race to develop an atomic bomb was on. The rest of the development history which lead to the bombing of Hiroshima and Nagasaki in 1945 is well chronicled. After World War II, development of more powerful weapons systems by the United States and the Soviet Union continued to advance nuclear science. It was this defense application that formed the basis for the commercial nuclear power industry.

Marra, J.

2010-05-05

255

Undiagnosed illnesses and radioactive warfare.  

PubMed

The internal contamination with depleted uranium (DU) isotopes was detected in British, Canadian, and United States Gulf War veterans as late as nine years after inhalational exposure to radioactive dust in the Persian Gulf War I. DU isotopes were also identified in a Canadian veteran's autopsy samples of lung, liver, kidney, and bone. In soil samples from Kosovo, hundreds of particles, mostly less than 5 microm in size, were found in milligram quantities. Gulf War I in 1991 resulted in 350 metric tons of DU deposited in the environment and 3-6 million grams of DU aerosol released into the atmosphere. Its legacy, Gulf War disease, is a complex, progressive, incapacitating multiorgan system disorder. The symptoms include incapacitating fatigue, musculoskeletel and joint pains, headaches, neuropsychiatric disorders, affect changes, confusion, visual problems, changes of gait, loss of memory, lymphadenopathies, respiratory impairment, impotence, and urinary tract morphological and functional alterations. Current understanding of its etiology seems far from being adequate. After the Afghanistan Operation Anaconda (2002), our team studied the population of Jalalabad, Spin Gar, Tora Bora, and Kabul areas, and identified civilians with the symptoms similar to those of Gulf War syndrome. Twenty-four-hour urine samples from 8 symptomatic subjects were collected by the following criteria: 1) the onset of symptoms relative to the bombing raids; 2) physical presence in the area of the bombing; and 3) clinical manifestations. Control subjects were selected among the sympotom-free residents in non-targeted areas. All samples were analyzed for the concentration and ratio of four uranium isotopes, (234)U, (235)U, (236)U and (238)U, by using a multicollector, inductively coupled plasma ionization mass spectrometry. The first results from the Jalalabad province revealed urinary excretion of total uranium in all subjects significantly exceeding the values in the nonexposed population. The analysis of the isotopic ratios identified non-depleted uranium. Studies of specimens collected in 2002 revealed uranium concentrations up to 200 times higher in the districts of Tora Bora, Yaka Toot, Lal Mal, Makam Khan Farm, Arda Farm, Bibi Mahro, Poli Cherki, and the Kabul airport than in the control population. Uranium levels in the soil samples from the bombsites show values two to three times higher than worldwide concentration levels of 2 to 3 mg/kg and significantly higher concentrations in water than the World Health Organization maximum permissible levels. This growing body of evidence undoubtedly puts the problem of prevention and solution of the DU contamination high on the priority list. PMID:14515407

Durakovi?, Asaf

2003-10-01

256

Laser decontamination of the radioactive lightning rods  

NASA Astrophysics Data System (ADS)

Between 1970 and 1980 Brazil experienced a significant market for radioactive lightning rods (RLR). The device consists of an air terminal with one or more sources of americium-241 attached to it. The sources were used to ionize the air around them and to increase the attraction of atmospheric discharges. Because of their ineffectiveness, the nuclear regulatory authority in Brazil suspended the license for manufacturing, commerce and installation of RLR in 1989, and determined that the replaced RLR were to be collected to a centralized radioactive waste management facility for treatment. The first step for RLR treatment is to remove the radioactive sources. Though they can be easily removed, some contaminations are found all over the remaining metal scrap that must decontaminated for release, otherwise it must be treated as radioactive waste. Decontamination using various chemicals has proven to be inefficient and generates large amounts of secondary wastes. This work shows the preliminary results of the decontamination of 241Am-contaminated metal scrap generated in the treatment of radioactive lightning rods applying laser ablation. A Nd:YAG nanoseconds laser was used with 300 mJ energy leaving only a small amount of secondary waste to be treated.

Potiens, A. J.; Dellamano, J. C.; Vicente, R.; Raele, M. P.; Wetter, N. U.; Landulfo, E.

2014-02-01

257

Radioactive Waste Management in A Hospital  

PubMed Central

Most of the tertiary care hospitals use radioisotopes for diagnostic and therapeutic applications. Safe disposal of the radioactive waste is a vital component of the overall management of the hospital waste. An important objective in radioactive waste management is to ensure that the radiation exposure to an individual (Public, Radiation worker, Patient) and the environment does not exceed the prescribed safe limits. Disposal of Radioactive waste in public domain is undertaken in accordance with the Atomic Energy (Safe disposal of radioactive waste) rules of 1987 promulgated by the Indian Central Government Atomic Energy Act 1962. Any prospective plan of a hospital that intends using radioisotopes for diagnostic and therapeutic procedures needs to have sufficient infrastructural and manpower resources to keep its ambient radiation levels within specified safe limits. Regular monitoring of hospital area and radiation workers is mandatory to assess the quality of radiation safety. Records should be maintained to identify the quality and quantity of radioactive waste generated and the mode of its disposal. Radiation Safety officer plays a key role in the waste disposal operations. PMID:21475524

Khan, Shoukat; Syed, AT; Ahmad, Reyaz; Rather, Tanveer A.; Ajaz, M; Jan, FA

2010-01-01

258

DEVELOPMENT OF SPECIFICATIONS FOR RADIOACTIVE WASTE PACKAGES  

E-print Network

The main objective of radioactive waste management is to protect people and their environment from the potential harmful effects of radioactive waste and to minimize the burden for future generations. Safe disposal of conditioned radioactive waste is considered the final step of waste management. Waste acceptance requirements, consistent with a disposal concept, should be defined either by national authorities or repository operators with the aim of meeting the safety goal of radioactive waste disposal. An important task for waste management organizations is to translate general waste acceptance requirements into detailed waste package specifications. Waste package specifications should be individually prepared and implemented for each type of radioactive waste package produced (considering both waste form and waste container) and should reflect specific characteristics of the waste package. Such specifications allow simpler and more accessible control and verification methods to be applied directly by the waste generators and disposal facility operators. Waste package specifications can also be directly implemented in quality assurance and quality control systems during waste processing and waste package control.

unknown authors

259

Pulmonary toxicity of stable and radioactive lanthanides.  

PubMed

The pulmonary toxicity of inhaled lanthanides has been the subject of debate. In question have been the relative contributions of radioactive vs. stable elements in the development of lanthanide-associated progressive pulmonary interstitial fibrosis. The central question of this debate is: Are lanthanide dusts that are devoid of radioactive contaminants capable of producing progressive pulmonary disease, or are lanthanide-induced lesions more appropriately termed "benign pneumoconioses"? This paper examines the epidemiologic and experimental record in order to answer the above question. It is clear from the available data that significant pathogenic potential of inhaled lanthanides exists and is related to the type and physicochemical form of the material inhaled and to the dose and duration of exposure. Contamination of the dust with radioactive materials may accelerate and enhance the pathologic response, depending on the form and dose of radioactivity encountered. Nevertheless, there is little evidence to suggest that the level of radioactive contamination of occupationally encountered lanthanide dusts is sufficient to be included as a risk factor for pulmonary disease. Thus, the pulmonary syndrome induced by stable rare earths includes progressive pulmonary fibrosis and should not be referred to as "benign pneumoconiosis." PMID:1955325

Haley, P J

1991-12-01

260

Environmental radioactivity in the Arctic, Antarctic  

SciTech Connect

This conference on radioactivity in the Arctic and Antarctic was held in Kirkenes, Norway and sponsored by the Norwegian Radiation Protection Authority and the Department of Radiation Physics, Sweden's University of Lund. Radioactivity in the Arctic is the result of both natural phenomena and human activities. Natural or background radioactivity is a result of the breakdown and erosion of rocks that contain naturally radioactive minerals. But the levels introduced by dumping, weapons testing, and industrial activities far exceed such natural levels. Conference delegates cited such contamination sources as: Chernobyl's nuclear reactor accident; Wastes from fuel reprocessing plants at Sellafield (UK) and La Hague (France); Weapons testing in and around Novaya Zemlya; Ocean dumping of reactors, waste containers, and liquid wastes; Runoff from watersheds containing soil and organic material contaminated by atmospheric fallout; Atmospheric fallout from decades of weapons tests by various nations; and, Accidents involving nuclear submarines. The potential for increased radioactive pollution is of great concern and these questions were addressed by several speakers.

Palmer, H.

1993-12-01

261

Potential impacts of pending residual radioactivity rules  

SciTech Connect

The purpose of this paper is to present an overview of pending rules governing residual radioactive release criteria and radioactive waste management, and the potential impact of these rules on the Fernald Scrap Metal program. More than 300,000 cubic meters of radioactively contaminated waste will be generated during the dismantlement of three complexes at the Fernald Site over the next year and a half. Under current regulations, as much as 70% (5,000 tons) of steel will be either recycled or re-used in controlled applications. Depending on regulatory developments, the ratios of recycling to burial will range from 100% burial to recycling more than 90% of the waste. The absence of federal rules and regulations for classification of permissible levels of residual radioactivity is one of the most troublesome issues in the nuclear industry. The issue is growing in importance with the approaching end of useful life for many nuclear power generating stations and the planned remediation of the DOE nuclear weapons complex. Federal regulators have been involved in the {open_quotes}Enhanced rulemaking{close_quotes} process for over two years. The DOE Fernald site offers a good opportunity for understanding the potential impacts of the pending residual radioactivity regulations due to the maturity of the planned D&D activities, aggressive recycling program, and simple nature of contamination. The Fernald experience may offer a point of departure for many facilities engaged in D&D and waste management.

Burns, D.D.

1995-04-01

262

Exoplanets' atmospheres: comparing and separating different sources of disequilibria  

NASA Astrophysics Data System (ADS)

The atmosphere of the only known (till nowadays) inhabited planet is characterized by a unique disequilibrium state in terms of chemical composition. Studying this state of disequilibrium is important for its potential role in the detection of life on other suitable planets [1][2][3]. However, different processes are able to produce chemical disequilibrium in planetary atmospheres, thus a tool to compute the extent of disequilibrium is needed. We developed a methodology to calculate the extent of atmospheric chemical disequilibrium [3][4]. A new computational framework called KROME has been applied to atmospheric models in order to give a correct computation of reaction? kinetics [5]. This methodology allows to compute, for models of different planets, the extent of disequilibrium due to several processes, such as fast vertical mixing, eddy diffusion, photochemistry, extremely diverse atmospheres due to tidal effect. Using Earth’s models, we also infer the potential extension of the effect of a biosphere on disequilibrium. Our results provide a comprehensive analysis of atmospheric disequilibrium for rocky planets, which can be also used for the detection of habitable conditions on farther planetary bodies. [1] Lovelock, J. E.: A physical basis for life detection experiments, Nature, 207, 568 (1965) [2] Kleidon, A., Physics of Life Reviews, 7, 424 (2010) [3] Simoncini E., Grassi T., Disequilibrium in planetary atmospheres: a first calculation for Earth using KROME, submitted to OLEB. [4] Kondepudi D., Prigogine I., Modern Thermodynamics, Wiley (1996) [5] Grassi, T., Bovino, S., Schleicher, D. R. G., Prieto, J., Seifried, D., Simoncini, E., Gianturco, F. A., in press on Mon. Not. R. Astron. Soc. MN-13-2848-MJ.R1

Simoncini, Eugenio; Brucato, John Robert

263

Assessing postzygotic isolation using zygotic disequilibria in natural hybrid zones.  

PubMed

Hybrid zones as windows on evolutionary processes provide a natural laboratory for studying the genetic basis and mechanisms of postzygotic isolation. One resultant pattern in hybrid zones is the Hardy-Weinberg disequilibrium (HWD) for a single locus or the linkage disequilibrium (LD) for multiple loci produced by natural selection against hybrids. However, HWD and the commonly used low-order gametic or composite digenic LD cannot fully reflect the pattern of the high-order genotypic interactions. Here we propose the use of zygotic LD to elucidate the selection mechanisms of postzygotic isolation, and its calculation is based on genotypic frequencies only, irrespective of the type of mating system. We numerically and analytically show that the maximum composite digenic LD is always greater than the maximum absolute zygotic LD under the linear-additive selection, but is comparable to or smaller than the maximum absolute zygotic LD under the strong epistatic selection. Selection mechanisms can be inferred by testing such differences. We analyze a previously reported mouse hybrid zone assayed with genome-wide SNPs, and confirm that the composite digenic LD cannot appropriately indicate all possible significant genotypic interactions for a given SNP pair. A large proportion of significant zygotic LDs, ?75% in general in the mouse hybrid zone, cannot be revealed from the composite digenic LD analysis. Statistical tests indicate that epistatic selection occurred among multiple loci in the mouse hybrid zone. The results highlight that the joint patterns of the composite digenic and zygotic LDs can help to elucidate the selection mechanism that is potentially involved in postzygotic isolation. PMID:24950065

Hu, Xin-Sheng; Yeh, Francis C

2014-01-01

264

Influence of Relic Neutrinos on Beta Radioactivity  

E-print Network

Results of calculations of distribution and motion of dark matter are presented. Considering neutrino as one of the components of dark matter and taking into account peculiar features of the interactions of slow neutrinos with matter, allow to make the conclusion that they may have tangible manifestations not only in the depths of the Universe but also on the Earth. Experimental results confirming predicted effects are described, including periodic variations of the beta radioactivity as well as count rate bursts for a beta radioactive source placed at the focal point of a parabolic mirror. Based on the data of astronomical observations, estimates of the mass of the particles influencing on beta radioactivity (about 20 eV) and their flux density (about 10^13 particles/cm^2 s) have been made. The discrepancy between our mass estimate and the 2 eV limit for the neutrino mass, established in the tritium experiments, is discussed.

A. G. Parkhomov

2010-10-08

265

Radioactive tank waste remediation focus area  

SciTech Connect

EM`s Office of Science and Technology has established the Tank Focus Area (TFA) to manage and carry out an integrated national program of technology development for tank waste remediation. The TFA is responsible for the development, testing, evaluation, and deployment of remediation technologies within a system architecture to characterize, retrieve, treat, concentrate, and dispose of radioactive waste stored in the underground stabilize and close the tanks. The goal is to provide safe and cost-effective solutions that are acceptable to both the public and regulators. Within the DOE complex, 335 underground storage tanks have been used to process and store radioactive and chemical mixed waste generated from weapon materials production and manufacturing. Collectively, thes tanks hold over 90 million gallons of high-level and low-level radioactive liquid waste in sludge, saltcake, and as supernate and vapor. Very little has been treated and/or disposed or in final form.

NONE

1996-08-01

266

Innovative solutions for new radioactive waste issues  

SciTech Connect

Major changes in the nuclear industry are being driven by factors associated with how effectively the industry manages its radioactive waste; the control of environmental releases and dosages to personnel, the reduction of specific radioactivity in low level waste, and the siting of an interim storage facility or disposal site for spent fuel. Chem-Nuclear Systems` has focused its technology development initiatives on developing solutions that address these critical radwaste issues. Their technology development includes new disposal techniques for their Barnwell Waste Management Facility, and new processes such as Thermex{trademark}, an EDTA extraction process that minimize low level radioactive waste, and DuraChem{trademark} for vitrification of low level waste. Chem-Nuclear has also developed packages for storage and transport of spent fuel and high level waste. Finally, they have the only facility in the United States licensed for treatment of liquid mixed waste.

Braun, J.L. [Chem-Nuclear Systems, Inc., Columbia, SC (United States)

1996-10-01

267

Radioactivity and electron acceleration in supernova remnants  

SciTech Connect

We argue that the decays of radioactive nuclei related to {sup 44}Ti and {sup 56}Ni ejected during supernova explosions can provide a vast pool of mildly relativistic positrons and electrons which are further accelerated to ultrarelativistic energies by reverse and forward shocks. This interesting link between two independent processes - the radioactivity and the particle acceleration - can be a clue for solution of the well known theoretical problem of electron injection in supernova remnants. In the case of the brightest radio source Cas A, we demonstrate that the radioactivity can supply adequate number of energetic electrons and positrons for interpretation of observational data provided that they are stochastically preaccelerated in the upstream regions of the forward and reverse shocks.

Zirakashvili, V. N. [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation, 142190 Troitsk, Moscow Region (Russian Federation); Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Aharonian, F. A. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)

2011-10-15

268

RADIOACTIVE SOURCE SECURITY: THE CULTURAL CHALLENGES.  

PubMed

Radioactive source security is an essential part of radiation protection. Sources can be abandoned, lost or stolen. If they are stolen, they could be used to cause deliberate harm and the risks are varied and significant. There is a need for a global security protection system and enhanced capability to achieve this. The establishment of radioactive source security requires 'cultural exchanges'. These exchanges include collaboration between: radiation protection specialists and security specialists; the nuclear industry and users of radioactive sources; training providers and regulators/users. This collaboration will facilitate knowledge and experience exchange for the various stakeholder groups, beyond those already provided. This will promote best practice in both physical and information security and heighten security awareness generally. Only if all groups involved are prepared to open their minds to listen to and learn from, each other will a suitable global level of control be achieved. PMID:25377752

Englefield, Chris

2014-11-01

269

Radioactive isotopes in solid-state physics  

E-print Network

Radioactive atoms have been used in solid-state physics and in material science for many decades. Besides their classical application as tracer for diffusion studies, nuclear techniques such as M\\"ossbauer spectroscopy, perturbed angular correlation, $\\beta$-NMR, and emission channelling have used nuclear properties (via hyperfine interactions or emitted particles) to gain microscopical information on the structural and dynamical properties of solids. During the last decade, the availability of many different radioactive isotopes as a clean ion beam at ISOL facilities such as ISOLDE at CERN has triggered a new era involving methods sensitive for the optical and electronic properties of solids, especially in the field of semiconductor physics. Extremely sensitive spectroscopic techniques like deep-level transient spectroscopy (DLTS), photoluminescence (PL), and Hall effect have gained a new quality by using radioactive isotopes. Because of their decay the chemical origin of an observed electronic and optical b...

Deicher, M

2002-01-01

270

Low radioactivity spectral gamma calibration facility  

SciTech Connect

A low radioactivity calibration facility has been constructed at the Nevada Test Site (NTS). This facility has four calibration models of natural stone that are 3 ft in diameter and 6 ft long, with a 12 in. cored borehole in the center of each model and a lead-shielded run pipe below each model. These models have been analyzed by laboratory natural gamma ray spectroscopy (NGRS) and neutron activation analysis (NAA) for their K, U, and Th content. Also, 42 other elements were analyzed in the NAA. The /sup 222/Rn emanation data were collected. Calibrating the spectral gamma tool in this low radioactivity calibration facility allows the spectral gamma log to accurately aid in the recognition and mapping of subsurface stratigraphic units and alteration features associated with unusual concentrations of these radioactive elements, such as clay-rich zones.

Mathews, M.A.; Bowman, H.R.; Huang, L., H.; Lavelle, M.J.; Smith, A.R.; Hearst, J.R.; Wollenberg, H.A.; Flexser, S.

1986-01-01

271

Type A radioactive liquid sample packaging family  

SciTech Connect

Westinghouse Hanford Company (WHC) has developed two packagings that can be used to ship Type A quantities of radioactive liquids. WHC designed these packagings to take advantage of commercially available items where feasible to reduce the overall packaging cost. The Hedgehog packaging can ship up to one liter of Type A radioactive liquid with no shielding and 15 cm of distance between the liquid and the package exterior, or 30 ml of liquid with 3.8 cm of stainless steel shielding and 19 cm of distance between the liquid and the package exterior. The One Liter Shipper can ship up to one liter of Type A radioactive liquid that does not require shielding.

Edwards, W.S.

1995-11-01

272

Cubic potential models for cluster radioactivity  

NASA Astrophysics Data System (ADS)

Cluster radioactivity is a process by which nuclei equal and heavier than the a-particleis emitted spontaneously. The clusters usually emitted in this process are the a-particle, carbon, oxygen, neon, magnesium, silicon etc. When the mass of the cluster becomes comparable with the mass of the daughter, symmetric fission takes place. Thus the cluster radioactivity is an intermediate process between the well known a-decay and the spontaneous fission. In earlier years such cluster radioactivity was found mostly in actinide nuclei like radium, uranium etc. Very recently it has been predicted that such decays are possible in a new region around 114Ba. There has been an exciting experimental detection of the emission of 12C from 114Ba leading to 102Sn, which is attracting a lot of attention recently. To study the phenomenon of cluster radioactivity there are various theoretical models in vogue. The existing models generally fall under two categories: the unified fission model (UFM) and the preformed cluster model (PCM). The physics of the UFM and the PCM are completely different. The UFM considers cluster radioactivity simply as a barrier penetration phenomenon in between the fission and the a-decay without worrying about the cluster being or not being preformed in the parent nucleus. In the PCM clusters are assumed to be preborn in a parent nucleus before they could penetrate the potential barrier with a given Q-value. The basic assumption of the UFM is that heavy clusters as well as the a-particle have equal probability of being preformed. In PCM, clusters of different sizes have different probabilities of their being preformed in the parent nucleus. We have developed three fission models during the last decade using the cubic potential for the pre-scission region. The use of these models in the study of cluster radioactivity in both the actinide and barium regions will be discussed in this talk in comparison with the other existing theories.

Shanmugam, G.

1999-09-01

273

Decontamination of protective clothing against radioactive contamination.  

PubMed

The aim of this study is to describe the experimental results of external surface mechanical decontamination of the studied materials forming selected suits. Seven types of personal protective suits declaring protection against radioactive aerosol contamination in different price ranges were selected for decontamination experiments. The outcome of this study is to compare the efficiency of a double-step decontamination process on various personal protective suits against radioactive contamination. A comparison of the decontamination effectiveness for the same type of suit, but for the different chemical mixtures ((140)La in a water-soluble or in a water-insoluble compound), was performed. PMID:25084793

Vošahlíková, I; Otáhal, P

2014-11-01

274

Microwave processing of radioactive materials-I  

SciTech Connect

This paper is the first of two papers that reviews the major past and present applications of microwave energy for processing radioactive materials, with particular emphasis on processing radioactive wastes. Microwave heating occurs through the internal friction produced inside a dielectric material when its molecules vibrate in response to an oscillating microwave field. For this presentation, we shall focus on the two FCC-approved microwave frequencies for industrial, scientific, and medical use, 915 and 2450 MHz. Also, because of space limitations, we shall postpone addressing plasma processing of hazardous wastes using microwave energy until a later date. 13 refs., 4 figs.

White, T.L.; Berry, J.B.

1989-01-01

275

[Surveillance of radioactive cesium in foods].  

PubMed

We surveyed foods on the market from areas that had been exposed to radioactive materials contamination following the Fukushima accident. We used a NaI (Tl) scintillation spectrometer for the screening tests and a germanium semiconductor detector for the final tests. Test results from 1,427 samples showed that 6 samples (0.4%) exceeded the regulatory limit of 500 Bq/kg. Considering the detection rate of radioactive cesium in each food category, we suggest that it is necessary to continue monitoring fruits such as chestnuts and ginkgo nuts, mushrooms (especially raw wood-shiitake), mountain vegetables, and sea fish. PMID:23676693

Nabeshi, Hiromi; Tsutsumi, Tomoaki; Ikarashi, Atsuko; Hachisuka, Akiko; Matsuda, Rieko

2013-01-01

276

Technology applications for radioactive waste minimization  

SciTech Connect

The nuclear power industry has achieved one of the most successful examples of waste minimization. The annual volume of low-level radioactive waste shipped for disposal per reactor has decreased to approximately one-fifth the volume about a decade ago. In addition, the curie content of the total waste shipped for disposal has decreased. This paper will discuss the regulatory drivers and economic factors for waste minimization and describe the application of technologies for achieving waste minimization for low-level radioactive waste with examples from the nuclear power industry.

Devgun, J.S.

1994-07-01

277

Perspectives of Radioactive Contamination in Nuclear War  

PubMed Central

The degrees of risk associated with the medical, industrial and military employment of nuclear energy are compared. The nature of radioactive contamination of areas and of persons resulting from the explosion of nuclear weapons, particularly the relationship between the radiation exposure and the amount of physical debris, is examined. Some theoretical examples are compared quantitatively. It is concluded that the amount of radio-activity that may be carried on the contaminated person involves a minor health hazard from gamma radiation, compared to the irradiation arising from contaminated areas. PMID:6015741

Waters, W. R.

1967-01-01

278

RADIOACTIVE MATERIALS IN BIOSOLIDS: DOSE MODELING  

EPA Science Inventory

The Interagency Steering Committee on Radiation Standards (ISCORS) has recently completed a study of the occurrence within the United States of radioactive materials in sewage sludge and sewage incineration ash. One component of that effort was an examination of the possible tra...

279

High-level radioactive wastes. Supplement 1  

SciTech Connect

This bibliography contains information on high-level radioactive wastes included in the Department of Energy's Energy Data Base from August 1982 through December 1983. These citations are to research reports, journal articles, books, patents, theses, and conference papers from worldwide sources. Five indexes, each preceded by a brief description, are provided: Corporate Author, Personal Author, Subject, Contract Number, and Report Number. 1452 citations.

McLaren, L.H. (ed.)

1984-09-01

280

Radioactive waste isolation: a national problem  

Microsoft Academic Search

The principal aim of the National Waste Terminal Storage (NWTS) program is to develop repositories in several different rock formations in various parts of the country. Rocks such as salt, shale, limestone, and granite may qualify as host media for the disposition of radioactive wastes in the proper environments. In general, the only requirement for any rock formation or storage

Lomenick

1977-01-01

281

Electroflotation Purification of Radioactive Waste Waters  

Microsoft Academic Search

Methods for purifying radioactive waste waters are reviewed. It is shown that the electrofiltration method with insoluble electrodes is promising at the stage of separation of liquid and solid phases. The arrangement, technical-economic characteristics, and a description of the operation of an electroflotator are given.

V. I. Il'in; V. A. Kolesnikov

2001-01-01

282

Safety Aspects in Radioactive Waste Management  

Microsoft Academic Search

Bezpe?nostné aspekty mana?mentu rádioaktívneho odpadu In recent years, within the framework of national as well as international programmes, notable advances and considerable experience have been reached, particularly in minimising of the production of radioactive wastes, conditioning and disposal of short- lived, low and intermediate level waste, vitrification of fission product solutions on an industrial scale and engineered storage of long-

Peter W. Brennecke

283

Radioactive waste management centers: an approach  

Microsoft Academic Search

Radioactive waste management centers would satisfy the need for a cost-effective, sound management system for nuclear wastes by the industry and would provide a well integrated solution which could be understood by the public. The future demands for nuclear waste processing and disposal by industry and institutions outside the United States Government are such that a number of such facilities

Lotts

1980-01-01

284

Safe transport of radioactive materials in Egypt  

NASA Astrophysics Data System (ADS)

In Egypt the national regulations for safe transport of radioactive materials (RAM) are based on the International Atomic Energy Agency (IAEA) regulations. In addition, regulations for the safe transport of these materials through the Suez Canal (SC) were laid down by the Egyptian Atomic Energy Authority (EAEA) and the Suez Canal Authority (SCA). They are continuously updated to meet the increased knowledge and the gained experience. The technical and protective measures taken during transport of RAM through SC are mentioned. Assessment of the impact of transporting radioactive materials through the Suez Canal using the INTERTRAN computer code was carried out in cooperation with IAEA. The transported activities and empty containers, the number of vessels carrying RAM through the canal from 1963 to 1991 and their nationalities are also discussed. The protective measures are mentioned.A review of the present situation of the radioactive wastes storage facilities at the Atomic Energy site at Inshas is given along with the regulation for safe transportation and disposal of radioactive wastes

El-Shinawy, Rifaat M. K.

1994-07-01

285

Recycling and Reuse of Radioactive Materials  

ERIC Educational Resources Information Center

The Radiochemistry Program at the University of Nevada, Las Vegas (UNLV) has a Radiation Protection Program that was designed to provide students with the ability to safely work with radioactive materials in quantities that are not available in other academic environments. Requirements for continuous training and supervision make this unique…

O'Dou, Thomas Joseph

2012-01-01

286

A Sensitive Cloud Chamber without Radioactive Sources  

ERIC Educational Resources Information Center

We present a sensitive diffusion cloud chamber which does not require any radioactive sources. A major difference from commonly used chambers is the use of a heat sink as its bottom plate. The result of a performance test of the chamber is given. (Contains 8 figures.)

Zeze, Syoji; Itoh, Akio; Oyama, Ayu; Takahashi, Haruka

2012-01-01

287

Hazardous chemical and radioactive wastes at Hanford  

SciTech Connect

The Hanford Site was established in 1944 to produce plutonium for defense. During the past four decades, a number of reactors, processing facilities, and waste management facilities have been built at Hanford for plutonium production. Generally, Hanford`s 100 Area was dedicated to reactor operation; the 200 Area to fuel reprocessing, plutonium recovery, and waste management; and the 300 Area to fuel fabrication and research and development. Wastes generated from these operations included highly radioactive liquid wastes, which were discharged to single- and double-shell tanks; solid wastes, including both transuranic (TRU) and low-level wastes, which were buried or discharged to caissons; and waste water containing low- to intermediate-level radioactivity, which was discharged to the soil column via near-surface liquid disposal units such as cribs, ponds, and retention basins. Virtually all of the wastes contained hazardous chemical as well as radioactive constituents. This paper will focus on the hazardous chemical components of the radioactive mixed waste generated by plutonium production at Hanford. The processes, chemicals used, methods of disposition, fate in the environment, and actions being taken to clean up this legacy are described by location.

Keller, J.F.; Stewart, T.L.

1991-07-01

288

Hazardous chemical and radioactive wastes at Hanford  

SciTech Connect

The Hanford Site was established in 1944 to produce plutonium for defense. During the past four decades, a number of reactors, processing facilities, and waste management facilities have been built at Hanford for plutonium production. Generally, Hanford's 100 Area was dedicated to reactor operation; the 200 Area to fuel reprocessing, plutonium recovery, and waste management; and the 300 Area to fuel fabrication and research and development. Wastes generated from these operations included highly radioactive liquid wastes, which were discharged to single- and double-shell tanks; solid wastes, including both transuranic (TRU) and low-level wastes, which were buried or discharged to caissons; and waste water containing low- to intermediate-level radioactivity, which was discharged to the soil column via near-surface liquid disposal units such as cribs, ponds, and retention basins. Virtually all of the wastes contained hazardous chemical as well as radioactive constituents. This paper will focus on the hazardous chemical components of the radioactive mixed waste generated by plutonium production at Hanford. The processes, chemicals used, methods of disposition, fate in the environment, and actions being taken to clean up this legacy are described by location.

Keller, J.F.; Stewart, T.L.

1991-07-01

289

Obtaining and Investigating Unconventional Sources of Radioactivity  

ERIC Educational Resources Information Center

This paper provides examples of naturally radioactive items that are likely to be found in most communities. Additionally, there is information provided on how to acquire many of these items inexpensively. I have found that the presence of these materials in the classroom is not only useful for teaching about nuclear radiation and debunking the…

Lapp, David R.

2010-01-01

290

Annual radioactive waste tank inspection program - 1999  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site (SRS) separations processes are contained in large underground carbon steel tanks. Inspections made during 1999 to evaluate these vessels and auxiliary appurtenances along with evaluations based on data accrued by inspections performed since the tanks were constructed are the subject of this report.

Moore, C.J.

2000-04-14

291

Canister arrangement for storing radioactive waste  

DOEpatents

The subject invention relates to a canister arrangement for jointly storing high level radioactive chemical waste and metallic waste resulting from the reprocessing of nuclear reactor fuel elements. A cylindrical steel canister is provided with an elongated centrally disposed billet of the metallic waste and the chemical waste in vitreous form is disposed in the annulus surrounding the billet.

Lorenzo, D.K.; Van Cleve, J.E. Jr.

1980-04-23

292

Method for decontamination of radioactive metal surfaces  

DOEpatents

Disclosed is a method for removing radioactive contaminants from metal surfaces by applying steam containing an inorganic acid and cerium IV. Cerium IV is applied to contaminated metal surfaces by introducing cerium IV in solution into a steam spray directed at contaminated metal surfaces. Cerium IV solution is converted to an essentially atomized or vapor phase by the steam.

Bray, L.A.

1996-08-13

293

Canister arrangement for storing radioactive waste  

DOEpatents

The subject invention relates to a canister arrangement for jointly storing high level radioactive chemical waste and metallic waste resulting from the reprocessing of nuclear reactor fuel elements. A cylindrical steel canister is provided with an elongated centrally disposed billet of the metallic waste and the chemical waste in vitreous form is disposed in the annulus surrounding the billet.

Lorenzo, Donald K. (Knoxville, TN); Van Cleve, Jr., John E. (Kingston, TN)

1982-01-01

294

Evaluation of Terrorist Interest in Radioactive Wastes  

Microsoft Academic Search

Since September 11, 2001, intelligence gathered from Al Qaeda training camps in Afghanistan, and the ensuing terrorist activities, indicates nuclear material security concerns are valid. This paper reviews available information on sealed radioactive sources thought to be of interest to terrorists, and then examines typical wastes generated during environmental management activities to compare their comparative 'attractiveness' for terrorist diversion. Sealed

J. N. McFee; J. M. Langsted; M. E. Young; J. E. Day

2006-01-01

295

Remediation of groundwater contaminated with radioactive compounds  

Technology Transfer Automated Retrieval System (TEKTRAN)

Both naturally radioactive isotopes and isotopes from man-made sources may appear in groundwater. Depending on the physical and chemical characteristics of the contaminant, different types of treatment methods must be applied to reduce the concentration. The following chapter discusses treatment opt...

296

Radiation safety of sealed radioactive sources.  

PubMed

Sealed radioactive sources are used in a wide variety of occupational settings and under differing regulatory/licensing structures. The definition of a sealed radioactive source varies between U.S. regulatory authorities and standard-setting organizations. Potential problems with sealed sources cover a range of risks and impacts. The loss of control of high activity sealed sources can result in very high or even fatal doses to members of the public who come in contact with them. Sources that are not adequately sealed and that fail can cause spread of contamination and potential intake of radioactive material. There is also the possibility that sealed sources may be (or threaten to be) used for terrorist purposes and disruptive opportunities. Until fairly recently, generally licensed sealed sources and devices received little, if any, regulatory oversight and were often forgotten, lost or unaccounted for. Nonetheless, generally licensed devices can contain fairly significant quantities of radioactive material, and there is some potential for exposure if a device is treated in a way for which it was never designed. Industrial radiographers use and handle high activity and/or high dose-rate sealed sources in the field with a high degree of independence and minimal regulatory oversight. Failure to follow operational procedures and properly handle radiography sources can and has resulted in serious injuries and death. Industrial radiographers have experienced a disproportionately large fraction of incidents that have resulted in unintended exposure to radiation. Sources do not have to contain significant quantities of radioactive material to cause problems in the event of their failure. A loss of integrity can cause the spread of contamination and potential exposure to workers and members of the public. The National Council on Radiation Protection and Measurements has previously provided recommendations on select aspects of sealed source programs. Future efforts to provide recommendations for sealed source programs are discussed. PMID:25551499

Pryor, Kathryn H

2015-02-01

297

Radioactive Waste Management in Central Asia - 12034  

SciTech Connect

After the collapse of the Soviet Union the newly independent states in Central Asia (CA) whose regulatory bodies were set up recently are facing problems with the proper management of radioactive waste and so called 'nuclear legacy' inherited from the past activities. During the former Soviet Union (SU) period, various aspects of nuclear energy use took place in CA republics of Kazakhstan, Kyrgyzstan, Tajikistan and Uzbekistan. Activities range from peaceful use of energy to nuclear testing for example at the former Semipalatinsk Nuclear Test Site (SNTS) in Kazakhstan, and uranium mining and milling industries in all four countries. Large amounts of radioactive waste (RW) have been accumulated in Central Asia and are waiting for its safe disposal. In 2008 the Norwegian Radiation Protection Authority (NRPA), with the support of the Norwegian Ministry of Foreign Affairs, has developed bilateral projects that aim to assist the regulatory bodies in Kazakhstan, Kyrgyzstan Tajikistan, and Uzbekistan (from 2010) to identify and draft relevant regulatory requirements to ensure the protection of the personnel, population and environment during the planning and execution of remedial actions for past practices and radioactive waste management in the CA countries. The participating regulatory authorities included: Kazakhstan Atomic Energy Agency, Kyrgyzstan State Agency on Environmental Protection and Forestry, Nuclear Safety Agency of Tajikistan, and State Inspectorate on Safety in Industry and Mining of Uzbekistan. The scope of the projects is to ensure that activities related to radioactive waste management in both planned and existing exposure situations in CA will be carried out in accordance with the international guidance and recommendations, taking into account the relevant regulatory practice from other countries in this area. In order to understand the problems in the field of radioactive waste management we have analysed the existing regulations through the so called 'Threat assessment' in each CA country which revealed additional problems in the existing regulatory documents beyond those described at the start of our ongoing bilateral projects in Kazakhstan, Kirgizistan Tajikistan and Uzbekistan. (authors)

Zhunussova, Tamara; Sneve, Malgorzata; Liland, Astrid [Norwegian Radiation Protection Authority (Norway)

2012-07-01

298

^ a Ris-R-622(EN) Environmental Radioactivity  

E-print Network

^ a Risø-R-622(EN) Environmental Radioactivity in the North Atlantic Region Includingthe Faroe #12;Environmental Radioactivity ^-^mm in the North Atlantic Region Including the Faroe Islands National Laboratory, Roskilde, Denmark January 1994 #12;Abstract Measurements of fallout radioactivity

299

B-1 2003 SITE ENVIRONMENTAL REPORT Concepts of Radioactivity  

E-print Network

B-1 2003 SITE ENVIRONMENTAL REPORT APPENDIX B Concepts of Radioactivity This section introduces some of the basic concepts of radioactivity to provide the general reader with a basic understanding here, inAppendix B, are discussions of the analyses used to quantify radioactive material, the common

Homes, Christopher C.

300

Working with Radioactive Materials in Clinical Areas -Documentation  

E-print Network

Working with Radioactive Materials in Clinical Areas - Documentation Procedure: 7.54 Created: 2008 Version: 1.1 Revised: 11/5/2013 10/22/2014 Working with Radioactive Materials in Clinical Areas of the City of New York, Article 175, Radiation Control1 and New York City Department of Health Radioactive

Jia, Songtao

301

MANAGEMENT OF SOLID RADIOACTIVE WASTE Revised August 2008  

E-print Network

k MANAGEMENT OF SOLID RADIOACTIVE WASTE Revised August 2008 Safety Services #12;MANAGEMENT OF SOLID RADIOACTIVE WASTES Page Minimisation 1 Streaming 2 Procedures 2 Keeping track of the activities placed for Appendices 4 and 5 22 Appendix 10 Flow chart of waste-streaming 23 #12;1 MANAGEMENT OF SOLID RADIOACTIVE

Davidson, Fordyce A.

302

1 INSTRODUCTION In the concept of geological radioactive waste disposal,  

E-print Network

1 INSTRODUCTION In the concept of geological radioactive waste disposal, argillite is being of the radioactive waste disposal, the host rock will be subjected to various thermo-hydro-mechanical loadings, thermal solicitation comes from the heat emitting from the radioactive waste packages. On one hand

Boyer, Edmond

303

Collation and presentation of radioactivity trend data from MAFF monitoring  

E-print Network

from radioactive waste discharges, and · To present this information in the context of time trends The scope of the project was defined to comprise the main sites discharging radioactive wastes in EnglandCollation and presentation of radioactivity trend data from MAFF monitoring programmes from 1994

304

40 CFR 227.30 - High-level radioactive waste.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2011-07-01 true High-level radioactive waste. 227.30 Section 227.30 Protection... Definitions § 227.30 High-level radioactive waste. High-level radioactive waste means the aqueous waste resulting...

2012-07-01

305

Method and apparatus for treatment of radioactive wastes  

Microsoft Academic Search

A radioactive waste discharged from a radioactive substance handling equipment is dried and powdered, and the powder is pelletized. The resulting pellets are stored in an inner vessel of a store vessel having a double structure for a predetermined period to attenuate the radioactivity of the pellets. Then, the pellets are taken out from the store vessel and packed into

M. Hirano; S. Horiuchi; M. Takeshima; T. Taniguchi; H. Yusa

1981-01-01

306

Method of and apparatus for producing radioactive waste package  

Microsoft Academic Search

Provided is a method of producing radioactive waste package. By evaporating and drying, the radioactive waste is reduced to a radioactive powder which is formed into pellets in order to ease its disposal. The pellets are received in a container and then impregnated therein with a thermoplastic composition so as to be integrally solidify in the container. The prior technical

M. Hirano; S. Horiuchi

1981-01-01

307

Exploring solid state physics properties with radioactive isotopes  

Microsoft Academic Search

Radioactive atoms have been used in solid state physics for many years. Established nuclear techniques such as Mbauer spectroscopy, perturbed angular correlation, -NMR and emission channelling have now been joined by new and successful tracer techniques like radioactive deep level transient spectroscopy, capacitance voltage measurements, Hall-effect measurements or photoluminescence spectroscopy. Numerous radioactive species, ranging from to , are employed to

Doris Forkel-Wirth

1999-01-01

308

Important Memo To: All supervisors of radioactive material laboratories  

E-print Network

Important Memo To: All supervisors of radioactive material laboratories From: Eric Boeldt, Penn on the form. This retraining is required of everyone currently working with radioactive materials and everyone refresher. A supervisor's authorization to use radioactive material may be suspended if the attached (yellow

Kaye, Jason P.

309

ION-EXCHANGE PROCESSES FOR REMOVING RADIOACTIVE CONTAMINATION FROM MILK  

Microsoft Academic Search

SUMMARY These studies on removing radioactive contamination from milk were carried on for the purpose of developing a feasible standby process for use in dairy plants in the event that radioactive fallout should reach hazardous levels. Current levels of all the radioactive contaminants are far below what is con- sidered hazardous levels; Iodine-131 is essentially undetectable in all milk supplies.

L. E. Edmondson

1964-01-01

310

RADIATION PROTECTION IN ASSOCIATION WITH BARE RADIOACTIVE MATERIALS. PART II  

Microsoft Academic Search

A description is given of the measures of organization necessary for ; safe handling of radioactive material and the methods for supervising the hazards ; of contamination. Furthermore, radioactive decontamination and removal of ; radioactive waste are briefly referred to. An annexal survey of different types ; of laboratories demonstrates the methods of furnishing these places in regard of ;

Gotte

1960-01-01

311

10 CFR 61.41 - Protection of the general population from releases of radioactivity.  

Code of Federal Regulations, 2011 CFR

...general population from releases of radioactivity. 61.41 Section 61.41 Energy...general population from releases of radioactivity. Concentrations of radioactive...should be made to maintain releases of radioactivity in effluents to the general...

2011-01-01

312

10 CFR 61.41 - Protection of the general population from releases of radioactivity.  

Code of Federal Regulations, 2012 CFR

...general population from releases of radioactivity. 61.41 Section 61.41 Energy...general population from releases of radioactivity. Concentrations of radioactive...should be made to maintain releases of radioactivity in effluents to the general...

2012-01-01

313

10 CFR 61.41 - Protection of the general population from releases of radioactivity.  

Code of Federal Regulations, 2010 CFR

...general population from releases of radioactivity. 61.41 Section 61.41 Energy...general population from releases of radioactivity. Concentrations of radioactive...should be made to maintain releases of radioactivity in effluents to the general...

2010-01-01

314

10 CFR 61.41 - Protection of the general population from releases of radioactivity.  

Code of Federal Regulations, 2013 CFR

...general population from releases of radioactivity. 61.41 Section 61.41 Energy...general population from releases of radioactivity. Concentrations of radioactive...should be made to maintain releases of radioactivity in effluents to the general...

2013-01-01

315

10 CFR 61.41 - Protection of the general population from releases of radioactivity.  

Code of Federal Regulations, 2014 CFR

...general population from releases of radioactivity. 61.41 Section 61.41 Energy...general population from releases of radioactivity. Concentrations of radioactive...should be made to maintain releases of radioactivity in effluents to the general...

2014-01-01

316

s.haszeldine@ed.ac.uk Radioactive waste Cumbria: Maryport, Silloth 21, 22 Nov 2012 1 Geological disposal of radioactive  

E-print Network

s.haszeldine@ed.ac.uk Radioactive waste Cumbria: Maryport, Silloth 21, 22 Nov 2012 1 Geological disposal of radioactive waste in Cumbria http://www.geos.ed.ac.uk/homes/rsh/MRWS_2012.html Stuart/rsh/ Allerdale_and_Copeland.html #12;Nuclear power s.haszeldine@ed.ac.uk Radioactive waste Cumbria: Maryport

317

BIOPROTA: an international forum for environmental modelling in support of long-term radioactive waste management  

SciTech Connect

An international Forum, BIOPROTA, has been set up and maintained which allows common long-term environmental radiological assessment problems, such as post-closure modelling studies to be identified and then addressed. The focus of the Forum is to address key uncertainties in environmental modelling and related dose assessment with special reference to evaluation of the long-term impact of contaminant releases associated with radioactive waste management. The application of shared resources results in effective resource management and the development of common solutions to common problems. The Forum began in 2002 and has benefited from the knowledge and experience of organisations from Belgium (SCK.CEN), Czech Republic (NRI), Canada (OPG), Finland (Posiva), France (ANDRA, EdF), Japan (NUMO), Korea (KAERI), Norway (NRPA), Spain (ENRESA, CIEMAT), Sweden (SKB, SSI), Switzerland (Nagra), UK (Nirex, Nexia, UKAEA) and the USA (EPRI). These organisations include a mixture of operators, regulators and research institutes, and hence, including the participation of their technical support organizations, constitutes a very broad-based Forum. Enviros has acted as the technical secretariat to the Forum since its formation. Initially the Forum focused on three themes aimed at advancing knowledge and improving model predictions relating to performance and safety assessments: Theme 1 Development of a database to meet the key biosphere assessment information deficiencies. Theme 2 Implementation of a series of tasks to address key modelling issues, including uncertainties and inconsistencies in the modelling of inhalation, irrigation and soil contamination dose pathways; and approaches to the modelling the transfer of radionuclides across the geosphere-biosphere interface zone (GBIZ). Theme 3 Provision of guidance on site characterisation and experimental and monitoring protocols relevant to improving confidence in the biosphere component of the overall performance assessment. Substantial work under Themes 2 and 3 was completed in 2005/06 resulting in the publication of a variety of reports and guidance documents. Results of the model comparisons conducted under Theme 2 suggest that we can be confident in model structures and we have gained knowledge of the sensitive assumptions. Population of the database produced under Theme 1 is ongoing after release of an initial version which focused on data for Cl-36, Se-79, Tc-99, I-129, Np-237 and U-series radionuclides. In 2006, BIOPROTA received further international interest. The 2006 annual workshop identified a series of current issues for which proposals for tasks aimed at addressing these issues are under development. This includes exchange of information on models and processes of relevance to Cl-36 behaviour, as well as modelling the disequilibrium in the U-238 decay chain in environmental systems; more precise understanding of released C-14 distribution within various environmental carbon pools; and studies of the GBIZ under environmental change. A special workshop was held on Cl-36 behaviour and the workshop report published. An overview of the current state of play in biosphere modeling and dose assessment programmes relating to radioactive waste management will be presented based on national presentations by Forum members at the 2007 workshop and the key research outputs developed through the Forum will be described. (authors)

Smith, K.L.; Smith, G. [Enviros Consulting Ltd, D5 Culham Science Centre, Abingdon, OX (United Kingdom); Laciok, A. [Nuclear Research Institute, CZ-25068 REZ (Costa Rica)

2007-07-01

318

Nuclear astrophysics with radioactive ions at FAIR  

E-print Network

The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process beta-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes.

Reifarth, R; Göbel, K; Heftrich, T; Heil, M; Koloczek, A; Langer, C; Plag, R; Pohl, M; Sonnabend, K; Weigand, M; Adachi, T; Aksouh, F; Al-Khalili, J; AlGarawi, M; AlGhamdi, S; Alkhazov, G; Alkhomashi, N; Alvarez-Pol, H; Alvarez-Rodriguez, R; Andreev, V; Andrei, B; Atar, L; Aumann, T; Avdeichikov, V; Bacri, C; Bagchi, S; Barbieri, C; Beceiro, S; Beck, C; Beinrucker, C; Belier, G; Bemmerer, D; Bendel, M; Benlliure, J; Benzoni, G; Berjillos, R; Bertini, D; Bertulani, C; Bishop, S; Blasi, N; Bloch, T; Blumenfeld, Y; Bonaccorso, A; Boretzky, K; Botvina, A; Boudard, A; Boutachkov, P; Boztosun, I; Bracco, A; Brambilla, S; Monago, J Briz; Caamano, M; Caesar, C; Camera, F; Casarejos, E; Catford, W; Cederkall, J; Cederwall, B; Chartier, M; Chatillon, A; Cherciu, M; Chulkov, L; Coleman-Smith, P; Cortina-Gil, D; Crespi, F; Crespo, R; Cresswell, J; Csatlós, M; Déchery, F; Davids, B; Davinson, T; Derya, V; Detistov, P; Fernandez, P Diaz; DiJulio, D; Dmitry, S; Doré, D; nas, J Due\\; Dupont, E; Egelhof, P; Egorova, I; Elekes, Z; Enders, J; Endres, J; Ershov, S; Ershova, O; Fernandez-Dominguez, B; Fetisov, A; Fiori, E; Fomichev, A; Fonseca, M; Fraile, L; Freer, M; Friese, J; Borge, M G; Redondo, D Galaviz; Gannon, S; Garg, U; Gasparic, I; Gasques, L; Gastineau, B; Geissel, H; Gernhäuser, R; Ghosh, T; Gilbert, M; Glorius, J; Golubev, P; Gorshkov, A; Gourishetty, A; Grigorenko, L; Gulyas, J; Haiduc, M; Hammache, F; Harakeh, M; Hass, M; Heine, M; Hennig, A; Henriques, A; Herzberg, R; Holl, M; Ignatov, A; Ignatyuk, A; Ilieva, S; Ivanov, M; Iwasa, N; Jakobsson, B; Johansson, H; Jonson, B; Joshi, P; Junghans, A; Jurado, B; Körner, G; Kalantar, N; Kanungo, R; Kelic-Heil, A; Kezzar, K; Khan, E; Khanzadeev, A; Kiselev, O; Kogimtzis, M; Körper, D; Kräckmann, S; Kröll, T; Krücken, R; Krasznahorkay, A; Kratz, J; Kresan, D; Krings, T; Krumbholz, A; Krupko, S; Kulessa, R; Kumar, S; Kurz, N; Kuzmin, E; Labiche, M; Langanke, K; Lazarus, I; Bleis, T Le; Lederer, C; Lemasson, A; Lemmon, R; Liberati, V; Litvinov, Y; Löher, B; Herraiz, J Lopez; Münzenberg, G; Machado, J; Maev, E; Mahata, K; Mancusi, D; Marganiec, J; Perez, M Martinez; Marusov, V; Mengoni, D; Million, B; Morcelle, V; Moreno, O; Movsesyan, A; Nacher, E; Najafi, M; Nakamura, T; Naqvi, F; Nikolski, E; Nilsson, T; Nociforo, C; Nolan, P; Novatsky, B; Nyman, G; Ornelas, A; Palit, R; Pandit, S; Panin, V; Paradela, C; Parkar, V; Paschalis, S; Paw\\lowski, P; Perea, A; Pereira, J; Petrache, C; Petri, M; Pickstone, S; Pietralla, N; Pietri, S; Pivovarov, Y; Potlog, P; Prokofiev, A; Rastrepina, G; Rauscher, T; Ribeiro, G; Ricciardi, M; Richter, A; Rigollet, C; Riisager, K; Rios, A; Ritter, C; Frutos, T Rodríguez; Vignote, J Rodriguez; Röder, M; Romig, C; Rossi, D; Roussel-Chomaz, P; Rout, P; Roy, S; Söderström, P; Sarkar, M Saha; Sakuta, S; Salsac, M; Sampson, J; Saez, J Sanchez del Rio; Rosado, J Sanchez; Sanjari, S; Sarriguren, P; Sauerwein, A; Savran, D; Scheidenberger, C; Scheit, H; Schmidt, S; Schmitt, C; Schnorrenberger, L; Schrock, P; Schwengner, R; Seddon, D; Sherrill, B; Shrivastava, A; Sidorchuk, S; Silva, J; Simon, H; Simpson, E; Singh, P; Slobodan, D; Sohler, D; Spieker, M; Stach, D; Stan, E; Stanoiu, M; Stepantsov, S; Stevenson, P; Strieder, F; Stuhl, L; Suda, T; Sümmerer, K; Streicher, B; Taieb, J; Takechi, M; Tanihata, I; Taylor, J; Tengblad, O; Ter-Akopian, G; Terashima, S; Teubig, P; Thies, R; Thoennessen, M; Thomas, T; Thornhill, J; Thungstrom, G; Timar, J; Togano, Y; Tomohiro, U; Tornyi, T; Tostevin, J; Townsley, C; Trautmann, W; Trivedi, T; Typel, S; Uberseder, E; Udias, J; Uesaka, T; Uvarov, L; Vajta, Z; Velho, P; Vikhrov, V; Volknandt, M; Volkov, V; von Neumann-Cosel, P; von Schmid, M; Wagner, A; Wamers, F; Weick, H; Wells, D; Westerberg, L; Wieland, O; Wiescher, M; Wimmer, C; Wimmer, K; Winfield, J S; Winkel, M; Woods, P; Wyss, R; Yakorev, D; Yavor, M; Cardona, J Zamora; Zartova, I; Zerguerras, T; Zgura, I; Zhdanov, A; Zhukov, M; Zieblinski, M; Zilges, A; Zuber, K

2013-01-01

319

Radioactive scrap metal decontamination technology assessment report  

SciTech Connect

Within the DOE complex there exists a tremendous quantity of radioactive scrap metal. As an example, it is estimated that within the gaseous diffusion plants there exists in excess of 700,000 tons of contaminated stainless steel. At present, valuable material is being disposed of when it could be converted into a high quality product. Liquid metal processing represents a true recycling opportunity for this material. By applying the primary production processes towards the material`s decontamination and re-use, the value of the strategic resource is maintained while drastically reducing the volume of material in need of burial. Potential processes for the liquid metal decontamination of radioactively contaminated metal are discussed and contrasted. Opportunities and technology development issues are identified and discussed. The processes compared are: surface decontamination; size reduction, packaging and burial; melting technologies; electric arc melting; plasma arc centrifugal treatment; air induction melting; vacuum induction melting; and vacuum induction melting and electroslag remelting.

Buckentin, J.M.; Damkroger, B.K.; Schlienger, M.E. [Sandia National Labs., Albuquerque, NM (United States). Liquid Metal Processing Lab.

1996-04-01

320

A Novel Radioactive Isotope Ion Target SCRIT  

SciTech Connect

Electron scattering is a superior method to investigate the internal structure, such as charge distribution, of atomic nuclei. Most of the radii of nuclei were determined unambiguously by that. However, radioactive isotopes (RI) which recently came up to a major research interest have not been accessible due to the difficulty in making fixed targets and taking measurements before they decay. We proposed a conceptually new target called SCRIT (Self-Confining Radioactive Isotope ion Target) as opposed to a collider method. The luminosity expected for SCRIT is inevitably low (typically on the order of 1.E+27/cm{sup 2}/s) and a large acceptance detector system is required. We plan to perform a coincidence measurement using an electron arm and a recoil ion detector which needs to be developed. Current status of the ion trapping with a prototype SCRIT and the background measurement results in an electron storage ring will be discussed.

Kurita, Kazuyoshi [Department of Physics, Rikkyo University, Nishi-Ikebukuro Toshima, Tokyo, 171-8501 (Japan); Cycltron Center, RIKEN, Wako, Saitama, 351-0198 (Japan); Masuda, Tetsuya [Department of Physics, Rikkyo University, Nishi-Ikebukuro Toshima, Tokyo, 171-8501 (Japan); Koseki, Tadashi [Accelerator Division I, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Noda, Akira; Shirai, Toshiyuki; Tongu, Hiromu [Center for Beam Science, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 (Japan); Furukawa, Yukihiro; Tamae, Tadaaki [Laboratory of Nuclear Science, Tohoku University, Mikamine, Taihaku, Sendai, 982-0826 (Japan); Ito, Sachiko; Emoto, Takashi; Nakamura, Masato; Wakasugi, Masanori; Yano, Yasushige [Cycltron Center, RIKEN, Wako, Saitama, 351-0198 (Japan); Ohnishi, Tetsuya; Suda, Toshimi; Takeda, Hiroyuki; Wang Shuo [RI Beam Science Laboratory, RIKEN, Wako, Saitama, 351-0198 (Japan)

2006-11-20

321

Radioactive hot cell access hole decontamination machine  

DOEpatents

Radioactive hot cell access hole decontamination machine. A mobile housing has an opening large enough to encircle the access hole and has a shielding door, with a door opening and closing mechanism, for uncovering and covering the opening. The housing contains a shaft which has an apparatus for rotating the shaft and a device for independently translating the shaft from the housing through the opening and access hole into the hot cell chamber. A properly sized cylindrical pig containing wire brushes and cloth or other disks, with an arrangement for releasably attaching it to the end of the shaft, circumferentially cleans the access hole wall of radioactive contamination and thereafter detaches from the shaft to fall into the hot cell chamber.

Simpson, William E. (Richland, WA)

1982-01-01

322

Airborne radioactivity surveys for phosphate in Florida  

USGS Publications Warehouse

Airborne radioactivity surveys totalling 5,600 traverse miles were made in ten areas in Florida, which were thought to be geologically favorable for the occurrence of uraniferous phosphate deposits. Abnormal radioactivity was recorded in eight of the ten areas surveyed. The anomalies are located in Bradford, Clay, Columbia, DeSoto, Dixie, Lake, Marion, Orange, Sumter, Taylor, and Union Counties. Two of the anomalies were investigated briefly on the ground. One resulted from a deposit of river-pebble phosphate in the Peace River valley; samples of the river pebble contain an average of 0.013 percent equivalent uranium. The other anomaly resulted from outcrops of leached phosphate rock containing as much as 0.016 percent equivalent uranium. Several anomalies in other areas were recorded at or near localities where phosphate deposits have been reported to occur.

Moxham, Robert M.

1953-01-01

323

Airborne radioactivity surveys for phosphate in Florida  

USGS Publications Warehouse

Airborne radioactivity surveys totaling 5, 600 traverse miles were made in 10 areas in Florida, which were thought to be geologically favorable for deposits of uraniferous phosphate. Abnormal radioactivity was recorded in 8 of the 10 areas surveyed. The anomalies are located in Bradford, Clay, Columbia, DeSoto, Dixie, Lake, Marion, Orange, Sumter, Taylor, and Union Counties. Two of the anomalies were investigated briefly on the ground. One resulted from a deposit of river-pebble phosphate in the Peace River valley; the river-pebble samples contain an average of 0.013 percent equivalent uranium. The other anomaly resulted from outcrops of leached phosphatic rock containing as much as 0. 016 percent equivalent uranium. Several anomalies in other areas were recorded at or near localities where phosphate deposits have been reported.

Moxham, Robert M.

1954-01-01

324

Proton radioactivity with a Yukawa effective interaction  

NASA Astrophysics Data System (ADS)

The half-lives of proton radioactivity of proton emitters are investigated theoretically. Proton-nucleus interaction potentials are obtained by folding the densities of the daughter nuclei with a finite-range effective nucleon-nucleon interaction having Yukawa form. The Wood-Saxon density distributions for the nuclei used in calculating the nuclear as well as the Coulomb interaction potentials are predictions of the interaction. The quantum mechanical tunneling probability is calculated within the WKB framework. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes. The effects of neutron-proton effective mass splitting in neutron-rich asymmetric matter as well as the nuclear matter incompressibility on the decay probability are investigated.

Routray, T. R.; Tripathy, S. K.; Dash, B. B.; Behera, B.; Basu, D. N.

2011-08-01

325

Proton radioactivity with a Yukawa effective interaction  

E-print Network

The half lives of proton radioactivity of proton emitters are investigated theoretically. Proton-nucleus interaction potentials are obtained by folding the densities of the daughter nuclei with a finite range effective nucleon-nucleon interaction having Yukawa form. The Wood-Saxon density distributions for the nuclei used in calculating the nuclear as well as the Coulomb interaction potentials are predictions of the interaction. The quantum mechanical tunneling probability is calculated within the WKB framework. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes. The effects of neutron-proton effective mass splitting in neutron rich asymmetric matter as well as the nuclear matter incompressibility on the decay probability are investigated.

T. R. Routray; S. K. Tripathy; B. B. Dash; B. Behera; D. N. Basu

2011-04-26

326

Treatment of Radioactive Reactive Mixed Waste  

SciTech Connect

PacificEcoSolutions, Inc. (PEcoS) has installed a plasma gasification system that was recently modified and used to destroy a trimethyl-aluminum mixed waste stream from Los Alamos National Laboratory (LANL.) The unique challenge in handling reactive wastes like trimethyl-aluminum is their propensity to flame instantly on contact with air and to react violently with water. To safely address this issue, PacificEcoSolutions has developed a new feed system to ensure the safe containment of these radioactive reactive wastes during transfer to the gasification unit. The plasma gasification system safely processed the radioactively contaminated trimethyl-metal compounds into metal oxides. The waste stream came from LANL research operations, and had been in storage for seven years, pending treatment options. (authors)

Colby, S.; Turner, Z.; Utley, D. [Pacific EcoSolutions, Inc., 2025 Battelle Boulevard, Richland, Washington 99354 (United States); Duy, C. [Los Alamos National Laboratory - LA-UR-05-8410, Post Office Box 1663 MS J595, Los Alamos, New Mexico 97545 (United States)

2006-07-01

327

Nuclear astrophysics with radioactive ions at FAIR  

E-print Network

The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process beta-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes.

R. Reifarth; S. Altstadt; K. Göbel; T. Heftrich; M. Heil; A. Koloczek; C. Langer; R. Plag; M. Pohl; K. Sonnabend; M. Weigand; T. Adachi; F. Aksouh; J. Al-Khalili; M. AlGarawi; S. AlGhamdi; G. Alkhazov; N. Alkhomashi; H. Alvarez-Pol; R. Alvarez-Rodriguez; V. Andreev; B. Andrei; L. Atar; T. Aumann; V. Avdeichikov; C. Bacri; S. Bagchi; C. Barbieri; S. Beceiro; C. Beck; C. Beinrucker; G. Belier; D. Bemmerer; M. Bendel; J. Benlliure; G. Benzoni; R. Berjillos; D. Bertini; C. Bertulani; S. Bishop; N. Blasi; T. Bloch; Y. Blumenfeld; A. Bonaccorso; K. Boretzky; A. Botvina; A. Boudard; P. Boutachkov; I. Boztosun; A. Bracco; S. Brambilla; J. Briz Monago; M. Caamano; C. Caesar; F. Camera; E. Casarejos; W. Catford; J. Cederkall; B. Cederwall; M. Chartier; A. Chatillon; M. Cherciu; L. Chulkov; P. Coleman-Smith; D. Cortina-Gil; F. Crespi; R. Crespo; J. Cresswell; M. Csatlós; F. Déchery; B. Davids; T. Davinson; V. Derya; P. Detistov; P. Diaz Fernandez; D. DiJulio; S. Dmitry; D. Doré; J. Due\\. nas; E. Dupont; P. Egelhof; I. Egorova; Z. Elekes; J. Enders; J. Endres; S. Ershov; O. Ershova; B. Fernandez-Dominguez; A. Fetisov; E. Fiori; A. Fomichev; M. Fonseca; L. Fraile; M. Freer; J. Friese; M. G. Borge; D. Galaviz Redondo; S. Gannon; U. Garg; I. Gasparic; L. Gasques; B. Gastineau; H. Geissel; R. Gernhäuser; T. Ghosh; M. Gilbert; J. Glorius; P. Golubev; A. Gorshkov; A. Gourishetty; L. Grigorenko; J. Gulyas; M. Haiduc; F. Hammache; M. Harakeh; M. Hass; M. Heine; A. Hennig; A. Henriques; R. Herzberg; M. Holl; A. Ignatov; A. Ignatyuk; S. Ilieva; M. Ivanov; N. Iwasa; B. Jakobsson; H. Johansson; B. Jonson; P. Joshi; A. Junghans; B. Jurado; G. Körner; N. Kalantar; R. Kanungo; A. Kelic-Heil; K. Kezzar; E. Khan; A. Khanzadeev; O. Kiselev; M. Kogimtzis; D. Körper; S. Kräckmann; T. Kröll; R. Krücken; A. Krasznahorkay; J. Kratz; D. Kresan; T. Krings; A. Krumbholz; S. Krupko; R. Kulessa; S. Kumar; N. Kurz; E. Kuzmin; M. Labiche; K. Langanke; I. Lazarus; T. Le Bleis; C. Lederer; A. Lemasson; R. Lemmon; V. Liberati; Y. Litvinov; B. Löher; J. Lopez Herraiz; G. Münzenberg; J. Machado; E. Maev; K. Mahata; D. Mancusi; J. Marganiec; M. Martinez Perez; V. Marusov; D. Mengoni; B. Million; V. Morcelle; O. Moreno; A. Movsesyan; E. Nacher; M. Najafi; T. Nakamura; F. Naqvi; E. Nikolski; T. Nilsson; C. Nociforo; P. Nolan; B. Novatsky; G. Nyman; A. Ornelas; R. Palit; S. Pandit; V. Panin; C. Paradela; V. Parkar; S. Paschalis; P. Paw\\lowski; A. Perea; J. Pereira; C. Petrache; M. Petri; S. Pickstone; N. Pietralla; S. Pietri; Y. Pivovarov; P. Potlog; A. Prokofiev; G. Rastrepina; T. Rauscher; G. Ribeiro; M. Ricciardi; A. Richter; C. Rigollet; K. Riisager; A. Rios; C. Ritter; T. Rodríguez Frutos; J. Rodriguez Vignote; M. Röder; C. Romig; D. Rossi; P. Roussel-Chomaz; P. Rout; S. Roy; P. Söderström; M. Saha Sarkar; S. Sakuta; M. Salsac; J. Sampson; J. Sanchez del Rio Saez; J. Sanchez Rosado; S. Sanjari; P. Sarriguren; A. Sauerwein; D. Savran; C. Scheidenberger; H. Scheit; S. Schmidt; C. Schmitt; L. Schnorrenberger; P. Schrock; R. Schwengner; D. Seddon; B. Sherrill; A. Shrivastava; S. Sidorchuk; J. Silva; H. Simon; E. Simpson; P. Singh; D. Slobodan; D. Sohler; M. Spieker; D. Stach; E. Stan; M. Stanoiu; S. Stepantsov; P. Stevenson; F. Strieder; L. Stuhl; T. Suda; K. Sümmerer; B. Streicher; J. Taieb; M. Takechi; I. Tanihata; J. Taylor; O. Tengblad; G. Ter-Akopian; S. Terashima; P. Teubig; R. Thies; M. Thoennessen; T. Thomas; J. Thornhill; G. Thungstrom; J. Timar; Y. Togano; U. Tomohiro; T. Tornyi; J. Tostevin; C. Townsley; W. Trautmann; T. Trivedi; S. Typel; E. Uberseder; J. Udias; T. Uesaka; L. Uvarov; Z. Vajta; P. Velho; V. Vikhrov; M. Volknandt; V. Volkov; P. von Neumann-Cosel; M. von Schmid; A. Wagner; F. Wamers; H. Weick; D. Wells; L. Westerberg; O. Wieland; M. Wiescher; C. Wimmer; K. Wimmer; J. S. Winfield; M. Winkel; P. Woods; R. Wyss; D. Yakorev; M. Yavor; J. Zamora Cardona; I. Zartova; T. Zerguerras; I. Zgura; A. Zhdanov; M. Zhukov; M. Zieblinski; A. Zilges; K. Zuber

2013-10-06

328

Greater confinement disposal of radioactive wastes  

Microsoft Academic Search

Low-level radioactive waste (LLW) includes a broad spectrum of different radionuclide concentrations, half-lives, and hazards. Standard shallow-land burial practice can provide adequate protection of public health and safety for most LLW. A small volume fraction (approx. 1%) containing most of the activity inventory (approx. 90%) requires specific measures known as greater-confinement disposal (GCD). Different site characteristics and different waste characteristics

L. E. Trevorrow; T. L. Gilbert; C. Luner; P. A. Merry-Libby; N. K. Meshkov; C. Yu

1985-01-01

329

Preparation of Radioactive Labelled (Co) Sulfitocobalamin  

Microsoft Academic Search

Farquharson and Adams (Br. J. Nutr. 36, 127-135 (1976)) have identified sulfitocobalamin (S03?Cbl) as one of the naturally occurring cobalamins (Cbls) in foods. We have devised a method of making radioactive labelled S03?Cbl for invivo and in vitro studies of this form of Cbl. Co labelled cyanocobalamin (Co CN-Cbl) was acid photolyzed to Co hydroxocobalamin (Co OH-Cbl) followed by ligand

James A. Begley; Carol Horch; Charles A. Hall

1978-01-01

330

Transport of Carbon Dioxide and Radioactive Waste  

Microsoft Academic Search

\\u000a A comparative assessment of carbon dioxide (CO2) and radioactive waste transport systems associated with electricity generation was undertaken on the basis of 15 criteria\\u000a grouped under three areas, namely the transport chain, policy aspects and state of the technology. For CO2, we considered exclusively the transport that would take place under a future large-scale capture and storage infrastructure.\\u000a Our study

Darío R. Gómez; Michael Tyacke

331

Time-dependent radioactivity distribution in MAFF  

Microsoft Academic Search

The Munich Accelerator for Fission Fragments is planned to be installed at the FRM II in Garching. It will operate a uranium-carbide-loaded graphite matrix as a target for neutron-induced fission. The radioactive reaction fragments leave the ion source as both, atoms and ions. For radiation safety it is imperative to have a basic understanding of the fragment distribution within the

F. Nebel; E. Zech; T. Faestermann; R. Krücken; P. Maier-Komor; W. Assmann; J. Szerypo; M. Groß; O. Kester; P. G. Thirolf; R. Grötzschel

2006-01-01

332

A radioactive ion beam facility using photofission  

Microsoft Academic Search

Use of a high-power electron linac as the driver accelerator for a Radioactive Ion Beam (RIB) facility is proposed. An electron beam of 30MeV and 100kW can produce nearly 5×1013 fissions\\/s from an optimized 235U target and about 60% of this from a natural uranium target. An electron beam can be readily transmitted through a thin window at the exit

William T Diamond

1999-01-01

333

Phosphate bonded solidification of radioactive incinerator wastes  

SciTech Connect

The incinerator at the Department of Energy Savannah River Site burns low level radioactive and hazardous waste. Ash and scrubber system waste streams are generated during the incineration process. Phosphate Ceramic technology is being tested to verify the ash and scrubber waste streams can be stabilized using this solidification method. Acceptance criteria for the solid waste forms include leachability, bleed water, compression testing, and permeability. Other testing on the waste forms include x-ray diffraction and scanning electron microscopy.

Walker, B. W.; Langton, C. A.; Singh, D.

1999-12-03

334

Performance assessment of radioactive waste repositories  

Microsoft Academic Search

The current plans for permanent disposal of radioactive waste call for its emplacement in deep underground repositories mined from geologically stable rock formations. The U.S. Nuclear Regulatory Commission and U.S. Environmental Protection Agency have established regulations setting repository performance standards for periods of up to 10,000 years after disposal. Compliance with these regulations will be based on a performance assessment

J. E. Campbell; R. M. Cranwell

1988-01-01

335

Fabrication of radioactive stents by ion implantation  

NASA Astrophysics Data System (ADS)

Worldwide about one million patients require treatment of stenosed coronary arteries annually. Often a tubular stainless steel mesh (stent) is implanted to mechanically support the injured vessel. Restenosis, an abundant complication (20%-30%) can be prevented, if the vessel is treated with ionizing radiation. Stents can deliver radiation if they are made radioactive. The radio isotope 32P is well suited when ion implanted. Radioactive ions sources require high efficiency to keep the radioactive inventory small. Reliability, ease of operation, and maintenance are mandatory. A small emittance is important to minimize losses during mass separation and beam transport. A 2.45 GHz ECR source was developed for the implantation of 32P. The source consists of two coils for the axial and a permanent hexapole for the radial confinement. The microwaves are fed in radially by a loop connected to a silver plated brass tube surrounding the plasma chamber. The plasma chamber is made from Pyrex. Neutron activated phosphorus, containing 30 ppm 32P, is introduced from the rear end on a rod. As support gas D2 is used. By this 32P+ can be separated from (31PD)+. The extraction is done in two steps: 60 kV-30 kV-ground. Mass separation is accomplished by a double focusing 90° magnet (radius 500 mm). During four years of operation about 1000 radioactive stents per year have been provided for animal experiments and clinical trials. Only one maintenance to exchange the extraction system due to degradation of high voltage stability was required so far.

Huttel, Erhard; Kaltenbaek, Johann; Schloesser, Klaus; Schweickert, Hermann

2002-02-01

336

Radioactive isotopes in solid state physics  

Microsoft Academic Search

A wide range of solid state physics techniques is using radioactive ion beams, both from on-line and off-line separators. The different techniques can be roughly subdivided into two classes: one, including the hyperfine techniques like Mößbauer spectroscopy (MS), Perturbed Angular Correlation (PAC) spectroscopy, beta-NMR and the ion-beam technique of Emission Channeling (EC). They all crucially depend on the availability of

D. Forkel-Wirth

1996-01-01

337

Radioactive isotopes in solid state physics  

Microsoft Academic Search

A wide range of solid state physics techniques is using radioactive ion beams, both from on-line and off-line separators. The different techniques can be roughly subdivided into two classes: one, including the hyperfine techniques like Mößbauer spectroscopy (MS), Perturbed Angular Correlation (PAC) spectroscopy, ?-NMR and the ion-beam technique of Emission Channeling (EC). They all crucially depend on the availability of

Doris Forkel-Wirth

1997-01-01

338

Natural radioactivity levels in Andalusian spas  

Microsoft Academic Search

Gross-? and gross-? activity, 222Rn, 226Ra and 224Ra of waters from several spas of Andalusia (Spain) were performed in order to determine their radioactivity. Radon concentration ranged from 0.225 to 130Bq\\/l. 226Ra and 224Ra concentrations ranged from 2 to 1367mBq\\/l and from 2 to 122mBq\\/l respectively. Correlations between the 222Rn and 226Ra concentrations and gross-? activity were obtained. A correlation

C Dueñas; M. C Fernández; C Enr??quez; J Carretero; E Liger

1998-01-01

339

Radioactive contamination of the Yenisei River  

Microsoft Academic Search

Based on observational data in the period 1971–1993, radioactive contamination of the Yenisei River ecosystem was analysed within 2000 km of the site of discharges from the Krasnoyarsk Mining and Chemical Industrial Complex. Data on the content of 24Na, 32P, 46Sc, 51Cr, 54Mn, 56Mn, 58Co, 60Co, 59Fe, 65Zn, 90Sr, 95Zr, 95Nb, 103Ru, 106Ru, 134Cs, 137Cs, 140Ba, 141Ce, 144Ce and 239Np

E. G. Tertyshnik

1995-01-01

340

Statistical analysis of radioactivity in the environment  

SciTech Connect

The pattern of radioactivity in surface soils of Area 5 of the Nevada Test Site is analyzed statistically by means of kriging. The 1962 event code-named Smallboy effected the greatest proportion of the area sampled, but some of the area was also affected by a number of other events. The data for this study were collected on a regular grid to take advantage of the efficiency of grid sampling. (ACR)

Barnes, M.G.; Giacomini, J.J.

1980-05-01

341

Lasers for the radioactive decontamination of concrete  

Microsoft Academic Search

The use of lasers for removing radioactive contamination from concrete surfaces is being investigated at the US Department of Energy`s Hanford Site. A major advantage of a laser decontamination process is that no additional waste is generated. Test results using 50- and 600-W YAG (yttrium-aluminum-garnet) lasers have been extrapolated to more powerful commercially available units. The minimum removal rate for

N. S. Cannon; D. J. Flesher

1993-01-01

342

A Simple Example of Radioactive Dating  

ERIC Educational Resources Information Center

Although nuclear half-life is vital to physics and physical science, and to sensitive societal issues from nuclear waste to the age of the Earth, a true lab on half-life is almost never done at the college or high school level. Seldom are students able to use radioactivity to actually date when an object came into being, as is done in this…

Brown, Todd

2014-01-01

343

A New Interpretation of Cluster Radioactivity Mechanism  

NASA Astrophysics Data System (ADS)

The basis for cluster radioactivity is the property of nuclei of light isotopes of elements heavier than lead to spontaneously form clusters -- nuclei of light elements -- from valence nucleons, which gives rise to asymmetric nuclear molecules. The cluster formation proceeds through successive excitation-free transfer of valence nucleons to the ? particle and to subsequent light nuclei. Nuclear molecule formation is accompanied by a considerable amount of released energy, which allows quantum-mechanical penetration of the cluster through the exit Coulomb barrier.

Cherepanov, E. A.; Volkov, V. V.

2015-11-01

344

Novel techniques to search for neutron radioactivity  

E-print Network

Two new methods to observe neutron radioactivity are presented. Both methods rely on the production and decay of the parent nucleus in flight. The relative velocity measured between the neutron and the fragment is sensitive to half-lives between ~1 and ~100 ps for the Decay in Target (DiT) method. The transverse position measurement of the neutron in the Decay in a Magnetic Field (DiMF) method is sensitive to half-lives between 10 ps and 1 ns.

M. Thoennessen; G. Christian; Z. Kohley; T. Baumann; M. Jones; J. K. Smith; J. Snyder; A. Spyrou

2013-07-08

345

Radioactive materials released from nuclear power plants  

SciTech Connect

Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1987 have been compiled and reported. Data on solid waste shipments as well as selected operating information have been included. This report supplements earlier annual reports issued by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1987 release data are summarized in tabular form. Data covering specific radionuclides are summarized. 16 tabs.

Tichler, J.; Norden, K.; Congemi, J. (Brookhaven National Lab., Upton, NY (USA))

1989-10-01

346

Radioactive materials released from nuclear power plants  

SciTech Connect

Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1988 have been compiled and reported. Data on solid waste shipments as well as selected operating information have been included. This report supplements earlier annual reports issued by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1988 release data are summarized in tabular form. Data covering specific radionuclides are summarized. 16 tabs.

Tichler, J.; Norden, K.; Congemi, J. (Brookhaven National Lab., Upton, NY (USA))

1991-05-01

347

Radioactive iodine therapy in cats with hyperthyroidism  

SciTech Connect

Eleven cats with hyperthyroidism were treated with radioactive iodine (/sup 131/I). Previous unsuccessful treatments for hyperthyroidism included hemithyroidectomy (2 cats) and an antithyroid drug (7 cats). Two cats had no prior treatment. Thyroid scans, using technetium 99m, showed enlargement and increased radionuclide accumulation in 1 thyroid lobe in 5 cats and in both lobes in 6 cats. Serum thyroxine concentrations were high and ranged from 4.7 to 18 micrograms/dl. Radioactive iodine tracer studies were used to determine peak radioactive iodine uptake (RAIU) and effective and biological half-lives. Activity of /sup 131/I administered was calculated from peak RAIU, effective half-life, and estimated thyroid gland weight. Activity of /sup 131/I administered ranged from 1.0 to 5.9 mCi. The treatment goal was to deliver 20,000 rad to hyperactive thyroid tissue. However, retrospective calculations based on peak RAIU and effective half-life obtained during the treatment period showed that radiation doses actually ranged from 7,100 to 64,900 rad. Complete ablation of the hyperfunctioning thyroid tissue and a return to euthyroidism were seen in 7 cats. Partial responses were seen in 2 cats, and 2 cats became hypothyroid. It was concluded that /sup 131/I ablation of thyroid tumors was a reasonable alternative in the treatment of hyperthyroidism in cats. The optimal method of dosimetry remains to be determined.

Turrel, J.M.; Feldman, E.C.; Hays, M.; Hornof, W.J.

1984-03-01

348

Radioactive Waste Burial Grounds. Environmental Information Document  

SciTech Connect

This document provides environmental information on postulated closure options for the Radioactive Waste Burial Grounds at the Savannah River Plant and was developed as background technical documentation for the Department of Energy`s proposed Environmental Impact Statement (EIS) on waste management activities for groundwater protection at the plant. The results of groundwater and atmospheric pathway analyses, accident analysis, and other environmental assessments discussed in this document are based upon a conservative analysis of all foreseeable scenarios as defined by the National Environmental Policy Act (CFR, 1986). The scenarios do not necessarily represent actual environmental conditions. This document is not meant to be used as a closure plan or other regulatory document to comply with required federal or state environmental regulations. The closure options considered for the Radioactive Waste Burial Grounds are waste removal and closure, no waste removal and closure, and no action. The predominant pathways for human exposure to chemical and/or radioactive constituents are through surface, subsurface, and atmospheric transport. Modeling calculations were made to determine the risks to human population via these general pathways for the three postulated closure options. An ecological assessment was conducted to predict the environmental impacts on aquatic and terrestrial biota. The relative costs for each of the closure options were estimated.

Jaegge, W.J.; Kolb, N.L.; Looney, B.B.; Marine, I.W.; Towler, O.A.; Cook, J.R.

1987-03-01

349

Future radioactive liquid waste streams study  

SciTech Connect

This study provides design planning information for the Radioactive Liquid Waste Treatment Facility (RLWTF). Predictions of estimated quantities of Radioactive Liquid Waste (RLW) and radioactivity levels of RLW to be generated are provided. This information will help assure that the new treatment facility is designed with the capacity to treat generated RLW during the years of operation. The proposed startup date for the RLWTF is estimated to be between 2002 and 2005, and the life span of the facility is estimated to be 40 years. The policies and requirements driving the replacement of the current RLW treatment facility are reviewed. Historical and current status of RLW generation at Los Alamos National Laboratory are provided. Laboratory Managers were interviewed to obtain their insights into future RLW activities at Los Alamos that might affect the amount of RLW generated at the Lab. Interviews, trends, and investigation data are analyzed and used to create scenarios. These scenarios form the basis for the predictions of future RLW generation and the level of RLW treatment capacity which will be needed at LANL.

Rey, A.S.

1993-11-01

350

Integration of Radioactive Material with Microcalorimeter Detectors  

NASA Astrophysics Data System (ADS)

Microcalorimeter detectors with embedded radioactive material offer many possibilities for new types of measurements and applications. We will discuss the designs and methods that we are developing for precise deposition of radioactive material and its encapsulation in the absorber of transition-edge sensor (TES) microcalorimeter detectors for two specific applications. The first application is total nuclear reaction energy (Q) spectroscopy for nuclear forensics measurements of trace actinide samples, where the goal is determination of ratios of isotopes with Q values in the range of 5-7 MeV. Simplified, rapid sample preparation and detector assembly is necessary for practical measurements, while maintaining good energy resolution. The second application is electron capture spectroscopy of isotopes with low Q values, such as Ho, for measurement of neutrino mass. Detectors for electron capture spectroscopy are designed for measuring energies up to approximately 6 keV. Their smaller heat capacity and physical size present unique challenges. Both applications require precise deposition of radioactive material and encapsulation in an absorber with optimized thermal properties and coupling to the TES. We have made detectors for both applications with a variety of designs and assembly methods, and will present their development.

Croce, M. P.; Bond, E. M.; Hoover, A. S.; Kunde, G. J.; Moody, W. A.; Rabin, M. W.; Bennett, D. A.; Hayes-Wehle, J.; Kotsubo, V.; Schmidt, D. R.; Ullom, J. N.

2014-09-01

351

Geological problems in radioactive waste isolation  

SciTech Connect

The problem of isolating radioactive wastes from the biosphere presents specialists in the fields of earth sciences with some of the most complicated problems they have ever encountered. This is especially true for high level waste (HLW) which must be isolated in the underground and away from the biosphere for thousands of years. Essentially every country that is generating electricity in nuclear power plants is faced with the problem of isolating the radioactive wastes that are produced. The general consensus is that this can be accomplished by selecting an appropriate geologic setting and carefully designing the rock repository. Much new technology is being developed to solve the problems that have been raised and there is a continuing need to publish the results of new developments for the benefit of all concerned. The 28th International Geologic Congress that was held July 9--19, 1989 in Washington, DC provided an opportunity for earth scientists to gather for detailed discussions on these problems. Workshop W3B on the subject, Geological Problems in Radioactive Waste Isolation -- A World Wide Review'' was organized by Paul A Witherspoon and Ghislain de Marsily and convened July 15--16, 1989 Reports from 19 countries have been gathered for this publication. Individual papers have been cataloged separately.

Witherspoon, P.A. (ed.)

1991-01-01

352

Molecular Optical Imaging with Radioactive Probes  

PubMed Central

Background Optical imaging (OI) techniques such as bioluminescence and fluorescence imaging have been widely used to track diseases in a non-invasive manner within living subjects. These techniques generally require bioluminescent and fluorescent probes. Here we demonstrate the feasibility of using radioactive probes for in vivo molecular OI. Methodology/Principal Findings By taking the advantages of low energy window of light (1.2–3.1 eV, 400–1000 nm) resulting from radiation, radionuclides that emit charged particles such as ?+ and ?? can be successfully imaged with an OI instrument. In vivo optical images can be obtained for several radioactive probes including 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG), Na18F, Na131I, 90YCl3 and a 90Y labeled peptide that specifically target tumors. Conclusions/Significance These studies demonstrate generalizability of radioactive OI technique. It provides a new molecular imaging strategy and will likely have significant impact on both small animal and clinical imaging. PMID:20208993

Liu, Hongguang; Ren, Gang; Miao, Zheng; Zhang, Xiaofen; Tang, Xiaodong; Han, Peizhen; Gambhir, Sanjiv S.; Cheng, Zhen

2010-01-01

353

Soils: man-caused radioactivity and radiation forecast  

SciTech Connect

Available in abstract form only. Full text of publication follows: One of the main tasks of the radiation safety guarantee is non-admission of the excess over critical radiation levels. In Russia they are man-caused radiation levels. Meanwhile any radiation measurement represents total radioactivity. That is why it is hard to assess natural and man-caused contributions to total radioactivity. It is shown that soil radioactivity depends on natural factors including radioactivity of rocks and cosmic radiation as well as man-caused factors including nuclear and non-nuclear technologies. Whole totality of these factors includes unpredictable (non-deterministic) factors - nuclear explosions and radiation accidents, and predictable ones (deterministic) - all the rest. Deterministic factors represent background radioactivity whose trends is the base of the radiation forecast. Non-deterministic factors represent man-caused radiation treatment contribution which is to be controlled. This contribution is equal to the difference in measured radioactivity and radiation background. The way of calculation of background radioactivity is proposed. Contemporary soils are complicated technologically influenced systems with multi-leveled spatial and temporary inhomogeneity of radionuclides distribution. Generally analysis area can be characterized by any set of factors of soil radioactivity including natural and man-caused factors. Natural factors are cosmic radiation and radioactivity of rocks. Man-caused factors are shown on Fig. 1. It is obvious that man-caused radioactivity is due to both artificial and natural emitters. Any result of radiation measurement represents total radioactivity i.e. the sum of activities resulting from natural and man-caused emitters. There is no gauge which could separately measure natural and man-caused radioactivity. That is why it is so hard to assess natural and man-caused contributions to soil radioactivity. It would have been possible if human activity had led to contamination of soil only by artificial radionuclides. But we can view a totality of soil radioactivity factors in the following way. (author)

Gablin, Vassily [Scientific-Industrial Association 'Radon', 7th Rostovsky Lane, Moscow 119121 (Russian Federation)

2007-07-01

354

Waste minimization for commercial radioactive materials users generating low-level radioactive waste. Revision 1  

SciTech Connect

The objective of this document is to provide a resource for all states and compact regions interested in promoting the minimization of low-level radioactive waste (LLW). This project was initiated by the Commonwealth of Massachusetts, and Massachusetts waste streams have been used as examples; however, the methods of analysis presented here are applicable to similar waste streams generated elsewhere. This document is a guide for states/compact regions to use in developing a system to evaluate and prioritize various waste minimization techniques in order to encourage individual radioactive materials users (LLW generators) to consider these techniques in their own independent evaluations. This review discusses the application of specific waste minimization techniques to waste streams characteristic of three categories of radioactive materials users: (1) industrial operations using radioactive materials in the manufacture of commercial products, (2) health care institutions, including hospitals and clinics, and (3) educational and research institutions. Massachusetts waste stream characterization data from key radioactive materials users in each category are used to illustrate the applicability of various minimization techniques. The utility group is not included because extensive information specific to this category of LLW generators is available in the literature.

Fischer, D.K.; Gitt, M.; Williams, G.A.; Branch, S. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Otis, M.D.; McKenzie-Carter, M.A.; Schurman, D.L. [Science Applications International Corp., Idaho Falls, ID (United States)

1991-07-01

355

The Spanish General Radioactive Waste Management Plan  

SciTech Connect

This paper mainly describes the strategies, the necessary actions and the technical solutions to be developed by ENRESA in the short, medium and long term, aimed at ensuring the adequate management of radioactive waste, the dismantling and decommissioning of nuclear and radioactive facilities and other activities, including economic and financial measures required to carry them out. Starting with the Spanish administrative organization in this field, which identifies the different agents involved and their roles, and after referring to the waste generation, the activities to be performed in the areas of LILW, SF and HLW management, decommissioning of installations and others are summarized. Finally, the future management costs are estimated and the financing system currently in force is explained. The so-called Sixth General Radioactive Waste Plan (6. GRWP), approved by the Spanish Government, is the 'master document' of reference where all the above mentioned issues are contemplated. In summary: The 6. GRWP includes the strategies and actions to be performed by Enresa in the coming years. The document, revised by the Government and subject to a process of public information, underlines the fact that Spain possesses an excellent infrastructure for the safe and efficient management of radioactive waste, from the administrative, technical and economic-financial points of view. From the administrative point of view there is an organisation, supported by ample legislative developments, that contemplates and governs the main responsibilities of the parties involved in the process (Government, CSN, ENRESA and waste producers). As regards the technical aspect, the experience accumulated to date by Enresa is particularly significant, as are the technologies now available in the field of management and for dismantling processes. As regards the economic-financial basis, a system is in place that guarantees the financing of radioactive waste management costs. This system is based on the generation of funds up front, during the operating lifetime of the facilities, through the application of fees established by Statutory provisions. Finally, a mandatory mechanism of annual revision for both technical issues and economic and financial aspects, allows to have updated all the courses of action. (authors)

Espejo, J.M.; Abreu, A. [National Company for Radioactive Waste Limited Company (ENRESA), Madrid (Spain)

2008-07-01

356

Experimental incineration of low level radioactive samples.  

PubMed

To determine the volume reduction potential for incineration of radioactivity in low-level radioactive waste, an incineration experiment was performed at the Okayama University Radioisotope Center (OURIC). Solid low-level radioactive samples (LLRS) were prepared for 15 routinely used radionuclides (45Ca, 1251, 32p, 33p, 35S, 59Fe, 123I, 131I, 67Ga, 99mTc, 111In, 3H, 14C, 51Cr, and 201Tl). For each radionuclide, incinerated one at a time, the smoke duct radioisotope concentration was less than 1/10 of the regulatory concentration limit (The Japanese law concerning prevention of radiation hazard due to radioisotopes, etc.). The radionuclide-containing combustible and semi-combustible LLRS were incinerated at the AP-1 50R furnace erected at OURIC, and the distribution of radioactivity inside and outside the furnace was measured. In the experimental incineration of LLRS containing these 15 radionuclides, the fractions released (RF) in the gas phase of the final smoke duct ranged from 0.165 to 0.99. The radioactivities remaining in the incineration residue were 99mTc, 87%; 59Fe, 83.1%; 45Ca, 75%; 51Cr, 62.1%; 33P, 62.0%; 32P, 61.1%; 67Ga, 57.7%; 35S, 26.0%; 111In, 21.1%; 201Tl, 16.6%; 123I, 11.9%; 131I, 8.2%; 125I, 2.4%; 14C, 0.39%; 3H, 0.04%. In the incineration of LLR S containing 35S, the rate of adhesion to the furnace wall was lower at high-temperature (809 degrees C) incineration than at low-temperature (376 degrees C) incineration. For LLRS containing one of the three radioiodines, 123I, 125I, or 131I, no such difference was observed between low (372 degrees C) and high (827 degrees C) temperature incineration (RF varied from 0.82 to 0.94). PMID:10910400

Yumoto, Y; Hanafusa, T; Nagamatsu, T; Okada, S

2000-08-01

357

Upgrading the Radioactive Waste Management Infrastructure in Azerbaijan  

SciTech Connect

Radionuclide uses in Azerbaijan are limited to peaceful applications in the industry, medicine, agriculture and research. The Baku Radioactive Waste Site (BRWS) 'IZOTOP' is the State agency for radioactive waste management and radioactive materials transport. The radioactive waste processing, storage and disposal facility is operated by IZOTOP since 1963 being significantly upgraded from 1998 to be brought into line with international requirements. The BRWS 'IZOTOP' is currently equipped with state-of-art devices and equipment contributing to the upgrade the radioactive waste management infrastructure in Azerbaijan in line with current internationally accepted practices. The IAEA supports Azerbaijan specialists in preparing syllabus and methodological materials for the Training Centre that is currently being organized on the base of the Azerbaijan BRWS 'IZOTOPE' for education of specialists in the area of safety management of radioactive waste: collection, sorting, processing, conditioning, storage and transportation. (authors)

Huseynov, A. [Baku Radioactive Waste Site IZOTOP, Baku (Azerbaijan); Batyukhnova, O. [State Unitary Enterprise Scientific and Industrial Association Radon, Moscow (Russian Federation); Ojovan, M. [Sheffield Univ., Immobilisation Science Lab. (United Kingdom); Rowat, J. [International Atomic Energy Agency, Dept. of Nuclear Safety and Security, Vienna (Austria)

2007-07-01

358

Environmental Assessment Radioactive Source Recovery Program  

SciTech Connect

In a response to potential risks to public health and safety, the U.S. Department of Energy (DOE) is evaluating the recovery of sealed neutron sources under the Radioactive Source Recovery Program (RSRP). This proposed program would enhance the DOE`s and the U.S. Nuclear Regulatory Commission`s (NRC`s) joint capabilities in the safe management of commercially held radioactive source materials. Currently there are no federal or commercial options for the recovery, storage, or disposal of sealed neutron sources. This Environmental Assessment (EA) analyzes the potential environmental impacts that would be expected to occur if the DOE were to implement a program for the receipt and recovery at the Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, of unwanted and excess plutonium-beryllium ({sup 238}Pu-Be) and americium-beryllium ({sup 241}Am-Be) sealed neutron sources. About 1 kg (2.2 lb) plutonium and 3 kg (6.6 lb) americium would be recovered over a 15-year project. Personnel at LANL would receive neutron sources from companies, universities, source brokers, and government agencies across the country. These neutron sources would be temporarily stored in floor holes at the CMR Hot Cell Facility. Recovery reduces the neutron emissions from the source material and refers to a process by which: (1) the stainless steel cladding is removed from the neutron source material, (2) the mixture of the radioactive material (Pu-238 or Am-241) and beryllium that constitutes the neutron source material is chemically separated (recovered), and (3) the recovered Pu-238 or Am-241 is converted to an oxide form ({sup 238}PuO{sub 2} or {sup 241}AmO{sub 2}). The proposed action would include placing the {sup 238}PuO{sub 2} or {sup 241}AmO{sub 2} in interim storage in a special nuclear material vault at the LANL Plutonium Facility.

NONE

1995-12-20

359

Time-dependent radioactivity distribution in MAFF  

NASA Astrophysics Data System (ADS)

The Munich Accelerator for Fission Fragments is planned to be installed at the FRM II in Garching. It will operate a uranium-carbide-loaded graphite matrix as a target for neutron-induced fission. The radioactive reaction fragments leave the ion source as both, atoms and ions. For radiation safety it is imperative to have a basic understanding of the fragment distribution within the beam line. Atoms leaving the graphite matrix will spread like a gas and stick to surfaces depending on their species. A probabilistic Monte-Carlo approach is used to predict the surface coating of internal surfaces of the beam line for all fission nuclides. To decrease calculation time, the problem is reduced to two dimensions with the surface areas being a measure for the probability, that they are hit by a particle. The program is completely time dependent to implement radioactive decay. Ions leaving the fission ion source are transported by electrostatic means towards the mass pre-separator, a low-resolution dipole magnet with a complex slit system in the focal plane. All unwanted ions are stopped at the slits, resulting in a high level of radioactive contamination. While it is advantageous for shielding purposes to have the majority of the contamination in one point, precautions must be taken to ensure that it stays that way. Material corrosion caused by sputtering will release previously implanted radionuclides. To reduce this effect, different methods are under investigation, one of which is changing the slit geometry. The considered designs will be described and experimental results will be shown.

Nebel, F.; Zech, E.; Faestermann, T.; Krücken, R.; Maier-Komor, P.; Assmann, W.; Szerypo, J.; Groß, M.; Kester, O.; Thirolf, P. G.; Grötzschel, R.

2006-05-01

360

Condensation Chemistry in Radioactive Supernova Gas  

NASA Astrophysics Data System (ADS)

New kinetic chemical paths are created during condensation by radioactivity. Supernova radioactivity not only dominates light curves, gamma rays and high excitation but also the chemistry of dust condensation. Dust normally is either C or oxides depending on whether C or O has greater abundance. Compton electrons dissociate the CO molecule in about one month, however, maintaining free atomic carbon at decreasing temperature. Our chemical model of SN1987A shows that linear C chains establish a near equilibrium between formation and destruction even when O > C. Isomerization to ringed carbon above n=24 atoms greatly reduces oxidation rates for them, enabling those rare seeds to grow to micron size during expansion time. In gas having C = O their abundances per C atom at 500d decline with C-atom number n as n-2/3 from N_24/N(C) = 10-20 at n=24. The abundances are less if C < O, but final graphite sizes are not. Maximum number is near n=10^15. Most carbon mass is calculated to lie in the largest graphite spheres, having mass fraction X=10-5 relative to C. This is comparable to the C mass fraction of micrometer SN graphite grains found in meteorites. Radiogenic ^44Ca from ^44Ti decay after C condensation establishes the supernova source for these condensates. Their total opacity suffices to shift emission lines in 87A blueward after 500d and also emits significant infrared luminosity. Parallel kinetic rates determine trace isotopes in the meteoritic SN graphites. The chemistry is kinetic rather than thermal equilibrium and is made possible by radiodeactivation of the CO trap for C. The ejected CO mass is an inverse measure of the ejected ^56Ni mass. A new chemical astronomy of supernova solids depends in these ways on the SN radioactivity.

Clayton, Donald; Liu, Weihong

1999-11-01

361

Fusion Induced by Radioactive Ion Beams  

E-print Network

The use of radioactive beams opens a new frontier for fusion studies. The coupling to the continuum can be explored with very loosely bound nuclei. Experiments were performed with beams of nuclei at or near the proton and neutron drip-lines to measure fusion and associated reactions in the vicinity of the Coulomb barrier. In addition, the fusion yield is predicted to be enhanced in reactions involving very neutron-rich unstable nuclei. Experimental measurements were carried out to investigate if it is feasible to use such beams to produce new heavy elements. The current status of these experimental activities is given in this review.

J. F. Liang; C. Signorini

2005-04-26

362

Proton radioactivity half lives with Skyrme interactions  

E-print Network

The potential barrier impeding the spontaneous emission of protons in the proton radioactive nuclei is calculated as the sum of nuclear, Coulomb and centrifugal contributions. The nuclear part of the proton-nucleus interaction potential is obtained in the energy density formalism using Skyrme effective interaction that results into a simple algebraic expression. The half-lives of the proton emitters are calculated for the different Skyrme sets within the improved WKB framework. The results are found to be in reasonable agreement with the earlier results obtained for more complicated calculations involving finite range interactions.

T. R. Routray; Abhishek Mishra; S. K. Tripathy; B. Behera; D. N. Basu

2012-05-31

363

Radioactive nuclides as tracers of environmental processes  

Microsoft Academic Search

Summary  Relatively short-lived radioactive nuclides of cosmogenic origin, such as7Be (T1\\/2=53.3 d),32P (14.3 d),33P (25.3 d),35S (87.4 d) as well as22Na (2.6 y) have come to be recognized as potential tools to trace environmental processes, such as precipitation, washout\\u000a (precipitation scavenging), resuspension, atmospheric particle deposition and deposition patterns of airborne contaminants,\\u000a aerosol deposition and aerosol trapping by above ground vegetation (air-to-vegetation

C. Papastefanou

2006-01-01

364

Particle beam generator using a radioactive source  

DOEpatents

The apparatus of the present invention selects from particles emitted by a radioactive source those particles having momentum within a desired range and focuses the selected particles in a beam having at least one narrow cross-dimension, and at the same time attenuates potentially disruptive gamma rays and low energy particles. Two major components of the present invention are an achromatic bending and focusing system, which includes sector magnets and quadrupole, and a quadrupole doublet final focus system. Permanent magnets utilized in the apparatus are constructed of a ceramic (ferrite) material which is inexpensive and easily machined.

Underwood, David G. (Naperville, IL)

1993-01-01

365

Some Perspectives on Future Proton Radioactivity Experiments  

SciTech Connect

Understanding the phenomenon of one-proton emission is crucial for addressing the question of the location of the limits of observable nuclei. Much of the current understanding of this radioactive decay process has been developed and refined through measurements of proton emitters above Z = 50, where {approx}30 proton-emitting nuclei have already been discovered and studied. However, despite the great experimental and theoretical efforts over recent years, some important questions remain unanswered. Possibilities for future experiments to tackle some of these issues are considered.

Page, R. D. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool, L69 7ZE (United Kingdom)

2011-11-30

366

RECLAMATION OF RADIOACTIVE MATERIAL PACKAGING COMPONENTS  

SciTech Connect

Radioactive material packages are withdrawn from use for various reasons; loss of mission, decertification, damage, replacement, etc. While the packages themselves may be decertified, various components may still be able to perform to their required standards and find useful service. The Packaging Technology and Pressurized Systems group of the Savannah River National Laboratory has been reducing the cost of producing new Type B Packagings by reclaiming, refurbishing, and returning to service the containment vessels from older decertified packagings. The program and its benefits are presented.

Abramczyk, G.; Nathan, S.; Loftin, B.; Bellamy, S.

2011-06-06

367

Corrosion resistant storage container for radioactive material  

DOEpatents

A corrosion resistant long-term storage container for isolating radioactive waste material in a repository. The container is formed of a plurality of sealed corrosion resistant canisters of different relative sizes, with the smaller canisters housed within the larger canisters, and with spacer means disposed between judxtaposed pairs of canisters to maintain a predetermined spacing between each of the canisters. The combination of the plural surfaces of the canisters and the associated spacer means is effective to make the container capable of resisting corrosion, and thereby of preventing waste material from leaking from the innermost canister into the ambient atmosphere.

Schweitzer, Donald G. (Bayport, NY); Davis, Mary S. (Wading River, NY)

1990-01-01

368

System for handling and storing radioactive waste  

DOEpatents

A system and method are claimed for handling and storing spent reactor fuel and other solid radioactive waste, including canisters to contain the elements of solid waste, storage racks to hold a plurality of such canisters, storage bays to store these racks in isolation by means of shielded doors in the bays. This system also includes means for remotely positioning the racks in the bays and an access tunnel within which the remotely operated means is located to position a rack in a selected bay. The modular type of these bays will facilitate the construction of additional bays and access tunnel extension.

Anderson, J.K.; Lindemann, P.E.

1982-07-19

369

Radioactive waste disposal via electric propulsion  

NASA Technical Reports Server (NTRS)

It is shown that space transportation is a feasible method of removal of radioactive wastes from the biosphere. The high decay heat of the isotopes powers a thermionic generator which provides electrical power for ion thrust engines. The massive shields (used to protect ground and flight personnel) are removed in orbit for subsequent reuse; the metallic fuel provides a shield for the avionics that guides the orbital stage to solar system escape. Performance calculations indicate that 4000 kg. of actinides may be removed per Shuttle flight. Subsidiary problems - such as cooling during ascent - are discussed.

Burns, R. E.

1975-01-01

370

Corrosion resistant storage container for radioactive material  

DOEpatents

A corrosion resistant long-term storage container for isolating high-level radioactive waste material in a repository is claimed. The container is formed of a plurality of sealed corrosion resistant canisters of different relative sizes, with the smaller canisters housed within the larger canisters, and with spacer means disposed between juxtaposed pairs of canisters to maintain a predetermined spacing between each of the canisters. The combination of the plural surfaces of the canisters and the associated spacer means is effective to make the container capable of resisting corrosion, and thereby of preventing waste material from leaking from the innermost canister into the ambient atmosphere.

Schweitzer, D.G.; Davis, M.S.

1984-08-30

371

BEARS: Radioactive Ion Beams at Berkeley  

SciTech Connect

A light-isotope radioactive ion beam capability has been added to the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory by coupling to the production cyclotron of the Berkeley Isotope Facility. The connection required the development and construction of a 350 m gas transport system between the two accelerators as well as automated cryogenic separation of the produced activity. The first beam developed, {sup 11}C, has been successfully accelerated with an on-target intensity of 1 x 10{sup 8} ions/sec at energies of around 10 MeV/u.

Powell, J.; Joosten, R.; Donahue, C.A.; Fairchild, R.F.; Fujisawa, J.; Guo, F.Q.; Haustein, P.E.; Larimer, R.-M.; Lyneis, C.M.; McMahan, M.A.; Moltz, D.M.; Norman, E.B.; O'Neil, J.P.; Ostas, M.A.; Rowe, M.W.; VanBrocklin, H.F.; Wutte, D.; Xie, Z.Q.; Xu, X.J.; Cerny, Joseph

2000-03-14

372

Astrophysics experiments with radioactive beams at ATLAS  

SciTech Connect

Reactions involving short-lived nuclei play an important role in nuclear astrophysics, especially in explosive scenarios which occur in novae, supernovae or X-ray bursts. This article describes the nuclear astrophysics program with radioactive ion beams at the ATLAS accelerator at Argonne National Laboratory. The CARIBU facility as well as recent improvements for the in-flight technique are discussed. New detectors which are important for studies of the rapid proton or the rapid neutron-capture processes are described. At the end we briefly mention plans for future upgrades to enhance the intensity, purity and the range of in-flight and CARIBU beams.

Back, B. B.; Clark, J. A.; Pardo, R. C.; Rehm, K. E., E-mail: rehm@anl.gov; Savard, G. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)] [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

2014-04-15

373

System for handling and storing radioactive waste  

DOEpatents

A system and method for handling and storing spent reactor fuel and other solid radioactive waste, including canisters to contain the elements of solid waste, storage racks to hold a plurality of such canisters, storage bays to store these racks in isolation by means of shielded doors in the bays. This system also includes means for remotely positioning the racks in the bays and an access tunnel within which the remotely operated means is located to position a rack in a selected bay. The modular type of these bays will facilitate the construction of additional bays and access tunnel extension.

Anderson, John K. (San Diego, CA); Lindemann, Paul E. (Escondido, CA)

1984-01-01

374

Hanford Site radioactive hazardous materials packaging directory  

SciTech Connect

The Hanford Site Radioactive Hazardous Materials Packaging Directory (RHMPD) provides information concerning packagings owned or routinely leased by Westinghouse Hanford Company (WHC) for offsite shipments or onsite transfers of hazardous materials. Specific information is provided for selected packagings including the following: general description; approval documents/specifications (Certificates of Compliance and Safety Analysis Reports for Packaging); technical information (drawing numbers and dimensions); approved contents; areas of operation; and general information. Packaging Operations & Development (PO&D) maintains the RHMPD and may be contacted for additional information or assistance in obtaining referenced documentation or assistance concerning packaging selection, availability, and usage.

McCarthy, T.L.

1995-12-01

375

Management of radioactive materials and wastes: Issues and progress  

SciTech Connect

This book presents papers on radioactive waste management. Topics considered include the classification of radioactive materials and wastes, low-level wastes, water management for radioactive waste facilities, compact commissions, shallow land burial, storage, transport, socio-political considerations, emergency plans, radiation standards, public health, radiation protection, radiation hazards, biological radiation effects, the Three Mile Island-2 accident, and a methodology for calculating radiation doses.

Majumdar, S.K.; Miller, E.W.

1985-01-01

376

Ultimate disposal of low and medium radioactive waste in France  

SciTech Connect

The National Radioactive Waste Management Agency (ANDRA) has been entrusted with the long-term management of radioactive waste. This paper presents the methodology of safety assessment used by ANDRA for a land disposal facility of radioactive waste with short or medium half-life and with low or medium specific activity. This methodology was used in the design of ``the Centre de stockage de l`Aube``.

Ringeard, C. [National Radioactive Waste Management Agency, Fontenay aux Roses (France). Environmental, Safety, Quality Dept.

1993-12-31

377

Karlsruhe Database for Radioactive Wastes (KADABRA) - Accounting and Management System for Radioactive Waste Treatment - 12275  

SciTech Connect

The data management system KADABRA was designed according to the purposes of the Cen-tral Decontamination Department (HDB) of the Wiederaufarbeitungsanlage Karlsruhe Rueckbau- und Entsorgungs-GmbH (WAK GmbH), which is specialized in the treatment and conditioning of radioactive waste. The layout considers the major treatment processes of the HDB as well as regulatory and legal requirements. KADABRA is designed as an SAG ADABAS application on IBM system Z mainframe. The main function of the system is the data management of all processes related to treatment, transfer and storage of radioactive material within HDB. KADABRA records the relevant data concerning radioactive residues, interim products and waste products as well as the production parameters relevant for final disposal. Analytical data from the laboratory and non destructive assay systems, that describe the chemical and radiological properties of residues, production batches, interim products as well as final waste products, can be linked to the respective dataset for documentation and declaration. The system enables the operator to trace the radioactive material through processing and storage. Information on the actual sta-tus of the material as well as radiological data and storage position can be gained immediately on request. A variety of programs accessed to the database allow the generation of individual reports on periodic or special request. KADABRA offers a high security standard and is constantly adapted to the recent requirements of the organization. (authors)

Himmerkus, Felix; Rittmeyer, Cornelia [WAK Rueckbau- und Entsorgungs- GmbH, 76339 Eggenstein-Leopoldshafen (Germany)

2012-07-01

378

Titanate-based adsorbents for radioactive ions entrapment from water.  

PubMed

This feature article reviews some titanate-based adsorbents for the removal of radioactive wastes (cations and anions) from water. At the beginning, we discuss the development of the conventional ion-exchangeable titanate powders for the entrapment of radioactive cations, such as crystalline silicotitanate (CST), monosodium titanate (MST), peroxotitanate (PT). Then, we specially emphasize the recent progress in the uptake of radioactive ions by one-dimensional (1D) sodium titanate nanofibers and nanotubes, which includes the synthesis and phase transformation of the 1D nanomaterials, adsorption ability (capacity, selectivity, kinetics, etc.) of radioactive cations and anions, and the structural evolution during the adsorption process. PMID:23412572

Yang, Dongjiang; Liu, Hongwei; Zheng, Zhanfeng; Sarina, Sarina; Zhu, Huaiyong

2013-03-21

379

Radioactive Ion Beam Production Capabilities At The Holifield Radioactive Ion Beam Facility  

NASA Astrophysics Data System (ADS)

The Holifield Radioactive Ion Beam Facility (HRIBF) is a national user facility for research with radioactive ion beams (RIBs) that has been in routine operation since 1996. It is located at Oak Ridge National Laboratory (ORNL) and operated by the ORNL Physics Division. The principal mission of the HRIBF is the production of high quality beams of shortlived radioactive isotopes to support research in nuclear structure physics and nuclear astrophysics. HRIBF is currently unique worldwide in its ability to provide neutron-rich fission fragment beams post-accelerated to energies above the Coulomb barrier for nuclear reactions. HRIBF produces RIBs by the isotope separator on-line (ISOL) technique using a particle accelerator system that consists of the Oak Ridge Isochronous Cyclotron (ORIC) driver accelerator, one of the two Injectors for Radioactive Ion Species (IRIS1 or IRIS2) production systems, and the 25-MV tandem electrostatic accelerator that is used for RIB post-acceleration. ORIC provides a light ion beam (proton, deuteron, or alpha) which is directed onto a thick target mounted in a target-ion source (TIS) assembly located on IRIS1 or IRIS2. Radioactive atoms that diffuse from the target material are ionized, accelerated, mass selected, and transported to the tandem accelerator where they are further accelerated to energies suitable for nuclear physics research. RIBs are transported through a beam line system to various experimental end stations including the Recoil Mass Spectrometer (RMS) for nuclear structure research, and the Daresbury Recoil Separator (DRS) for nuclear astrophysics research. HRIBF also includes two off-line ion source test facilities, one low-power on-line ISOL test facility (OLTF), and one high-power on-line ISOL test facility (HPTL). This paper provides an overview and status update of HRIBF, describes the recently completed 4.7M IRIS2 addition and incorporation of laser systems for beam production and purification, and discusses a proposed replacement of the ORIC driver accelerator.

Beene, J. R.; Dowling, D. T.; Gross, C. J.; Juras, R. C.; Liu, Y.; Meigs, M. J.; Mendez, A. J.; Nazarewicz, W.; Sinclair, J. W.; Stracener, D. W.; Tatum, B. A.

2011-06-01

380

DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS  

SciTech Connect

The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) important to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are in the form of tabulated functions with pH and log (line integral) CO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. The output data from this report are fundamental inputs for Total System Performance Assessment for the License Application (TSPA-LA) to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for all of the actinides. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise addressed.

NA

2004-11-22

381

The political science of radioactive waste disposal  

SciTech Connect

This paper was first presented at the annual meeting of the HPS in New Orleans in 1984. Twelve years later, the basic lessons learned are still found to be valid. In 1984, the following things were found to be true: A government agency is preferred by the public over a private company to manage radioactive waste. Semantics are important--How you say it is important, but how it is heard is more important. Public information and public relations are very important, but they are the last thing of concern to a scientist. Political constituency is important. Don`t overlook the need for someone to be on your side. Don`t forget that the media is part of the political process-they can make you or break you. Peer technical review is important, but so is citizen review. Sociology is an important issue that scientists and technical people often overlook. In summary, despite the political nature of radioactive waste disposal, it is as true today as it was in 1984 that technical facts must be used to reach sound technical conclusions. Only then, separately and openly, should political factors be considered. So, what can be said today that wasn`t said in 1984? Nothing. {open_quotes}It`s deja vu all over again.{close_quotes}

Jacobi, L.R. Jr. [Texas Los Level Radioactive Waste Disposal Authority, Austin, TX (United States)

1996-06-01

382

Ethernet-based automation in radioactivity measurements  

SciTech Connect

The paper describes an integrated radioactivity measurements laboratory involved in a New York State program of monitoring environmental radioactivity and bioassay samples. The laboratory is set up as a comprehensive Ethernet network that integrates radiation detectors, electronics hardware components as well as software automation and communications. Two DEC VAXstations 3100 and 3200 are central to the system. The VAXstation 3100 runs the Canberra/Nuclear Data Genie data-acquisition program. The Acquisition Interface Modules interface the ADCs to the Ethernet. Using the DEC Pathworks, the VAXstation 3100 is also a server for the Ethernet-based network of several 486 and 386 PCs. A designated PC can display the Genie acquisition window, in addition to the main window at VAXstation 3100. Another PC collects data from several NaI detectors using the Oxford/Nucleus DMR-II program. The paper also describe the plans for the future upgrades such as installation of VAXstation 4000/90 as well as interfacing the proportional counters and surface barrier detectors to the network.

Schwenker, C.D.; Daly, J.C. [Wadsworth Center for Laboratories and Research, Albany, NY (United States); Semkow, T.M.; Kitto, M.E. [State Univ. of New York, Albany, NY (United States)

1993-12-31

383

Fred Hoyle, primary nucleosynthesis and radioactivity  

NASA Astrophysics Data System (ADS)

Primary nucleosynthesis is defined as that which occurs efficiently in stars born of only H and He. It is responsible not only for increasing the metallicity of the galaxy but also for the most abundant gamma-ray-line emitters. Astrophysicists have inappropriately cited early work in this regard. The heavily cited B2FH paper ( Burbidge et al., 1957) did not effectively address primary nucleosynthesis whereas Hoyle ( Hoyle, 1954) had done so quite thoroughly in his infrequently cited 1954 paper. Even B2FH with Hoyle as coauthor seems strangely to not have appreciated what Hoyle ( Hoyle, 1954) had achieved. I speculate that Hoyle must not have thoroughly proofread the draft written in 1956 by E.M. and G.R. Burbidge. The clear roadmap of primary nucleosynthesis advanced in 1954 by Hoyle describes the synthesis yielding the most abundant of the radioactive isotopes for astronomy, although that aspect was unrealized at the time. Secondary nucleosynthesis has also produced many observable radioactive nuclei, including the first gamma-ray-line emitter to be discovered in the galaxy and several others within stardust grains. Primary gamma-ray emitters would have been even more detectable in the early galaxy, when the birth rate of massive stars was greater; but secondary emitters, such as 26Al, would have been produced with smaller yield then owing to smaller abundance of seed nuclei from which to create them.

Clayton, Donald D.

2008-10-01

384

Marie Curie and the Science of Radioactivity  

NSDL National Science Digital Library

This digital exhibit explores the life and accomplishments of Marie Curie, the Nobel-Prize winning physicist who discovered the radioactive elements polonium and radium. The exhibit integrates primary source lab notes, diary and journal entries, and historic photos to give a poignant view of Curie's struggles: growing up in the Russian-controlled Poland of the late 19th Century, being the target of repeated discrimination during her higher education in Paris, working with radioactive materials in substandard lab conditions, dealing with the consuming grief of her husband, Pierre's, accidental death in 1906, and overcoming challenges to win two Nobel Prizes. Editor's Note: It can be difficult for students to appreciate science as a human endeavor. This resource was designed to help learners grasp the hardships and obstacles often faced by pioneering scientists, especially women and minorities. Just as important, it gives them a glimpse at the joys of discovery. For a simulation on the same topic, see Related Materials: PhET Alpha Decay, which contains a very good accompanying lesson plan for high school teachers.

385

2p radioactivity studied by tracking technique  

SciTech Connect

The recent advance in experimental studies of short-lived exotic nuclei beyond the proton drip line is presented. In particular, in-flight decays of proton-unbound nuclei with picosecond lifetimes can be probed by a novel technique which tracks all decay products precisely, and the decay vertices as well as the angular correlations of the fragments are deduced from the measured trajectories. The corresponding pioneering experiment which identified a previously-unknown isotope {sup 19}Mg and its two-proton (2p) radioactivity as well as studied the reference 2p decay of the known isotope {sup 16}Ne is described. Systematic studies of other 2p precursors beyond the proton drip line are foreseen with this powerful technique whose sensitivity is larger by factor of 30 in comparison with a conventional invariant-mass method. The 2p radioactivity candidates {sup 30}Ar, {sup 34}Ca and {sup 26}S are discussed. Information about the respective one-proton unbound nuclei can be obtained with this technique by evaluating proton-heavy-fragment correlations. Systematic studies of nuclei beyond the proton drip line, e.g., the well-known proton resonances above the 'waiting points' in the astrophysical rp-process, {sup 69}Br and {sup 73}Br are feasible.

Mukha, Ivan [CSIC-IFIC Universidad de Valencia, E-46071 Valencia (Spain)

2010-06-01

386

BEARS: radioactive ion beams at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88'' Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88'' Cyclotron's Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p,n) and (p, {alpha}) reactions on low-Z targets. A test program is currently being conducted at the 88'' Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial {sup 11}C beams of up to 2.5x10{sup 7} ions/sec and {sup 14}O beams of 3x10{sup 5} ions/sec.

Powell, J.; Guo, F. Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C.; Moltz, D. M.; Norman, E. B.; O'Neil, J. P.; Rowe, M. W.; VanBrocklin, H. F.; Xie, Z. Q.; Xu, X. J.; Cerny, Joseph [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Haustein, P. E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1998-12-21

387

BEARS: radioactive ion beams at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88{sup {double_prime}} Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88{sup {double_prime}} Cyclotron{close_quote}s Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p,n) and (p, {alpha}) reactions on low-Z targets. A test program is currently being conducted at the 88{sup {double_prime}} Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial {sup 11}C beams of up to 2.5{times}10{sup 7}ions/sec and {sup 14}O beams of 3{times}10{sup 5}ions/sec. {copyright} {ital 1998 American Institute of Physics.}

Powell, J.; Guo, F.Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C.; Moltz, D.M.; Norman, E.B.; O`Neil, J.P.; Rowe, M.W.; VanBrocklin, H.F.; Xie, Z.Q.; Xu, X.J.; Cerny, Joseph [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)] Haustein, P.E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1998-12-01

388

Electrolytic Targets for Radioactive Ion Beam Production  

NASA Astrophysics Data System (ADS)

Traditional methods of producing beams of radioactive ions (RIBs) through bombardment of thick targets have employed thermal diffusion to transport radioactive species through the surface of the material. By employing a certain class of materials known as super-ionic conductors as target materials, very fast ionic mobilities can be realized. Since the newly formed RIB species are in an ionic form, electromechanical transport is possible using an applied electric field. Such a technique offers several potential advantages over traditional target systems. First, faster mass transfer of electropositive/negative species through the material could be possible allowing access to shorter-lived RIB species. Second, since highly porous targets geometries would not be required, faster effusive transport to the ion source would be possible along with more efficient heat transfer to cooling media. This report describes the preliminary results of an experiment in which the electrolytic transport of F through ZrO_2/Y_2O3 lattice was investigated and quantified.

Welton, R. F.; Janney, M. A.; Beene, J. R.; Mueller, P. E.; Stracener, D. W.

1999-10-01

389

Folding model analysis of alpha radioactivity  

E-print Network

Radioactive decay of nuclei via emission of $\\alpha$ particles has been studied theoretically in the framework of a superasymmetric fission model using the double folding (DF) procedure for obtaining the $\\alpha$-nucleus interaction potential. The DF nuclear potential has been obtained by folding in the density distribution functions of the $\\alpha$ nucleus and the daughter nucleus with a realistic effective interaction. The M3Y effective interaction has been used for calculating the nuclear interaction potential which has been supplemented by a zero-range pseudo-potential for exchange along with the density dependence. The nuclear microscopic $\\alpha$-nucleus potential thus obtained has been used along with the Coulomb interaction potential to calculate the action integral within the WKB approximation. This subsequently yields microscopic calculations for the half lives of $\\alpha$ decays of nuclei. The density dependence and the exchange effects have not been found to be very significant. These calculations provide reasonable estimates for the lifetimes of $\\alpha$ radioactivity of nuclei.

D. N. Basu

2003-07-29

390

Radioactivities induced in some LDEF samples  

NASA Technical Reports Server (NTRS)

Radioactivities induced in several Long Duration Exposure Facilities (LDEF) samples were measured by low-level counting at Los Alamos and elsewhere. These radionuclides have activities similar to those observed in meteorites and lunar samples. Some trends were observed in these measurements in terms of profiles in trunnion layers and as a function of radionuclide half-life. Several existing computer codes were used to model the production by the protons trapped in the Earth's radiation belts and by the galactic cosmic rays of some of these radionuclides, Mn-54 and Co-57 in steel, Sc-46 in titanium, and Na-22 in alloys of titanium and aluminum. Production rates were also calculated for radionuclides possibly implanted in LDEF, Be-7, Be-10, and C-14. Enhanced concentrations of induced isotopes in the surfaces of trunnion sections relative to their concentrations in the center are caused by the lower-energy protons in the trapped radiation. Secondary neutrons made by high-energy trapped protons and by galactic cosmic rays produce much of the observed radioactivities, especially deep in an object. Comparisons of the observed to calculated activities of several radionuclides with different half-lives indicate that the flux of trapped protons at LDEF decreased significantly at the end of the mission.

Reedy, Robert C.; Moss, Calvin E.; Bobias, S. George; Masarik, Jozef

1993-01-01

391

Radioactive equilibrium in ancient marine sediments  

USGS Publications Warehouse

Radioactive equilibrium in eight marine sedimentary formations has been studied by means of direct determinations of uranium, radium and thorium. Alpha-particle counting has also been carried out in order to cross-calibrate thick-source counting techniques. The maximum deviation from radioactive equilibrium that has been noted is 11 per cent-indicating that there is probably equilibrium in all the formations analyzed. Thick-source alpha-particle counting by means of a proportional counter or an ionization chamber leads to high results when the samples contain less than about 10 p.p.m. of uranium. For samples having a higher content of uranium the results are in excellent agreement with each other and with those obtained by direct analytical techniques. The thorium contents that have been obtained correspond well to the average values reported in the literature. The uranium content of marine sediments may be appreciably higher than the average values that have been reported for sedimentary rocks. Data show that there is up to fourteen times the percentage of uranium as of thorium in the formations studied and that the percentage of thorium never exceeds that of uranium. While the proximity of a depositional environment to a land mass may influence the concentration of uranium in a marine sediment, this is not true with thorium. ?? 1955.

Breger, I.A.

1955-01-01

392

RADIOACTIVE CHEMICAL ELEMENTS IN THE ATOMIC TABLE.  

SciTech Connect

In the 1949 Report of the Atomic Weights Commission, a series of new elements were added to the Atomic Weights Table. Since these elements had been produced in the laboratory and were not discovered in nature, the atomic weight value of these artificial products would depend upon the production method. Since atomic weight is a property of an element as it occurs in nature, it would be incorrect to assign an atomic weight value to that element. As a result of that discussion, the Commission decided to provide only the mass number of the most stable (longest-lived) known isotope as the number to be associated with these entries in the Atomic Weights Table. As a function of time, the mass number associated with various elements has changed as longer-lived isotopes of a particular elements has been found in nature, or as improved half-life values of an element's isotopes might cause a shift in the longest-lived isotope from one mass number to another. In the 1957 Report of the Atomic Weights Commission, it was decided to discontinue the listing of the mass number in the Atomic Weights Table on the grounds that the kind of information supplied by the mass number is inconsistent with the primary purpose of the Table, i.e., to provide accurate values of ''these constants'' for use in chemical calculations. In addition to the Table of Atomic Weights, the Commission included an auxiliary Table of Radioactive Elements for the first time, where the entry would be the isotope of that element which was most stable, i.e., it had the longest known half-life. In their 1973 report, the Commission noted that the users of the Atomic Weights Table were dissatisfied with the omission of values in the Table for some elements and it was decided to reintroduce the mass number for elements. In their 1983 report, the Commission decided that radioactive elements were considered to lack a characteristic terrestrial isotopic composition, from which an atomic weight value could be calculated to five or more figure accuracy, without prior knowledge of the sample. These elements were again listed in the table with no further information, is., no mass number or atomic weight value. For the elements, which have no stable or long-lived isotopes, the data on radioactive half-lives and relative atomic masses for the nuclides of interest have been evaluated. The values of the half-lives their uncertainties are listed. The uncertainties are given in the last digit quoted of the half-life vale and shown in parentheses. The criteria for consideration of entries in this Table continue to be the same as it has been for over fifty years. It is the same criteria, which are used for all data that are evaluated for inclusion in the Atomic Weight's Table. If a report of data is published in a peer-reviewed journal, that data is evaluated and considered for inclusion in the appropriate table of the biennial report of the Atomic Weights Commission. As better data might become available in the future, the information that is contained in either of the tables may be modified. The information contained in the Table of Radioactive Elements should enable the user to calculate the atomic weight for any sample of radioactive material, which might have a variety of isotopic compositions. The atomic mass values have been taken from the 2003 Atomic Mass Table. Most of these half-lives have already been documented in various sources.

HOLDEN, N.E.

2005-08-13

393

Radioactivity in municipal sewage and sludge.  

PubMed Central

OBJECTIVE: To determine the environmental consequences of discharges of radioactivity from a large medical research facility into municipal sewage, specifically 131I activity in sewage sludge, and the radiation exposures to workers and the public when sludges are incinerated. METHODS: The authors measured radioactivity levels in the sludge at the Ann Arbor, Michigan, Waste Water Treatment Plant following radioiodine treatments of two patients at the University of Michigan hospital complex and performed a series of calculations to estimate potential radiation doses due to releases of 131I from incineration of sewage sludge. RESULTS: Approximately 1.1% of the radioactive 131I administered therapeutically to patients was measured in the primary sludge. Radiation doses from incineration of sludge were calculated to be 0.048 millirem (mrem) for a worker during a period in which the incinerator filtration system failed, a condition that could be considered to represent maximum exposure conditions, for two nine-hour days. Calculated results for a more typically exposed worker (with the filtration system in operation and a 22-week period of incineration) yielded a committed effective dose equivalent of 0.066 mrem. If a worker were exposed to both conditions during the period of incineration, the dose was calculated to be 0.11 mrem. For a member of the public, the committed effective dose equivalent was calculated as 0.003 mrem for a 22-week incineration period. Exposures to both workers and the public were a very small fraction of a typical annual dose (about 100 mrem excluding radon, or 300 mrem with radon) due to natural background radiation. Transport time to the treatment plant for radioiodine was found to be much longer than that of a normal sewage, possibly due to absorption of iodine by organic material in the sewer lines. The residence time of radioiodine in the sewer also appears to be longer than expected. CONCLUSION: 131I in land-applied sludge presents few health concerns because sufficient decay occurs before it can reach the public however, incineration, which is done in winter months, directly releases the 131I from sewage sludge to the atmosphere, and even though exposures to both workers and the public were found to be considerably lower than 1% of natural background, incineration of sludge in a pathway for public exposure. Although 131I was readily measurable in sewage sludge, only about 1% of the radioione administered to patients was found in the sludge. The fate of the remaining radioactivity has not been established; some may be in secondary and tertiary residuals, but it is quite likely that most passed through the plant and was discharged in dilute concentrations in plant emissions. The behavior of radioiodine and other radioactive materials released into municipal seweage systems, such as those from large medical facilities, is not yet well understood. PMID:9258296

Martin, J E; Fenner, F D

1997-01-01

394

B-1 2002 SITE ENVIRONMENTAL REPORT APPENDIX B: CONCEPTS OF RADIOACTIVITY  

E-print Network

B-1 2002 SITE ENVIRONMENTAL REPORT APPENDIX B: CONCEPTS OF RADIOACTIVITY APPENDIX B Concepts of Radioactivity This section introduces some of the basic concepts of radioactivity. It is designed to provide.Adiscussion of the analyses used to qualitatively quantify radioactive material, the common sources of radioactivity

Homes, Christopher C.

395

Low-level radioactive waste management: A national perspective  

SciTech Connect

This article discusses two general topics on low-level radioactive waste management. Some comments on the reopening of the Barnwell, South Carolina, disposal site and the future of radioactive waste disposal in the United States are discussed, and a brief overview of recent contributions to state`s efforts by the Department of Energy`s National Low-Level Waste Management Program.

NONE

1995-11-01

396

Dose Evaluation Assessment of Contaminated Skin with Radioactive Substances  

Microsoft Academic Search

In one of the accidents that might happen in the nuclear power station, there is a contamination accident caused by radioactive corrosion products during a periodic inspection. It is necessary to presume the skin absorbed dose from the adhesion area and the contamination density to forecast the level of the skin hazard by the adhesion of the radioactive substance. However,

Hideki KATO; Sukehiko KOGA; Takashi MUKOYAMA; Hirotaka TOMATSU; Yusuke SUZUKI; Shoichi SUZUKI

2009-01-01

397

10 CFR 20.1005 - Units of radioactivity.  

Code of Federal Regulations, 2011 CFR

... 1 2011-01-01 2011-01-01 false Units of radioactivity. 20.1005 Section 20.1005 Energy NUCLEAR REGULATORY...RADIATION General Provisions § 20.1005 Units of radioactivity. For the purposes of this part, activity is...

2011-01-01

398

10 CFR 20.1005 - Units of radioactivity.  

Code of Federal Regulations, 2013 CFR

... 1 2013-01-01 2013-01-01 false Units of radioactivity. 20.1005 Section 20.1005 Energy NUCLEAR REGULATORY...RADIATION General Provisions § 20.1005 Units of radioactivity. For the purposes of this part, activity is...

2013-01-01

399

10 CFR 20.1005 - Units of radioactivity.  

Code of Federal Regulations, 2010 CFR

... 1 2010-01-01 2010-01-01 false Units of radioactivity. 20.1005 Section 20.1005 Energy NUCLEAR REGULATORY...RADIATION General Provisions § 20.1005 Units of radioactivity. For the purposes of this part, activity is...

2010-01-01

400

The Identification of Factors Influencing College Students' Attitudes toward Radioactivity.  

ERIC Educational Resources Information Center

The two basic questions considered in this study were: (1) What attitudes do college students hold toward radioactivity? and (2) What are some characteristics associated with the college students who hold the more favorable attitudes toward radioactivity? The sample studied included 1,205 mostly undergraduate students at the University of Texas at…

Crater, Harold L., Jr.

401

10 CFR 20.1005 - Units of radioactivity.  

Code of Federal Regulations, 2014 CFR

... 1 2014-01-01 2014-01-01 false Units of radioactivity. 20.1005 Section 20.1005 Energy NUCLEAR REGULATORY...RADIATION General Provisions § 20.1005 Units of radioactivity. For the purposes of this part, activity is...

2014-01-01

402

10 CFR 20.1005 - Units of radioactivity.  

Code of Federal Regulations, 2012 CFR

... 1 2012-01-01 2012-01-01 false Units of radioactivity. 20.1005 Section 20.1005 Energy NUCLEAR REGULATORY...RADIATION General Provisions § 20.1005 Units of radioactivity. For the purposes of this part, activity is...

2012-01-01

403

Ceramic blocks of pulp obtained from coagulation of radioactive effluents  

Microsoft Academic Search

Coagulation is one of the important steps in the present technology of processing large-volume lowactivity effluents, and serves to bring about a new waste product, a sludge or pulp concentrating an appreciable portion of the radioactive contaminants and requiring specific storage conditions. The average radioactivity of these pulps is 10 -2 to 10 -4 Ci\\/liter; they account for a significant

V. I. Spitsyn; V. D. Balukova; A. V. Volkova

1967-01-01

404

Characterization of plutonium in Maxey Flats radioactive trench leachates  

Microsoft Academic Search

Plutonium in trench leachates at the Maxey Flats radioactive waste disposal site exists as dissolved species, primarily complexes of the tetravalent ion with strong organic ligands such as ethylenediaminetetraacetic acid. The complexes are not sorbed well by sediment and are only partly precipitated by ferric hydroxide. These results indicate the importance of isolating radioactive waste from organic matter. 3 tables.

J. M. Cleveland; T. F. Rees

1981-01-01

405

Proteomics of field samples in radioactive Chernobyl area.  

PubMed

Two serious nuclear accidents during the past quarter of a century contaminated large agricultural areas with radioactivity. The remediation and possible recovery of radio-contaminated areas for agricultural purposes require comprehensive characterization of plants grown in such places. Here we describe the quantitative proteomics method that we use to analyze proteins isolated from seeds of plants grown in radioactive Chernobyl zone. PMID:24136546

Klubicová, Katarína; Rashydov, Namik M; Hajduch, Martin

2014-01-01

406

High-Level Radioactive Waste: Safe Storage and Ultimate Disposal.  

ERIC Educational Resources Information Center

Described are problems and techniques for safe disposal of radioactive waste. Degrees of radioactivity, temporary storage, and long-term permanent storage are discussed. Included are diagrams of estimated waste volumes to the year 2000 and of an artist's conception of a permanent underground disposal facility. (SL)

Dukert, Joseph M.

407

A model approach to radioactive waste disposal at Sellafield  

E-print Network

A model approach to radioactive waste disposal at Sellafield R. 5. Haszeldine* and C. Mc of the great environmentalproblems of our age is the safe disposal of radioactive waste for geological time periods. Britain is currently investigating a potential site for underground burial of waste, near

Haszeldine, Stuart

408

Risk methodology for geologic disposal of radioactive waste  

Microsoft Academic Search

Steps to be taken in the development of a methodology for the assessment of the long-term risks from radioactive waste disposal in deep, geologic media are outlined. The first phase involves the development of analytical models to represent the processes by which radioactive waste might leave the waste repository, enter the surface environment and eventually reach humans, and the definition

J. E. Campbell; R. T. Dillon; M. S. Tierney; H. T. Davis; P. E. McGrath; F. J. Pearson Jr.; H. R. Shaw; J. C. Helton; F. A. Donath

1978-01-01

409

Transporting Radioactive Waste: An Engineering Activity. Grades 5-12.  

ERIC Educational Resources Information Center

This brochure contains an engineering activity for upper elementary, middle school, and high school students that examines the transportation of radioactive waste. The activity is designed to inform students about the existence of radioactive waste and its transportation to disposal sites. Students experiment with methods to contain the waste and…

HAZWRAP, The Hazardous Waste Remedial Actions Program.

410

Detecting and Locating Radioactive Signals with Wireless Sensor Networks  

E-print Network

Detecting and Locating Radioactive Signals with Wireless Sensor Networks Tonglin Zhang Department-765-4940558 AbstractMethods of detecting and locating nuclear radioac- tive targets via wireless sensor networks (WSN model, radia- tion and radioactive isotopes, wireless sensor network. I. INTRODUCTION Currently, using

Zhang, Tonglin

411

Process for treatment of detergent-containing radioactive liquid wastes  

Microsoft Academic Search

A detergent-containing radioactive liquid waste originating from atomic power plants is concentrated to have about 10 wt. % detergent concentration, then dried in a thin film evaporator, and converted into powder. Powdered activated carbon is added to the radioactive waste in advance to prevent the liquid waste from foaming in the evaporator by the action of surface active agents contained

K. Kamiya; K. Chino; K. Funabashi; S. Horiuchi; K. Motojima

1984-01-01

412

Equipment for volume-reducing treatment of radioactive waste  

Microsoft Academic Search

An equipment for the volume-reducing treatment of a radioactive waste is disclosed. The equipment comprises means for drying and milling radioactive waste liquor, waste sludge, waste resin and the like generated from an atomic power plant, means for pelletizing the powder obtained from the drying and milling means and means for charging the pellet thus formed into a drum. The

S. Horiuchi; M. Hirano; S. Hirayama; H. Iinuma; R. Ishikawa

1984-01-01

413

TREATMENT OF MOSQUITO LARVAE AND ADULTS WITH RADIOACTIVE PHOSPHORUS  

Microsoft Academic Search

Studies were made to determine how to introduce radioactive phosphoric ; acid (P³²) into both larvae and adult mosquitoes in amounts that would be ; detectable with radioactive measuring devices. Aedes sticticus (Meig.) and A. ; vexans (Meig.) mosquitoes gave 544 to 897 cpm above background after they had ; been allowed to feed on the blood of rats that

W. W. Yates; C. M. Gjulin; A. W. Lindquist; J. S. Butts

1951-01-01

414

SPATIAL AND TIME FLUCTUATIONS OF NATURAL ATMOSPHERIC RADIOACTIVITY  

Microsoft Academic Search

Measurements were made of the natural radioactivity close to the ground ; at nine geographic points resulting from variable radioactive emanations from the ; soil. The mean values and the maxima are given for radon and its decay products ; and for the field intensity. Parallel measurements of natural reactivity ; and vertical turbulent mixing factors were carried out and

S. G. Malokhov; G. S. Kirdin; A. V. Kovda; T. I. Sisigina

1960-01-01

415

Radioactive Waste Information for 1998 and Record-To-Date  

SciTech Connect

This document presents detailed data, bar graphs, and pie charts on volume, radioactivity; isotopic identity, origin, and status of radioactive waste for calendar year 1998 at the Idaho National Engineering and Environmental Laboratory (INEEL). The data presented are from the INEEL Integrated Waste Information System.

D. L. French; R. E. Tallman; K. A. Taylor

1999-07-01

416

Artificial Radioactivity of Dysprosium and other Rare Earth Elements  

Microsoft Academic Search

IN their pioneer work on artificial radioactivity through neutron bombardment, Fermi and his collaborators announced the discovery of the activity of some of the rare earth elements, namely, of lanthanum, praseodymium, neodymium, samarium and gadolinium. Recently, Sugden1 found that terbium shows an appreciable, and europium a very strong, radioactivity after bombardment with neutrons. We find that dysprosium shows an unusually

G. Hevesy; Hilde Levi

1935-01-01

417

PRETREATMENT OF LIQUID RADIOACTIVE WASTES FOR UNDERGROUND DISPOSAL  

Microsoft Academic Search

The paper summarizes the experimental data on pretreatment of liquid radioactive wastes for underground disposal. The technologies of the pretreatment of low -, intermediate - and high- level radioactive wastes which is necessary to exclude the appearance of precipitates in geological formation are described in some detail. The pH values are controlled and addition of complexing agents (to form the

I. M. Kosareva; M. K. Savushkina; A. K. Pikaev

418

Radioactive Effluents from Nuclear Power Plants Annual Report 2008  

SciTech Connect

This report describes radioactive effluents from commercial nuclear power plants (NPPs) in the United States. This information was reported by the licensees for radioactive discharges that occurred in 2008. The report provides information relevant to the potential impact of NPPs on the environment and on public health.

U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation

2010-12-10

419

Radioactive Effluents from Nuclear Power Plants Annual Report 2007  

SciTech Connect

This report describes radioactive effluents from commercial nuclear power plants (NPPs) in the United States. This information was reported by the licensees for radioactive discharges that occurred in 2007. The report provides information relevant to the potential impact of NPPs on the environment and on public health.

U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation

2010-12-10

420

STUDIES ON THE DEPOSITION AND REMOVAL OF RADIOACTIVE SOIL  

Microsoft Academic Search

The rate of deposition and removal of a radioactive milk soil from ; several surfaces have been studied. The nature of the surface exhibited a small ; but measurable effect on the rate of deposition of a radioactive milk soil on the ; surfaces tested. However, the surfaces showed no significant effect on the rate ; of soil removal. The

I. J. Pflug; T. I. Hedrick; O. W. Kaufmann; R. A. Keppeler; C. G. Pheil

1961-01-01

421

Have the sharps been used with RADIOACTIVE MATERIALS?  

E-print Network

the contents of the sharps container. · Separate different half life isotopes per radiation safety manualHave the sharps been used with RADIOACTIVE MATERIALS? DISPOSAL: · Place all lab glass items that are free of biohazardous, chemical, and radioactive contaminants*? *To determine if your chemical container

422

Naturally Occurring Radioactive Materials in Cargo at US Borders  

SciTech Connect

In the U.S. and other countries, large numbers of vehicles pass through border crossings each day. The illicit movement of radioactive sources is a concern that has resulted in the installation of radiation detection and identification instruments at border crossing points. This activity is judged to be necessary because of the possibility of an act of terrorism involving a radioactive source that may include any number of dangerous radionuclides. The problem of detecting, identifying, and interdicting illicit radioactive sources is complicated by the fact that many materials present in cargo are somewhat radioactive. Some cargo contains naturally occurring radioactive material or technologically-enhanced naturally occurring radioactive material that may trigger radiation portal monitor alarms. Man-made radioactive sources, especially medical isotopes, are also frequently observed and produce alarms. Such nuisance alarms can be an operational limiting factor for screening of cargo at border crossings. Information about the nature of the radioactive materials in cargo that can interfere with the detection of radionuclides of concern is necessary. This paper provides such information for North American cargo, but the information may also be of use to border control officials in other countries. (PIET-43741-TM-361)

Kouzes, Richard T.; Ely, James H.; Evans, John C.; Hensley, Walter K.; Lepel, Elwood A.; McDonald, Joseph C.; Schweppe, John E.; Siciliano, Edward R.; Strom, Daniel J.; Woodring, Mitchell L.

2006-01-01

423

Mosses beta radioactivity in Katirli mountain-Bursa, TURKEY  

Microsoft Academic Search

Mosses are one of the most widely used procedures to determine via plant of radioactive contamination. The high concentrating capacity of mosses may be used as bioindicator of environmental radioactive contamination. In this study, the mosses were collected in region of Katirli Mountain in northwestern Turkey, activities were determined using TENNELEC LB 1000-PW detector. Samples of mosses growing on soil,

A. G. Kahraman; G. Kaynak; G. Akkaya; A. Gultekin; O. Gurler; S. Yalcin

2007-01-01

424

Control of radioactive material transport in sodium-cooled reactors  

Microsoft Academic Search

The Radioactivity Control Technology (RCT) program was established by the Department of Energy to develop and demonstrate methods to control radionuclide transport to ex-core regions of sodium-cooled reactors. This radioactive material is contained within the reactor heat transport system with any release to the environment well below limits established by regulations. However, maintenance, repair, decontamination, and disposal operations potentially expose

Brehm

2008-01-01

425

The Study of Radioactive Drugs in Human Subjects  

Cancer.gov

Basic research for the purpose of advancing scientific knowledge The research is intended to obtain basic information regarding the metabolism of radioactive drugs including kinetics, distribution, dosimetry, and localization OR Obtain basic information regarding human physiology, pathophysiology, and biochemistry of radioactive drugs.

426

Area 5 Radioactive Waste Management Site Safety Assessment Document  

SciTech Connect

The Area 5 Radioactive Waste Management Safety Assessment Document evaluates site characteristics, facilities and operating practices which contribute to the safe handling and storage/disposal of radioactive wastes at the Nevada Test Site. Physical geography, cultural factors, climate and meteorology, geology, hydrology (with emphasis on radionuclide migration), ecology, natural phenomena, and natural resources are discussed and determined to be suitable for effective containment of radionuclides. Also considered, as a separate section, are facilities and operating practices such as monitoring; storage/disposal criteria; site maintenance, equipment, and support; transportation and waste handling; and others which are adequate for the safe handling and storage/disposal of radioactive wastes. In conclusion, the Area 5 Radioactive Waste Management Site is suitable for radioactive waste handling and storage/disposal for a maximum of twenty more years at the present rate of utilization.

Horton, K.K.; Kendall, E.W.; Brown, J.J.

1980-02-01

427

Dutch geologic radioactive waste disposal project  

NASA Astrophysics Data System (ADS)

Geologic disposal of radioactive waste is reviewed. The radionuclide release consequences of an accidental flooding of the underground excavations was studied. The results of the quantitative examples made for different effective cross sections of the permeable layer connecting the mine excavations with the boundary of the salt dome are that under all circumstances the concentration of the waste nuclides in drinking water will remain well within the ICRP maximum permissible concentrations. Further analysis work was done on what minima can be achieved for both the maximum local rock salt temperatures at the disposal borehole walls and the maximum global rock salt temperatures halfway between a square of disposal boreholes. Different multilayer disposal configurations were analyzed and compared.

Hamstra, J.; Verkerk, B.

428

RADIOACTIVE MATERIAL PACKAGING TORQUE REQUIREMENTS COMPLIANCE  

SciTech Connect

Shipping containers used to transport radioactive material (RAM) in commerce employ a variety of closure mechanisms. Often, these closure mechanisms require a specific amount of torque be applied to a bolt, nut or other threaded fastener. It is important that the required preload is achieved so that the package testing and analysis is not invalidated for the purpose of protecting the public. Torque compliance is a means of ensuring closure preload, is a major factor in accomplishing the package functions of confinement/containment, sub-criticality, and shielding. This paper will address the importance of applying proper torque to package closures, discuss torque value nomenclature, and present one methodology to ensure torque compliance is achieved.

Watkins, R.; Leduc, D.

2011-03-24

429

Measurements with radioactive beams at ATLAS.  

SciTech Connect

Reactions of interest to nuclear astrophysics have been studied with radioactive beams at the ATLAS accelerator. Using a modified ISOL technique, beams of {sup 18}F (T{sub 1/2} = 110 min) and {sup 56}Ni (T{sub 1/2} = 6.1d) were produced and the reactions {sup 18}F(p,{alpha}){sup 15}O, {sup 18}F(p,{gamma}){sup 19}Ne, and {sup 56}Ni(d,p){sup 57}Ni have been investigated. The results indicate that the {sup 18}F(p,{gamma}) route is a small contributor to the breakout from the hot CNO cycle into the rp process, while the {sup 56}Ni(p,{gamma}){sup 57}Cu rate is about ten times larger than previously assumed.

Rehm, K. E.

1998-08-06

430

A Simple Example of Radioactive Dating  

NASA Astrophysics Data System (ADS)

Although nuclear half-life is vital to physics and physical science, and to sensitive societal issues from nuclear waste to the age of the Earth, a true lab on half-life is almost never done at the college or high school level. Seldom are students able to use radioactivity to actually date when an object came into being, as is done in this experiment. The procedure described here uses a radiation monitor and at least two 60Co sources of different ages: the students collect data and are able to calculate how much older one source is than the other. The theory and technique involved make this an easily transferable lesson when studying carbon dating.

Brown, Todd

2014-02-01

431

Standard guide for sampling radioactive tank waste  

E-print Network

1.1 This guide addresses techniques used to obtain grab samples from tanks containing high-level radioactive waste created during the reprocessing of spent nuclear fuels. Guidance on selecting appropriate sampling devices for waste covered by the Resource Conservation and Recovery Act (RCRA) is also provided by the United States Environmental Protection Agency (EPA) (1). Vapor sampling of the head-space is not included in this guide because it does not significantly affect slurry retrieval, pipeline transport, plugging, or mixing. 1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

American Society for Testing and Materials. Philadelphia

2011-01-01

432

Submersible purification system for radioactive water  

SciTech Connect

A portable, submersible water purification system for use in a pool of water containing radioactive contamination includes a prefilter for filtering particulates from the water. A resin bed is then provided for removal of remaining dissolved, particulate, organic, and colloidal impurities from the prefiltered water. A sterilizer then sterilizes the water. The prefilter and resin bed are suitably contained and are submerged in the pool. The sterilizer is water tight and located at the surface of the pool. The water is circulated from the pool through the prefilter, resin bed, and sterilizer by suitable pump or the like. In the preferred embodiment, the resin bed is contained within a tank which stands on the bottom of the pool and to which a base mounting the prefilter and pump is attached. An inlet for the pump is provided adjacent the bottom of the pool, while the sterilizer and outlet for the system is located adjacent the top of the pool.

Abbott, Michael L. (Fort Collins, CO); Lewis, Donald R. (Pocatello, ID)

1989-01-01

433

Astronomy with Radioactivities: Chapter 9, Nuclear Reactions  

E-print Network

Nuclear reaction rates determine the abundances of isotopes in stellar burning processes. A multitude of reactions determine the reaction flow pattern which is described in terms of reaction network simulations. The reaction rates are determined by laboratory experiments supplemented by nuclear reaction and structure theory. We will discuss the experimental approach as well as the theoretical tools for obtaining the stellar reaction rates. A detailed analysis of a reaction is only possible for a few selected cases which will be highlighted in this section. The bulk of nuclear reaction processes is however described in terms of a statistical model approach, which relies on global nuclear structure and reaction parameters such as level density and mass and barrier penetration, respectively. We will discuss a variety of experimental facilities and techniques used in the field, this includes low energy stable beam experiments, measurements at radioactive beam accelerators, and neutron beam facilities.

M. Wiescher; T. Rauscher

2010-11-01

434

Taipower`s radioactive waste management program  

SciTech Connect

Nuclear safety and radioactive waste management are the two major concerns of nuclear power in Taiwan. Recognizing that it is an issue imbued with political and social-economic concerns, Taipower has established an integrated nuclear backend management system and its associated financial and mechanism. For LLW, the Orchid Island storage facility will play an important role in bridging the gap between on-site storage and final disposal of LLW. Also, on-site interim storage of spent fuel for 40 years or longer will provide Taipower with ample time and flexibility to adopt the suitable alternative of direct disposal or reprocessing. In other words, by so exercising interim storage option, Taipower will be in a comfortable position to safely and permanently dispose of radwaste without unduly forgoing the opportunities of adopting better technologies or alternatives. Furthermore, Taipower will spare no efforts to communicate with the general public and make her nuclear backend management activities accountable to them.

Lee, B.C.C. [Taiwan Power Co., Taipei (Taiwan, Province of China). Nuclear Backend Management Dept.

1996-09-01

435

Evaluation of radioactive scrap metal recycling  

SciTech Connect

This report evaluates the human health risks and environmental and socio-political impacts of options for recycling radioactive scrap metal (RSM) or disposing of and replacing it. Argonne National Laboratory (ANL) is assisting the US Department of Energy (DOE), Office of Environmental Restoration and Waste Management, Oak Ridge Programs Division, in assessing the implications of RSM management alternatives. This study is intended to support the DOE contribution to a study of metal recycling being conducted by the Task Group on Recycling and Reuse of the Organization for Economic Cooperation and Development. The focus is on evaluating the justification for the practice of recycling RSM, and the case of iron and steel scrap is used as an example in assessing the impacts. To conduct the evaluation, a considerable set of data was compiled and developed. Much of this information is included in this document to provide a source book of information.

Nieves, L.A.; Chen, S.Y.; Kohout, E.J.; Nabelssi, B.; Tilbrook, R.W.; Wilson, S.E.

1995-12-01

436

Room air monitor for radioactive aerosols  

DOEpatents

A housing assembly for use with a room air monitor for simultaneous collection and counting of suspended particles includes a casing containing a combination detector-preamplifier system at one end, a filter system at the other end, and an air flow system consisting of an air inlet formed in the casing between the detector-preamplifier system and the filter system and an air passageway extending from the air inlet through the casing and out the end opposite the detector-preamplifier combination. The filter system collects suspended particles transported directly through the housing by means of the air flow system, and these particles are detected and examined for radioactivity by the detector-pre The U.S. Government has rights in this invention pursuant to Contract No. DE-AC04-76DP03533 between the Department of Energy and Rockwell International Corporation.

Balmer, David K. (Broomfield, CO); Tyree, William H. (Boulder, CO)

1989-04-11

437

Room air monitor for radioactive aerosols  

DOEpatents

A housing assembly for use with a room air monitor for simultaneous collection and counting of suspended particles includes a casing containing a combination detector-preamplifier system at one end, a filter system at the other end, and an air flow system consisting of an air inlet formed in the casing between the detector-preamplifier system and the filter system and an air passageway extending from the air inlet through the casing and out the end opposite the detector-preamplifier combination. The filter system collects suspended particles transported directly through the housing by means of the air flow system, and these particles are detected and examined for radioactivity by the detector-preamplifier combination. 2 figs.

Balmer, D.K.; Tyree, W.H.

1987-03-23

438

Natural Radioactivity of Boron Added Clay Samples  

SciTech Connect

Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of different fields especially in dermatology application. Using clay such a field it is important to measure its natural radioactivity. Thus the purpose of this study is to measure {sup 226}Ra, {sup 232}Th and {sup 40}K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3''x3'' NaI(Tl) detector. From the measured activity the radium equivalent activities (Ra{sub eq}), external hazard index (H{sub ex}), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

Akkurt, I.; Guenoglu, K. [Sueleyman Demirel University, Faculty of Arts and Sciences, Dept. of Physics, Isparta (Turkey); Canakcii, H. [Gaziantep University, Engineering Faculty, Civil Engineering Dept., Gaziantep (Turkey); Mavi, B. [Amasya University, Faculty of Arts and Sciences, Dept. of Physics, Amasya (Turkey)

2011-12-26

439

Natural radioactivity levels in lake sediment samples.  

PubMed

The radioactivity concentrations of nuclides (238)U, (232)Th and (40)K in lake sediments collected from 15 different stations at Alt?nkaya dam lake and 12 different stations at Derbent dam lake in Turkey were measured using high-resolution gamma-ray spectrometry. The measurement was done using a coaxial HPGe detector system coupled to the Ortec-Dspect jr digital MCA system. The average measured activity concentrations of the nuclides (238)U, (232)Th and (40)K were found to be 19.5, 27.7 and 460 Bq kg(-1) in Alt?nkaya dam, whereas the activity concentrations were 18.8, 25.5 and 365 Bq kg(-1) in Derbent dam, respectively. The measured activity concentrations in the present study have been compared with similar measurements from different locations in the world. PMID:23528330

Ero?lu, Hakan; Kabadayi, Önder

2013-09-01

440

Porous Matrixes for Immobilization of Radioactive Wastes  

SciTech Connect

The process was studied and the technology developed to obtain a highly porous coke based material with the solid dispersed filler (zirconium dioxide); properties and technological characteristics of the material were investigated. Technological process was developed for the fabrication of products out of the highly porous high melting compound (zirconium carbide). Technology for the fabrication of products out of the highly porous high melting compound bypassing the necessity of obtaining the dry radioactive feed powders and allows producing the material with a wide range of compositions and properties. In this paper we describe a technological process for the fabrication of materials, assuming the impregnation of a porous zirconium carbide form by the liquid highly concentrated solution of actinides followed by the decomposition of the obtained product during the thermal treatment to form stable oxides. We are investigating the properties of the final form as a possible target in a nuclear reactors to use neutrons to burn up the actinides. (authors)

Ershov, B.G.; Minaev, A.A.; Afonin, M.M.; Kuznetsov, D.G. [Institute of Physical Chemistry and Electrochemisrty, Russian Academy of Sciences, Moscow (Russian Federation)

2007-07-01

441

Radioactive Waste Management Complex performance assessment: Draft  

SciTech Connect

A radiological performance assessment of the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory was conducted to demonstrate compliance with appropriate radiological criteria of the US Department of Energy and the US Environmental Protection Agency for protection of the general public. The calculations involved modeling the transport of radionuclides from buried waste, to surface soil and subsurface media, and eventually to members of the general public via air, ground water, and food chain pathways. Projections of doses were made for both offsite receptors and individuals intruding onto the site after closure. In addition, uncertainty analyses were performed. Results of calculations made using nominal data indicate that the radiological doses will be below appropriate radiological criteria throughout operations and after closure of the facility. Recommendations were made for future performance assessment calculations.

Case, M.J.; Maheras, S.J.; McKenzie-Carter, M.A.; Sussman, M.E.; Voilleque, P.

1990-06-01

442

Radioactive implant induced X-ray emission  

NASA Astrophysics Data System (ADS)

Two approaches with X-ray excitation sources directly inside a sample have been examined: mixing a sample in solution with a radioisotope or bombardment of a solid specimen with a radioactive ion beam. The radioisotopes used weere 3H, 35S, 125I, with detection limits of, for example, 20 ?g/g for Ag excited by a 125I implant of ˜75 kBq; 100 ?g/g for Ti excited by a 3H implant of ˜7 MBq. For comparable detection limits, the source strengths required are ˜10 3 less than that needed with external sources. The elemental coverage and the capabilities for simultaneous multielement detection are similar to "conventional" XES. In the beam implant mode, the spot size and energy of the beam provide for spatially resolved in situ X-ray excitation at a desired location inside a solid.

Joyce, J. R.; Sanni, A. O.; Schweikert, E. A.

443

Radioactively Contaminated Scrap Metal An International Approach to Monitoring, Interception & Managing  

E-print Network

Radioactively Contaminated Scrap Metal An International Approach to Monitoring, Interception of uncontrolled radioactive source incidents. Aside from radiation exposure to workers and the public, this unwanted radioactive scrap material causes environmental and facility contamination with cleanup costs

444

49 CFR 173.422 - Additional requirements for excepted packages containing Class 7 (radioactive) materials.  

Code of Federal Regulations, 2011 CFR

...PACKAGINGS Class 7 (Radioactive) Materials § 173...containing Class 7 (radioactive) materials. An excepted package of Class 7 (radioactive) material that is prepared...substance or a hazardous waste, the shipping...

2011-10-01

445

77 FR 25760 - Low-Level Radioactive Waste Management and Volume Reduction  

Federal Register 2010, 2011, 2012, 2013, 2014

...NRC-2011-0183] Low-Level Radioactive Waste Management and Volume Reduction...Policy Statement on Low-Level Radioactive Waste (LLRW) Volume Reduction...Blending of Low-Level Radioactive Waste'' (ADAMS Accession No....

2012-05-01

446

49 CFR 173.424 - Excepted packages for radioactive instruments and articles.  

Code of Federal Regulations, 2012 CFR

...AND PACKAGINGS Class 7 (Radioactive) Materials § 173.424 Excepted packages for radioactive instruments and articles. A radioactive instrument or article...hazardous substance or hazardous waste, shipping papers and...

2012-10-01

447

25 CFR 170.906 - Who cleans up radioactive and hazardous material spills?  

Code of Federal Regulations, 2012 CFR

... true Who cleans up radioactive and hazardous material... Hazardous and Nuclear Waste Transportation § 170.906 Who cleans up radioactive and hazardous material...responsible for cleanup of a radioactive or hazardous...

2012-04-01

448

49 CFR 173.421 - Excepted packages for limited quantities of Class 7 (radioactive) materials.  

Code of Federal Regulations, 2014 CFR

...AND PACKAGINGS Class 7 (Radioactive) Materials § 173.421...limited quantities of Class 7 (radioactive) materials. A Class 7 (radioactive) material with an activity...hazardous substance or hazardous waste, shipping papers, and...

2014-10-01

449

49 CFR 173.424 - Excepted packages for radioactive instruments and articles.  

Code of Federal Regulations, 2013 CFR

...AND PACKAGINGS Class 7 (Radioactive) Materials § 173.424 Excepted packages for radioactive instruments and articles. A radioactive instrument or article...hazardous substance or hazardous waste, shipping papers and...

2013-10-01

450

49 CFR 173.422 - Additional requirements for excepted packages containing Class 7 (radioactive) materials.  

Code of Federal Regulations, 2010 CFR

...PACKAGINGS Class 7 (Radioactive) Materials § 173...containing Class 7 (radioactive) materials. An excepted package of Class 7 (radioactive) material that is prepared...substance or a hazardous waste, the shipping...

2010-10-01

451

49 CFR 173.424 - Excepted packages for radioactive instruments and articles.  

Code of Federal Regulations, 2014 CFR

...AND PACKAGINGS Class 7 (Radioactive) Materials § 173.424 Excepted packages for radioactive instruments and articles. A radioactive instrument or article...hazardous substance or hazardous waste, shipping papers and...

2014-10-01

452

25 CFR 170.901 - What standards govern transportation of radioactive and hazardous materials?  

Code of Federal Regulations, 2011 CFR

...standards govern transportation of radioactive and hazardous materials...Provisions Hazardous and Nuclear Waste Transportation § 170.901...standards govern transportation of radioactive and hazardous materials...regulations for the shipment of radioactive and hazardous materials....

2011-04-01

453

25 CFR 170.906 - Who cleans up radioactive and hazardous material spills?  

Code of Federal Regulations, 2010 CFR

... false Who cleans up radioactive and hazardous material... Hazardous and Nuclear Waste Transportation § 170.906 Who cleans up radioactive and hazardous material...responsible for cleanup of a radioactive or hazardous...

2010-04-01

454

78 FR 9746 - Request To Amend a License To Export Radioactive Waste  

Federal Register 2010, 2011, 2012, 2013, 2014

...License To Export Radioactive Waste Pursuant to 10...Scientific Class A radioactive Up to a maximum...Janurary 10, mixed waste total of 420 conforming...varying combinations radioactive disposition. Amend...imported mixed waste) in to: 1)...

2013-02-11

455

49 CFR 173.424 - Excepted packages for radioactive instruments and articles.  

Code of Federal Regulations, 2010 CFR

...AND PACKAGINGS Class 7 (Radioactive) Materials § 173.424 Excepted packages for radioactive instruments and articles. A radioactive instrument or article...hazardous substance or hazardous waste, shipping papers and...

2010-10-01

456

25 CFR 170.906 - Who cleans up radioactive and hazardous material spills?  

Code of Federal Regulations, 2013 CFR

... false Who cleans up radioactive and hazardous material... Hazardous and Nuclear Waste Transportation § 170.906 Who cleans up radioactive and hazardous material...responsible for cleanup of a radioactive or hazardous...

2013-04-01

457

25 CFR 170.901 - What standards govern transportation of radioactive and hazardous materials?  

Code of Federal Regulations, 2010 CFR

...standards govern transportation of radioactive and hazardous materials...Provisions Hazardous and Nuclear Waste Transportation § 170.901...standards govern transportation of radioactive and hazardous materials...regulations for the shipment of radioactive and hazardous materials....

2010-04-01

458

49 CFR 173.421 - Excepted packages for limited quantities of Class 7 (radioactive) materials.  

Code of Federal Regulations, 2012 CFR

...substance or hazardous waste, shipping papers...nonfixed (removable) radioactive surface contamination...bears the marking “Radioactive”; (5) The package...quantity of Class 7 (radioactive) material that is a...substance or a hazardous waste, is not subject to...

2012-10-01

459

49 CFR 173.421 - Excepted packages for limited quantities of Class 7 (radioactive) materials.  

Code of Federal Regulations, 2011 CFR

...substance or hazardous waste, shipping papers...nonfixed (removable) radioactive surface contamination...bears the marking “Radioactive”; (5) The package...quantity of Class 7 (radioactive) material that is a...substance or a hazardous waste, is not subject to...

2011-10-01

460

25 CFR 170.901 - What standards govern transportation of radioactive and hazardous materials?  

Code of Federal Regulations, 2013 CFR

...standards govern transportation of radioactive and hazardous materials...Provisions Hazardous and Nuclear Waste Transportation § 170.901...standards govern transportation of radioactive and hazardous materials...regulations for the shipment of radioactive and hazardous materials....

2013-04-01

461

49 CFR 173.422 - Additional requirements for excepted packages containing Class 7 (radioactive) materials.  

Code of Federal Regulations, 2014 CFR

...containing Class 7 (radioactive) materials. An excepted package of Class 7 (radioactive) material that is...substance or a hazardous waste, the shipping paper...applicable to Class 7 (radioactive) materials in §§...

2014-10-01

462

49 CFR 173.422 - Additional requirements for excepted packages containing Class 7 (radioactive) materials.  

Code of Federal Regulations, 2012 CFR

...PACKAGINGS Class 7 (Radioactive) Materials § 173...containing Class 7 (radioactive) materials. An excepted package of Class 7 (radioactive) material that is prepared...substance or a hazardous waste, the shipping...

2012-10-01

463

77 FR 20077 - Request for a License To Export Radioactive Waste  

Federal Register 2010, 2011, 2012, 2013, 2014

...Request for a License To Export Radioactive Waste Pursuant to 10 CFR 110.70...Inc., February 14, 2012, radioactive waste tons of or disposal by a February...XW019, in the form of ash radioactive waste licensed facility...

2012-04-03

464

49 CFR 173.421 - Excepted packages for limited quantities of Class 7 (radioactive) materials.  

Code of Federal Regulations, 2010 CFR

...substance or hazardous waste, shipping papers...nonfixed (removable) radioactive surface contamination...bears the marking “Radioactive”; (5) The package...quantity of Class 7 (radioactive) material that is a...substance or a hazardous waste, is not subject to...

2010-10-01

465

49 CFR 173.421 - Excepted packages for limited quantities of Class 7 (radioactive) materials.  

Code of Federal Regulations, 2013 CFR

...substance or hazardous waste, shipping papers...nonfixed (removable) radioactive surface contamination...bears the marking “Radioactive”; (5) The package...quantity of Class 7 (radioactive) material that is a...substance or a hazardous waste, is not subject to...

2013-10-01

466

49 CFR 173.422 - Additional requirements for excepted packages containing Class 7 (radioactive) materials.  

Code of Federal Regulations, 2013 CFR

...PACKAGINGS Class 7 (Radioactive) Materials § 173...containing Class 7 (radioactive) materials. An excepted package of Class 7 (radioactive) material that is prepared...substance or a hazardous waste, the shipping...

2013-10-01

467

78 FR 7818 - Request To Amend a License To Export Radioactive Waste  

Federal Register 2010, 2011, 2012, 2013, 2014

...License To Export Radioactive Waste Pursuant to 10 CFR...Inc.; Class A radioactive The total Amend to...28, 2012; January waste as slightly quantity...facility, the Class A radioactive secondary waste will waste...

2013-02-04