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1

Evidence from 10 Be and U series disequilibria on  

E-print Network

Evidence from 10 Be and U series disequilibria on the possible contamination of mid-ocean ridge series disequilibria measured in mid-ocean ridge basalts (MORB) can be perturbed by contamination series; 10 Be; basalt; contamination; mid-ocean ridge. Index Terms: Isotopic composition/chemistry; trace

Langmuir, Charles H.

2

Transport of radionuclides in an unconfined chalk aquifer inferred from U-series disequilibria  

Microsoft Academic Search

U-series disequilibria measured in waters and rocks from a chalk aquifer in France have been used as an analog for long-term radionuclide migration. Drill core samples from a range of depths in the vadose zone and in the saturated zone, as well as groundwater samples were analyzed for 238U, 234U, 232Th and 230Th to determine transport mechanisms at the water\\/rock

Amélie Hubert; Bernard Bourdon; Eric Pili; Laure Meynadier

2006-01-01

3

Assimilation of the plutonic roots of the Andean arc controls variations in U-series disequilibria at Volcan Llaima, Chile  

NASA Astrophysics Data System (ADS)

U-series disequilibria provide important constraints on the processes and time scales of melt production, differentiation, and transport in subduction settings. Such constraints, which are essential for understanding the chemical evolution of the continental crust, are conventionally based on the assumption that the U-series disequilibria measured in mafic lavas are produced during mantle metasomatism and melting, and that intracrustal differentiation and assimilation have limited impacts. Here we show that mantle-derived U-series disequilibria in mafic lavas erupted at Volcán Llaima, Chile are significantly diminished by assimilation of plutonic rocks forming Llaima's subvolcanic basement. This contamination process is extremely subtle in terms of "classical" indicators of crustal assimilation like Sr, Nd or Pb isotopes because it is a manifestation of assimilative recycling of the plutonic roots of the arc. This process results in variations in U-series disequilibria and incompatible trace element ratios that are significant compared to regional and global variability in arc magmas. Furthermore, it yields linear correlations between U-series excesses and incompatible trace element ratios that are generally interpreted as slab-fluid indicators and chronometers, or tracers of sediment recycling in subduction zone. Cannibalization of ancestral magmas by ascending melts warrants careful evaluation when considering the components and chemical fluxes in subduction zones. Linear arrays defined by activity ratios of U-series nuclides with different half-lives may be the most reliable indicators of assimilative recycling of ancestral intrusive magmas.

Reubi, O.; Bourdon, B.; Dungan, M. A.; Koornneef, J. M.; Sellés, D.; Langmuir, C. H.; Aciego, S.

2011-02-01

4

Characterization of Contaminant Transport Using Naturally-Occurring U-Series Disequilibria  

SciTech Connect

Study the migration of nuclear waste contaminants in subsurface fractured systems using naturally occurring uranium and thorium-series radionuclides as tracers under in-situ physico-chemical and hydrogeologic conditions. Radioactive disequilibria among members of these decay-series nuclides can provide information on the rates of adsorption-desorption and transport of contaminants as well as on fluid transport and rock dissolution in a natural setting.

TEH-LUNG KU

2001-06-01

5

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...

6

Are U-Series Disequilibria Transparent to Crustal Processing of Magma? A Case Study at Bezymianny and Klyuchevskoy Volcanoes, Kamchatka, Russia  

NASA Astrophysics Data System (ADS)

Disequilibria in the short-lived uranium-series isotopic system can provide timescales of magma production, modification and transport in all tectonic settings. In volcanic arcs, the field has converged on the concept that (238U/230Th) and (226Ra/230Th) activities greater than one are a result of fluid fluxing from the slab to mantle wedge, and that the preservation of (226Ra/230Th) disequilibria requires rapid transport of melts from the mantle wedge to the surface (226Ra returns to equilibrium with 230Th in ~8000 years). The need for rapid transport coupled with the incompatibility of U-series elements suggest that U-series fractionation is not measurably affected by crustal processes. However, some well-studied arc systems, including the very productive Central Kamchatka Depression (CKD) of the Kamchatkan volcanic arc, show U-series data that are in conflict with this commonly accepted model. Our study focuses on two neighboring volcanic systems, Bezymianny and Klyuchevskoy volcanoes in the CKD. Separated by ~10km, these two systems are thought to share the same mantle source. Klyuchevskoy has primitive compositions (51-56 wt%) while Bezymianny erupts more differentiated andesites (57-63 wt% SiO2); therefore, by examining the U-series signals in these two systems it is possible to decouple a primary signal from one having undergone crustal processing. We record whole rock (238U/230Th) values for Bezymianny ranging from 0.94 to 0.96 in modern eruptive products, while (226Ra/230Th) are >1. We also observe a similar signal in older (212-6791BP) tephra deposits from Klyuchevskoy, measuring (238U/230Th) of 0.92-0.99 (unpublished data, collaborative research with the KALMAR project). (238U/230Th) <1 in arcs have mostly been reported from areas of thick continental crust (Andes; Sigmarsson et al. 1998, Garrison et al. 2006, Jicha et al. 2007) or from an arc where phases such as garnet and/or Al-rich clinopyroxene can retain a high U/Th in the crystalline residue (Jicha et al. 2009). Bezymianny and Klyuchevskoy have low Sr/Y (15.5-19.9), which precludes a significant influence of garnet in generating the observed Th-excess in the CKD. We investigate the possibility of shallow crustal processes such as fractional crystallization, and/or assimilation of local bulk rock or partial melts to fractionate U, Th, and Ra from one another. In particular, we focus on minor mineral phases, such as apatite and magnetite, which are present during early stages of differentiation (andesites) and may fractionate U from Th. We measure U and Th content in these phases in-situ by LA-ICP-MS to obtain average mineral-melt partitioning for each sample with U-series data. Using such average partition coefficients allows us to take into account variations in parameters such as temperature, pressure, and oxygen fugacity that may vary from sample to sample. This mineral trace element data is supported by bulk rock geochemistry and Pb isotope data to evaluate the effects of crustal processing on the U-series system during magma transport and storage.

Kayzar, T. M.; Nelson, B. K.; Bachmann, O.; Portnyagin, M.; Ponomareva, V.

2010-12-01

7

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

8

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

9

Diffusive fractionation of U-series radionuclides during mantle melting and shallow-level melt cumulate interaction  

Microsoft Academic Search

U-series radioactive disequilibria in basaltic lavas have been used to infer many important aspects of melt generation and extraction processes in Earth's mantle and crust, including the porosity of the melting zone, the solid mantle upwelling rate, and the melt transport rate. Most of these inferences have been based on simplified theoretical treatments of the fractionation process, which assume equilibrium

James A. van Orman; Alberto E. Saal; Bernard Bourdon; Erik H. Hauri

2006-01-01

10

Diffusive fractionation of U-series radionuclides during mantle melting and shallow-level melt–cumulate interaction  

Microsoft Academic Search

U-series radioactive disequilibria in basaltic lavas have been used to infer many important aspects of melt generation and extraction processes in Earth’s mantle and crust, including the porosity of the melting zone, the solid mantle upwelling rate, and the melt transport rate. Most of these inferences have been based on simplified theoretical treatments of the fractionation process, which assume equilibrium

James A. Van Orman; Alberto E. Saal; Bernard Bourdon; Erik H. Hauri

2006-01-01

11

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

12

Internal tides and sediment dynamics in the deep sea—Evidence from radioactive 234Th/ 238U disequilibria  

NASA Astrophysics Data System (ADS)

Residual flow, barotropic tides and internal (baroclinic) tides interact in a number of ways with kilometer-scale seafloor topography such as abyssal hills and seamounts. Because of their likely impact on vertical mixing such interactions are potentially important for ocean circulation and the mechanisms and the geometry of these interactions are a matter of ongoing studies. In addition, very little is known about how these interactions are reflected in the sedimentary record. This multi-year study investigates if flow/topography interactions are reflected in distributional patterns of the natural short-lived (half-life: 24.1 d) particulate-matter tracer 234Th relative to its conservative (non-particle-reactive) and very long-lived parent nuclide 238U. The sampling sites were downstream of, or surrounded by, fields of short seamounts and, therefore, very likely to be influenced by nearby flow/topography interactions. At the sampling sites between about 200 and 1000 m above the seafloor recurrent 'fossil' disequilibria were detected. 'Fossil' disequilibria are defined by clearly detectable 234Th/ 238U disequilibria (total 234Th radioactivity < 238U radioactivity, indicating a history of intense particulate 234Th scavenging and particulate-matter settling from the sampled parcel of water) and conspicuously low particle-associated 234Th activities. 'Fossil' disequilibria were centered at levels in the water column that correspond to the average height of the short seamounts near the sampling sites. This suggests the 'fossil' disequilibria are formed on the seamount slopes. Moreover, the magnitude of the 'fossil' disequilibria suggests that the slopes of the short seamounts in the study region are characterized by particularly vigorous fluid dynamics. Since 'fossil' disequilibria already occurred at ˜ O(1-10 km) away from the seamount slopes it is likely that these vigorous fluid dynamics rapidly decay away from the slopes on scales of O(1-10 km). These conclusions are supported by the horizontal distribution and magnitude of the modeled total (barotropic+baroclinic) tidal current velocities of the predominating tidal M 2 constituent: on (near-)critical seamount slopes baroclinic tides lead to localized [˜ O(1 km)] increases of the overall tidal current velocity by a factor of ˜ 2, thereby pushing the total current velocity well above the threshold for sediment erosion. The results of this and a previous study [Turnewitsch, R., Reyss, J.-L., Chapman, D.C., Thomson, J., Lampitt, R.S., 2004. Evidence for a sedimentary fingerprint of an asymmetric flow field surrounding a short seamount. Earth and Planetary Science Letters 222(3-4), 1023-1036] show that kilometer-scale flow/topography interactions leave a marine geochemical imprint. This imprint may help develop new sediment proxies for the reconstruction of past changes of fluid dynamics in the deep sea, including residual and tidal flow. Sedimentary records controlled by kilometer-scale seafloor elevations are promising systems for the reconstruction of paleo-changes of deep-ocean fluid dynamics. For the sediment-based reconstruction of paleo-parameters other than physical oceanographic ones it may be advisable to avoid kilometer-scale topography altogether.

Turnewitsch, Robert; Reyss, Jean-Louis; Nycander, Jonas; Waniek, Joanna J.; Lampitt, Richard S.

2008-12-01

13

U-Series Transport Studies at the Pena Blanca, Mexico Natural Analog Site  

SciTech Connect

Natural analogs provide a line of evidence that supports the understanding of how natural and engineered processes would occur over long time frames and large spatial scales at a potential nuclear waste repository at Yucca Mountain, Nevada. Studies of U-series disequilibria within and around uranium deposits can provide valuable information on the timing of actinide mobility and hence the stability of a potential repository over geologic time scales. The Nopal I uranium deposit at Pena Blanca, Mexico, is situated in unsaturated tuff that is similar in composition to the Topopah Spring Tuff of Yucca Mountain and closely matches other evaluation criteria for suitable natural analogs. By modeling the observed radioactive isotope disequilibria at Nopal I, we can estimate the rates of sorption-desorption and dissolution-precipitation of the radionuclides over time. Such information is vital to the testing or validation of performance assessment models for geologic nuclear waste disposal.

A. M. Simmons; M. T. Murrell

2001-05-31

14

Magma dynamics at Mt Etna: Constraints from U-Th-Ra-Pb radioactive disequilibria and Sr isotopes in historical lavas  

Microsoft Academic Search

238U-230Th-226Ra-210Pb disequilibria and87Sr\\/86Sr ratios have been measured in a suite of prehistoric and historical lava flows from Mt. Etna. Whereas Th isotope ratios remain nearly constant during the whole period studied,226Ra and87\\/Sr86Sr data allow us to distinguish two mainepisodes in the volcanic history.For most of the past two millenia until 1970 A.D., Ra and Ba exhibit a similar behaviour (decreasing

Michel Condomines; Jean-Claude Tanguy; Vale´rie Michaud

1995-01-01

15

The U-series dating of (biogenic) carbonates C Hillaire-Marcel  

E-print Network

or counting methods of shorter-lived daughter isotopes (e.g., 226 Ra, 210 Pb, 234 Th, 228 Th, 228 Ra) inform-232 Th disequilibria) and up to 3 months (234 Th-excess). U-series isotopes, and especially

Long, Bernard

16

Diffusive fractionation of U-series radionuclides during mantle melting and shallow-level melt cumulate interaction  

NASA Astrophysics Data System (ADS)

U-series radioactive disequilibria in basaltic lavas have been used to infer many important aspects of melt generation and extraction processes in Earth's mantle and crust, including the porosity of the melting zone, the solid mantle upwelling rate, and the melt transport rate. Most of these inferences have been based on simplified theoretical treatments of the fractionation process, which assume equilibrium partitioning of U-series nuclides among minerals and melt. We have developed a numerical model in which solid-state diffusion controls the exchange of U-series nuclides among multiple minerals and melt. First the initial steady-state distribution of nuclides among the phases, which represents a balance between diffusive fluxes and radioactive production and decay, is calculated. Next, partial melting begins, or a foreign melt is introduced into the system, and nuclides are again redistributed among the phases via diffusion. U-series nuclides can be separated during this stage due to differences in their diffusivity; radium in particular, and possibly protactinium as well, can be strongly fractionated from slower-diffusing thorium and uranium. We show that two distinct processes are not required for the generation of 226Ra and 230Th excesses in mid-ocean ridge basalts, as has been argued previously; instead the observed negative correlations of the ( 226Ra/ 230Th) activity ratio with ( 230Th/ 238U) and with the extent of trace element enrichment may result from diffusive fractionation of Ra from Th during partial melting of the mantle. Alternatively, the ( 226Ra/ 230Th) disequilibrium in mid-ocean ridge basalts may result from diffusive fractionation during shallow-level interaction of mantle melts with gabbroic cumulates, and we show that the results of the interaction have a weak dependence on the age of the cumulate if both plagioclase and clinopyroxene are present.

Van Orman, James A.; Saal, Alberto E.; Bourdon, Bernard; Hauri, Erik H.

2006-09-01

17

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

18

U-Th-Ra Disequilibria in Lavas from the 2004-2005 Eruption of Mt. St. Helens  

Microsoft Academic Search

Decay of several nuclides in the U-series decay chain occurs on timescales similar to those of a variety of magmatic processes. Thus, analyses of the disequilibria between different parent\\/daughter pairs within this series have been used successfully to trace crystal populations and to describe the time scales of crystallization and magma storage in volcanic systems. Previous work with six samples

C. T. Donnelly; K. M. Cooper

2005-01-01

19

A New Model for U-Series Isotope Fractionation During Igneous Processes, With Finite Diffusion and Multiple Solid Phases  

NASA Astrophysics Data System (ADS)

U-series radioactive disequilibria in basaltic lavas have been used to infer many important aspects of melt generation and extraction processes, including the porosity of the melting zone, the mantle upwelling rate, and the melt transport rate. These inferences are based on simplified models for the fractionation of U-series isotopes during melting and melt transport. The commonly used "dynamic melting" and "equilibrium porous flow" models neglect solid-state diffusion and do not consider the influence of multiple solid phases on the initial distribution and subsequent fractionation of U-series isotopes. These factors can be very important, particularly for 226Ra which has a short half-life (~1600 yrs) and is strongly partitioned into minerals like plagioclase, amphibole, and mica while being almost perfectly excluded from clinopyroxene and garnet, the major U and Th bearing minerals in peridotite. Ignoring diffusion and multi-phase effects can lead to conclusions about the melting process that have no basis in reality. We have developed a numerical model that takes into account the effects of solid-state diffusion and considers the distribution of U-series isotopes among multiple solid phases and melt at each step of the melting process. In an undisturbed rock in secular equilibrium, daughter isotopes will tend to be transferred among the component phases until they reach a steady state in which diffusive fluxes are balanced by radioactive production and decay. In general the individual minerals will be neither in secular equilibrium (on the equiline) nor in partitioning equilibrium with each other (on a horizontal line on the equiline diagram), unless diffusion is very slow or very fast relative to the daughter decay rate. We start with an arbitrary distribution of daughter isotopes among the phases in the system, then turn on diffusion and allow isotopes to redistribute themselves until the steady state is reached (on a time scale comparable to the half-life of the isotope). Next, partial melting begins, or a foreign melt is introduced into the system, and isotopes are again redistributed among the phases via diffusion. U-series isotopes can be strongly fractionated during this stage due to differences in diffusivity. The diffusive fractionation can be much larger than equilibrium fractionation, and may even be in the opposite sense. We performed a series of calculations to simulate interaction of MORB liquids with "old" cpx+plag bearing gabbro in bulk secular equilibrium. In the gabbro at steady state, most of the U and Th reside in the cpx, and most of the 226Ra resides in the plagioclase. Because Ra diffusion in plagioclase is much faster than Th diffusion in cpx, large fractionations of 226Ra and 230Th can take place. If the MORB is more depleted than a melt that would be in equilibrium with the gabbro, then it acquires excess 226Ra; if it is more enriched, it acquires a 226Ra deficit. Interaction with gabbros will tend to produce large Ra excesses in D-MORB (> 5), but small Ra excesses (or even Ra deficits) in E-MORB. This is consistent with observations, and suggests that 226Ra-230Th disequilibria in MORB can be explained by shallow-level processes, and may give no information on processes of mantle melting.

van Orman, J.; Saal, A.; Bourdon, B.; Hauri, E.

2002-12-01

20

U SERIES DISEQUILIBRIA: INSIGHTS INTO MANTLE MELTING AND THE TIMESCALES OF MAGMA  

E-print Network

clues about the nature and mineralogy of mantle sources, mantle upwelling rates and porosity, fluid ), the long-lived isotopes of uranium and thorium (238 U, 235 U, and 232 Th) decay ultimately to isotopes

Jellinek, Mark

21

Comparison of U-Th-Ra Disequilibria in multiple crystal populations in lava from the current eruption of Mt. St. Helens  

Microsoft Academic Search

Decay of several nuclides in the U-series decay chain occurs on timescales similar to those of a variety of magmatic processes. Thus, analyses of the disequilibria between different parent\\/daughter pairs within this series have been used successfully to trace crystal populations and to describe the time scales of crystallization and magma storage in volcanic systems. Previous analyses of samples from

C. Donnelly; K. M. Cooper

2006-01-01

22

U-series disequilibrium constraints on the origin of adakites  

NASA Astrophysics Data System (ADS)

No consensus has been reached concerning the origin of adakites that represent a subgroup of calk-alkaline lavas formed at convergent margins. The particular composition of these adakites is ascribed to the role of garnet in fractionating key trace element ratios. However, it is not clear if garnet is a residual phase during slab melting, lower crustal melting or a fractionating phase from a parental basaltic liquid. Here, we present U-series criteria that allow clear distinction between different petrogenetic processes for this particular type of magma. Adakites from several volcanoes of the Austral Volcanic Zone (S-Chile), under which a young and hot oceanic crust is slowly subducted, have been shown to have constant 230Th-excess over 238U ascribed to partial slab melting with eclogitic residue. In marked contrast, historical adakites from the Guagua Pichincha volcano (Ecuador), above the subducting Galapagos Ridge, all display 238U- and 226Ra excesses over 230Th (max 45% and 26%, respectively). As in the case of most arc lavas, such 230Th deficit is readily explained by important fluid-addition of U and Ra. Hydrous flux melting of the mantle wedge would generate water-rich basalts that upon fractional crystallisation can form the adikites in Ecuador. Moreover, the amount of fluid recorded by the U-Ra-Th systematics in Guagua Pichincha magmas can be shown to increase towards the present, and consequently the potential explosivity of the erupted magma. In summary, U-series disequilibria seem to be a good tracer for the origin of adakites that clearly can be formed in more than one way.

Sigmarsson, O.; Chmeleff, J.

2009-12-01

23

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

Microsoft Academic Search

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

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

2006-01-01

24

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

Microsoft Academic Search

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

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

2006-01-01

25

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

26

Minimum speed limit for ocean ridge magmatism from 210Pb-226Ra-230Th disequilibria.  

PubMed

Although 70 per cent of global crustal magmatism occurs at mid-ocean ridges-where the heat budget controls crustal structure, hydrothermal activity and a vibrant biosphere-the tempo of magmatic inputs in these regions remains poorly understood. Such timescales can be assessed, however, with natural radioactive-decay-chain nuclides, because chemical disruption to secular equilibrium systems initiates parent-daughter disequilibria, which re-equilibrate by the shorter half-life in a pair. Here we use 210Pb-226Ra-230Th radioactive disequilibria and other geochemical attributes in oceanic basalts less than 20 years old to infer that melts of the Earth's mantle can be transported, accumulated and erupted in a few decades. This implies that magmatic conditions can fluctuate rapidly at ridge volcanoes. 210Pb deficits of up to 15 per cent relative to 226Ra occur in normal mid-ocean ridge basalts, with the largest deficits in the most magnesium-rich lavas. The 22-year half-life of 210Pb requires very recent fractionation of these two uranium-series nuclides. Relationships between 210Pb-deficits, (226Ra/230Th) activity ratios and compatible trace-element ratios preclude crustal-magma differentiation or daughter-isotope degassing as the main causes for the signal. A mantle-melting model can simulate observed disequilibria but preservation requires a subsequent mechanism to transport melt rapidly. The likelihood of magmatic disequilibria occurring before melt enters shallow crustal magma bodies also limits differentiation and heat replenishment timescales to decades at the localities studied. PMID:16177787

Rubin, K H; van der Zander, I; Smith, M C; Bergmanis, E C

2005-09-22

27

Seasonal and spatial dynamics of 234 U disequilibria  

E-print Network

Seasonal and spatial dynamics of 234 Th//238 U disequilibria in southern Lake Michigan James T 2004. [1] Measurements of 234 Th/238 U disequilibria were made on an approximately bimonthly basis over. Measured median activities of dissolved (234 Th were 8.0 and 60.6 dpm m

Waples, James T.

28

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

29

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

30

Quantifying Radionuclides Migration From U-series in an Unconfined Aquifer  

NASA Astrophysics Data System (ADS)

With the increase of contaminant flux of radionuclides in the environment, there is a need to understand and model the processes that control the distribution of uranium and its daughter products during transport within aquifers. We have used U-series disequilibria as an analogue for the transport of anthropogenic nuclides in a small watershed of a chalk aquifer in Eastern France. We have measured naturally occurring U and Th isotopes in rock and water phases in order to determine transport mechanisms at water/rock interface and quantify parameters controlling the migration of radionuclides. The studied aquifer has a double porosity and is characterised by a saturated matrix up to 40m above the water-table and variably saturated fractures. Measurements of U and Th isotopic composition in the water phase were performed on a MC-ICPMS which enable in particular high precision measurements of (230Th/232Th) activity ratio. Water samples were obtained from wells both in low and high water-table conditions. Chalk samples were collected at the same wells and were analysed also for U-series and Sr isotopes. We observed seasonal precipitation of uranium ((234U/238U) activity ratio above 1) in the zone of water-table fluctuation linked with the oversaturation of water with respect to calcite during low water-table period. (230Th/232Th) activity ratios in water are lower than in the substratum meaning that the time of water infiltration is not long enough to allow an equilibration of groundwater with rock. Water acquires its Th isotopic composition when interacting with another phase of the aquifer (soil) and joins the water-table mainly through fractures. The complete data set obtained on solid and liquid phases of the aquifer allow us mass balance calculations and to model the behaviour of uranium and thorium during transport. The 1-D model we have developed considers a transient behaviour of radionuclides in the aquifer and for the first time allows the calculation of the evolution of rock composition with time. We have then calculated a global uranium weathering rate within the aquifer of 2.5 10-6 y-1.

Hubert, A.; Bourdon, B.; Pili, E.

2004-12-01

31

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

32

U-series and Sr-Nd-Pb isotopic studies of lavas erupted from 1909 to 2000 on Mt. Cameroon volcano (West Africa)  

NASA Astrophysics Data System (ADS)

Here we present precise measurements of 238U-230Th-226Ra disequilibria in lavas erupted within the last 100 years on Mt. Cameroon volcano, together with major and trace elements, and Sr-Nd-Pb isotope ratios, to unravel the source and processes of basaltic magmatism at intraplate tectonic settings. All the samples possess 238U-230Th-226Ra disequilibria with 230Th (18-24 %) and 226Ra (9-21 %) excesses, and a positive correlation in a (226Ra/230Th)-(230Th/238U) diagram is observed. The degree of 238U-230Th-226Ra disequilibria is markedly different in lavas of individual eruption ages, although the (230Th/232Th) ratio is constant irrespective of eruption age. When U-series results are combined with Pb isotope ratios, negative correlations are observed in the (230Th/238U)-(206Pb/204Pb) and (226Ra/230Th)-(206Pb/204Pb) diagrams. Fractional crystallization in a shallow magma chamber involving the decay of 230Th and 226Ra does not account for the correlations. Crustal contamination is not the cause of the observed isotopic variations because continental crust is considered to have extremely different Pb isotope compositions and U/Th ratios. Melting of a chemically heterogeneous mantle might explain the Mt. Cameroon data, but dynamic melting with extremely high partition coefficients for U and Th are required. The most plausible scenario to produce the geochemical characteristics of Mt. Cameroon samples is the interaction of melt derived from the asthenospheric mantle with overlying sub-continental lithospheric mantle which has elevated U/Pb (>1) and Pb isotope ratios (206Pb/204Pb >20.9), due to Mesozoic-early Cenozoic metasomatism.

Yokoyama, T.; Aka, F. T.; Kusakabe, M.; Nakamura, E.

2006-12-01

33

The U-series toolbox for paleoceanography Gideon M. Henderson  

E-print Network

-mail: boba@ldeo.columbia.edu Reviews in Mineralogy and Geochemistry "Uranium Series Geochemistry" Revised (Cochran and Masque, 2003). 2. U-series isotopes in the ocean environment 2.1 The ocean uranium budget Uranium has a reasonably constant seawater concentration in both space and time, varying only in line

Henderson, Gideon

34

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

35

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

36

Atmospheric dust contribution to budget of U-series nuclides in weathering profiles. The Mount Cameroon volcano  

NASA Astrophysics Data System (ADS)

Analysis of U-series nuclides in weathering profiles is developed today for constraining time scale of soil and weathering profile formation (e.g., Chabaux et al., 2008). These studies require the understanding of U-series nuclides sources and fractionation in weathering systems. For most of these studies the impact of aeolian inputs on U-series nuclides in soils is usually neglected. Here, we propose to discuss such an assumption, i.e., to evaluate the impact of dust deposition on U-series nuclides in soils, by working on present and paleo-soils collected on the Mount Cameroon volcano. Recent Sr, Nd, Pb isotopic analyses performed on these samples have indeed documented significant inputs of Saharan dusts in these soils (Dia et al., 2006). We have therefore analyzed 238U-234U-230Th nuclides in the same samples. Comparison of U-Th isotopic data with Sr-Nd-Pb isotopic data indicates a significant impact of the dust input on the U and Th budget of the soils, around 10% for both U and Th. Using Sr-Nd-Pb isotopic data of Saharan dusts given by Dia et al. (2006) we estimate U-Th concentrations and U-Th isotope ratios of dusts compatible with U-Th data obtained on Saharan dusts collected in Barbados (Rydell H.S. and Prospero J.M., 1972). However, the variations of U/Th ratios along the weathering profiles cannot be explained by a simple mixing scenario between material from basalt and from the defined atmospheric dust pool. A secondary uranium migration associated with chemical weathering has affected the weathering profiles. Mass balance calculation suggests that U in soils from Mount Cameroon is affected at the same order of magnitude by both chemical migration and dust accretion. Nevertheless, the Mount Cameroon is a limit case were large dust inputs from continental crust of Sahara contaminate basaltic terrain from Mount Cameroon volcano. Therefore, this study suggests that in other contexts were dust inputs are lower, or the bedrocks more concentrated in U and Th, the dust contribution will not significantly influence U-series dating. Chabaux F., Bourdon B., Riotte J. (2008). U-series Geochemistry in weathering profiles, river waters and lakes. Radioactivity in the Environment, 13, 49-104. Dia A., Chauvel C., Bulourde M. and Gérard M. (2006). Eolian contribution to soils on Mount Cameroon: Isotopic and trace element records. Chem. Geol. 226, 232-252. Rydell H.S. and Prospero J.M. (1972). Uranium and thorium concentrations in wind-borne Saharan dust over the western equatorial north atlantic ocean. EPSL 14, 397-402.

Pelt, E.; Chabaux, F. J.; Innocent, C.; Ghaleb, B.

2009-12-01

37

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.

Menking, Kirsten

38

Interrelationships between Amerindian tribes of lower Amazonia as manifest by HLA haplotype disequilibria.  

PubMed Central

HLA B-C haplotypes exhibit common disequilibria in populations drawn from four continents, indicating that they are subject to broadly active selective forces. However, the A-B and A-C associations we have examined show no consistent disequilibrium pattern, leaving open the possibility that these disequilibria are due to descent from common progenitors. By examining HLA haplotype distributions, I have explored the implications that would follow from the hypothesis that biological selection played no role in determining A-C disequilibria in 10 diverse tribes of the lower Amazon Basin. Certain haplotypes are in strong positive disequilibria across a broad geographic area, suggesting that members of diverse tribes descend from common ancestors. On the basis of the extent of diffusion of the components of these haplotypes, one can estimate that the progenitors lived less than 6,000 years ago. One widely encountered lineage entered the area within the last 1,200 years. When haplotype frequencies are used in genetic distance measurements, they give a pattern of relationships very similar to that obtained by conventional chord measurements based on several genetic markers; but more than that, when individual haplotype disequilibria in the several tribes are compared, multiple origins of a single tribe are discernible and relationships are revealed that correlate more closely to geographic and linguistic patterns than do the genetic distance measurements. PMID:6595946

Black, F L

1984-01-01

39

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

40

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

41

Large CO2 disequilibria in tropical lakes Humberto Marotta,1,2  

E-print Network

Large CO2 disequilibria in tropical lakes Humberto Marotta,1,2 Carlos M. Duarte,2 Sebastian Sobek,3 November 2009. [1] On the basis of a broad compilation of data on pCO2 in surface waters, we show tropical lakes to be, on average, far more supersaturated and variable in CO2 (geometric mean ± SE pCO2 = 1804

Wehrli, Bernhard

42

U-series Isotopes and the Time Scales of Magmatic Processes  

NASA Astrophysics Data System (ADS)

The first published record of a radioactive decay chain was 100 years ago this year, and the sequence of isotopes in the U and Th decay chains were largely determined in the following ten years. Isotopes of U, Th, Pa, Ra and Pb with half-lives in the range 75,000 to 22 years have had a major impact in our understanding of magmatic processes, because the time scales of magmatic processes are similar to the half lives of these isotopes, and physically realistic models of natural processes require information on the rates at which those processes occur. U-Th-Pa-Ra isotopes can now be measured by mass spectrometry, routinely with errors of less than ~1%. A key characteristic is that U-series isotopes can change significantly by radioactive decay while the crystals and rocks were forming. At subduction zones fluids may be transferred from the downgoing slab in a few 1000 years. In most tectonic settings the magmas and the peridotite matrix spend different lengths of time in the melt zone, and typically the observed isotope fractionation implies some form of dynamic melting process. New U-Pa isotope data for 40 young lavas from 7 different arcs worldwide have, with one exception, (231Pa/235U) > 1, and extend to values as high as 2.48. Their U/Nb ratios are < 9.0 and so > 80% of the U has been added from the subducting slab, and large enrichments of Pa over U occurred during melting and melt transport. The ages of phenocrysts and the time scale of differentiation of the host magma can be different, and in a number of cases it has been shown that the phenocrysts formed after the fractional crystallisation responsible for the whole rock composition. Different approaches are therefore used to investigate the crystallisation history and the differentiation of magmatic suites: crystallisation rates are ~ 10-10 to 10-11 cm/s, whereas differentiation to high silica magmas may take up to 2 x 105 years. The ages of crystals at the time of eruption can range back to 2-3 x 105 years, the older ages tend to be in the more evolved rock types, and it can take 105 years for high silica magmas to be generated at individual volcanic centres. Thus, the generation of evolved magmas is often thermally controlled, and the rates of fractional crystallisation have, for example, been linked to volcanic power outputs. In contrast, crystallisation in response to magma degassing or decompression, may be too fast for much fractional crystallisation to take place.

Hawkesworth, C. J.; Peate, D. W.; Regelous, M.; Turner, S. P.; George, R. M.

2003-12-01

43

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

44

Sample geometry and U uptake in archaeological teeth: implications for U-series and ESR dating  

NASA Astrophysics Data System (ADS)

Post-deposition U uptake by bones and teeth is the most significant source of inaccuracy in both U-series and ESR dating. In most cases assumptions about the form of U uptake are required to calculate a date. We have been using the diffusion-adsorption (D-A) model of U uptake to predict the rate of uptake and spatial distribution of U and U-series isotopes in bones, and calculate open-system ages. Here we develop a similar model to predict U uptake in enamel and enamel-dentine systems. We find that the traditional models of U uptake, namely linear and early uptake providing maximum and minimum ages, are not universally applicable. Geochemical changes in the burial environment can lead to leaching or recent accumulation of U. In addition, the geometry of the tooth affects the pattern of U accumulation, with some areas of the enamel showing uptake between early and linear, while other areas of the same tooth may exhibit sublinear (recent) uptake. We show, however, how the measurement of the U and U-series isotope distributions (profiles) for a tooth can be combined to model uptake, and provide more reliable U-series dates or ESR dosimetry.

Pike, Alistair W. G.; Hedges, Robert E. M.

2001-12-01

45

Modeling of U-series Radionuclide Transport Through Soil at Pena Blanca, Chihuahua, Mexico  

NASA Astrophysics Data System (ADS)

The Nopal I uranium deposit is located at Pena Blanca in Chihuahua, Mexico. Mining of high-grade uranium ore occurred in the early 1980s, with the ore stockpiled nearby. The stockpile was mostly cleared in the 1990s; however, some of the high-grade boulders have remained there, creating localized sources of radioactivity for a period of 25-30 years. This provides a unique opportunity to study radionuclide transport, because the study area did not have any uranium contamination predating the stockpile in the 1980s. One high-grade boulder was selected for study based upon its shape, location, and high activity. The presumed drip-line off of the boulder was marked, samples from the boulder surface were taken, and then the boulder was moved several feet away. Soil samples were taken from directly beneath the boulder, around the drip-line, and down slope. Eight of these samples were collected in a vertical profile directly beneath the boulder. Visible flakes of boulder material were removed from the surficial soil samples, because they would have higher concentrations of U-series radionuclides and cause the activities in the soil samples to be excessively high. The vertical sampling profile used 2-inch thicknesses for each sample. The soil samples were packaged into thin plastic containers to minimize the attenuation and to standardize sample geometry, and then they were analyzed by gamma-ray spectroscopy with a Ge(Li) detector for Th-234, Pa-234, U-234, Th-230, Ra-226, Pb-214, Bi-214, and Pb-210. The raw counts were corrected for self-attenuation and normalized using BL-5, a uranium standard from Beaverlodge, Saskatchewan. BL-5 allowed the counts obtained on the Ge(Li) to be referenced to a known concentration or activity, which was then applied to the soil unknowns for a reliable calculation of their concentrations. Gamma ray spectra of five soil samples from the vertical profile exhibit decreasing activities with increasing depth for the selected radionuclides. Independent multi-element analyses of three samples by ICP-MS show decreasing uranium concentration with depth as well. The transport of the radionuclides is evaluated using STANMOD, a Windows-based software package for evaluating solute transport in porous media using analytical solutions of the advection-dispersion solute transport equation. The package allows various one-dimensional, advection-dispersion parameters to be determined by fitting mathematical solutions of theoretical transport models to observed data. The results are promising for future work on the release rate of radionuclides from the boulder, the dominant mode of transport (e.g., particulate or dissolution), and the movement of radionuclides through porous media. The measured subsurface transport rates provide modelers with a model validation dataset.

Pekar, K. E.; Goodell, P. C.; Walton, J. C.; Anthony, E. Y.; Ren, M.

2007-05-01

46

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

47

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.

48

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

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

2000-01-01

49

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

50

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

51

Use of U-Series Isotopic Disequilibrium to Investigate the Nature and Distribution of Actively Flowing Fractures  

NASA Astrophysics Data System (ADS)

Groundwater transport of radioisotopes from underground nuclear tests at the Nevada National Security Site (NNSS) is of concern to the U.S. Department of Energy. Extensive testing was conducted near or below the regional water table (saturated zone; SZ) at Pahute Mesa and within the unsaturated (or partially saturated) zone at Rainier Mesa. Groundwater flow in these rocks is believed to occur mainly through a connected network of fractures. To better understand flow in these fractured rocks, we analyzed U-series isotopes (238U-234U-230Th) from drill core samples. In rock isolated from flow over the last million years, isotopes in the 238U decay chain reach a state of radioactive secular equilibrium, where 234U/238U and 230Th/238U activity ratios (AR) = 1.0. More recent water-rock interaction results in mobilization of 234U relative to 238U, and U relative to Th in migrating waters. Rock surfaces that incorporate this U or are leached of 234U and U will show U-series disequilibrium. Isotope data can thus provide time-sensitive information on hydrologic conditions in host rocks without directly observing or measuring flowing water. To investigate NNSS fracture networks, core was selected from confining units (bedded and zeolitized felsic tuffs) and aquifers (felsic welded tuffs and lavas) in five boreholes on Pahute Mesa and two boreholes on Rainier Mesa. Samples include interiors of intact core as well as natural fracture surfaces and brecciated core. Intact core and brecciated samples were crushed and powdered. Fracture surfaces were sampled using dental burs to remove the outer 0.1 to 0.5 mm of fracture surfaces, which may have thin mineral coatings of zeolites, clays, and Mn oxides. Samples were totally digested, spiked with a 236U-229Th tracer, and analyzed by a solid-source TRITON° mass spectrometer equipped with an energy filter and single ion counter. Results show that 8 of 9 intact core samples have 234U/238U AR within ±5% of 1.0, suggesting little or no water-rock interaction over the last several hundred thousand years. In contrast, discrete fracture surfaces (N=37) have 234U/238U AR ranging from 2.09 to 0.34, although the median value is 1.04. About one third of the 28 SZ fracture surfaces have 234U/238U AR within 5% of 1.0. Remaining SZ fractures tend to have 234U/238U > 1.0,indicating that U incorporation from migrating groundwater (234U/238U AR ? 2-4) is an important process. Furthermore, samples with isotopic disequilibrium commonly plot along the equiline (equal 234U/238U and 230Th/238U AR) regardless of sample type or location. This pattern cannot be explained by deposition and closed-system isotope evolution of secondary minerals. Instead, it suggests a quasi-steady-state balance of processes including sorption or leaching of U associated with migrating solutions and in-situ production, decay, and ?-recoil of 230Th and 234U. These data will be used to help constrain numerical models of fracture-matrix interaction and spatial distribution of flowing versus non-flowing fractures.

Nichols, P. J.; Paces, J. B.; Neymark, L. A.; Rajaram, H.

2011-12-01

52

Indirect crustal contamination: evidence from isotopic and chemical disequilibria in minerals from alkali basalts and nephelinites from northern Tanzania  

Microsoft Academic Search

Alkali basalts and nephelinites from the volcanic province of northern Tanzania contain pyroxene and nepheline that show\\u000a evidence for chemical and\\/or isotopic disequilibria with their host magmas. Olivine, pyroxene, nepheline and plagioclase all\\u000a appear to be partially xenocrystic in origin. Five whole rock\\/mineral separate pairs have been analyzed for Sr, Nd, and Pb\\u000a isotopic compositions. The 206Pb\\/204Pb ratios are distinct

Cassi R. Paslick; Alex N. Halliday; Rebecca A. Lange; Dodie James; J. Barry Dawson

1996-01-01

53

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

54

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

55

U-series dating and geochemical tracing of late Quaternary travertine in co-seismic fissures  

NASA Astrophysics Data System (ADS)

We present a method to constrain the timing of fissure generation related to late Quaternary seismic events using the uranium-series technique. Dated samples were from travertine deposits precipitated in co-seismic extensional fissures along major active faults in Western Turkey. Stable isotope and REE data indicate that the precipitation of the fissure travertines was not controlled by the hydrologic regime that is responsible for the speolethem deposition in the same region. Moreover, the REE composition and concentration of the water from which the fissure travertine precipitated were significantly different from those of the current geothermal waters in the study area. The carbonate generation in the co-seismic fissures is interpreted to be the product of rapid precipitation from deeply infiltrated and CO 2-enriched surface water during seismic strain cycles. Results show that U-series dating of fracture-filling travertine deposits from seismically active areas provide important temporal information relevant to establishing recurrence intervals of late Quaternary and prehistoric major earthquake events. Precise dating of prehistoric earthquakes may be of great value for seismic hazard studies and earthquake forecasting research, for which accurate estimates of recurrence intervals are critical.

Uysal, I. Tonguç; Feng, Yuexing; Zhao, Jian-xin; Altunel, Erhan; Weatherley, Dion; Karabacak, Volkan; Cengiz, Oya; Golding, Suzanne D.; Lawrence, Michael G.; Collerson, Kenneth D.

2007-05-01

56

Regolith formation rate from U-series nuclides: Implications from the study of a spheroidal weathering profile in the Rio Icacos watershed (Puerto Rico)  

NASA Astrophysics Data System (ADS)

A 2 m-thick spheroidal weathering profile, developed on a quartz diorite in the Rio Icacos watershed (Luquillo Mountains, eastern Puerto Rico), was analyzed for major and trace element concentrations, Sr and Nd isotopic ratios and U-series nuclides (238U-234U-230Th-226Ra). In this profile a 40 cm thick soil horizon is overlying a 150 cm thick saprolite which is separated from the basal corestone by a ˜40 cm thick rindlet zone. The Sr and Nd isotopic variations along the whole profile imply that, in addition to geochemical fractionations associated to water-rock interactions, the geochemical budget of the profile is influenced by a significant accretion of atmospheric dusts. The mineralogical and geochemical variations along the profile also confirm that the weathering front does not progress continuously from the top to the base of the profile. The upper part of the profile is probably associated with a different weathering system (lateral weathering of upper corestones) than the lower part, which consists of the basal corestone, the associated rindlet system and the saprolite in contact with these rindlets. Consequently, the determination of weathering rates from 238U-234U-230Th-226Ra disequilibrium in a series of samples collected along a vertical depth profile can only be attempted for samples collected in the lower part of the profile, i.e. the rindlet zone and the lower saprolite. Similar propagation rates were derived for the rindlet system and the saprolite by using classical models involving loss and gain processes for all nuclides to interpret the variation of U-series nuclides in the rindlet-saprolite subsystem. The consistency of these weathering rates with average weathering and erosion rates derived via other methods for the whole watershed provides a new and independent argument that, in the Rio Icacos watershed, the weathering system has reached a geomorphologic steady-state. Our study also indicates that even in environments with differential weathering, such as observed for the Puerto Rico site, the radioactive disequilibrium between the nuclides of a single radioactive series (here 238U-234U-230Th-226Ra) can still be interpreted in terms of a simplified scenario of congruent weathering. Incidentally, the U-Th-Ra disequilibrium in the corestone samples confirms that the outermost part of the corestone is already weathered.

Chabaux, F.; Blaes, E.; Stille, P.; di Chiara Roupert, R.; Pelt, E.; Dosseto, A.; Ma, L.; Buss, H. L.; Brantley, S. L.

2013-01-01

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

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

59

U-series and ESR analyses of bones and teeth relating to the human burials from Skhul  

Microsoft Academic Search

In order to resolve long-standing issues surrounding the age of the Skhul early modern humans, new analyses have been conducted, including the dating of four well-provenanced fossils by ESR and U-series. If the Skhul burials took place within a relatively short time span, then the best age estimate lies between 100 and 135ka. This result agrees very well with TL

Rainer Grün; Chris Stringer; Frank McDermott; Roger Nathan; Naomi Porat; Steve Robertson; Lois Taylor; Graham Mortimer; Stephen Eggins; Malcolm McCulloch

2005-01-01

60

Evaluating U-series tools for weathering rate and duration on a soil sequence of known ages  

NASA Astrophysics Data System (ADS)

Four soil profiles of known age (40, 250, 600 and 3000 ka) from the Merced soil chronosequence in California were analysed for U and Th isotopes, and for major- and trace-element compositions, to test the assumption that leaching of U-series isotopes is a first order process with an invariant rate constant, as frequently assumed when applying this isotopic tool to determine weathering duration and sediment residence time. Average (230Th/238U) values for each profile decrease from a high of 1.28 in the youngest soil (40 ka) to 1.09, 0.99 and 0.98 in the 250 ka, 600 ka and 3000 ka soils respectively. (234U/238U) values also show variation across the 4 soils. The simultaneous variation in (230Th/238U) and (234U/238U) cannot be explained by a first-order kinetic model with invariant rate constants and instead requires that leaching coefficients for the U-series isotopes change with time. The observed data is consistent with a two-stage model that reflects an initial period of fast leaching of U and Th from a readily weathered soil pool (such as grain boundaries or defects), followed by slow leaching from a more resistant soil pool. Application of such a two-stage model may lead to significantly shorter calculated timescales of weathering than those obtained by the widely applied single-stage model of U-series weathering, which assumes no change in leaching coefficients over time. The results of this study have wide implications for published and future use of U-series tools in weathering studies.

Keech, Andrew R.; West, A. Joshua; Pett-Ridge, Julie C.; Henderson, Gideon M.

2013-07-01

61

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

62

Organic carbon-water concentration quotients (II(SOC)S and pi(poc)S): measuring apparent chemical disequilibria and exploring the impact of black carbon in Lake Michigan.  

PubMed

Chemical concentration quotients measured between water and total organic carbon (TOC) in sediment (II(SOC)) or suspended particulates (pi(poc)) in southern Lake Michigan reveal up to 2 orders of magnitude differences for polychlorinated biphenyl (PCB), dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and polycyclic aromatic hydrocarbon (PAH) compounds with similar octanol-water partition coefficients (K(ow)S). Apparent disequilibria for PAHs, PCDDs, and PCDFs, determined as measured II(SOC)S or pi(poc)S divided by their organic carbon equilibrium partitioning values, are significantly greater than disequilibria of PCBs with similar K(ow)S. Apparent disequilibria, when adjusted for black carbon content by using published black carbon nonlinear partition coefficients (K(f,bc)S) and a Freundlich exponent (n(f)) value = 0.7, still exceed equilibrium predictions for the PAHs, PCBs, and PCDDs but with the PCDF disequilibria uniquely below equilibrium. While Monte Carlo analysis of all the variables associated with the black carbon adjusted disequilibria provides wide confidence intervals for individual chemicals, the large class disequilibria differences between PAHs and PCDFs with respect to the PCBs and PCDDs are highly significant. Use of the PCDD K(f,bc)S for calculating both the PCDF and PCDD disequilibria eliminates their extreme divergence. On the basis of the complexity of carbonaceous geosorbent effects and the apparent variable degrees of chemical sequestration in particles, the disequilibria can be adjusted by chemical class to meet expected near equilibrium conditions between suspended particles and water in the hypolimnion. Although these adjustments to the disequilibria calculations produce consistent and plausible values, the complexities of variable carbonaceous geosorbent affinities for these chemicals in Lake Michigan presently favor use of measured, rather than a priori modeled, steady-state total organic carbon-water concentration quotients indexed to TOC as biogenic organic carbon. PMID:18546698

Burkhard, Lawrence P; Cook, Philip M; Lukasewycz, Marta T

2008-05-15

63

Project EARTH-13-GMH2: U-series nuclides as tracers of modern ocean processes Supervisors: Prof. Gideon Henderson and Dr. Alex Thomas  

E-print Network

. Gideon Henderson and Dr. Alex Thomas Uranium is soluble in seawater and its three isotopes ­ 238 U, 235 U. The U-series toolbox for paleoceanography. Reviews in Mineralogy and Geochemistry 52, 493-531. Hsieh, Y

Henderson, Gideon

64

Regolith production and transport in the Susquehanna Shale Hills Critical Zone Observatory, Part 1: Insights from U-series isotopes  

NASA Astrophysics Data System (ADS)

investigate the timescales of regolith formation on hillslopes with contrasting topographic aspect, we measured U-series isotopes in regolith profiles from two hillslopes (north facing versus south facing) within the east-west trending Shale Hills catchment in Pennsylvania. This catchment is developed entirely on the Fe-rich, Silurian Rose Hill gray shale. Hillslopes exhibit a topographic asymmetry: The north-facing hillslope has an average slope gradient of ~20°, slightly steeper than the south-facing hillslope (~15°). The regolith samples display significant U-series disequilibrium resulting from shale weathering. Based on the U-series data, the rates of regolith production on the two ridgetops are indistinguishable (40 ± 22 versus 45 ± 12 m/Ma). However, when downslope positions are compared, the regolith profiles on the south-facing hillslope are characterized by faster regolith production rates (50 ± 15 to 52 ± 15 m/Ma) and shorter durations of chemical weathering (12 ± 3 to 16 ± 5 ka) than those on the north-facing hillslope (17 ± 14 to 18 ± 13 m/Ma and 39 ± 20 to 43 ± 20 ka). The south-facing hillslope is also characterized by faster chemical weathering rates inferred from major element chemistry, despite lower extents of chemical depletion. These results are consistent with the influence of aspect on regolith formation at Shale Hills; we hypothesize that aspect affects such variables as temperature, moisture content, and evapotranspiration in the regolith zone, causing faster chemical weathering and regolith formation rates on the south-facing side of the catchment. The difference in microclimate between these two hillslopes is inferred to have been especially significant during the periglacial period that occurred at Shale Hills at least ~15 ka before present. At that time, the erosion rates may also have been different from those observed today, perhaps denuding the south-facing hillslope of regolith but not quite stripping the north-facing hillslope. An analysis of hillslope evolution and response timescales with a linear mass transport model shows that the current landscape at Shale Hills is not in geomorphologic steady state (i.e., so-called dynamic equilibrium) but rather is likely still responding to the climate shift from the Holocene periglacial to the modern, temperate conditions.

Ma, Lin; Chabaux, Francois; West, Nikki; Kirby, Eric; Jin, Lixin; Brantley, Susan

2013-06-01

65

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

66

Comparing POC export from 234Th\\/ 238U and 210Po\\/ 210Pb disequilibria with estimates from sediment traps in the northwest Mediterranean  

Microsoft Academic Search

We compare POC fluxes estimated using 234Th\\/238U and 210Po\\/210Pb disequilibria at the DYFAMED site, northwestern Mediterranean Sea. We also compare the POC fluxes estimated from these two isotope pairs with fluxes below the euphotic zone measured in moored sediment traps. The POC flux at 200m estimated from 234Th and 210Po deficits and the POC\\/210Po or POC\\/234Th on >70?m filterable particles

G. Stewart; J. K. Cochran; J. C. Miquel; P. Masque; J. Szlosek; A. M. Rodriguez y Baena; S. W. Fowler; B. Gasser; D. J. Hirschberg

2007-01-01

67

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

68

Soil formation rates determined from Uranium-series isotope disequilibria in soil profiles from the southeastern Australian highlands  

NASA Astrophysics Data System (ADS)

The sustainability of soil resources is determined by the balance between the rates of production and removal of soils. Samples from four weathering profiles at Frogs Hollow in the upper catchment area of the Murrumbidgee River (southeastern Australia) were analyzed for their uranium-series (U-series) isotopic composition to estimate soil production rates. Sequential leaching was conducted on sample aliquots to assess how U-series nuclides are distributed between primary and secondary minerals. Soil is increasingly weathered from bottom to top which is evident from the decrease in (234U/238U) ratios and increase in relative quartz content with decreasing soil depth. One soil profile shows little variation in mineralogy and U-series geochemistry with depth, explained by the occurrence of already extensively weathered saprolite, so that further weathering has minimal effect on mineralogy and geochemistry. Al2O3 is mobilized from these soils, and hence a silicon-based weathering index treating Al2O3 as mobile is introduced, which increases with decreasing soil depth, in all profiles. Leached and unleached aliquots show similar mineralogy with slight variation in relative concentrations, whereas the elemental and isotopic composition of uranium and thorium show notable differences between leached and unleached samples. Unleached samples show systematic variations in uranium-series isotopic compositions with depth compared to leached samples. This is most likely explained by the mobilization of U and Th from the samples during leaching. Soil residence times are calculated by modeling U-series activity ratios for each profile separately. Inferred timescales vary up to 30 kyr for unleached aliquots from profile F1 to up to 12 kyr for both leached and unleached aliquots from profile F2. Muscovite content shows a linear relationship with U-series derived soil residence times. This relationship provides an alternative method to estimate residence timescales for profiles with significant U-series data scatter. Using this alternative approach, inferred soil residence times up to 33 kyr for leached samples of profile F1 and up to 34 kyr for leached samples of profile F3 were determined. A linear relationship between soil residence times and WIS (Si-based Weathering Index) exists and is used to estimate soil residence times for profile F3 (up to 28 kyr) and F4 (up to 37 kyr). The linear relationship between soil depth and calculated residence time allows determination of soil production rates, which range from 10 to 24 mm/kyr and are comparable to the rates determined previously using cosmogenic isotopes at the same site (Heimsath et al., 2001b). This implies that at this site, on the highland plateau of southeastern Australia, soil thickness has reached steady-state, possibly as a result of stable tectonic conditions but despite variable climatic conditions over the timescale of soil development. Soil-mantled landscapes are the geomorphic expression of this balance between soil production and denudation, and our results show that in tectonically quiescent regions, this landscape can be achieved in less than 30 kyr.

Suresh, P. O.; Dosseto, A.; Hesse, P. P.; Handley, H. K.

2013-10-01

69

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

70

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

71

U-Series and Amino-acde racemization geochronology of Bermuda - Implications for Eustatic Sea-Llevel fluctuation over the past 250,000 years  

Microsoft Academic Search

Bermuda is a stable, mid-oceanic carbonate platform for which a particularly complete record of Late Pleistocene eustatic sea-level fluctuation has been reconstructed from a detailed study of geological field relationships combined with an extensive programme of U-series and amino-acid racemization geochronology. Only twice in the past 250,000 yr. has sea level in Bermuda been above its present level, once at

Russell S. Harmon; Richard M. Mitterer; Nivat Kriausakul; Lynton S. Land; Henry P. Schwarcz; Peter Garrett; Grahame J. Larson; H. Len Vacher; Mark Rowe

1983-01-01

72

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

Microsoft Academic Search

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

Joel Pederson; Karl Karlstrom; Warren Sharp; William McIntosh

2002-01-01

73

Behaviour of nuclides and U-series disequilibrium in clayey sediments: application to the Late Jurassic record from the eastern Paris basin  

Microsoft Academic Search

We present a record of U-series disequilibrium covering the Callovo-Oxfordian-Thitonian times of the Late Jurassic carbonated platform from the eastern part of the Paris basin. The Callovo-Oxfordian clayey layer is the potential host rock for reconnaissance work carried out by Andra (e.g., Agence Nationale de Gestion des Déchets Radioactifs) in eastern France, the objective of which is the designing and

J. Casanova; Ph. Négrel; C. Innocent; J. Brulhet

2003-01-01

74

A combined U-series, radiocarbon and stable isotope approach for constructing a Pleistocene lake hydrograph: an example from Surprise Valley, California  

NASA Astrophysics Data System (ADS)

Lake records and lake hydrographs provide an integrated record of the hydrologic conditions across a watershed. To provide useful constraints on past changes in climate, robust hydrographs require concordance among multiple geochronologic approaches as well as supporting geochemical and hydrologic evidence. Dating shoreline or near-shore lacustrine carbonates using U-series and radiocarbon methods is one approach for developing the age-elevation constraints to construct lake hydrographs. Geochemical analyses (e.g., stable isotopes, elemental ratios, U-series measurements) of modern waters and sediments, as well as the primary carbonate samples, can be used to assess the potential influence of open-system behavior, detrital Th corrections, or pedogenic overprinting on the calculated ages. Additionally, topographic analyses (e.g., basin pour point, shoreline elevations and sample locations) further constrain the spatial relevance and relationships between sample localities. To evaluate the timing and magnitude of the most recent late Pleistocene lake cycle in Surprise Valley, California, we analyzed 111 sub-samples from 22 laminated shoreline tufa samples using U-series disequilibrium geochronology, and pair these analyses with 15 radiocarbon ages. To further assess the radiocarbon and U-series ages, we measured the stable isotope (?18O and ?13C) and elemental (Sr/Ca) signatures of the tufa samples, and characterized the range of (234U/238U) observed in the modern waters and playas within the watershed. Topographic analysis verified that Lake Surprise is a closed, inward draining basin, and demonstrated lateral correspondence between samples from the four targeted shoreline sets. Multiple lines of evidence revealed that samples from the highest shorelines are likely from older, higher lake cycles and were influenced by variable amounts of open-system exchange or pedogenic overprinting. The measured U concentrations of ~300 to 1200 ng/g, with (238U/232Th) from ~3 to 12, and (230Th/232Th) as low as 1.7, required correction procedures to produce accurate ages. Using the Total Sample Dissolution method on suites of >5 sub-samples, we calculated U-series isochron ages using paired 2-D Rosholt isochrons determined by error-weighted linear least squares regressions. We found concordance between most isochron ages and single sample detrital Th corrected ages. Additionally, Rosholt isochron ((238U/232Th) vs. (230Th/232Th)) intercepts and modern carbonate measurements indicate that the (230Th/232Th) of the detrital Th end-member has remained consistent, at a value of ~1.3. Most samples demonstrated concordance between the U-series ages and radiocarbon ages, but four samples had U-series ages that were on average ~1.35 kyr older than the paired radiocarbon ages. Spanning 10 to 30 ka, this new lake hydrograph places the highest lake level, ~176 m above present-day playa, at >15.2 ka. During the Last Glacial Maximum (19 to 26 ka) Lake Surprise stood at moderate levels, at ~80 m above modern playa. This coupled approach to hydrograph construction demonstrates how age-elevation data from multiple geochronologic methods can be corroborated and interpreted within the context of geochemical and topographic analyses.

Ibarra, D. E.; Weaver, K. L.; Harris, C.; Maher, K.

2013-12-01

75

High-resolution mapping of uranium and other trace elements in recrystallized aragonite calcite speleothems from caves in the Pyrenees (France): Implication for U-series dating  

NASA Astrophysics Data System (ADS)

Aragonite and calcite speleothems were sampled in the cave of Pierre Saint-Martin (Pyrénées-Atlantiques, France). These speleothems contain significant amounts of uranium and strontium, which were measured spatially and chemically by nuclear microprobe analysis. Sr and U distributions are highly varied, with a marked contrast between aragonite and calcite because the aragonite concentrates Sr and U. On the other hand, Zn is preferentially located in calcite and in layers of organic matter trapped in CaCO 3. Sr contents ranged from 440 to 1100 ?g/g in the calcite and 4900 to 18,500 ?g/g in the aragonite. U concentrations show remarkably high values from 11 to 19 ?g/g in the calcite and 89 to 350 ?g/g in the aragonite. These U and Sr concentrations are amongst the highest measured in supergene speleothems deposited by infiltrating meteoric waters. X-ray absorption experiments with synchrotron radiation suggested that uranium was incorporated in its hexavalent oxidation state in both aragonite and calcite. Recrystallization from aragonite into calcite was indicated by micromorphological observations for some of the samples. This recrystallization process may explain the uranium loss in neogenic calcite deposits and consequently the opening of the geochemical system, which can lead to errors in age dating with the U-series dating method. Uranium loss in recrystallized calcite is one of the important aspects to be considered in U-series dating and more generally for U geochemical stability in CaCO 3.

Ortega, Richard; Maire, Richard; Devès, Guillaume; Quinif, Yves

2005-09-01

76

Growth of north-east Atlantic cold-water coral reefs and mounds during the Holocene: A high resolution U-series and 14C chronology  

NASA Astrophysics Data System (ADS)

We investigated the Holocene growth history of the Mingulay Reef Complex, a seascape of inshore cold-water coral reefs off western Scotland, using U-series and radiocarbon dating methods. Both chronologies revealed episodic occurrences of the reef framework-forming scleractinian coral Lophelia pertusa during the late Holocene. Downcore U-series dating revealed unprecedented reef growth rates of up to 12 mm a-1 with a mean rate of 3-4 mm a-1. Our study highlighted a persistent hiatus in coral occurrence from 1.4 ka to modern times despite present day conditions being conducive for coral growth. The growth history of the complex was punctuated at least twice by periods of reduced growth rates: 1.75-2.8 ka, 3.2-3.6 ka and to a lesser extent at 3.8-4 ka and at 4.2 ka. Timing of coral hiatuses and reduced reef growth rates at Mingulay were synchronous with those occurring across the wider northern European region, which suggests a close relationship between these ecosystems and large-scale shifts in palaeoenvironmental regimes associated with changes to the North Atlantic subpolar gyre.

Douarin, Mélanie; Elliot, Mary; Noble, Stephen R.; Sinclair, Daniel; Henry, Lea-Anne; Long, David; Moreton, Steven G.; Murray Roberts, J.

2013-08-01

77

Consequences of differential trace element adsorption at melt-solid interfaces on generating U-series excesses during porous melt flow  

NASA Astrophysics Data System (ADS)

Measurements of U-series secular disequilibrium in lavas offers promising constraints on the rates of melt generation and transport through the mantle and crust. U-series excesses are produced by any mechanism that changes the relative residence time of parent and daughter nuclides. Although the details of U-series melt transport models differ, they all rely on melt-solid partitioning to separate nuclides and this leads to a number of challenges in interpreting observed U-series excesses. It is also not certain how melt-solid partitioning of trace elements determined on a volume or mass proportion basis from laboratory experiments applies to the pore-scale distribution of these trace elements during porous melt flow. Alternatively, the pore-scale distribution of trace elements could be controlled in part by surface-effects, such as adsorption at grain boundaries or grain-boundary partitioning, as inferred from some experiments (e.g. [1-2]). We demonstrate through a simple model of trace element adsorption that surface effects can change the relative residence time of trace elements during porous melt flow. Our approach is to calculate pore-scale, steady-state, melt flow fields in digitized representations of igneous microstructures using a lattice-Boltzmann (LB) method. We then use a Lagrangian random-walk algorithm to calculate individual tracer (atom) trajectories based on the local melt velocity and a stochastic component to model molecular diffusion. Adsorption of tracers is modeled using a Monte-Carlo approach, i.e. tracer trajectories that intersect melt-solid interfaces will "stick" if a random number from a uniform distribution is less than a given probability, p, for adsorption for that specific element. We also allow adsorbed tracers to return to the melt with probability (1- p). Unlike melt-solid partitioning, that controls trace element residence times by the relative mass or volume of solid-phase proportions, our calculations suggest that with adsorption trace element residence times are sensitive to the Peclet (Pe) number (ratio of the product of advection and pore-size to molecular diffusivity) and the geometry and topology of the microstructure. Trace element residence times increase with decreasing Pe as the contribution of random molecular diffusion is maximized and the probability of intersection at melt-solid interfaces is increased. Likewise, trace element residence times increase, at lower Pe, with increased specific (volume normalized) surface area of melt-solid interfaces. Our initial results suggest that surface- effects, such as adsorption, have observable consequences for U-series excesses and might offer a new interpretation of melting and melt transport in the mantle and crust. 1. Hiraga et al. Nature04; 2. Hiraga et al. AM03.

Hersum, T.; Spiegelman, M.; Kelemen, P.

2006-12-01

78

Enhancing in-situ U-series accessory mineral chronometry to constrain pace and processes of magma accumulation, storage, and eruption  

NASA Astrophysics Data System (ADS)

Over the past decade, deciphering absolute crystallization ages at micro-scales through in-situ U-series dating has spearheaded conceptual changes in the understanding of how magmas evolve en route to the surface. U-Th and U-Pb zircon geochronology by secondary ionization mass spectrometry (SIMS) now routinely accesses a continuous age spectrum extending well into the Holocene with ka precision for individual analysis spots ~25 - 40 ?m in diameter. SIMS depth profiling further increases spatial resolution at least tenfold. These developments are epitomized by studies that document multiple generations of zircon growth, predating eruptions by 10's to 100's of ka, as common features in silicic volcanics. Recently, these methods have been enhanced by (1) linking ages to Ti-in-zircon thermometry and trace element or oxygen isotopic fingerprinting; (2) tracking compositional changes with age in accessory minerals sensitive to magma differentiation, such as allanite; and (3) combining U-Th zircon ages with other chronometers, such as (U-Th)/He zircon or 226Ra-230Th-238U plagioclase dating. The emerging picture reveals a wide gamut of processes acting in magma bodies, including piecemeal, compartmentalized magma aggregation, protracted and thermally retrograde crystal storage coupled with magma differentiation, thermal rejuvenation and recycling of crystal mushes and solidified intrusions or magma chamber rinds, and wall rock assimilation. For the future, experimental constraints on accessory mineral-melt partitioning (e.g., Ayers and Luo, 2008: Geochim Cosmochim Acta, v. 72, p. A39) promise to put interpretation of zircon compositions on firmer footing, as is the case for additional accessory mineral saturation calibrations and improved modeling of existing ones (e.g., Harrison et al., 2007: Geology, v. 35, p. 635-638). By the same token, new experimental constraints on U-series element partitioning (e.g., Miller et al., 2007: Am Min, v. 92, p. 1535-1538) should enhance precision and applicability of mineral chronometers. Moreover, analytical advances in high spatial resolution SIMS hold promise for utilizing melt inclusions in zircon as an additional repository for constraining the chemical and thermal evolution of magmas.

Schmitt, A. K.

2008-12-01

79

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

80

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

81

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

NASA Astrophysics Data System (ADS)

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.

Muhs, Daniel R.; Simmons, Kathleen R.; Schumann, R. Randall; Halley, Robert B.

2011-03-01

82

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

83

Biogeochemical responses to late-winter storms in the Sargasso Sea, III—Estimates of export production using 234Th: 238U disequilibria and sediment traps  

NASA Astrophysics Data System (ADS)

Direct measurements of new production and carbon export in the subtropical North Atlantic Ocean appear to be too low when compared to geochemical-based estimates. It has been hypothesized that episodic inputs of new nutrients into surface water via the passage of mesoscale eddies or winter storms may resolve at least some of this discrepancy. Here, we investigated particulate organic carbon (POC), particulate organic nitrogen (PON), and biogenic silica (BSiO 2) export using a combination of water column 234Th: 238U disequilibria and free-floating sediment traps during and immediately following two weather systems encountered in February and March 2004. While these storms resulted in a 2-4-fold increase in mixed layer NO 3 inventories, total chlorophyll a and an increase in diatom biomass, the systems were dominated by generally low 234Th: 238U disequilibria, suggesting limited particle export. Several 234Th models were tested, with only those including non-steady state and vertical upwelling processes able to describe the observed 234Th activities. Although upwelling velocities were not measured directly in this study, the 234Th model suggests reasonable rates of 2.2-3.7 m d -1. Given the uncertainties associated with 234Th derived particle export rates and sediment traps, both were used to provide a range in sinking particle fluxes from the upper ocean during the study. 234Th particle fluxes were determined applying the more commonly used steady state, one-dimensional model with element/ 234Th ratios measured in sediment traps. Export fluxes at 200 m ranged from 1.91±0.20 to 4.92±1.22 mmol C m -2 d -1, 0.25±0.08 to 0.54±0.09 mmol N m -2 d -1, and 0.22±0.04 to 0.50±0.06 mmol Si m -2 d -1. POC export efficiencies (Primary Production/Export) were not significantly different from the annual average or from time periods without storms, although absolute POC fluxes were elevated by 1-11%. This increase was not sufficient, however, to resolve the discrepancy between our observations and geochemical-based estimates of particle export. Comparison of PON export rates with simultaneous measurements of NO 3- uptake derived new production rates suggest that only a fraction, <35%, of new production was exported as particles to deep waters during these events. Measured bSiO 2 export rates were more than a factor of two higher ( p<0.01) than the annual average, with storm events contributing as much as 50% of annual bSiO 2 export in the Sargasso Sea. Furthermore it appears that 65-95% (average 86±14%) of the total POC export measured in this study was due to diatoms. Combined these results suggest that winter storms do not significantly increase POC and PON export to depth. Rather, these storms may play a role in the export of bSiO 2 to deep waters. Given the slower remineralization rates of bSiO 2 relative to POC and PON, this transport may, over time, slowly decrease water column silicate inventories, and further drive the Sargasso Sea towards increasing silica limitation. These storm events may further affect the quality of the POC and PON exported, given the large association of this material with diatoms during these periods.

Maiti, Kanchan; Benitez-Nelson, Claudia R.; Lomas, Michael W.; Krause, Jeffrey W.

2009-06-01

84

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

85

U-series in Fe-U-rich fracture fillings from the oxidised cap of the “Mina Fe” uranium deposit (Spain): implications for processes in a radwaste repository  

Microsoft Academic Search

Within the framework of the ENRESA (Spain) natural analogue programme, the U-ore deposit of “Mina Fe” is being studied as a natural analogue of radioactive spent fuel behaviour. In this context, the knowledge of the role played by fracture minerals as scavengers of certain analogue elements, mainly U, and the establishment of the time scale of the rock-water interaction processes

M. T Crespo; L Pérez del Villar; A. J Quejido; M Sánchez; J. S Cózar; M Fernández-D??az

2003-01-01

86

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

87

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

88

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; Smith, David

2010-06-28

89

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

90

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

91

On the Quality of ENSDF {gamma}-Ray Intensity Data for {gamma}-Ray Spectrometric Determination of Th and U and Their Decay Series Disequilibria, in the Assessment of the Radiation Dose Rate in Luminescence Dating of Sediments  

SciTech Connect

In luminescence dating of sediments, one of the most interesting tools for the determination of the annual radiation dose is Ge {gamma}-ray spectrometry. Indeed, it yields information on both the content of the radioelements K, Th, and U, and on the occurrence - in geological times - of disequilibria in the Th and U decay series. In the present work, two methodological variants of the {gamma}-spectrometric analysis were tested, which largely depend on the quality of the nuclear decay data involved: (1) a parametric calibration of the sediment measurements, and (2) the correction for the heavy spectral interference of the 226Ra 186.2 keV peak by 235U at 185.7 keV. The performance of these methods was examined via the analysis of three Certified Reference Materials, with the introduction of {gamma}-ray intensity data originating from ENSDF. Relevant conclusions were drawn as to the accuracy of the data and their uncertainties quoted.

Corte, Frans de; Vandenberghe, Dimitri; Wispelaere, Antoine de [Institute for Nuclear Sciences, Ghent University, Proeftuinstraat 86, B-9000 Gent (Belgium)

2005-05-24

92

On the Quality of ENSDF ?-Ray Intensity Data for ?-Ray Spectrometric Determination of Th and U and Their Decay Series Disequilibria, in the Assessment of the Radiation Dose Rate in Luminescence Dating of Sediments  

NASA Astrophysics Data System (ADS)

In luminescence dating of sediments, one of the most interesting tools for the determination of the annual radiation dose is Ge ?-ray spectrometry. Indeed, it yields information on both the content of the radioelements K, Th, and U, and on the occurrence — in geological times — of disequilibria in the Th and U decay series. In the present work, two methodological variants of the ?-spectrometric analysis were tested, which largely depend on the quality of the nuclear decay data involved: (1) a parametric calibration of the sediment measurements, and (2) the correction for the heavy spectral interference of the 226Ra 186.2 keV peak by 235U at 185.7 keV. The performance of these methods was examined via the analysis of three Certified Reference Materials, with the introduction of ?-ray intensity data originating from ENSDF. Relevant conclusions were drawn as to the accuracy of the data and their uncertainties quoted.

De Corte, Frans; Vandenberghe, Dimitri; De Wispelaere, Antoine

2005-05-01

93

On the limits of using combined U-series/ESR method to date fossil teeth from two Early Pleistocene archaeological sites of the Orce area (Guadix-Baza basin, Spain)  

NASA Astrophysics Data System (ADS)

The combined U-series/electron spin resonance (ESR) dating method was applied to nine teeth from two Early Pleistocene archaeological sites located in the Orce area (Guadix-Baza Basin, Southern Spain): Fuente Nueva-3 (FN-3) and Barranco León (BL). The combination of biostratigraphy and magnetostratigraphy places both sites between the Olduvai and Jaramillo subchrons (1.78-1.07 Ma). Our results highlight the difficulty of dating such old sites and point out the limits of the combined U-series/ESR dating method based on the US model. We identified several sources of uncertainties that may lead to inaccurate age estimates. Seven samples could not be dated because the dental tissues had (230Th/234U) activity ratios higher than equilibrium, indicating that uranium had probably leached from these tissues. It was however possible to calculate numerical estimates for two of the teeth, both from FN-3. One yielded a Middle Pleistocene age that seems to be strongly underestimated; the other provided an age of 1.19 ± 0.21 Ma, in agreement with data obtained from independent methods. The latter result gives encouragement that there are samples that can be used for routine dating of old sites.

Duval, Mathieu; Falguères, Christophe; Bahain, Jean-Jacques; Grün, Rainer; Shao, Qingfeng; Aubert, Maxime; Dolo, Jean-Michel; Agustí, Jordi; Martínez-Navarro, Bienvenido; Palmqvist, Paul; Toro-Moyano, Isidro

2012-05-01

94

Radioactive Materials Product Stewardship  

E-print Network

...................................................................................................26 Low Level Waste (LLW) Disposal RegulationsRadioactive Materials Product Stewardship ABackground Report for the National Dialogue on Radioactive Materials Product Stewardship Prepared by the: Product Stewardship Institute University

95

Radioactive iodine uptake  

MedlinePLUS

Iodine uptake test; RAIU ... to swallow a liquid or capsule containing radioactive iodine. After a certain period of time (usually 4 ... have: Diarrhea (may decrease absorption of the radioactive iodine) Had recent CT scans using intravenous or oral ...

96

Radioactive Materials License Commitments  

E-print Network

Radioactive Materials License Commitments for The University of Texas at Austin May 2009 July 2009 in the use of radioactive materials. In July 1963, the State of Texas granted The University of Texas at Austin a broad radioactive materials license for research, development and instruction. While this means

97

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

98

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  

Microsoft Academic Search

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

Lewis A. Owena; Jordon Brightb; Robert C. Finkelc; Manoj K. Jaiswald; Darrell S. Kaufmanb; Shannon Mahane; Ulrich Radtkef; Joan S. Schneiderg; Warren Sharph; Ashok K. Singhvid; Claude N. Warreni

99

ORNL radioactive waste operations  

SciTech Connect

Since its beginning in 1943, ORNL has generated large amounts of solid, liquid, and gaseous radioactive waste material as a by-product of the basic research and development work carried out at the laboratory. The waste system at ORNL has been continually modified and updated to keep pace with the changing release requirements for radioactive wastes. Major upgrading projects are currently in progress. The operating record of ORNL waste operation has been excellent over many years. Recent surveillance of radioactivity in the Oak Ridge environs indicates that atmospheric concentrations of radioactivity were not significantly different from other areas in East Tennesseee. Concentrations of radioactivity in the Clinch River and in fish collected from the river were less than 4% of the permissible concentration and intake guides for individuals in the offsite environment. While some radioactivity was released to the environment from plant operations, the concentrations in all of the media sampled were well below established standards.

Sease, J.D.; King, E.M.; Coobs, J.H.; Row, T.H.

1982-01-01

100

Formation of Pedogenic Carbonates in the Semi-arid Rio Grande Valley: Insights from Carbon, Major elements, and U-series isotopes in Natural and Agricultural Soils of Southern New Mexico and Western Texas  

NASA Astrophysics Data System (ADS)

Accumulation of pedogenic carbonates in arid and semi-arid soils affects soil porosity, water infiltration, and global carbon cycle. We investigate formation rates of these carbonates under different land uses in the semi-arid Rio Grande valley using mineralogy, concentrations of major elements (including C), and U-series isotopes. Our study sites include one alfalfa farm (Alfalfa) at El Paso, TX under frequent irrigation with saline water from the Rio Grande River, and one natural shrub field under natural rainfall conditions at the USDA Jornada Experimental Range (Jornada) in NM. Major minerals observed at Alfalfa and Jornada are calcite, quartz, and feldspars. Calcite/quartz ratios increase upward in the profile at Alfalfa, suggesting formation of carbonates in shallow soils. Consistently, total carbon increases toward the soil surface at Alfalfa, contributed by both soil organic carbon and soil inorganic carbon (pedogenic carbonates). Concentrations of major elements (e.g Ca, Mg, and Sr) also increase toward the surface at Alfalfa, suggesting surface addition. Alternating trends of enrichment and depletion are observed throughout the soil profiles. In contrast, calcite/quartz ratios decrease toward the surface at Jornada, indicative of leaching at shallow soils and redeposition of calcite at depth. This is in agreement with high soil inorganic carbon contents measured at depth. At Jornada however, the Ca, Mg and Sr concentrations decrease toward the surface, showing typical depletion profiles. (234U/238U) activity ratios in bulk soils increase upward at Alfalfa while at Jornada (234U/238U) ratios decrease toward the surface. (234U/238U) ratios at Alfalfa suggest surface addition of U onto shallow soils probably from irrigation water, which is known to have high (234U/238U) ratios. Jornada shows preferential loss of 234U upward. U-series disequilibrium in pedogenic carbonates enables calculation of their formation ages. At Alfalfa, carbonate ages range from 2.2 × 1.7 ka to 15× 17 ka. Furthermore, these ages decrease with depth suggesting faster carbonate precipitation downward. These ages most likely represent mixing of natural old carbonates and recently formed carbonates due to frequent irrigation. The carbonates at Jornada however, are much older ranging from 14.5 × 6.8 ka to 117 × 26 ka. Older carbonates at Jornada could be due to slower water infiltration from limited rainfall, Ca and insufficient dissolved inorganic carbon (DIC) thus slow formation of pedogenic carbonates. Our findings show differing carbonate formation rates in arid zones. In agricultural settings, carbonates are precipitated faster due to loading of Ca and DIC from flood irrigation. Soil organic carbon is also an important C reservoir, releasing soil CO2 to form carbonates. In natural settings however, relatively older carbonate suggest slower precipitation kinetics.

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

2013-12-01

101

New heavy proton radioactivities  

SciTech Connect

The new proton radioactivities {sup 165,166,167}Ir, {sup 171}Au, and {sup 185}Bi have been observed, extending our knowledge of proton radioactivity up to and beyond the Z=82 closed shell. For Z=77 and 79, the transitions can be explained using simple shell-model arguments. The case of {sup 185}Bi represents the first example of proton radioactivity from an intruder state.

Davids, C.N. [Argonne National Lab., IL (United States); Woods, P.J. [Edinburgh Univ. (United Kingdom); Batchelder, J.C. [Louisiana State Univ., Baton Rouge, LA (United States)] [and others

1995-08-01

102

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

103

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.

104

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

105

A Remote Radioactivity Experiment  

ERIC Educational Resources Information Center

Imagine a high school with very few experimental resources and limited budgets that prevent the purchase of even basic laboratory equipment. For example, many high schools do not have the means of experimentally studying radioactivity because they lack Geiger counters and/or good radioactive sources. This was the case at the first high school one…

Jona, Kemi; Vondracek, Mark

2013-01-01

106

Radioactive Decay Events Model  

NSDL National Science Digital Library

The EJS Radioactive Decay Events Model simulates the decay of a radioactive sample using discrete random events. It displays the number of events (radioactive decays) as a function of time in a given time interval. You can change the initial number of nuclei, the decay constant and the time interval for the event distribution. The Radioactive Decay Events model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ms_explicit_RadioactiveDecayEvents.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-01-23

107

A Remote Radioactivity Experiment  

NASA Astrophysics Data System (ADS)

Imagine a high school with very few experimental resources and limited budgets that prevent the purchase of even basic laboratory equipment. For example, many high schools do not have the means of experimentally studying radioactivity because they lack Geiger counters and/or good radioactive sources. This was the case at the first high school one of us (MV) worked at, and after talking with numerous colleagues we know this is still the case at many schools. What options are there then for physics teachers to allow their students to experimentally investigate certain characteristics of radioactivity, such as how distance affects the intensity of radiation coming from a radioactive source? There are computer simulations that can be run, or perhaps the teacher has a light sensor and tries to make an analogy between the intensity of light from a light bulb and the intensity of radiation from a radioactive source based on geometric arguments to get an inverse-square law. But for many there is no direct experimental option if one does not possess a Geiger counter and good radioactive sample. It is for that teacher and class of students that an online, remote radioactivity experiment was created.

Jona, Kemi; Vondracek, Mark

2013-01-01

108

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 scintillation vials must be collected separately. 5. Any "mixed waste" must be cleared with the RSO and labeled

Jia, Songtao

109

Understanding radioactive waste  

SciTech Connect

This document contains information on all aspects of radioactive wastes. Facts are presented about radioactive wastes simply, clearly and in an unbiased manner which makes the information readily accessible to the interested public. The contents are as follows: questions and concerns about wastes; atoms and chemistry; radioactivity; kinds of radiation; biological effects of radiation; radiation standards and protection; fission and fission products; the Manhattan Project; defense and development; uses of isotopes and radiation; classification of wastes; spent fuels from nuclear reactors; storage of spent fuel; reprocessing, recycling, and resources; uranium mill tailings; low-level wastes; transportation; methods of handling high-level nuclear wastes; project salt vault; multiple barrier approach; research on waste isolation; legal requiremnts; the national waste management program; societal aspects of radioactive wastes; perspectives; glossary; appendix A (scientific American articles); appendix B (reference material on wastes). (ATT)

Murray, R.L.

1981-12-01

110

Radioactivity in Spanish spas.  

PubMed

There are large number of spas in Spain and there is a lack of data concerning their radioactivity. The levels of radioactivity in a wide sample of Spanish spas were measured with special attention being paid to the radon and radium concentrations in the water, and to radon concentration in the indoor air of the spas. This study is primarily concerned with the radioactivity of the spas of one region in Spain--Cantabria--and particularly one spa where we measured radon levels in water as high as 824 Bq/l and over 5000 Bq/m3 in the air of the rooms. We then considered a wider sample including virtually all of the radioactive spas in the country. The results indicate that a fairly large number of spas have radon levels in water that are moderately high and they are used for the treatment of diseases without radiation protection measures for patients or staff at the spas. PMID:7899856

Soto, J; Fernández, P L; Quindós, L S; Gómez-Arozamena, J

1995-01-27

111

Commentary on Residual Radioactivity.  

National Technical Information Service (NTIS)

Upon the recommendation of its Radiation Advisory Committee, the Science Advisory Board urges the Agency to develop Federal radiation protection guidance specifically for removal or remediation actions for radioactive substances at various locations, incl...

1992-01-01

112

Environmental Radioactivity Intercomparison, 1993.  

National Technical Information Service (NTIS)

The results of the fourth in a series of environmental radioactivity intercomparison exercises is detailed. In general, the results are satisfactory and a comparable performance to the previous exercises has been achieved. In particular there has been an ...

S. M. Jerome, E. M. E. Perkin, S. E. M. Lucas, M. J. Woods, J. C. J. Dean

1994-01-01

113

Environmental Radioactivity Intercomparison, 1992.  

National Technical Information Service (NTIS)

Following on from two previous environmental radioactivity measurement intercomparison exercises, NPL conducted a third intercomparison of this sort in 1992. The results from the first two exercises were generally satisfactory, although the problem of cas...

S. M. Jerome, M. J. Woods, S. E. M. Lucas, A. C. Hooley

1993-01-01

114

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

115

Container for radioactive materials  

DOEpatents

A container for housing a plurality of canister assemblies containing radioactive material and disposed in a longitudinally spaced relation within a carrier to form a payload package concentrically mounted within the container. The payload package includes a spacer for each canister assembly, said spacer comprising a base member longitudinally spacing adjacent canister assemblies from each other and a sleeve surrounding the associated canister assembly for centering the same and conducting heat from the radioactive material in a desired flow path.

Fields, Stanley R. (Richland, WA)

1985-01-01

116

Kinetics of Radioactive Decay  

Microsoft Academic Search

\\u000a Radioactivity also known as radioactive decay, nuclear transformation, and nuclear disintegration is a spontaneous process\\u000a by which an unstable parent nucleus emits a particle or electromagnetic radiation and transforms into a more stable daughter\\u000a nucleus that may or may not be stable. An unstable daughter nucleus will decay further in a decay series until a stable nuclear\\u000a configuration is reached.

Ervin B. Podgoršak

117

Radioactive gold ring dermatitis  

SciTech Connect

A superficial squamous cell carcinoma developed in a woman who wore a radioactive gold ring for more than 30 years. Only part of the ring was radioactive. Radiation dose measurements indicated that the dose to basal skin layer was 2.4 Gy (240 rad) per week. If it is assumed that the woman continually wore her wedding ring for 37 years since purchase, she would have received a maximum dose of approximately 4600 Gy.

Miller, R.A.; Aldrich, J.E. (Dalhousie Univ., Halifax, Nova Scotia (Canada))

1990-08-01

118

Radioactive Decay Calculator  

NSDL National Science Digital Library

This online calculator computes radioactive decay, timed decay, and timed solid disposal for a databank containing 116 isotopes. It also features University of British Columbia disposal limits and a unit converter and date/time calculators. These tools calculate the half-life for selected isotopes; radioactive decay final activity, given the initial activity and decay time; the decay time, given the initial and final activities; and the decay time, given the mass of a solid and the initial activity.

Enns, Alan

119

Detailed U-series study in MORB glasses from ~8°48 S, ~9°33 S MAR and adjacent seamounts: Spatial and temporal constraints on melt mixing processes and implications for scales of source variation  

NASA Astrophysics Data System (ADS)

We present new U-series (238U-230Th-^{226}Ra) data in young glasses from the South Mid Atlantic Ridge to the south of the Ascension FZ. This part of the spreading axis is relatively slow spreading (36 mm/yr) and it shows large variations in axial depth, crustal thickness and samples melts with significant variations in major and trace element geochemistry as well as Sr, Nd, and Pb isotopic composition. From north to south, the ridge has been divided into segments labeled A1 through to A4. The A3 segment is characterized by excess melting causing along-axis transportation of enriched melts northwards (towards A2), a process that is associated with rift propagation and isotopic and geochemical gradients. Here we focus on lavas from two geographically confined areas within segments A2 and A3, in addition to lavas from the off-axis Grattan seamount (A3), all of which are young and recently subjected to detailed ROV-based mapping and sampling. The A2 lavas are mostly N-MORB, but also include more depleted compositions. In the U-Th equiline diagram, the A2 lavas define two arrays that run oblique to each other: a near horizontal array with (230Th)/(232Th) ~1.15 consisted of the most depleted lavas, and a relatively steep array with (238U)/(232Th) ~0.94 formed by the N-MORB lavas. The steep array points towards A3 segment lavas that are offset towards lower (230Th)/(232Th). Similarly, the A3 lavas that are typical E-MORB, define a flat array at lower (230Th)/(232Th) of ~1.00-1.03, as well as, a steep array that forms the extension of the steep A2 array. The Grattan seamount lavas plot on this steep array with (230Th)/(232Th) ~1.05. The different arrays are interpreted as mixing lines, yet, the scale over which mixing occurs vary from intra- to inter-segment scale. The relatively flat arrays defined within A2 and A3 are likely formed by mixing of melts that are produced from the same local package of compositionally heterogeneous mantle rock. None of these flat arrays are likely to have formed by crustal interaction (involving old crust), because there is no systematic variation of chemical composition with (230Th)/(238U), i.e., proximity to the equiline. The steep inter-segment (A2-A3) array is formed by endmembers produced wide apart, and that mix over long distances (~100 km). Based on the well-defined inter-segment U-Th mixing arrays and preliminary Ra data, the melt transport process cannot have taken more than some thousand years. Further radium data on these lavas will help to better constrain the timing of these mixing process. Finally, the gradational shift in depletion level (Th and Th/U) observed at local scale within both segments occurs over very short distances (A2: ~1 km, A3: <0.5 km), suggesting the underlying mantle to be heterogeneous at similar length scales.

Kokfelt, T. F.; Hauff, F.; Haase, K.; Devey, C.

2006-12-01

120

Radioactive Decay Distribution Model  

NSDL National Science Digital Library

The EJS Radioactive Decay Distribution Model simulates the decay of a radioactive sample using discrete random events. It displays the distribution of the number of events (radioactive decays) in a fixed time interval. If each event is assumed to occur independently and spontaneously with a constant probability, the resulting distribution if the Poisson distribution. You can change the initial number of nuclei, the decay constant and the time interval for the event distribution. The Radioactive Decay Distribution model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ms_explicit_RadioactiveDecayDistribution.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-01-23

121

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

122

Container for radioactive materials  

DOEpatents

A container is claimed for housing a plurality of canister assemblies containing radioactive material. The several canister assemblies are stacked in a longitudinally spaced relation within a carrier to form a payload concentrically mounted within the container. The payload package includes a spacer for each canister assembly, said spacer comprising a base member longitudinally spacing adjacent canister assemblies from each other and sleeve surrounding the associated canister assembly for centering the same and conducting heat from the radioactive material in a desired flow path. 7 figures.

Fields, S.R.

1984-05-30

123

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

SciTech Connect

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 {sup 238}U 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 a 50-km transect in the direction of the prevailing monsoonal winds in the region. The study was performed by means of unconventional 'sticky vinyl' passive dust collectors, occasionally supported by high-volume air filter samplers. The data from the flux measurements show an inverse square to inverse cubic dependence, and the dry deposition exhibits an inverse square dependence, of radionuclide load vs. distance. The pit has been the predominant contributor of long-lived U series radionuclides to the environment within the radius of several kilometers from the operations. An aerial dispersion computer code (LUCIFER), based on a Gaussian plume model, was developed for the project. Experimental data were used as the code input data. Good agreement between the measured data and the normalized computed results was obtained.

Pettersson, H.B.; Koperski, J. (Lund Univ. Teaching Hospital (Sweden))

1991-05-01

124

Residual radioactivity criteria  

SciTech Connect

This paper provides an overview of current and future decommissioning standards applicable in the United States. The standards promulgated by both the US Department of Energy (DOE) and the US Nuclear Regulatory Commission (NRC), as well as standards proposed by the American National Standards Institute, are presented. A summary is presented of the recent NRC actions to produce revised residual radioactivity criteria.

Kennedy, W.E. Jr.

1992-06-01

125

Table of radioactive isotopes  

Microsoft Academic Search

This book provides a comprehensive and critical evaluation of the nuclear and atomic properties of radioactive isotopes. Detailed radiation data for about 2000 of the 2755 known nuclides are presented in this up-to-date and concise book. The main section is organized by mass number (A), with entries for a given A derived from and referenced to the most recent corresponding

Edgardo Browne; Richard B. Firestone; V. S. Shirley

1986-01-01

126

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

127

Internal and External Radioactive Backgrounds  

E-print Network

Chapter 3 Internal and External Radioactive Backgrounds New physics is often discovered by pushing of the low energies involved. There are many radioactive elements that have decays at lower energies which;Chapter 3: Internal and External Radioactive Backgrounds 104 the rate of background. High-energy neutrino

128

Hazardous and radioactive substances in  

E-print Network

Hazardous and radioactive substances in danisH Marine Waters Ingela Dahllöf & Jesper H. Andersen University #12;#12;Hazardous and radioactive substances in danisH Marine Waters #12;#12;Hazardous and radioactive substances in danisH Marine Waters Ingela Dahllöf and Jesper H. Andersen Editors Agency

129

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

Microsoft Academic Search

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

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

2003-01-01

130

Radioactive ion detector  

DOEpatents

Apparatus for detecting the presence, in aqueous media, of substances which emit alpha and/or beta radiation and determining the oxidation state of these radioactive substances, that is, whether they are in cationic or anionic form. In one embodiment, a sensor assembly has two elements, one comprised of an ion-exchange material which binds cations and the other comprised of an ion-exchange material which binds anions. Each ion-exchange element is further comprised of a scintillation plastic and a photocurrent generator. When a radioactive substance to which the sensor is exposed binds to either element and emits alpha or beta particles, photons produced in the scintillation plastic illuminate the photocurrent generator of that element. Sensing apparatus senses generator output and thereby indicates whether cationic species or anionic species or both are present and also provides an indication of species quantity.

Bower, Kenneth E. (Los Alamos, NM); Weeks, Donald R. (Saratoga, CA)

1997-01-01

131

Radioactive ion detector  

DOEpatents

Apparatus for detecting the presence, in aqueous media, of substances which emit alpha and/or beta radiation and determining the oxidation state of these radioactive substances, that is, whether they are in cationic or anionic form. In one embodiment, a sensor assembly has two elements, one comprised of an ion-exchange material which binds cations and the other comprised of an ion-exchange material which binds anions. Each ion-exchange element is further comprised of a scintillation plastic and a photocurrent generator. When a radioactive substance to which the sensor is exposed binds to either element and emits alpha or beta particles, photons produced in the scintillation plastic illuminate the photocurrent generator of that element. Sensing apparatus senses generator output and thereby indicates whether cationic species or anionic species or both are present and also provides an indication of species quantity. 2 figs.

Bower, K.E.; Weeks, D.R.

1997-08-12

132

MARE: Mars Radioactivity Experiment  

NASA Astrophysics Data System (ADS)

MARE is an experiment for the measurement of the beta and gamma radioactivity in space and in the Martian soil, both at the surface and in the subsurface. This will be accomplished by means of a dosimeter and a spectrometer. The radiation dose rate to which crews will be exposed is one of the hazards that has to be quantified before the human exploration of Mars may begin. Data for evaluating radioactivity levels at Martian surface are of great interest for environmental studies related to life in general. The dosimeter will be able to measure the beta and gamma radiation dose received, with a responsivity which is very close to that of a living organism. The dosimeter is based on thermo-luminescence pills which emit an optical signal proportional to the absorbed dose when heated. Radioactive elements ((40) K, (235) U, (238) U and (232) Th) can be used as a mean of tracing the evolution of a terrestrial planet. These radioactive elements are the source of the internal heat, which drives convection in the mantle. They have been redistributed in this process and they are now concentrated in the crust where they are accessible for study. Their different behavior during the fractionation process can be used as a mean to investigate the geochemical characteristic of Mars. The spectrometer, a scintillation radiation absorber system for single event counting, is capable of detecting gamma photons with energies between 200 KeV and 10 MeV. The detected events will be processed in such a way to allow the recognition of the spectral signature of different decay processes, and thus the identification and the measurement of the concentrations of different radionuclides in the Martian soil.

di Lellis, A. M.; Capria, M. T.; Espinasse, S.; Magni, G.; Orosei, R.; Piccioni, G.; Federico, C.; Minelli, G.; Pauselli, C.; Scarpa, G.

1999-09-01

133

Radioactive waste storage issues  

SciTech Connect

In the United States we generate greater than 500 million tons of toxic waste per year which pose a threat to human health and the environment. Some of the most toxic of these wastes are those that are radioactively contaminated. This thesis explores the need for permanent disposal facilities to isolate radioactive waste materials that are being stored temporarily, and therefore potentially unsafely, at generating facilities. Because of current controversies involving the interstate transfer of toxic waste, more states are restricting the flow of wastes into - their borders with the resultant outcome of requiring the management (storage and disposal) of wastes generated solely within a state`s boundary to remain there. The purpose of this project is to study nuclear waste storage issues and public perceptions of this important matter. Temporary storage at generating facilities is a cause for safety concerns and underscores, the need for the opening of permanent disposal sites. Political controversies and public concern are forcing states to look within their own borders to find solutions to this difficult problem. Permanent disposal or retrievable storage for radioactive waste may become a necessity in the near future in Colorado. Suitable areas that could support - a nuclear storage/disposal site need to be explored to make certain the health, safety and environment of our citizens now, and that of future generations, will be protected.

Kunz, D.E.

1994-08-15

134

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

135

Radioactive and magnetic investigations  

NASA Technical Reports Server (NTRS)

Age and growth pattern determination of manganese nodules were explored. Two methods are discussed: (1) measurement of the presence of radioactive iodine isotopes; which is effective only up to 3.105 years, and (2) measurements of magnetism. The growth rates of three nodules were determined. The surface of the nodule was recent, and the overall age of the nodule could be determined with accuracy of better than 30%. Measurement of paleomagnetic effect was attempted to determine wider age ranges, however, the measured sign changes could not be interpreted as paleomagnetic reversals.

Heye, D.; Beiersdorf, H.

1979-01-01

136

Radioactive Ion Sources  

E-print Network

This chapter provides an overview of the basic requirements for ion sources designed and operated in radioactive ion beam facilities. The facilities where these sources are operated exploit the isotope separation online (ISOL) technique, in which a target is combined with an ion source to maximize the secondary beam intensity and chemical element selectivity. Three main classes of sources are operated, namely surface-type ion sources, arc discharge-type ion sources, and finally radio-frequency-heated plasma-type ion sources.

Stora, T

2014-01-01

137

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

138

RADIOACTIVE MATERIALS SENSORS  

SciTech Connect

Providing technical means to detect, prevent, and reverse the threat of potential illicit use of radiological or nuclear materials is among the greatest challenges facing contemporary science and technology. In this short article, we provide brief description and overview of the state-of-the-art in sensor development for the detection of radioactive materials, as well as an identification of the technical needs and challenges faced by the detection community. We begin with a discussion of gamma-ray and neutron detectors and spectrometers, followed by a description of imaging sensors, active interrogation, and materials development, before closing with a brief discussion of the unique challenges posed in fielding sensor systems.

Mayo, Robert M.; Stephens, Daniel L.

2009-09-15

139

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

140

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

141

Tracking Radioactive Sources in Commerce  

E-print Network

Area Network­mobile phone, ethernet and/or satellite � security--encryption, short broadcast bursts of specific packages © Missing sealed radioactive sources pose a significant environmental and health risk of radioactive consumer products � Use in terrorist activities Effective package tracking system can prevent loss

142

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

143

10 CFR Appendix E to Part 835 - Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting...  

Code of Federal Regulations, 2013 CFR

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2013-01-01

144

10 CFR Appendix E to Part 835 - Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting...  

Code of Federal Regulations, 2010 CFR

... false Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting and Labeling Requirements...Part 835—Values for Establishing Sealed Radioactive Source Accountability and Radioactive...

2010-01-01

145

10 CFR Appendix E to Part 835 - Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting...  

Code of Federal Regulations, 2012 CFR

... false Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting and Labeling Requirements...Part 835—Values for Establishing Sealed Radioactive Source Accountability and Radioactive...

2012-01-01

146

10 CFR Appendix E to Part 835 - Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting...  

... false Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting and Labeling Requirements...Part 835—Values for Establishing Sealed Radioactive Source Accountability and Radioactive...

2014-01-01

147

10 CFR Appendix E to Part 835 - Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting...  

Code of Federal Regulations, 2011 CFR

... false Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting and Labeling Requirements...Part 835—Values for Establishing Sealed Radioactive Source Accountability and Radioactive...

2011-01-01

148

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

149

10 CFR 39.47 - Radioactive markers.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Radioactive markers. 39.47 Section 39.47 Energy NUCLEAR...LOGGING Equipment § 39.47 Radioactive markers. The licensee may use radioactive markers in wells only if the individual...

2010-01-01

150

49 CFR 172.556 - RADIOACTIVE placard.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false RADIOACTIVE placard. 172.556 Section 172...SECURITY PLANS Placarding § 172.556 RADIOACTIVE placard. (a) Except for size and color, the RADIOACTIVE placard must be as follows:...

2010-10-01

151

10 CFR 39.47 - Radioactive markers.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Radioactive markers. 39.47 Section 39.47...WELL LOGGING Equipment § 39.47 Radioactive markers. The licensee may use radioactive markers in wells only if the individual...

2012-01-01

152

10 CFR 39.47 - Radioactive markers.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Radioactive markers. 39.47 Section 39.47...WELL LOGGING Equipment § 39.47 Radioactive markers. The licensee may use radioactive markers in wells only if the individual...

2011-01-01

153

46 CFR 147.100 - Radioactive materials.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 false Radioactive materials. 147.100 Section 147.100...Requirements for Particular Materials § 147.100 Radioactive materials. (a) Radioactive materials must not be brought on...

2010-10-01

154

49 CFR 172.556 - RADIOACTIVE placard.  

Code of Federal Regulations, 2012 CFR

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2012-10-01

155

46 CFR 147.100 - Radioactive materials.  

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2014-10-01

156

49 CFR 172.556 - RADIOACTIVE placard.  

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2014-10-01

157

46 CFR 147.100 - Radioactive materials.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 2011-10-01 false Radioactive materials. 147.100 Section 147.100...Requirements for Particular Materials § 147.100 Radioactive materials. (a) Radioactive materials must not be brought on...

2011-10-01

158

10 CFR 39.47 - Radioactive markers.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Radioactive markers. 39.47 Section 39.47...WELL LOGGING Equipment § 39.47 Radioactive markers. The licensee may use radioactive markers in wells only if the individual...

2013-01-01

159

46 CFR 147.100 - Radioactive materials.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 false Radioactive materials. 147.100 Section 147.100...Requirements for Particular Materials § 147.100 Radioactive materials. (a) Radioactive materials must not be brought on...

2013-10-01

160

49 CFR 172.556 - RADIOACTIVE placard.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false RADIOACTIVE placard. 172.556 Section 172...SECURITY PLANS Placarding § 172.556 RADIOACTIVE placard. (a) Except for size and color, the RADIOACTIVE placard must be as follows:...

2013-10-01

161

46 CFR 147.100 - Radioactive materials.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 2012-10-01 false Radioactive materials. 147.100 Section 147.100...Requirements for Particular Materials § 147.100 Radioactive materials. (a) Radioactive materials must not be brought on...

2012-10-01

162

49 CFR 172.556 - RADIOACTIVE placard.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false RADIOACTIVE placard. 172.556 Section 172...SECURITY PLANS Placarding § 172.556 RADIOACTIVE placard. (a) Except for size and color, the RADIOACTIVE placard must be as follows:...

2011-10-01

163

10 CFR 39.47 - Radioactive markers.  

...2014-01-01 2014-01-01 false Radioactive markers. 39.47 Section 39.47...WELL LOGGING Equipment § 39.47 Radioactive markers. The licensee may use radioactive markers in wells only if the individual...

2014-01-01

164

Radioactive Materials Manual Scope and Applicability  

E-print Network

Radioactive Materials Manual Scope and Applicability Procedures and information in this manual material. Radioactive material covered includes all sealed and unsealed sources. Sealed sources of radioactive material contained within machinery such as liquid scintillation counters, gas chromatographs

Rhoads, James

165

How Does Radioactive Decay Work?  

NSDL National Science Digital Library

This teacher's guide with exercises is intended to help teach the topics of radioactive decay and its use to determine age. It identifies four main concepts that students are likely to struggle with: spontaneity (randomness) of radioactive decay; the importance of isotopes; the concept of half-life; and how to choose which system of isotopes to use to determine age. The guide presents suggestions on how to make these ideas more understandable, and provides three exercises that can be used to demonstrate radioactive decay. Links to additional materials and information are embedded in the resource.

Wenner, Jennifer M.

2010-11-17

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

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

169

Disposal of low-level radioactive wastes  

Microsoft Academic Search

The generation of low-level radioactive waste is a natural consequence of the societal uses of radioactive materials. These uses include the application of radioactive materials to the diagnosis and treatment of human disease and to research into the causes of human disease and their prevention. Currently, low level radioactive wastes are disposed of in one of three shallow land-burial disposal

W HENDEE

1986-01-01

170

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

171

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

172

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

E-print Network

options for mixed waste and the University's storage capacity for this material is limited. CarefullyRSSC RADIOACTIVE WASTE DISPOSAL 08/2011 7-1 CHAPTER 7 RADIOACTIVE WASTE DISPOSAL PAGE I. Radioactive Waste Disposal

Slatton, Clint

173

Radioactive Ion Beams and Radiopharmaceuticals  

NASA Astrophysics Data System (ADS)

Experiments performed at radioactive ion beam facilities shed new light on nuclear physics and nuclear structure, as well as nuclear astrophysics, materials science and medical science. The many existing facilities, as well as the new generation of facilities being built and those proposed for the future, are a testament to the high interest in this rapidly expanding field. The opportunities inherent in radioactive beam facilities have enabled the search for radioisotopes suitable for medical diagnosis or therapy. In this article, an overview of the production techniques and the current status of RIB facilities and proposals will be presented. In addition, accelerator-generated radiopharmaceuticals will be reviewed.

Laxdal, R. E.; Morton, A. C.; Schaffer, P.

2014-02-01

174

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

175

Radioactive dating of the elements  

NASA Technical Reports Server (NTRS)

The extent to which an accurate determination of the age of the Galaxy, and thus a lower bound on the age of the universe, can be obtained from radioactive dating is discussed. Emphasis is given to the use of the long-lived radioactive nuclei Re-187, Th-232, U-238, and U-235. The nature of the production sites of these and other potential Galactic chronometers is examined along with their production ratios. Age determinations from models of nucleocosmochronology are reviewed and compared with age determination from stellar sources and age constraints form cosmological considerations.

Cowan, John J.; Thielemann, Friedrich-Karl; Truran, James W.

1991-01-01

176

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research  

E-print Network

's personal copy Internal tides and sediment dynamics in the deep sea-- Evidence from radioactive 234 Th/238 U-lived (half-life: 24.1 d) particulate-matter tracer 234 Th relative to its conservative (non detected. `Fossil' disequilibria are defined by clearly detectable 234 Th/238 U disequilibria (total 234 Th

Nycander, Jonas

177

METHOD OF PURIFYING RADIOACTIVE WATER  

Microsoft Academic Search

The utilization of lithothamnium calcareum as an ion exchanger for the ; decontamination of radioactive water is described. In order to retain cobalt and ; strontium the ion exchanger is mixed with calcium silicate or borate; ; alternatively sodium phosphate is added to the water prior to the purification ; process. (NPO)

D. Acfi; M. Schmitt; M. Neveu

1959-01-01

178

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

179

Radioactive iodine labeled phenolic amines  

SciTech Connect

The invention is accomplished by the formation at the site of use of the radioactive amine of the invention which is then injected immediately into the mammal for diagnostic purposes. The compounds of the invention are as follows: 1-HO,2-(R1-N(-R2)-(H2C)N-N(-R3)-H2C-);4-I,6-R4-BENZENE In the above compound, R/sub 1/, R/sub 2/, R/sub 3/ and R/sub 4/ are independently any straight or branched alkyl of between 1 and about 10 carbons; n may be between 1 and about 20. In the invention, the radio labeling of the invention compound is accomplished immediately prior to use of the radio labeled material. The compounds of the invention when boiled for about 15 minutes with iodine-123, a radioactive material, undergo a substitution of radioactive for non-radioactive iodine such that the compound becomes labeled and suitable for use. The compound itself, prior to radio labeling, is storage stable.

Blau, M.; Kung, H.F.; Tramposch, K.M.

1984-02-07

180

Radioactive waste: Politics and technology  

SciTech Connect

This book presents an analysis of the divergent strategies used to forge radioactive waste policies in great Britain, Germany, and Sweden. Some basic knowledge of nuclear technology and its public policy development is needed. The book points out that developing institutional frameworks that permit agreement and consent is the principal challenge of radwaste management and places the problem of consent in an institutional framework.

Berkhout, F.

1995-08-01

181

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

182

Environmental Geochemistry of Radioactive Contamination  

Microsoft Academic Search

Psychometric studies of public perception of risk have shown that dangers associated with radioactive contamination are considered the most dreaded and among the least understood hazards (Slovic, 1987). Fear of the risks associated with nuclear power and associated contamination has had important effects on policy and commercial decisions in the last few decades. In the US, no new nuclear power

M. D. Siegel; C. R. Bryan

2003-01-01

183

Radioactive Au for potential radiotherapeutic application .  

E-print Network

??Radioactive gold-198/199 can be used in therapeutic radiopharmaceutical agents to combat cancer. In this thesis, two projects involving the development of radioactive gold-198/199 are described.… (more)

Kan, Para, 1980-

2010-01-01

184

The Radioactive Beam Program at Argonne  

E-print Network

In this talk I will present selected topics of the ongoing radioactive beam program at Argonne and discuss the capabilities of the CARIBU radioactive ion production facility as well as plans for construction of a novel superconducting solenoid spectrometer.

B. B. Back

2006-06-06

185

National survey on the natural radioactivity and 222Rn exhalation rate of building materials in The Netherlands.  

PubMed

The present study reports on results of a nation-wide survey on the natural radioactivity concentrations and Rn exhalation rates of the prevailing building materials in the Netherlands. In total 100 samples were taken and analyzed for the activity concentrations of Ra, Ra, Th, and K and for their Rn exhalation rate. The sampled materials consisted of gypsum products, aerated concrete, sand-lime and clay bricks, mortars and concrete, representing about 95% of the stony building materials used in the construction of Dutch homes. The laboratory analyses were performed according to two well-documented standard procedures, the interlaboratory reproducibility of which is found to be within 5% on average. The highest radionuclide concentrations were found in a porous inner wall brick to which fly ash was added. The second highest were clay bricks with average Ra and Ra levels around 40 Bq kg. Concrete and mortar show the highest exhalation rates with a fairly broad range of 1 to 13 microBq (kg s). Low natural radioactivity levels are associated with either natural gypsum (products) or gypsum from flue gas desulphurization units, and low exhalation rates with clay bricks. To evaluate the radiological impact the radioactivity concentrations in each sample were combined into a so-called dose factor, representing the absorbed dose rate in a room with a floor, walls and ceiling of 20 cm of the material in question. For that purpose, calculations with the computer codes MCNP, Marmer and MicroShield on the specific absorbed dose rates were incorporated in the paper. The results of these codes corresponded within 6% and average values were calculated at 0.90, 1.10, and 0.080 nGy h per Bq kg for the U series, the Th series, and K, respectively. Model calculations on the external dose rate, based on the incidence of the various building materials in 1,336 living rooms, are in accordance with measured data. PMID:16891895

de Jong, P; van Dijk, W; van der Graaf, E R; de Groot, T J H

2006-09-01

186

Radioactivity in Food and the Environment, 2006  

E-print Network

................................................................................................................................27 2. Nuclear fuel production and reprocessing ................................................................................................................22 1.2.1 Radioactive waste disposal from nuclear sites

187

49 CFR 175.705 - Radioactive contamination.  

...2014-10-01 2014-10-01 false Radioactive contamination. 175.705 Section...Classification of Material § 175.705 Radioactive contamination. (a) A carrier...contact by any person with Class 7 (radioactive) materials that may have been...

2014-10-01

188

Life cycle management of radioactive materials packaging  

Microsoft Academic Search

The objective of life cycle management of radioactive materials packaging is to ensure the safety functions (i.e. containment of radioactivity, protection against radiation, and criticality safety for fissile contents) during the entire life cycle of the packaging in storage, transportation and disposal. A framework has been developed for life cycle management regarding type B radioactive and fissile materials packaging, drawing

Y. Liu; S. Bellamy; J. Shuler

2007-01-01

189

Natural radioactivity in groundwater – a review  

Microsoft Academic Search

The issue of natural radioactivity in groundwater is reviewed, with emphasis on those radioisotopes which contribute in a significant way to the overall effective dose received by members of the public due to the intake of drinking water originating from groundwater systems. The term ‘natural radioactivity’ is used in this context to cover all radioactivity present in the environment, including

Nguyen Dinh Chau; Marek Dulinski; Pawel Jodlowski; Jakub Nowak; Kazimierz Rozanski; Monika Sleziak; Przemyslaw Wachniew

2011-01-01

190

Future radioactive liquid waste streams study  

Microsoft Academic Search

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

Rey

1993-01-01

191

Device for the pulverization of radioactive wastes  

Microsoft Academic Search

A device is claimed for pulverizing incombustible large solid radioactive wastes arising from atomic power plants or the like. The device comprises a furnace body provided with a vacant space for melting radioactive wastes, a gripper mounted on the furnace body to support the radioactive waste, plasma torches mounted on the furnace body to irradiate a plasma arc toward the

T. Adachi; S. Hiratake

1982-01-01

192

On the production of radioactive stents  

NASA Astrophysics Data System (ADS)

In the last years radioactive stents proved to inhibit neointima formation. This paper describes the actual status of producing such radioactive stents. After a short discussion of the different radioisotopes suitable for radioactive stents, potential production methods are discussed. The ion beam implantation of P-32 applied at the Karlsruhe Research Center shall be described in more detail.

Schlösser, K.; Schweickert, H.

2001-07-01

193

Radioactive waste treatment technologies and environment  

SciTech Connect

The radioactive waste treatment and conditioning are the most important steps in radioactive waste management. At the Slovak Electric, plc, a range of technologies are used for the processing of radioactive waste into a form suitable for disposal in near surface repository. These technologies operated by JAVYS, PLc. Nuclear and Decommissioning Company, PLc. Jaslovske Bohunice are described. Main accent is given to the Bohunice Radwaste Treatment and Conditioning Centre, Bituminization plant, Vitrification plant, and Near surface repository of radioactive waste in Mochovce and their operation. Conclusions to safe and effective management of radioactive waste in the Slovak Republic are presented. (authors)

HORVATH, Jan; KRASNY, Dusan [JAVYS, PLc. - Nuclear and Decommisioning Company, PLc. (Slovakia)

2007-07-01

194

Public attitudes about radioactive waste  

SciTech Connect

Public attitudes about radioactive waste are changeable. That is my conclusion from eight years of social science research which I have directed on this topic. The fact that public attitudes about radioactive waste are changeable is well-known to the hands-on practitioners who have opportunities to talk with the public and respond to their concerns-practitioners like Ginger King, who is sharing the podium with me today. The public`s changeability and open-mindedness are frequently overlooked in studies that focus narrowly on fear and dread. Such studies give the impression that the outlook for waste disposal solutions is dismal. I believe that impression is misleading, and I`d like to share research findings with you today that give a broader perspective.

Bisconti, A.S. [Council for Energy Awareness, Washington, DC (United States)

1992-12-31

195

Optimization of radioactive waste storage.  

PubMed

In several countries, low-level radioactive wastes are treated and stored awaiting construction and operation of a final repository. In some cases, interim storage may be extended for decades requiring special attention regarding security issues. The International Atomic Energy Agency (IAEA) recommends segregation of wastes that may be exempted from interim storage or ultimate disposal. The paper presents a method to optimize the decision making process regarding exemption vs. interim storage or ultimate disposal of these wastes. PMID:17228185

Dellamano, José Claudio; Sordi, Gian-Maria A A

2007-02-01

196

Radioactive liquid waste treatment facility  

Microsoft Academic Search

The Radioactive Liquid Waste Treatment Facility (RLWTF) at Argonne National Laboratory-West (ANL-W) in Idaho provides improved treatment for low-level aqueous waste compared to conventional systems. A unique, patented evaporated system is used in the RLWTF. SHADE (shielded hot air drum evaporator, US Patent No. 4,305,780) is a low-cost disposable unit constructed from standard components and is self-shielded. The results of

1984-01-01

197

Environmental Geochemistry of Radioactive Contamination  

NASA Astrophysics Data System (ADS)

Psychometric studies of public perception of risk have shown that dangers associated with radioactive contamination are considered the most dreaded and among the least understood hazards (Slovic, 1987). Fear of the risks associated with nuclear power and associated contamination has had important effects on policy and commercial decisions in the last few decades. In the US, no new nuclear power plants were ordered between 1978 and 2002, even though it has been suggested that the use of nuclear power has led to significantly reduced CO2 emissions and may provide some relief from the potential climatic changes associated with fossil fuel use. The costs of the remediation of sites contaminated by radioactive materials and the projected costs of waste disposal of radioactive waste in the US dwarf many other environmental programs. The cost of disposal of spent nuclear fuel at the proposed repository at Yucca Mountain will likely exceed 10 billion. The estimated total life cycle cost for remediation of US Department of Energy (DOE) weapons production sites ranged from 203-247 billion dollars in constant 1999 dollars, making the cleanup the largest environmental project on the planet (US DOE, 2001). Estimates for the cleanup of the Hanford site alone exceeded $85 billion through 2046 in some of the remediation plans.Policy decisions concerning radioactive contamination should be based on an understanding of the potential migration of radionuclides through the geosphere. In many cases, this potential may have been overestimated, leading to decisions to clean up contaminated sites unnecessarily and exposing workers to unnecessary risk. It is important for both the general public and the scientific community to be familiar with information that is well established, to identify the areas of uncertainty and to understand the significance of that uncertainty to the assessment of risk.

Siegel, M. D.; Bryan, C. R.

2003-12-01

198

Radioactive fuel cell storage rack  

SciTech Connect

A radioactive fuel cell storage rack is comprised of structural elements including elements which are hollow and cruciform in section. Each leg of the cruciform structural element includes a neutron shield therein. The free end of the legs of the cruciform structural element converge so as to have an included angle of approximately 90/sup 0/. The rack is comprised of such cruciform elements as well as cooperating elements which are generally T and L shaped in section.

Holtz, M.; Singh, K.P.

1983-05-03

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

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

201

Radioactive Waste Management BasisSept 2001  

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 RWMB 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 meeeting the requirements of DOE Order 435.1 deviate from the DOE Manual 435.1-1 and Implementation Guide.

Goodwin, S S

2011-08-31

202

Radioactive iodine labeled phenolic amines  

Microsoft Academic Search

The invention is accomplished by the formation at the site of use of the radioactive amine of the invention which is then injected immediately into the mammal for diagnostic purposes. The compounds of the invention are as follows: 1-HO,2-(R1-N(-R2)-(H2C)N-N(-R3)-H2C-);4-I,6-R4-BENZENE In the above compound, Râ, Râ, Râ and Râ are independently any straight or branched alkyl of between 1 and about

M. Blau; H. F. Kung; K. M. Tramposch

1984-01-01

203

Radioactive beams with the HHIRF accelerators  

SciTech Connect

There is an increasing interest in radioactive ion beams for astrophysics and nuclear physics research and applied programs. This interest has led to an International Conference on Radioactive Nuclear Beams and a Workshop on the Science of Intense Radioactive Ion Beams. In addition, a steering committee has been formed to consider the development of a very large and intense RIB facility in North America to produce both proton- and neutron-rich beams. This report discusses development of these beams.

Olsen, D.K.; Alton, G.D.; Baktash, C.; Dowling, D.T.; Garrett, J.D.; Haynes, D.L.; Jones, C.M.; Juras, R.C., Lane, S.N.; Lee, I.Y.; Meigs, M.J.; Mills, G.D.; Mosko, S.W.; Tatum, B.A. Toth, K.S. (Oak Ridge National Lab., TN (USA)); Carter, H.K. (UNISOR, Oak Ridge, TN (USA))

1991-01-01

204

Radioactive Waste: Resources for Environmental Literacy  

NSDL National Science Digital Library

Since World War II, hundreds of thousands of tons of radioactive materials have been produced in the United States. How we will dispose of nuclear waste is a controversial issue with a large technical component. This book provides a useful resource for enhancing student understanding of the physics of radioactivity as well as the storage and disposal of radioactive waste. It encourages students to discuss these complex environmental issues using arguments based on the science behind issues related to radioactivity, technology, risk assessment, and tradeoffs.

Council, Environmental L.; National Science Teachers Association (NSTA)

2007-05-16

205

Natural radioactivity of the moon and planets  

NASA Astrophysics Data System (ADS)

In this report the main results of the study of natural radioactivity of the solar system bodies are considered. The radioactivity of the moon and planets was measured from orbiters and landers. The radioactivity of the returned lunar samples was studied with laboratory equipment. Analysis of the radioactivity data shows the bimodal structure of surfaces of the moon, Venus, Mars (ancient crust and young volcanic formations). Volcanic formations on all bodies, probably, consist of basaltic rocks. The compositions of ancient crusts are different (gabbro-anorthositic on the moon and maybe on Mars, granite-metamorphic on the earth and maybe on Venus).

Surkov, Iu. A.

206

Subseabed storage of radioactive waste  

NASA Astrophysics Data System (ADS)

The subject of the storage of nuclear wastes products incites emotional responses from the public, and thus the U.S. Subseabed Disposal Program will have to make a good case for waste storage beneath the ocean floor. The facts attendant, however, describe circumstances necessitating cool-headed analysis to achieve a solution to the growing nuclear waste problem. Emotion aside, a good case indeed is being made for safe disposal beneath the ocean floor.The problems of nuclear waste storage are acute. A year ago, U.S. military weapons production had accumulated over seventy-five million gallons of high-level radioactive liquid waste; solid wastes, such as spent nuclear fuel rods from reactors, amounted to more than 12,000 tons. These wastes are corrosive and will release heat for 1000 years or more. The wastes will remain dangerously radioactive for a period of 10,000 years. There are advantages in storing the wastes on land, in special underground repositories, or on the surface. These include the accessibility to monitor the waste and the possibility of taking action should a container rupture occur, and thus the major efforts to determine suitable disposal at this time are focused on land-based storage. New efforts, not to be confused with ocean dumping practices of the past, are demonstrating that waste containers isolated in the clays and sediments of the ocean floor may be superior (Environ. Sci. Tech., 16, 28A-37A 1982).

Bell, Peter M.

207

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

2010-03-30

208

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

209

Radioactive Waste Disposal Implications of Extending Part IIA to cover Radioactively Contaminated Land  

Microsoft Academic Search

A short study has been carried out of the potential radioactive waste disposal issues associated with the proposed extension of Part IIA to address radioactively contaminated land, where there is no other suitable existing legislation. It was found that there is likely to be an availability problem with respect to disposal at landfills of the radioactive wastes arising from remediation.

DJ Nancarrow

210

Natural and artificial radioactivity in the lower atmosphere  

Microsoft Academic Search

The origin of natural terrestrial radioactivity was studied including: ; radioactive element families; decay chains of Rn and Th; and radioactive half-; lives of daughter products. Natural radioactivity due to the action of cosmic ; radiation was also considered. The production of artificial radioactive aerosols ; in the air as a result of nuclear explosions and nuclear reactor Operation (in

A. Renoux; G. Madelaine

1973-01-01

211

Assessing Postzygotic Isolation Using Zygotic Disequilibria in Natural Hybrid Zones  

PubMed Central

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

212

Spills of Radioactive Materials -Emergency Procedures  

E-print Network

with low-level contamination and working towards the center or highest contamination areas. Clean up to radioactive waste container. For surface decontamination, use soap and water and cleansers appropriateSpills of Radioactive Materials - Emergency Procedures Procedure: 7.53 Created: 1/16/2014 Version

Jia, Songtao

213

THE RADIOACTIVITY OF THE ATMOSPHERE AND HYDROSPHERE  

Microsoft Academic Search

A brief account is given of the nature of geochemical, meteorological, ; and oceanographic problems involved in the interpretation of the distribution of ; radioactivity in the atmosphere and hydrosphere. The radioactivity is discussed ; as to source, primary radionuclides and their daughters, cosmic-ray production, ; and artificial production. (W.D.M.);

H E Suess

1958-01-01

214

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

215

Radioactivity in Food and the Environment, 2002  

E-print Network

, Food Standards Agency Mr Ken Ledgerwood Chief Industrial Pollution and Radiochemical InspectorRadioactivity in Food and the Environment, 2002 RIFE - 8 2003 #12;1 ENVIRONMENT AGENCY ENVIRONMENT AND HERITAGE SERVICE FOOD STANDARDS AGENCY SCOTTISH ENVIRONMENT PROTECTION AGENCY Radioactivity in Food

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

Radioactivity in Food and the Environment, 1995  

E-print Network

, of the Directorate of Fisheries Research (DFR) at Lowestoft for the Radiological Safety Division of the Food ScienceRadioactivity in Food and the Environment, 1995 Ministry of Agriculture, Fisheries and Food, 1996 RIFE - 1 #12;#12;1 MINISTRY OF AGRICULTURE, FISHERIES AND FOOD Radioactivity in Food

218

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

219

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 mvoes 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.

Andrews, Katherine M. (Pittsburgh, PA); Starenchak, Robert W. (Youngwood, PA)

1989-01-01

220

Radioactive liquid waste treatment facility  

SciTech Connect

The Radioactive Liquid Waste Treatment Facility (RLWTF) at Argonne National Laboratory-West (ANL-W) in Idaho provides improved treatment for low-level aqueous waste compared to conventional systems. A unique, patented evaporated system is used in the RLWTF. SHADE (shielded hot air drum evaporator, US Patent No. 4,305,780) is a low-cost disposable unit constructed from standard components and is self-shielded. The results of testing and recent operations indicate that evaporation rates of 2 to 6 gph (8 to 23 L/h) can be achieved with a single unit housed in a standard 30-gal (114-L) drum container. The operating experience has confirmed the design evaporation rate of 60,000 gal (227,000 L) per year, using six SHADE's. 2 references, 2 figures, 2 tables.

Black, R.L.

1984-07-01

221

Astrophysics with Radioactive Atomic Nuclei  

E-print Network

We propose to advance investigations of electromagnetic radiation originating in atomic nuclei beyond its current infancy to a true astronomy. This nuclear emission is independent from conditions of gas, thus complements more traditional stronomical methods used to probe the nearby universe. Radioactive gamma-rays arise from isotopes which are made in specific locations inside massive stars, their decay in interstellar space traces an otherwise not directly observable hot and tenuous phase of the ISM, which is crucial for feedback from massive stars. Its intrinsic clocks can measure characteristic times of processes within the ISM. Frontier questions that can be addressed with studies in this field are the complex interiors of massive stars and supernovae which are key agents in galactic dynamics and chemical evolution, the history of star-forming and supernova activity affecting our solar-system environment, and explorations of occulted and inaccessible regions of young stellar nurseries in our Galaxy.

Diehl, R; Boggs, S; Burkert, A; Chieffi, A; Gehrels, N; Greiner, J; Hartmann, D H; Kanbach, G; Meynet, G; Prantzos, N; Ryan, J; Thielemann, F K; Zinnecker, H

2009-01-01

222

Natural radioactivity in Spanish soils  

SciTech Connect

The program of studies and surveys of natural radiation and radioactivity in Spain organized by our research group at the end of the 1980s included a 4-y national survey to determine the concentrations of natural radionuclides in soil. Results obtained from measurements of soil samples collected nationwide at >900 sampling sites are reported and discussed in this paper. Correlations between absorbed dose rates in air calculated from natural radionuclide concentrations in soil and terrestrial gamma dose rates measured experimentally outdoors are shown for the different autonomous regions of Spain. Assessment is also made of the dose to the Spanish population from outdoor exposure to terrestrial gamma rays. 26 refs., 5 figs., 2 tabs.

Quindos, L.S.; Fernandez, P.L.; Soto, J. [Univ. of Cantabria, Santander (Spain)] [and others

1994-02-01

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

46 CFR 109.559 - Explosives and radioactive materials.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Explosives and radioactive materials. 109.559 Section 109...Miscellaneous § 109.559 Explosives and radioactive materials. Except as authorized...charge, no person may use explosives or radioactive materials and equipment on a...

2011-10-01

225

41 CFR 50-204.28 - Storage of radioactive materials.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2009-07-01 true Storage of radioactive materials. 50-204.28 Section 50-204...Radiation Standards § 50-204.28 Storage of radioactive materials. Radioactive materials stored in a nonradiation area...

2011-07-01

226

46 CFR 109.559 - Explosives and radioactive materials.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Explosives and radioactive materials. 109.559 Section 109...Miscellaneous § 109.559 Explosives and radioactive materials. Except as authorized...charge, no person may use explosives or radioactive materials and equipment on a...

2010-10-01

227

10 CFR 835.1201 - Sealed radioactive source control.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Sealed radioactive source control. 835.1201 Section...OCCUPATIONAL RADIATION PROTECTION Sealed Radioactive Source Control § 835.1201 Sealed radioactive source control. Sealed...

2012-01-01

228

46 CFR 109.559 - Explosives and radioactive materials.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Explosives and radioactive materials. 109.559 Section 109...Miscellaneous § 109.559 Explosives and radioactive materials. Except as authorized...charge, no person may use explosives or radioactive materials and equipment on a...

2013-10-01

229

49 CFR 172.310 - Class 7 (radioactive) materials.  

... 2014-10-01 false Class 7 (radioactive) materials. 172.310 Section... Marking § 172.310 Class 7 (radioactive) materials. In addition to any...subpart, each package containing Class 7 (radioactive) materials must be marked as...

2014-10-01

230

41 CFR 50-204.28 - Storage of radioactive materials.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Storage of radioactive materials. 50-204.28 Section 50-204...Radiation Standards § 50-204.28 Storage of radioactive materials. Radioactive materials stored in a nonradiation area...

2013-07-01

231

46 CFR 109.559 - Explosives and radioactive materials.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Explosives and radioactive materials. 109.559 Section 109...Miscellaneous § 109.559 Explosives and radioactive materials. Except as authorized...charge, no person may use explosives or radioactive materials and equipment on a...

2012-10-01

232

49 CFR 172.403 - Class 7 (radioactive) material.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Class 7 (radioactive) material. 172.403 Section 172... Labeling § 172.403 Class 7 (radioactive) material. (a) Unless excepted...of this subchapter, each package of radioactive material must be labeled as...

2013-10-01

233

10 CFR 835.1202 - Accountable sealed radioactive sources.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Accountable sealed radioactive sources. 835.1202 Section 835...OCCUPATIONAL RADIATION PROTECTION Sealed Radioactive Source Control § 835.1202 Accountable sealed radioactive sources. (a) Each...

2012-01-01

234

48 CFR 52.223-7 - Notice of radioactive materials.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Notice of radioactive materials. 52.223-7 Section...and Clauses 52.223-7 Notice of radioactive materials. As prescribed in 23...insert the following clause: Notice of Radioactive Materials (JAN 1997)...

2013-10-01

235

10 CFR 835.1201 - Sealed radioactive source control.  

...2014-01-01 2014-01-01 false Sealed radioactive source control. 835.1201 Section...OCCUPATIONAL RADIATION PROTECTION Sealed Radioactive Source Control § 835.1201 Sealed radioactive source control. Sealed...

2014-01-01

236

49 CFR 172.403 - Class 7 (radioactive) material.  

... 2014-10-01 false Class 7 (radioactive) material. 172.403 Section 172... Labeling § 172.403 Class 7 (radioactive) material. (a) Unless excepted...of this subchapter, each package of radioactive material must be labeled as...

2014-10-01

237

41 CFR 50-204.28 - Storage of radioactive materials.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2009-07-01 true Storage of radioactive materials. 50-204.28 Section 50-204...Radiation Standards § 50-204.28 Storage of radioactive materials. Radioactive materials stored in a nonradiation area...

2012-07-01

238

48 CFR 245.7310-6 - Radioactive material.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Radioactive material. 245.7310-6 Section...Contractor Inventory 245.7310-6 Radioactive material. The following shall be...capable of emitting ionized radiation: Radioactive Material Purchasers are warned...

2010-10-01

239

10 CFR 835.1202 - Accountable sealed radioactive sources.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Accountable sealed radioactive sources. 835.1202 Section 835...OCCUPATIONAL RADIATION PROTECTION Sealed Radioactive Source Control § 835.1202 Accountable sealed radioactive sources. (a) Each...

2011-01-01

240

41 CFR 50-204.28 - Storage of radioactive materials.  

...2014-07-01 2014-07-01 false Storage of radioactive materials. 50-204.28 Section 50-204...Radiation Standards § 50-204.28 Storage of radioactive materials. Radioactive materials stored in a nonradiation area...

2014-07-01

241

10 CFR 835.1201 - Sealed radioactive source control.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Sealed radioactive source control. 835.1201 Section...OCCUPATIONAL RADIATION PROTECTION Sealed Radioactive Source Control § 835.1201 Sealed radioactive source control. Sealed...

2010-01-01

242

48 CFR 52.223-7 - Notice of radioactive materials.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 false Notice of radioactive materials. 52.223-7 Section...and Clauses 52.223-7 Notice of radioactive materials. As prescribed in 23...insert the following clause: Notice of Radioactive Materials (JAN 1997)...

2012-10-01

243

41 CFR 50-204.28 - Storage of radioactive materials.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 true Storage of radioactive materials. 50-204.28 Section 50-204...Radiation Standards § 50-204.28 Storage of radioactive materials. Radioactive materials stored in a nonradiation area...

2010-07-01

244

10 CFR 835.1202 - Accountable sealed radioactive sources.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Accountable sealed radioactive sources. 835.1202 Section 835...OCCUPATIONAL RADIATION PROTECTION Sealed Radioactive Source Control § 835.1202 Accountable sealed radioactive sources. (a) Each...

2013-01-01

245

10 CFR 835.1201 - Sealed radioactive source control.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Sealed radioactive source control. 835.1201 Section...OCCUPATIONAL RADIATION PROTECTION Sealed Radioactive Source Control § 835.1201 Sealed radioactive source control. Sealed...

2011-01-01

246

10 CFR 835.1201 - Sealed radioactive source control.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Sealed radioactive source control. 835.1201 Section...OCCUPATIONAL RADIATION PROTECTION Sealed Radioactive Source Control § 835.1201 Sealed radioactive source control. Sealed...

2013-01-01

247

10 CFR 76.83 - Transfer of radioactive material.  

Code of Federal Regulations, 2012 CFR

...radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive...

2012-01-01

248

10 CFR 76.83 - Transfer of radioactive material.  

Code of Federal Regulations, 2010 CFR

...radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive...

2010-01-01

249

10 CFR 76.83 - Transfer of radioactive material.  

Code of Federal Regulations, 2013 CFR

...radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive...

2013-01-01

250

10 CFR 76.83 - Transfer of radioactive material.  

...radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive...

2014-01-01

251

10 CFR 76.83 - Transfer of radioactive material.  

Code of Federal Regulations, 2011 CFR

...radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive...

2011-01-01

252

49 CFR 172.436 - RADIOACTIVE WHITE-I label.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 false RADIOACTIVE WHITE-I label. 172.436 Section 172... Labeling § 172.436 RADIOACTIVE WHITE-I label. (a) Except for size and color, the RADIOACTIVE WHITE-I label must be as follows:...

2012-10-01

253

Radioactive waste management and practice in Bangladesh  

SciTech Connect

A large amount of low- and medium-level radioactive wastes are being generated in different parts of Bangladesh. The solid wastes are being collected in steel containers and liquid wastes are collected in plastic carboys and drums. Gaseous Ar-41 is discharged into the atmosphere through the 25 m height stack under controlled conditions after proper monitoring. The solid radioactive wastes collected are approximately 5 m{sup 3} (1988--1992) with gross beta-gamma surface dose rates from 0.30 {micro}Sv/h to 250 {micro}Sv/h. The liquid radioactive wastes are approximately 200 liters (1988--1992) with gross-beta-gamma surface dose rates from 0.30 {micro}Sv/h to 1 mSv/h. The solid and liquid wastes presently being collected are mostly short lived and low level and safely stored according to international safety codes of practice. Radioactive waste packages collected during the 5-yrs study totaled 16, representing a collective volume of {approximately} 7.5 m{sup 3}. The problem of management of radioactive waste in Bangladesh is not so serious at present because the wastes arising are small now. A computerized data base has been developed to document inventory of all radioactive waste arising in the country. The current practices of collection, handling, safe storage and management of the radioactive wastes are reported in this paper.

Mollah, A.S.; Rahman, M.M. [Atomic Energy Research Establishment, Dhaka (Bangladesh). Inst. of Nuclear Science and Technology

1993-12-31

254

Offgas treatment for radioactive waste incinerators  

SciTech Connect

Incineration of radioactive materials for resource recovery or waste volume reduction is recognized as an effective waste treatment method that will increase in usage and importance throughout the nuclear industry. The offgas cleanup subsystem of an incineration process is essential to ensure radionuclide containment and protection of the environment. Several incineration processes and associated offgas cleanup systems are discussed along with potential application of commercial pollution control components to radioactive service. Problems common to radioactive waste incinerator offgas service are identified and areas of needed research and development effort are noted.

Stretz, L.A.; Koenig, R.A.

1980-01-01

255

Procedures for interstitial radioactive gold grains  

SciTech Connect

Detailed implantation procedures and safety guidelines for use of interstitial radioactive gold grains are presented. These guidelines have been found to be of practical value for personnel involved with the implant to ensure compliance with regulations but are not necessarily the only procedures which could be utilized. Topics covered include: Description of Grains and Implantation, Management and Planning of Au-198, Source Logging, Source Transportation, Source Accounting During and After Implant, Room Monitoring, Recording, Dosimetry Films, Nursing Procedures, Levels in Patients Containing Radioactivity, and Patient Discharge of Radioactive Patients.

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

1989-01-01

256

Evaluation of Terrorist Interest in Radioactive Wastes  

SciTech Connect

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 radioactive sources have been evaluated in numerous studies to assess their security and attractiveness for use as a terrorist weapon. The studies conclude that tens of thousands of curies in sealed radioactive sources are available for potential use in a terrorist attack. This risk is mitigated by international efforts to find lost and abandoned sources and bring them under adequate security. However, radioactive waste has not received the same level of scrutiny to ensure security. This paper summarizes the activity and nature of radioactive sources potentially available to international terrorists. The paper then estimates radiation doses from use of radioactive sources as well as typical environmental restoration or decontamination and decommissioning wastes in a radioactive dispersal device (RDD) attack. These calculated doses indicate that radioactive wastes are, as expected, much less of a health risk than radioactive sources. The difference in radiation doses from wastes used in an RDD are four to nine orders of magnitude less than from sealed sources. We then review the International Atomic Energy Agency (IAEA) definition of 'dangerous source' in an adjusted comparison to common radioactive waste shipments generated in environmental management activities. The highest waste dispersion was found to meet only category 1-3.2 of the five step IAEA scale. A category '3' source by the IAEA standard 'is extremely unlikely, to cause injury to a person in the immediate vicinity'. The obvious conclusion of the analysis is that environmental management generated radioactive wastes have substantially less impact than radioactive sources if dispersed by terrorist-induced explosion or fire. From a health standpoint, the impact is very small. However, there is no basis to conclude that wastes are totally unattractive for use in a disruptive or economic damage event. Waste managers should be cognizant of this potential and take measures to ensure security of stored waste and waste shipments. (authors)

McFee, J.N.; Langsted, J.M.; Young, M.E. [Shaw Environmental and Infrastructure, Inc., 9201 East Dry Creek Rd. Centennial, CO 80112 (United States); Day, J.E. [Shaw Environmental and Infrastructure, Inc., 1725 Duke St, Suite 400, Alexandria, VA 22314 (United States)

2006-07-01

257

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

258

Radioactivities related to coal mining.  

PubMed

Natural radioactivity concentrations due to the coal mining in Gabal El-Maghara, North Sinai, Egypt, were determined using gamma-ray spectroscopy. Coal, water and soil samples were investigated in this study. The (226)Ra, (232)Th and (40)K activity concentrations in coal before extraction were 18.5 +/- 0.5, 29.5 +/- 1.2 and 149.0 +/- 8.4 Bq kg(-1), respectively. These concentrations were reduced to 18-22% after extraction due to the clay removal of the coal ore. The activity contents of the water and soil samples collected from the surrounding area did not show any evidence of enhancement due to the mining activities. Absorbed dose rate and effective dose equivalent in the mine environment were 29.4 nGy h(-1) and 128.0 microSv a(-1), respectively. The measured activity concentrations in the mine environment and the surrounding areas (5 km away from the mine) are similar to that found in other regions in North and South Sinai. Based on the measurements of gamma-ray emitting radionuclides, the mine activity does not lead to any enhancement in the local area nor represents any human risk. PMID:16049576

Seddeek, Mostafa K; Sharshar, Taher; Ragab, Hossam S; Badran, Hussein M

2005-08-01

259

Is Radioactive Decay Really Exponential?  

E-print Network

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 12,550 years by comparing radiocarbon dates with dates obtained from dendrochronology. It is well known that this approach shows that radiocarbon dates of over 3,000 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.

Philip J. Aston

2012-04-26

260

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

261

Radioactive Materials Released from Nuclear Power Plants.  

National Technical Information Service (NTIS)

Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1979 have been compiled and reported. Data on solid waste shipments as well as selected operating information have been included. This report su...

J. Tichler, C. Benkovitz

1981-01-01

262

Issues of natural radioactivity in phosphates  

SciTech Connect

The fertilization of phosphorus (P) fertilizers is essential in agricultural production, but phosphates contain in dependence on their origin different amounts of trace elements. The problem of cadmium (Cd) loads and other heavy metals is well known. However, only a limited number of investigations examined the contamination of phosphates with the two heaviest metals, uranium (U) and thorium (Th), which are radioactive. Also potassium (K) is lightly radioactive. Measurements are done n the radioactivity content of phosphates, P fertilizers and soils. The radiation doses to workers and public as well as possible contamination of soils from phosphate rock or fertilizer caused by these elements or their daughter products is of interest with regard to radiation protection. The use of P fertilizers is necessary for a sustainable agriculture, but it involves radioactive contamination of soils. The consequences of the use of P fertilizers is discussed, also with regard to existing and proposed legislation. 11 refs., 2 figs., 7 tabs.

Schnug, E.; Haneklaus, S. [Institute of Plant Nutrition and Soil Science, Braunschweig (Germany); Schnier, C. [GKSS-Research Centre, Geesthacht (Germany); Scholten, L.C. [KEMA, Arnhem (Netherlands)

1996-12-31

263

Demonstration of radioactive decay using pennies  

NSDL National Science Digital Library

A demonstration (with full class participation) to illustrate radioactive decay by flipping coins. Shows students visually the concepts of exponential decay, half-life and randomness. Works best in large classes -- the more people, the better.

Wenner, Jennifer

264

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

265

Fractal and Topological Complexity of Radioactive Contamination.  

National Technical Information Service (NTIS)

There is verified the hypothesis about multifractal nature of radioactive contamination due to nuclear explosions on Semipalatinsk test site (STS) in Kazakhstan. The fields of terrestrial contamination have extreme high variability caused by a number of n...

N. G. Makarenko, L. M. Karimova, A. G. Terekhov, M. M. Novak

2000-01-01

266

Using Popcorn to Simulate Radioactive Decay  

NSDL National Science Digital Library

Popping popcorn in your class is an excellent way to illustrate both the spontaneity and irreversible change associated with radioactive decay. It helps students to understand the unpredictability of decay.

Wenner, Jennifer

267

Radioactivity in Food and the Environment, 2009  

E-print Network

...............................................................................................................................29 2. Nuclear fuel production and reprocessing ................................................................................................................22 1.2.1 Radioactive waste disposal from nuclear sites ..................................................................................22 1.2.2 International agreements, the UK Discharge Strategy and building new nuclear power stations

268

Dissolved Concentration Limits of Radioactive Elements.  

National Technical Information Service (NTIS)

The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, ther...

2005-01-01

269

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

270

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

271

Use of Radioactive Iodine for Thyroid Cancer  

PubMed Central

Context Substantial uncertainty persists over the indications for radioactive iodine for thyroid cancer. Use of radioactive iodine over time and the correlates of its use remain unknown. Objective To determine practice patterns, the degree to which hospitals vary in their use of radioactive iodine, and factors that contribute to this variation Design, Setting, Patients We performed time trend analysis of radioactive iodine use in a cohort of 189,219 well-differentiated thyroid cancer patients treated at 981 hospitals associated with the National Cancer Database between 1990 and 2008. We used multilevel analysis to assess the correlates of patient and hospital characteristics on radioactive iodine use in the cohort treated from 2004–2008. Main Outcome Measure Use of radioactive iodine after total thyroidectomy Results Between 1990 and 2008, across all tumor sizes, there was a significant rise in the proportion of well-differentiated thyroid cancer patients receiving radioactive iodine (1373/3397, versus 11539/20620, P<0.001). Multivariable analysis of patients treated from 2004 to 2008 found that there was a statistical difference in radioactive iodine use between AJCC stage I and IV (odds ratios (OR) 0.34 (0.31–0.37) but not between stage II/III versus IV (OR 0.97 (0.88–1.07), 1.06 (0.95–1.17), respectively). In addition to patient and tumor characteristics, hospital volume was associated with radioactive iodine use. Wide variation in radioactive iodine use existed, and only 21.1% of this variation was accounted for by patient and tumor characteristics. Hospital type and case volume accounted for 17.1% of the variation. After adjusting for available patient, tumor, and hospital characteristics, much of the variance, 29.1%, was attributable to unexplained hospital characteristics. Conclusions Among patients treated for well-differentiated thyroid cancer at hospitals in the National Cancer Database, there was an increase in the proportion receiving radioactive iodine between 1990 and 2008; much of the variation in use was associated with hospital characteristics. PMID:21846853

Haymart, MR; Banerjee, M; Stewart, AK; Koenig, RJ; Birkmeyer, JD; Griggs, JJ

2012-01-01

272

Liquid radioactive waste subsystem design description  

SciTech Connect

The Liquid Radioactive Waste Subsystem provides a reliable system to safely control liquid waste radiation and to collect, process, and dispose of all radioactive liquid waste without impairing plant operation. Liquid waste is stored in radwaste receiver tanks and is processed through demineralizers and temporarily stored in test tanks prior to sampling and discharge. Radwastes unsuitable for discharge are transferred to the Solid Radwaste System.

NONE

1986-06-01

273

Radioactivity in Silver Induced by Fast Neutrons  

Microsoft Academic Search

Radioactive silver, Ag112, has been produced by fast neutron bombardment of Cd112 and In115. A half-life period of 3.2 hours is observed with the upper limit of the electron beta-ray spectrum at 2.2 Mev. Gamma-rays are also emitted, the number per beta-ray is about four. The radioactive silver isomer, Ag106, produced by fast neutron bombardment of Ag107, has a positron

M. L. Pool

1938-01-01

274

Tokai Radioactive Ion Accelerator Complex (TRIAC)  

NASA Astrophysics Data System (ADS)

An ISOL-based radioactive nuclear beam (RNB) facility, Tokai Radioactive Ion Accelerator Complex (TRIAC), has been jointly developed by High Energy Accelerator Research Organization (KEK) and Japan Atomic Energy Agency (JAEA). The facility started to supply RNBs for experiments in 2005 and RNBs including fission fragments with energies up to 1.1MeV/A are available in the present. Several experimental studies were performed successfully using 8Li beams with various energies.

Watanabe, Y. X.; Arai, S.; Arakaki, Y.; Fuchi, Y.; Hirayama, Y.; Imai, N.; Ishiyama, H.; Jeong, S. C.; Kawakami, H.; Miyatake, H.; Niki, K.; Nomura, T.; Okada, M.; Oyaizu, M.; Tanaka, M. H.; Tomizawa, M.; Yoshikawa, N.; Abe, S.; Hanashima, S.; Hashimoto, T.; Ichikawa, S.; Ikezoe, H.; Ishii, T.; Ishizaki, N.; Kabumoto, H.; Katayama, I.; Koizumi, M.; Matsuda, M.; Mitsuoka, S.; Nakanoya, T.; Nishio, K.; Ohuchi, I.; Osa, A.; Sato, T. K.; Takeuchi, S.; Tayama, H.; Tsukihashi, Y.

2007-11-01

275

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

276

Public involvement in radioactive waste management decisions  

SciTech Connect

Current repository siting efforts focus on Yucca Mountain, Nevada, where DOE`s Office of Civilian Radioactive Waste Management (OCRWM) is conducting exploratory studies to determine if the site is suitable. The state of Nevada has resisted these efforts: it has denied permits, brought suit against DOE, and publicly denounced the federal government`s decision to study Yucca Mountain. The state`s opposition reflects public opinion in Nevada, and has considerably slowed DOE`s progress in studying the site. The Yucca Mountain controversy demonstrates the importance of understanding public attitudes and their potential influence as DOE develops a program to manage radioactive waste. The strength and nature of Nevada`s opposition -- its ability to thwart if not outright derail DOE`s activities -- indicate a need to develop alternative methods for making decisions that affect the public. This report analyzes public participation as a key component of this openness, one that provides a means of garnering acceptance of, or reducing public opposition to, DOE`s radioactive waste management activities, including facility siting and transportation. The first section, Public Perceptions: Attitudes, Trust, and Theory, reviews the risk-perception literature to identify how the public perceives the risks associated with radioactivity. DOE and the Public discusses DOE`s low level of credibility among the general public as the product, in part, of the department`s past actions. This section looks at the three components of the radioactive waste management program -- disposal, storage, and transportation -- and the different ways DOE has approached the problem of public confidence in each case. Midwestern Radioactive Waste Management Histories focuses on selected Midwestern facility-siting and transportation activities involving radioactive materials.

NONE

1994-04-01

277

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

278

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

279

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

280

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

281

Wide range radioactive gas concentration detector  

DOEpatents

A wide range radioactive gas concentration detector and monitor which is capable of measuring radioactive gas concentrations over a range of eight orders of magnitude. The device of the present invention is designed to have an ionization chamber which is sufficiently small to give a fast response time for measuring radioactive gases but sufficiently large to provide accurate readings at low concentration levels. Closely spaced parallel plate grids provide a uniform electric field in the active region to improve the accuracy of measurements and reduce ion migration time so as to virtually eliminate errors due to ion recombination. The parallel plate grids are fabricated with a minimal surface area to reduce the effects of contamination resulting from absorption of contaminating materials on the surface of the grids. Additionally, the ionization chamber wall is spaced a sufficient distance from the active region of the ionization chamber to minimize contamination effects.

Anderson, David F. (Los Alamos, NM)

1984-01-01

282

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

283

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

284

Characterization and conditioning of radioactive graphite  

SciTech Connect

The shutdown of Vandellos I nuclear power station and JEN-1 experimental reactor in Spain presents the problem of the future conditioning and disposal of radioactive graphite from the decommissioning of both reactors. The main aim of this work is the study and development of chemical processes for the treatment of radioactive graphite from nuclear installations in order to achieve its proper disposal. The following stages are being studied: characterization of inactive and radioactive graphite, extraction of radionuclides, leaching of tritium and C-14, impermeabilization of graphite by a metallic coating or cement covering, in order to minimize leaching of radionuclides during disposal. In this work the authors review the study covering the first three tasks listed with the Graphite from the Spanish nuclear power station Vandellos I.

Esteban-Duque, A.; Uriarte, A.; Suarez, A.; Fabrellas, B.; Gonzalez, A. [CIEMAT, Madrid (Spain). Div. Tecnologia de Residuos

1993-12-31

285

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

286

Summary -- Experiments with Radioactive Beams Working Group  

SciTech Connect

During the course of the workshop, a wide range of futuristic radioactive-beam experiments were discussed. These extended from the study of electroweak interactions in nuclei to materials science, nuclear astrophysics, and a host of nuclear physics investigations. Emphasis was placed on illustrating how these prototypical experiments could be done, discussing what types of detection systems would be needed, exploring the new problems which would be confronting the radioactive beam experimenter, and better defining the beam requirements. Contained herein is a summary of these discussions.

Vieira, D.J. (Los Alamos National Lab., NM (United States)); Wiescher, M. (Notre Dame Univ., IN (United States))

1992-01-01

287

Summary -- Experiments with Radioactive Beams Working Group  

SciTech Connect

During the course of the workshop, a wide range of futuristic radioactive-beam experiments were discussed. These extended from the study of electroweak interactions in nuclei to materials science, nuclear astrophysics, and a host of nuclear physics investigations. Emphasis was placed on illustrating how these prototypical experiments could be done, discussing what types of detection systems would be needed, exploring the new problems which would be confronting the radioactive beam experimenter, and better defining the beam requirements. Contained herein is a summary of these discussions.

Vieira, D.J. [Los Alamos National Lab., NM (United States); Wiescher, M. [Notre Dame Univ., IN (United States)

1992-12-31

288

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

289

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

290

Microwave remediation of hazardous and radioactive wastes  

SciTech Connect

A team from the Westinghouse Savannah River Technology Center (WSRC - a DOE Laboratory), and the University of Florida (UF - academia), has been active for about a decade in development of microwave technology for specialized waste management applications. This interaction has resulted in the development of unique equipment and uses of microwave energy for a variety of important applications for remediation of hazardous and radioactive wastes. Discussed are results of this unique technology for processing of electronic circuitry and components, medical wastes, discarded tires, and transuranic radioactive wastes.

Wicks, G.G.

2000-04-28

291

Level Statistics of Stable and Radioactive Nuclei  

E-print Network

The spectral statistics of nuclei undergo through the major forms of radioactive decays ((\\alpha)(\\beta^-), and(\\beta^+) (or EC)) and also stable nuclei are investigated. With employing the MLE technique in the nearest neighbor spacing framework, the chaoticity parameters are estimated for sequences prepared by all the available empirical data. The ML-based estimated values propose a deviation to more regular dynamics in sequences constructed by stable nuclei in compare to unstable ones. In the same mass regions, nuclei transmitted through (\\alpha)decay explore less regularity in their spectra in compare to other radioactive nuclei.

M. A. Jafarizadeh; N. Fouladi; H. Sabri; B. Rashidian Maleki

2012-02-28

292

Radioactive Ion Beam Production Capabilities at the Holifield Radioactive Ion Beam Facility  

SciTech Connect

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 HRIBF is the production of high-quality beams of short-lived 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.

Beene, James R [ORNL; Dowling, Darryl T [ORNL; Gross, Carl J [ORNL; Juras, Raymond C [ORNL; Liu, Yuan [ORNL; Meigs, Martha J [ORNL; Mendez, II, Anthony J [ORNL; Nazarewicz, Witold [ORNL; Sinclair, John William [ORNL; Stracener, Daniel W [ORNL; Tatum, B Alan [ORNL

2011-01-01

293

Solid radioactive waste subsystem design description  

SciTech Connect

The Solid Radioactive Waste Subsystem provides reliable processing of collected solid waste to meet the requirements of 10CFR20 and 10CFR61. The methods utilized are cement solidification for sludges, resins, liquids, and noncompactible waste, and compaction for dry compressible waste. The drums of processed waste will be stored until transported off-site for disposal at a licensed burial site.

NONE

1986-06-01

294

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

295

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

296

Annual Radioactive Waste Tank Inspection Program - 1998  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site separations processes are contained in large underground carbon steel tanks. Inspections made during 1998 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.

McNatt, F.G.

1999-10-27

297

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

298

Annual radioactive waste tank inspection program: 1995  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site (SRS) separations processes are contained in large underground carbon steel tanks. Inspections made during 1995 to evaluate these vessels and evaluations based on data accrued by inspections performed since the tanks were constructed are the subject of this report

McNatt, F.G. Sr.

1996-04-01

299

ANNUAL RADIOACTIVE WASTE TANK INSPECTION PROGRAM 2008  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site (SRS) separations and vitrification processes are contained in large underground carbon steel tanks. Inspections made during 2008 to evaluate these vessels and other waste handling facilities along with evaluations based on data from previous inspections are the subject of this report.

West, B.; Waltz, R.

2009-06-11

300

Annual radioactive waste tank inspection program - 1992  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site (SRS) separations processes are contained in large underground carbon steel tanks. Inspections made during 1992 to evaluate these vessels and evaluations based on data accrued by inspections made since the tanks were constructed are the subject of this report.

McNatt, F.G.

1992-12-31

301

Annual Radioactive Waste Tank Inspection Program - 1997  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site (SRS) separations processes are contained in large underground carbon steel tanks. Inspections made during 1997 to evaluate these vessels, and evaluations based on data accrued by inspections performed since the tanks were constructed are the subject of this report.

McNatt, F.G. [Westinghouse Savannah River Company, AIKEN, SC (United States)

1998-05-01

302

Annual radioactive waste tank inspection program - 1996  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site (SRS) separations processes are contained in large underground carbon steel tanks. Inspections made during 1996 to evaluate these vessels, and evaluations based on data accrued by inspections performed since the tanks were constructed, are the subject of this report.

McNatt, F.G.

1997-04-01

303

Annual Radioactive Waste Tank Inspection Program 1994  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site (SRS) separations processes are contained in large underground carbon steel tanks. Inspections made during 1994 to evaluate these vessels and evaluations based on data accrued by inspections made since the tanks were constructed are the subject of this report.

McNatt, F.G. Sr.

1995-04-01

304

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

305

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

306

Predicting Induced Radioactivity at High Energy Accelerators  

SciTech Connect

Radioactive nuclides are produced at high-energy electron accelerators by different kinds of particle interactions with accelerator components and shielding structures. Radioactivity can also be induced in air, cooling fluids, soil and groundwater. The physical reactions involved include spallations due to the hadronic component of electromagnetic showers, photonuclear reactions by intermediate energy photons and low-energy neutron capture. Although the amount of induced radioactivity is less important than that of proton accelerators by about two orders of magnitude, reliable methods to predict induced radioactivity distributions are essential in order to assess the environmental impact of a facility and to plan its decommissioning. Conventional techniques used so far are reviewed, and a new integrated approach is presented, based on an extension of methods used at proton accelerators and on the unique capability of the FLUKA Monte Carlo code to handle the whole joint electromagnetic and hadronic cascade, scoring residual nuclei produced by all relevant particles. The radiation aspects related to the operation of superconducting RF cavities are also addressed.

Fasso, Alberto

1999-08-27

307

Radioactivity in Food and the Environment, 2004  

E-print Network

Radioactivity in Food and the Environment, 2004 RIFE - 10 2005 #12;Food Standards Agency Emergency Service Industrial Pollution and Radiochemical Inspectorate Calvert House 23 Castle Place Belfast BT1 1FY ISSN 1365-6414 #12;1 ENVIRONMENT AGENCY ENVIRONMENT AND HERITAGE SERVICE FOOD STANDARDS AGENCY SCOTTISH

308

Radioactivity in Food and the Environment, 2005  

E-print Network

Radioactivity in Food and the Environment, 2005 RIFE - 11 2006 #12;Food Standards Agency Emergency Service Industrial Pollution and Radiochemical Inspectorate Calvert House 23 Castle Place Belfast BT1 1FY ISSN 1365-6414 #12; ENVIRONMENT AGENCY ENVIRONMENT AND HERITAGE SERVICE FOOD STANDARDS AGENCY SCOTTISH

309

RADIOACTIVE METALLOFULLERENES: HOT ATOM CHEMISTRY ASPECTS.  

E-print Network

with radioactive isotopes can be useful for medical diagnostics, therapy of cancer and immunotherapy. Itinerary in reactor on metallofullerenes and what is survivability of original chemical form at thermal neutron is retention, percent of capture events which retain the original molecule. The thermal neutron capture results

Titov, Anatoly

310

Marie Curie and the Science of Radioactivity  

NSDL National Science Digital Library

This web site is an online exhibit about Marie Curie, the discoverer of the radioactive elements polonium and radium and the first person to win two Nobel prizes. The exhibit provides an interactive account of Marie Curie's life, complete with photographs, maps, and links to more information. This is part of the Center for the History of Physics of the American Institute for Physics.

2006-12-07

311

Preparation and characterization of radioactive castanospermine  

Microsoft Academic Search

A procedure for the preparation of tritiated castanospermine is described. The tritiated alkaloid was shown to be chromatographically identical to the native material and exhibited the same inhibitory properties. Radiolabeled castanospermine tightly bound to purified intestinal sucrase. Following gel chromatography, each mole of enzyme was shown to have bound 1 mol of the radioactive alkaloid. Cultured MDCK cells were also

R. W. Keenan; Y. T. Pan; A. D. Elbein

1987-01-01

312

Radioactive Ion Beams for Stewardship Science  

NASA Astrophysics Data System (ADS)

Measurements of particular reaction sequences that influence the cumulative fission yield of specific fission products of interest for stewardship science as well as for nuclear reactions on radiochemical detectors used in testing nuclear devices are often not accessible with radioactive targets because of short half-lives, high specific activities or availability of sufficient target material. Therefore, a possible surrogate reaction for (n,?) is the neutron transfer in (d,p) or (d,p?) reactions, which can be measured with ion beams of short-lived radioactive species in inverse kinematics. The Center of Excellence for Radioactive Ion Beam Studies for Stewardship Science is developing experimental techniques for measuring (d,p) reactions. Therefore, a strong component of our center is the development of accelerated radioactive ion beams such as 48V, 73,74As, 92,94,95Sr, 82Ge, 132,134Sn, Zr, Mo, Tc, and others. Some of these beams had not been available before, because the elements are refractory, or some beams require higher beam intensity or purity. Beam development techniques include different actinide targets, e.g. ThO2, molecular sideband formation, e.g. for Sr and possibly charge-exchange processes. This talk will consider specific beams of interested for our center. This research was sponsored by the NNSA under Stewardship Science Academic Alliance program through DOE Cooperative Agreement # DE-FC03-3NA00143.

Kronenberg, Andreas; Carter, H. K.; Spejewski, E. H.

2006-10-01

313

Recycling radioactively contaminated materials: Experience and prognosis  

SciTech Connect

In recent years, federal agencies, especially the U.S. Department of Energy (DOE), the U.S. Department of Defense (DOD), the U.S. Environmental Protection Agency, and the U.S. Nuclear Regulatory Commission (NRC), as well as the commercial nuclear enterprise, have begun to consider certain radioactively contaminated materials as resources for beneficial reuse rather than wastes. Most outstanding among these materials is metal that has become radioactively contaminated in various activities of the nuclear enterprise. The DOE began to move in the early 1970s to manage contaminated scrap metals as a potential resource rather than a waste. In the mid-1980s, Oak Ridge Operations Office (ORO) initiated moves to involve private industry in responding to DOE needs in dealing with scrap metal. As a result of this action, three firms showed positive moves toward the beneficial reuse of radioactively contaminated scrap metal, both surface and volumetrically contaminated. From among these industrial firms, one was selected to deal with the specified ORO scrap metal inventories and has, at its own expense, developed technologies and constructed processing facilities to deal with large masses of radioactively contaminated metals from any source.

Large, D.E.; Arrowsmith, H.W. (SEG Inc., Oak Ridge, TN (United States))

1993-01-01

314

Thyroid Cancer Following Exposure to Radioactive Iodine  

Microsoft Academic Search

Although external radiation is a well-known cause of human thyroid cancer, the risk from exposure of the thyroid gland to internal radiation is not well defined. This is of practical importance because of the extensive use of radioactive iodine in medical practice and the potential for release of iodine radionuclides into the environment. The purpose of this review is to

Jacob Robbins; Arthur B. Schneider

2000-01-01

315

A literature Review on Radioactivity Transfer to  

E-print Network

year are considered even though dealing with the long-lived nuclei, 90 Sr and 1 3 7 Cs. Before� *ISE Rise-R-450 A literature Review on Radioactivity Transfer to Plants and Soil Ole John Nielsen Risø National Laboratory, DK-4000 Roskilde, Denmark July 1981 #12;RIS�-R-450 A LITERATURE REVIEW

316

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

317

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

318

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

319

10 CFR 835.1202 - Accountable sealed radioactive sources.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Accountable sealed radioactive sources. 835.1202 Section 835.1202 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Sealed Radioactive Source Control § 835.1202 Accountable...

2010-01-01

320

10 CFR 39.69 - Radioactive contamination control.  

Code of Federal Regulations, 2012 CFR

... Energy 1 2012-01-01 2012-01-01 false Radioactive contamination control. 39.69 Section 39.69 Energy...WELL LOGGING Radiation Safety Requirements § 39.69 Radioactive contamination control. (a) If the licensee...

2012-01-01

321

10 CFR 39.69 - Radioactive contamination control.  

Code of Federal Regulations, 2013 CFR

... Energy 1 2013-01-01 2013-01-01 false Radioactive contamination control. 39.69 Section 39.69 Energy...WELL LOGGING Radiation Safety Requirements § 39.69 Radioactive contamination control. (a) If the licensee...

2013-01-01

322

10 CFR 39.69 - Radioactive contamination control.  

Code of Federal Regulations, 2011 CFR

... Energy 1 2011-01-01 2011-01-01 false Radioactive contamination control. 39.69 Section 39.69 Energy...WELL LOGGING Radiation Safety Requirements § 39.69 Radioactive contamination control. (a) If the licensee...

2011-01-01

323

10 CFR 39.69 - Radioactive contamination control.  

Code of Federal Regulations, 2010 CFR

... Energy 1 2010-01-01 2010-01-01 false Radioactive contamination control. 39.69 Section 39.69 Energy...WELL LOGGING Radiation Safety Requirements § 39.69 Radioactive contamination control. (a) If the licensee...

2010-01-01

324

10 CFR 39.69 - Radioactive contamination control.  

... Energy 1 2014-01-01 2014-01-01 false Radioactive contamination control. 39.69 Section 39.69 Energy...WELL LOGGING Radiation Safety Requirements § 39.69 Radioactive contamination control. (a) If the licensee...

2014-01-01

325

40 CFR 147.3005 - Radioactive waste injection wells.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Radioactive waste injection wells. 147.3005 Section 147...EPA-ADMINISTERED UNDERGROUND INJECTION CONTROL PROGRAMS Lands of...147.3005 Radioactive waste injection wells. Notwithstanding §§...

2010-07-01

326

Depleted uranium: a contemporary controversy for the teaching of radioactivity  

Microsoft Academic Search

Depleted uranium has been used in recent military conflicts and the media have reported the danger from radioactivity. This context provides a good way to keep students' attention when introducing the subject of radioactivity at GCSE or advanced level.

Mark Whalley

2006-01-01

327

10 CFR 76.81 - Authorized use of radioactive material.  

Code of Federal Regulations, 2012 CFR

...radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the...

2012-01-01

328

10 CFR 76.81 - Authorized use of radioactive material.  

Code of Federal Regulations, 2010 CFR

...radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the...

2010-01-01

329

10 CFR 76.81 - Authorized use of radioactive material.  

Code of Federal Regulations, 2011 CFR

...radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the...

2011-01-01

330

10 CFR 76.81 - Authorized use of radioactive material.  

Code of Federal Regulations, 2013 CFR

...radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the...

2013-01-01

331

10 CFR 76.81 - Authorized use of radioactive material.  

...radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the...

2014-01-01

332

Development of sampling methodic of radioactive materials and measurements in performing radioactive inspection of APS  

SciTech Connect

This report describes sampling methods and methods of determination of radioactive contamination which are needed in reactor decommissioning. The decommissioning of the Armenian Power Plant is and inspection techniques is discussed.

Matusevich, E.S.; Cherkashin, V.A. [Obninsk Institute of Nuclear Power Engineering (Russian Federation)

1993-12-31

333

Commercial low-level radioactive waste transportation safety history  

Microsoft Academic Search

An excellent safety record has been established for the transport of commercial low-level radioactive waste. By using the Radioactive Material Incident Report data base to evaluate transportation accidents involving commercial low-level radioactive waste, it was found that there have been only four transportation accidents involving the release of commercial low-level radioactive waste in the last 20 years. The accidents were

1992-01-01

334

Stable radioactive diagnostic agent and a non-radioactive carrier therefor  

SciTech Connect

A stable non-radioactive carrier for use in production of /sup 99/ /SUP m/ Tc-labeled radioactive diagnostic agent comprising a chelating agent, a water-soluble reducing agent for pertechnetate and a stabilizer chosen from ascorbic acid and erythorbic acid, and their pharmaceutically acceptable salts and esters in an amount of more than about 100 moles per 1 mol of said water-soluble reducing agent.

Azuma, M.; Hazue, M.

1984-12-18

335

Concentration of radioactive components in liquid low-level radioactive waste by membrane distillation  

Microsoft Academic Search

The paper addresses some aspects of liquid low-level radioactive waste (LLLW) purification. Since the volume of liquid low-level wastes is usually large and the activity is rather low, the radioactive substances separated from the non-active portion have to be concentrated into the small volume for subsequent conditioning and disposal. The need for the improvement of decontamination and minimisation of the

G. Zakrzewska-Trznadel; M. Harasimowicz; A. G. Chmielewski

1999-01-01

336

Review of physics, instrumentation and dosimetry of radioactive isotopes  

NASA Technical Reports Server (NTRS)

General radioactive isotope information, stressing radioactivity, methods of measurement, and dosimetry of radioactive nuclides have been reviewed to serve as a reference for the medical profession. Instability of radionuclides, principal types of emission, and measurement of ionizing radiation are among the topics discussed.

Sinclair, W. K.

1967-01-01

337

Low-level radioactive waste regulation: Science, politics and fear  

Microsoft Academic Search

An inevitable consequence of the use of radioactive materials is the generation of radioactive wastes and the public policy debate over how they will be managed. In 1980, Congress shifted responsibility for the disposal of low-level radioactive wastes from the federal government to the states. This act represented a sharp departure from more than 30 years of virtually absolute federal

1988-01-01

338

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

339

40 CFR 227.30 - High-level radioactive waste.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 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

340

49 CFR 172.440 - RADIOACTIVE YELLOW-III label.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false RADIOACTIVE YELLOW-III label. 172.440...PLANS Labeling § 172.440 RADIOACTIVE YELLOW-III label. (a) Except for size and color, the RADIOACTIVE YELLOW-III label must be as...

2010-10-01

341

49 CFR 172.440 - RADIOACTIVE YELLOW-III label.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false RADIOACTIVE YELLOW-III label. 172.440...PLANS Labeling § 172.440 RADIOACTIVE YELLOW-III label. (a) Except for size and color, the RADIOACTIVE YELLOW-III label must be as...

2012-10-01

342

40 CFR 227.30 - High-level radioactive waste.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 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

343

49 CFR 172.440 - RADIOACTIVE YELLOW-III label.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false RADIOACTIVE YELLOW-III label. 172.440...PLANS Labeling § 172.440 RADIOACTIVE YELLOW-III label. (a) Except for size and color, the RADIOACTIVE YELLOW-III label must be as...

2011-10-01

344

49 CFR 172.436 - RADIOACTIVE WHITE-I label.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false RADIOACTIVE WHITE-I label. 172.436 Section...SECURITY PLANS Labeling § 172.436 RADIOACTIVE WHITE-I label. (a) Except for size and color, the RADIOACTIVE WHITE-I label must be as...

2010-10-01

345

40 CFR 227.30 - High-level radioactive waste.  

...2014-07-01 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

346

49 CFR 172.440 - RADIOACTIVE YELLOW-III label.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false RADIOACTIVE YELLOW-III label. 172.440...PLANS Labeling § 172.440 RADIOACTIVE YELLOW-III label. (a) Except for size and color, the RADIOACTIVE YELLOW-III label must be as...

2013-10-01

347

49 CFR 172.440 - RADIOACTIVE YELLOW-III label.  

...2014-10-01 2014-10-01 false RADIOACTIVE YELLOW-III label. 172.440...PLANS Labeling § 172.440 RADIOACTIVE YELLOW-III label. (a) Except for size and color, the RADIOACTIVE YELLOW-III label must be as...

2014-10-01

348

49 CFR 172.436 - RADIOACTIVE WHITE-I label.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false RADIOACTIVE WHITE-I label. 172.436 Section...SECURITY PLANS Labeling § 172.436 RADIOACTIVE WHITE-I label. (a) Except for size and color, the RADIOACTIVE WHITE-I label must be as...

2011-10-01

349

49 CFR 172.436 - RADIOACTIVE WHITE-I label.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false RADIOACTIVE WHITE-I label. 172.436 Section...SECURITY PLANS Labeling § 172.436 RADIOACTIVE WHITE-I label. (a) Except for size and color, the RADIOACTIVE WHITE-I label must be as...

2013-10-01

350

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

351

49 CFR 172.436 - RADIOACTIVE WHITE-I label.  

...2014-10-01 2014-10-01 false RADIOACTIVE WHITE-I label. 172.436 Section...SECURITY PLANS Labeling § 172.436 RADIOACTIVE WHITE-I label. (a) Except for size and color, the RADIOACTIVE WHITE-I label must be as...

2014-10-01

352

Status report on the Holifield Radioactive Ion Beam Project  

Microsoft Academic Search

In July 1992, a project was started to reconfigure the Holifield Heavy Ion Research Facility (HHIRF) to form the Holifield Radioactive Ion Beam Facility (HRIBF). This ORNL project to produce medium-intensity, proton-rich, radioactive ion beams (RIBS) for astrophysics, nuclear physics, and applied research was first described to the SNEAP community at Chalk River in 1992. To briefly review, radioactive ions

M. J. Meigs; G. D. Alton; R. L. Auble

1994-01-01

353

Radioactive waste management in developing and newly industrialized countries  

Microsoft Academic Search

Radioactive wastes are mostly produced in countries with military nuclear programmes. However, non-nuclear weapon countries, with solely commercial nuclear industries, also produce radioactive wastes. Moreover, uranium and thorium mining and milling wastes, as well as other kinds of low-level radioactive wastes like those resulting from radiological accidents, can also be found in developing and newly industrialized countries. The paper discusses

A. S. Paschoa; A. Tranjan Filho

1995-01-01

354

Modification of Poisson Distribution in Radioactive Particle Counting.  

ERIC Educational Resources Information Center

This paper focuses on radioactive practicle counting statistics in laboratory and field applications, intended to aid the Health Physics technician's understanding of the effect of indeterminant errors on radioactive particle counting. It indicates that although the statistical analysis of radioactive disintegration is best described by a Poisson…

Drotter, Michael T.

355

49 CFR 175.701 - Separation distance requirements for packages containing Class 7 (radioactive) materials in...  

...requirements for packages containing Class 7 (radioactive) materials in passenger-carrying...requirements for packages containing Class 7 (radioactive) materials in passenger-carrying...passenger-carrying aircraft between Class 7 (radioactive) materials labeled RADIOACTIVE...

2014-10-01

356

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

E-print Network

of sites · These are sites where water flow is favourable to disposal of radioactive waste. · Identified.haszeldine@ed.ac.uk Radioactive waste Cumbria 6, 7 Sept 2012 10 MRWS asked BGS to map the excluded zones in 2010 mineral or water into the sea and fresh water ....... discharge at or near the coast.s.haszeldine@ed.ac.uk Radioactive waste

357

Biosorption of radioactive thorium by Sargassum filipendula.  

PubMed

In the present work, the biosorption of radioactive thorium was investigated using a dry biomass of Sargassum filipendula as the biosorbent material. Radioactive solutions containing between 2.0 and 500.0 microg thorium were tested by biosorption with S. filipendula, yielding uptake capacities from 20 to 100%, depending on the concentration of the solution. Kinetic studies indicated that equilibrium between the thorium solution and the solid fraction was achieved after three hours of contact and that a second-order model could express the equilibrium kinetics. In order to investigate the maximum biosorption capacity of the biomass an isotherm was done, based on the experimental data, which revealed the maximum uptake capacity to be 2.59 micromol thorium/g biomass. The experimental data fitted well to a Langmuir model, which provided a good correlation between the experimental and predicted thorium uptake values. PMID:16960279

Picardo, Marta Cristina; de Melo Ferreira, Ana Cristina; Augusto da Costa, Antonio Carlos

2006-09-01

358

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

359

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

360

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

361

Solar Powered Radioactive Air Monitoring Stations  

SciTech Connect

Environmental monitoring of ambient air for radioactive material is required as stipulated in the PNNL Site radioactive air license. Sampling ambient air at identified preferred locations could not be initially accomplished because utilities were not readily available. Therefore, solar powered environmental monitoring systems were considered as a possible option. PNNL purchased two 24-V DC solar powered environmental monitoring systems which consisted of solar panels, battery banks, and sampling units. During an approximate four month performance evaluation period, the solar stations operated satisfactorily at an on-site test location. They were subsequently relocated to their preferred locations in June 2012 where they continue to function adequately under the conditions found in Richland, Washington.

Barnett, J. M.; Bisping, Lynn E.; Gervais, Todd L.

2013-10-30

362

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

363

Soluble pig for radioactive waste transfer lines  

SciTech Connect

Flushing transfer pipe after radioactive waste transfers generates thousands of gallons of additional radioactive waste each year at the Hanford site. The use of pneumatic pigging with waste soluble pigs as a means to clear transfer piping may be an effective alternative to raw water flushes. A feasibility study was performed by a group of senior mechanical engineering students for their senior design project as part of their curriculum at Washington State University. The students divided the feasibility study into three sub-projects involving: (1) materials research, (2) delivery system design, and (3) mockup fabrication and testing. The students screened through twenty-three candidate materials and selected a thermoplastic polymer combined 50:50 wt% with sucrose to meet the established material performance criteria. The students also prepared a conceptual design of a remote pneumatic delivery system and constructed a mockup section of transfer pipe for testing the prototype pigs.

Ohl, P.C., Westinghouse Hanford

1996-12-02

364

Comparative alkali washing of simulated radioactive sludge  

SciTech Connect

The treatment of large volumes of radioactive sludge generated from uranium and plutonium recovery processes is a pressing problem in the environmental restoration currently planned at various U.S. Department of Energy sites. This sludge, commonly stored in underground tanks, is mainly in the form of metal oxides or precipitated metal hydroxides and the bulk of this material is nonradioactive. One method being developed to pretreat this waste takes advantage of the amphoteric character of aluminum and other nonradioactive elements. Previous studies have reported on the dissolution of eleven elements from simulated sludge using NaOH solutions up to 6M. This work provides a comparative study using KOH. The effectiveness of the alkali washing as a treatment method to reduce the bulk of radioactive sludge requiring long term isolation will be discussed.

Fugate, G.A.; Ensor, D.D. [Tennessee Technological Univ., Cookeville, TN (United States); Egan, B.Z. [Oak Ridge National Lab., TN (United States)

1996-10-01

365

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

366

Energy distribution mapping of beta radioactive sources  

NASA Astrophysics Data System (ADS)

We have developed a novel procedure in extracting the energy distribution of radioactive beta emitters that has a direct application in detector energy calibration. The method employs a highly non-uniform magnetic field from a permanent dipole magnet and an array of 12 0.1×0.1×31 cm3 scintillating fibers. By scanning the radioactive source across the entire entrance face of the magnet and recording the exit position of the electrons on the dispersive plane, we generated a full 2D map of the energy-position correlation functions. By combining the ADC spectra and a Geant4 simulation of the experimental setup, we were able to reconstruct the entire energy spectrum of a 25 ?Ci90Sr/ 90Y point source used within a 1.4% accuracy.

Guèye, Paul

2007-08-01

367

Standard Model tests with trapped radioactive atoms  

E-print Network

We review the use of laser cooling and trapping for Standard Model tests, focusing on trapping of radioactive isotopes. Experiments with neutral atoms trapped with modern laser cooling techniques are testing several basic predictions of electroweak unification. For nuclear $\\beta$ decay, demonstrated trap techniques include neutrino momentum measurements from beta-recoil coincidences, along with methods to produce highly polarized samples. These techniques have set the best general constraints on non-Standard Model scalar interactions in the first generation of particles. They also have the promise to test whether parity symmetry is maximally violated, to search for tensor interactions, and to search for new sources of time reversal violation. There are also possibilites for exotic particle searches. Measurements of the strength of the weak neutral current can be assisted by precision atomic experiments using traps of small numbers of radioactive atoms, and sensitivity to possible time-reversal violating electric dipole moments can be improved.

J. A. Behr; G. Gwinner

2008-10-22

368

Handbook of high-level radioactive waste transportation  

SciTech Connect

The High-Level Radioactive Waste Transportation Handbook serves as a reference to which state officials and members of the general public may turn for information on radioactive waste transportation and on the federal government`s system for transporting this waste under the Civilian Radioactive Waste Management Program. The Handbook condenses and updates information contained in the Midwestern High-Level Radioactive Waste Transportation Primer. It is intended primarily to assist legislators who, in the future, may be called upon to enact legislation pertaining to the transportation of radioactive waste through their jurisdictions. The Handbook is divided into two sections. The first section places the federal government`s program for transporting radioactive waste in context. It provides background information on nuclear waste production in the United States and traces the emergence of federal policy for disposing of radioactive waste. The second section covers the history of radioactive waste transportation; summarizes major pieces of legislation pertaining to the transportation of radioactive waste; and provides an overview of the radioactive waste transportation program developed by the US Department of Energy (DOE). To supplement this information, a summary of pertinent federal and state legislation and a glossary of terms are included as appendices, as is a list of publications produced by the Midwestern Office of The Council of State Governments (CSG-MW) as part of the Midwestern High-Level Radioactive Waste Transportation Project.

Sattler, L.R.

1992-10-01

369

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

370

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

371

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

372

Procedures for radioactive I-125 seed implants  

SciTech Connect

Typical safety procedures and guidelines for the use of radioactive I-125 seed implant are presented. Topics covered include: Physical properties, management and planning of I-125, source logging, source transportation, source accounting during and after implant, room monitoring, recording, dosimetry films, nursing procedures, discharge of patient. These guidelines have been found to be of practical value for personnel involved with the implant to ensure compliance with the regulations, but are not necessarily the only procedures that could be utilized.

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

1988-12-01

373

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

374

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

375

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

376

Gain stabilization for radioactivity well logging apparatus  

SciTech Connect

A new and improved gain stabilization system for radioactivity well logging apparatus is of the type having a scintillation crystal and optically coupled photomultiplier in a sonde to detect radiation in the borehole and formation elements in response to neutron bombardment. The gain stabilization system includes a light emitting diode driven by a pulser and furnishing scintillations to the photomultiplier, resulting in a stabilization pulse which is furnished to electronic circuitry at the surface for stabilization purposes.

Whatley, H.A.

1980-09-02

377

Cross-section measurements for radioactive samples  

Microsoft Academic Search

The measurement of (n,p), (n,..cap alpha..) and (n,..gamma..) cross sections for radioactive nuclei is of interest to both nuclear physics and astrophysics. For example, using these reactions, properties of levels in nuclei at high excitation energies, which are difficult or impossible to study using other reactions, can be investigated. Also, reaction rates for both big-bang and stellar nucleosynthesis can be

P. E. Koehler; H. A. OBrien

1988-01-01

378

Mound Laboratory Cyclone Incinerator for radioactive waste  

Microsoft Academic Search

The Cyclone Incinerator at Mound Laboratory, funded by the Division of Waste Management, Production and Reprocessing of ERDA, is capable of handling various types of combustible radioactive wastes, either by batch or by continuous feed. In batch operation, the burn chamber is a 55-gallon drum which permits the in-situ burning of wastes directly in the storage drum. Off-the-shelf components have

S. S. Freeman; L. M. Klingler; D. F. Luthy; J. E. Todd

1977-01-01

379

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

380

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

381

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

382

Transient and secular radioactive equilibrium revisited  

E-print Network

The two definitions of radioactive equilibrium are revisited in this paper. The terms activity equilibrium and effective life equilibrium are proposed to take the place of currently used terms transient equilibrium and secular equilibrium. The proposed new definitions have the advantage of providing a clearer physics meaning. Besides the well known instant activity equilibrium, another class of exact effective life-time equilibrium is also discussed in this letter.

Zhang, Qinghui; Amols, Howard

2014-01-01

383

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

384

Scrap metals industry perspective on radioactive materials.  

PubMed

With more than 80 reported/confirmed accidental melts worldwide since 1983 and still counting, potential contamination by radioactive materials remains as a major concern among recycled scrap and steel companies. Some of these events were catastrophic and have cost the industry millions of dollars in business and, at the same time, resulted in declining consumer confidence. It is also known that more events with confirmed radioactive contamination have occurred that involve mining of old steel slag and skull dumps. Consequently, the steel industry has since undergone massive changes that incurred unprecedented expenses through the installation of radiation monitoring systems in hopes of preventing another accidental melt. Despite such extraordinary efforts, accidental melts continue to occur and plague the industry. One recent reported/confirmed event occurred in the Republic of China in 2004, causing the usual lengthy shutdown for expensive decontamination efforts before the steel mill could resume operations. With this perspective in mind, the metal industry has a long-standing opposition to the release of radioactive materials of any kind to commerce for fear of contamination and the potential consequences. PMID:17033460

Turner, Ray

2006-11-01

385

BEARS: Radioactive ion beams at LBNL  

SciTech Connect

BEARS (Berkeley Experiments with Accelerated Radioactive Species) 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 inch 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 inch 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 inch 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.

Powell, J.; Guo, F.Q. [Lawrence Berkeley National Lab., CA (United States); Haustein, P.E. [Brookhaven National Lab., Upton, NY (United States). Chemistry Dept.] [and others

1998-07-01

386

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

387

Radioactive waste management in the former USSR  

SciTech Connect

Radioactive waste materials--and the methods being used to treat, process, store, transport, and dispose of them--have come under increased scrutiny over last decade, both nationally and internationally. Nuclear waste practices in the former Soviet Union, arguably the world's largest nuclear waste management system, are of obvious interest and may affect practices in other countries. In addition, poor waste management practices are causing increasing technical, political, and economic problems for the Soviet Union, and this will undoubtedly influence future strategies. this report was prepared as part of a continuing effort to gain a better understanding of the radioactive waste management program in the former Soviet Union. the scope of this study covers all publicly known radioactive waste management activities in the former Soviet Union as of April 1992, and is based on a review of a wide variety of literature sources, including documents, meeting presentations, and data base searches of worldwide press releases. The study focuses primarily on nuclear waste management activities in the former Soviet Union, but relevant background information on nuclear reactors is also provided in appendixes.

Bradley, D.J.

1992-06-01

388

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

389

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

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

390

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

391

Novel Solvent for the Simultaneous recovery of Radioactive Nuclides from Liquid Radioactive Wastes  

SciTech Connect

The present invention relates to solvents, and methods, for selectively extracting and recovering radionuclides, especially cesium and strontium, rare earths and actinides from liquid radioactive wastes. More specifically, the invention relates to extracting agent solvent compositions comprising complex organoboron compounds, substituted polyethylene glycols, and neutral organophosphorus compounds in a diluent. The preferred solvent comprises a chlorinated cobalt dicarbollide, diphenyl-dibutylmethylenecarbamoylphosphine oxide, PEG-400, and a diluent of phenylpolyfluoroalkyl sulfone. The invention also provides a method of using the invention extracting agents to recover cesium, strontium, rare earths and actinides from liquid radioactive waste.

Romanovskiy, Valeriy Nicholiavich; Smirnov, Lgor V.; Babain, Vasiliy A.; Todd, Terry A.; Brewer, Ken N.

1999-10-07

392

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

393

Active remote detection of radioactivity based on electromagnetic signatures  

NASA Astrophysics Data System (ADS)

This paper presents a new concept for the remote detection of radioactive materials. The concept is based on the detection of electromagnetic signatures in the vicinity of radioactive material and can enable stand-off detection at distances greater than 100 m. Radioactive materials emit gamma rays, which ionize the surrounding air. The ionized electrons rapidly attach to oxygen molecules forming O2- ions. The density of O2- around radioactive material can be several orders of magnitude greater than background levels. The elevated population of O2- extends several meters around the radioactive material. Electrons are easily photo-detached from O2- ions by laser radiation. The photo-detached electrons, in the presence of laser radiation, initiate avalanche ionization which results in a rapid increase in electron density. The rise in electron density induces a frequency modulation on a probe beam, which becomes a direct spectral signature for the presence of radioactive material.

Sprangle, P.; Hafizi, B.; Milchberg, H.; Nusinovich, G.; Zigler, A.

2014-01-01

394

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

395

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

396

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

397

Astrophysics experiments with radioactive beams at ATLAS  

NASA Astrophysics Data System (ADS)

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.; Savard, G.

2014-04-01

398

Radioactive heat sources in the lunar interior.  

NASA Technical Reports Server (NTRS)

Published models for the moon's thermal history typically imply present day central temperatures far too high to be consistent with the recently proposed lunar temperature profile of Sonett et al. (1971). Furthermore, chemical data on Apollo samples show that the moon is depleted relative to chondrites in volatile elements, and possibly enriched relative to chondrites in refractory elements. Additional thermal models have therefore been investigated in order to set upper limits on lunar radioactivity consistent with the proposed temperature distribution. For an initially cold, uniform moon, devoid of potassium, a maximum uranium content of 23 parts per billion is inferred.

Hays, J. F.

1972-01-01

399

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

400

Preparation and characterization of radioactive castanospermine  

SciTech Connect

A procedure for the preparation of tritiated castanospermine is described. The tritiated alkaloid was shown to be chromatographically identical to the native material and exhibited the same inhibitory properties. Radiolabeled castanospermine tightly bound to purified intestinal sucrase. Following gel chromatography, each mole of enzyme was shown to have bound 1 mol of the radioactive alkaloid. Cultured MDCK cells were also shown to take up the labeled castanospermine. This compound should be a useful tool in the investigation of enzymes that are responsible for the processing of glycoprotein oligosaccharides.

Keenan, R.W.; Pan, Y.T.; Elbein, A.D.

1987-06-01

401

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, D.G.

1993-03-30

402

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

403

Electronic Denitration Savannah River Site Radioactive Waste  

SciTech Connect

Electrochemical destruction of nitrate in radioactive Savannah River Site Waste has been demonstrated in a bench-scale flow cell reactor. Greater than 99% of the nitrate can be destroyed in either an undivided or a divided cell reactor. The rate of destruction and the overall power consumption is dependent on the cell configuration and electrode materials. The fastest rate was observed using an undivided cell equipped with a nickel cathode and nickel anode. The use of platinized titanium anode increased the energy requirement and costs compared to a nickel anode in both the undivided and divided cell configurations.

Hobbs, D.T.

1995-04-11

404

World new facilities for radioactive isotope beams  

NASA Astrophysics Data System (ADS)

The use of unstable nuclei in the form of energetic beams for nuclear physics studies is now entering into a new era. "New-generation" facilities are either in operation, under construction or being planned. They are designed to provide radioactive isotope (RI) beams with very high intensities over a wide range of nuclides. These facilities are expected to provide opportunities to study nuclear structure, astrophysical nuclear processes and nuclear matter with large proton-neutron imbalance in grate detail. This article reports on the current status of such new-generation RI-beam facilities around the world.

Motobayashi, Tohru

2014-03-01

405

2p radioactivity studies with a TPC  

SciTech Connect

After the discovery of two-proton radioactivity in 2002, an important effort has been made in order to observe each emitted particle individually. Energy and angular correlations between the protons should reveal details about the mechanism of this exotic decay mode. In this framework, an experiment has been performed at LISE/GANIL, where the two protons emitted in the decay of {sup 54}Zn have been individually observed for the first time. Angular and energy correlations were determined and allowed a first comparison with theoretical predictions.

Ascher, P.; Audirac, L.; Blank, B.; Delalee, F.; Demonchy, C. E.; Giovinazzo, J.; Leblanc, S.; Pedroza, J.-L.; Pibernat, J.; Serani, L. [Centre d'Etudes Nucleaires de Bordeaux Gradignan-Universite Bordeaux 1-UMR 5797 CNRS/IN2P3, Chemin du Solarium, BP120, 33175 Gradignan (France); Adimi, N. [Centre d'Etudes Nucleaires de Bordeaux Gradignan-Universite Bordeaux 1-UMR 5797 CNRS/IN2P3, Chemin du Solarium, BP120, 33175 Gradignan (France); Faculte de Physique, USTHB, B.P.32, El Alia, 16111 Bab Ezzouar, Alger (Algeria); Borcea, C.; Companis, I. [National Institute for Physics and Nuclear Engineering, P.O. Box MG6, Bucharest-Margurele (Romania); Brown, B. A. [Department of Physics and Astronomy, and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Oliveira Santos, F. de; Grevy, S.; Thomas, J.-C. [Grand Accelerateur National d'Ions Lourds, CEA/DSM-CNRS/IN2P3, 14076 Caen Cedex05 (France); Grigorenko, L. V.; Perrot, L. [Flerov Laboratory of Nuclear Reactions, JINR, Dubna 141980 (Russian Federation); Srivastava, P. [Nuclear Physics Group, Department of Physics, University of Allahabad (India); and others

2011-11-30

406

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

407

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

408

Particle beam generator using a radioactive source  

SciTech Connect

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, D.G.

1991-12-31

409

Data base for radioactive waste management: review of low-level radioactive waste disposal history  

Microsoft Academic Search

This document is prepared in three volumes and provides part of the technical support to the draft environmental impact statement (NUREG-0782) on a proposed regulation, 10CFR Part 61, setting forth licensing requirements for land disposal of low level radioactive waste. Volume 1 is a summary and analysis of the history of low level waste disposal at both commercial and government

J. J. Clancy; D. F. Gray; O. I. Oztunali

1981-01-01

410

"Radio-Active" Learning: Visual Representation of Radioactive Decay Using Dice  

ERIC Educational Resources Information Center

The idea of using a dice game to simulate radioactive decay is not new. However, modern pedagogy encourages, if not requires, us to provide multiple representations and visualizations for our students. The advantage of interactive engagement methods also has been made clear. Here we describe a highly visual and interactive use of dice to develop…

Klein, Lynda; Kagan, David

2010-01-01

411

Robust technique using an imaging plate to detect environmental radioactivity.  

PubMed

The Fukushima Daiichi Nuclear Power Plant was severely damaged by the Great East Japan Earthquake on 11 March 2011. Consequently, a large amount of radioactive material was accidentally released. Recently, the focus has been on quantification of environmental radioactive material. However, conventional techniques require complicated and expensive measurement equipment. In this research, the authors developed a simple method to detect environmental radioactive material with an imaging plate (IP). Two specific measurement subjects were targeted: measurements for the depth distribution of radioactive material in soil and surface contamination of a building roof. For the measurement of depth distribution of radioactive material in soil, the authors ascertained that the concentration of environmental radioactivity was highest at 5 cm below the surface, and it decreased with depth. For the measurement of surface contamination of the building roof, the authors created a contamination map of the building roof. The detector developed could contact the ground directly, and unlike other survey meters, it was not influenced by peripheral radioactivity. In this study, the authors verified the feasibility of measurement of environmental radioactivity with an IP. Although the measured values of the IP were relative, further work is planned to perform evaluations of absolute quantities of radioactive material. PMID:23439139

Isobe, Tomonori; Mori, Yutaro; Takada, Kenta; Sato, Eisuke; Sakurai, Hideyuki; Sakae, Takeji

2013-04-01

412

Data bases concerning the transportation of radioactive materials  

SciTech Connect

This paper will describe two data bases which provide supporting information on radioactive material transport experience in the United States. The Radioactive Material Incident Report (RMIR) documents accident/incident experience from 1971 to the present from data acquired from the US Department of Transportation (DOT) and the Nuclear Regulatory Commission (NRC). The Radioactive Material Postnotification (RAMPOST) data base documents the shipments that have taken place for Highway Route Controlled Quantities (HRCQ) of radioactive material. HRCQ shipments are post notified (that is, after the shipment) to the DOT.

Cashwell, C [Applied Physics, Inc., Albuquerque, NM (United States); McClure, J D [Sandia National Labs., Albuquerque, NM (United States)

1992-03-01

413

Titanate-based adsorbents for radioactive ions entrapment from water  

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

414

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

415

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

SciTech Connect

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. II; Nazarewicz, W.; Sinclair, J. W.; Stracener, D. W.; Tatum, B. A. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2011-06-01

416

Radioactive materials in biosolids : dose modeling.  

SciTech Connect

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 transport of radioactivity from sludge into the local environment and the subsequent exposure of humans. A stochastic environmental pathway model was applied separately to seven hypothetical, generic sludge-release scenarios, leading to the creation of seven tables of Dose-to-Source Ratios (DSR), which can be used in translating from specific activity in sludge into dose to an individual. These DSR values were then combined with the results of an ISCORS survey of sludge and ash at more than 300 publicly owned treatment works, to explore the potential for radiation exposure of sludge workers and members of the public. This paper provides a brief overview of the pathway modeling methodology employed in the exposure and dose assessments and discusses technical aspects of the results obtained.

Wolbarst, A. B.; Chiu, W. A; Yu, C.; Aiello, K.; Bachmaier, J. T.; Bastian, R. K.; Cheng, J. -J.; Goodman, J.; Hogan, R.; Jones, A. R.; Kamboj, S.; Lenhartt, T.; Ott, W. R.; Rubin, A.; Salomon, S. N.; Schmidt, D. W.; Setlow, L. W.; Environmental Science Division; U.S. EPA; Middlesex County Utilities Authority; U.S. DOE; U.S. NRC; NE Ohio Regional Sewer District

2006-01-01

417

Field tests using radioactive matter 2.  

PubMed

Results of field tests with explosive dispersal of a radioactive substance (RaS) are presented. The paper deals with tests exploiting artificial obstacles as a continuation and expansion of the tests used in this study performed in free area described previously. The essential goal of the tests was to estimate the distribution of the released RaS in the case of intentional abuse of radioactive sources and to get a set of data applicable to testing physical or mathematical models of propagation. Effects of different geometrical and meteorological conditions on the distribution of dispersed RaS were studied via the assessment of dose rate, surface and volume activities, aerosol mass and activity aerodynamic diameters. The principal results can be summarised as follows: the prevalent proportion of the activity of the radionuclide dispersed by an explosion (born by the blast wave and by air convection) is transferred to the detection system/collecting pads essentially within the first minute. Enhanced aerosol mass concentrations were also detected within the same period. The RaS carried by the blast wave passed through the polygon (50 m) within <1 s. An expected crucial impact of meteorological conditions at the moment of the explosion and shortly after was proved by the tests. PMID:22923250

Rulik, P; Prouza, Z; Hovorka, J; Beckova, V; Cespirova, I; Fronka, A; Helebrant, J; Hulka, J; Kuca, P; Skrkal, J

2013-04-01

418

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

419

Radioactive-waste incineration at Purdue University  

SciTech Connect

A study conducted at Purdue University to evaluate the feasibility of using a small (45 kg/h), inexpensive (less than $10K) incinerator for incinerating low-level radioactive waste is described. An oil-fired, dual-chamber pathological waste incinerator was installed on a 12.7-cm-thick concrete floor in a metal quonset building. A standard EPA Method 5 sampling train was used to obtain stack samples. Also, stack gas velocity was measured with a type 5 pitot tube; stack temperature was measured with a thermocouple and pyrometer. The incinerator was tested for emissions from incineration of laboratory animal carcasses, liquid scintillation fluid, and trash. Emissions measured were particulates, SO/sub x/, NO/sub x/, Cl, CO, CO/sub 2/, H/sub 2/O, and unburned hydrocarbons in the particulate fraction. Three analyses were then averaged to arrive at the final determinations. Results of the study demonstrated the feasibility and cost-effectiveness of incinerating radioactive animal carcasses and liquid scintillation fluids, since emissions from those waste types were within EPA and State of Indiana limits. However, emissions from burning of trash exceeded State of Indiana limits. Therefore, incineration of trash alone, particularly if it contains glass or significant amounts of plastic, is not a recommended use of the tested equipment.

Not Available

1982-11-01

420

Storage rings for radioactive ion beams  

NASA Astrophysics Data System (ADS)

Storage rings for radioactive heavy ions can be applied for a wide range of experiments in atomic and nuclear physics. The rare isotope beams are produced in flight via fragmentation or fission of high-intensity primary ions and they circulate in the storage ring at moderately relativistic energies (typically between 0.1 GeV/u up to 1 GeV/u). Due to their production mechanism they are usually highly charged or even fully stripped. The circulating radioactive heavy ion beams can be used to measure nuclear properties such as masses and decay times, which, in turn, can depend strongly on the ionic charge state. The storage rings must have large acceptances and dynamic apertures. The subsequent application of stochastic precooling of the secondary ions which are injected with large transverse and longitudinal emittances, and electron cooling to reach very high phase space densities has turned out to be a helpful tool for experiments with short-lived ions having lifetimes down to a few seconds. Some of these experiments have already been performed at the experimental storage ring ESR at GSI. The storage ring complex of the FAIR project is intended to enhance significantly the range of experimental possibilities. It is planned to extend the scope of experimental possibilities to collisions with electron or antiproton beams.

Nolden, F.; Dimopoulou, C.; Dolinskii, A.; Steck, M.

2008-10-01

421

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

422

25 Years of Radioactive Beams at TRIUMF  

NASA Astrophysics Data System (ADS)

It has been 25 years since the first radioactive beams were produced at TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics. These first beams, ^37,38K and ^25Na, were produced using the innovative TISOL (Test Isotope Separator On-Line) prototype facility and started the path to the present ISAC (Isotope Separator and ACcelerator) facility, considered one of the best accelerated radioactive beam facilities in the world today, and the new ARIEL (Advanced Rare IsotopE Laboratory) facility, presently under construction. It is time to acknowledge the role TISOL played in opening this path, and explore some of its achievements during its years of operation. TISOL enabled experiments measuring the decay of very short-lived isotopes, including information needed for energy production in novae, an atom trap to measure neutrino momenta from beta decay, a key experiment in understanding the production of carbon and oxygen in the Universe, and other studies. This presentation will give a short history of TISOL, aspects of its original technical characteristics and a summary of its scientific achievements.

D'Auria, John M.

2012-10-01

423

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

424

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

425

77 FR 36017 - Regulatory Guide 7.3, Procedures for Picking Up and Receiving Packages of Radioactive Material  

Federal Register 2010, 2011, 2012, 2013

...Packages of Radioactive Material.'' The...Compliance with Packaging Requirements...Receipt of Radioactive Material'' which...Compliance with Packaging Requirements...Receipt of Radioactive Material.''...

2012-06-15

426

INEEL Radioactive Liquid Waste Reduction Program  

SciTech Connect

Reduction of radioactive liquid waste, much of which is Resource Conservation and Recovery Act (RCRA) listed, is a high priority at the Idaho National Technology and Engineering Center (INTEC). Major strides in the past five years have lead to significant decreases in generation and subsequent reduction in the overall cost of treatment of these wastes. In 1992, the INTEC, which is part of the Idaho National Environmental and Engineering Laboratory (INEEL), began a program to reduce the generation of radioactive liquid waste (both hazardous and non-hazardous). As part of this program, a Waste Minimization Plan was developed that detailed the various contributing waste streams, and identified methods to eliminate or reduce these waste streams. Reduction goals, which will reduce expected waste generation by 43%, were set for five years as part of this plan. The approval of the plan led to a Waste Minimization Incentive being put in place between the Department of Energy–Idaho Office (DOE-ID) and the INEEL operating contractor, Lockheed Martin Idaho Technologies Company (LMITCO). This incentive is worth $5 million dollars from FY-98 through FY-02 if the waste reduction goals are met. In addition, a second plan was prepared to show a path forward to either totally eliminate all radioactive liquid waste generation at INTEC by 2005 or find alternative waste treatment paths. Historically, this waste has been sent to an evaporator system with the bottoms sent to the INTEC Tank Farm. However, this Tank Farm is not RCRA permitted for mixed wastes and a Notice of Non-compliance Consent Order gives dates of 2003 and 2012 for removal of this waste from these tanks. Therefore, alternative treatments are needed for the waste streams. This plan investigated waste elimination opportunities as well as treatment alternatives. The alternatives, and the criteria for ranking these alternatives, were identified through Value Engineering meetings with all of the waste generators. The most promising alternatives were compared by applying weighting factors to each based on how well the alternative met the established criteria. From this information, an overall ranking of the various alternatives was obtained and a path forward recommended.

Tripp, Julia Lynn; Archibald, Kip Ernest; Argyle, Mark Don; Demmer, Ricky Lynn; Miller, Rose Anna; Lauerhass, Lance

1999-03-01

427

The importance of U-series dating for understanding the Quaternary geology  

E-print Network

at the con- sequential geomorphology and sedimentology. Of particular importance to the project significantly more developed sedimentology. The sedimentology of the Kyrenia Terrace is a relatively mature

428

Stratigraphy and U-series geochronology of Late Quaternary megatsunami deposits in Hawaii  

NASA Astrophysics Data System (ADS)

Our previous work on Kohala, Hawaii, established that the elevated marine basalt boulder conglomerates found there represent at least one, and probably two megatsunami events in the late Pleistocene. Together with the evidence for giant submarine landslides off western Hawaii island from contemporaneous flank failures of Mauna Loa volcano and identical sequences of submarine terraces off the NW coasts of the islands of Hawaii and Lanai, our hydrodynamic modeling indicates that all islands in the Hawaiian chain must have been affected by these giant waves. We present new dating of these deposits on Hawaii, Lanai and Maui islands together with stratigraphic interpretations of their impacts and origins. We used uranium-series dating of in situ coral clasts to constrain the age of the marine conglomerates, using multiple ion counting- inductively coupled plasma-mass spectrometry techniques, and used 87Sr/86Sr ratios of carbonates to help delineate their origins where marine fossils were absent. Southern Lanai records at least four megatsunami events: at 110 ka, 135 ka, 200 ka, and 240 ka, that likely correspond to the Alika phase 2, Alika phase 1, and two stages of the older South Kona giant submarine landslides. These event dates also correspond to O- isotopic stages 5d, 5e, 7a and 7b, and are in agreement with a changing-climate trigger mechanism for volcanic flank collapse proposed in previous work by ourselves and others. On southern Lanai, there is evidence for two megatsunami deposits in stratigraphic succession in the vicinity of Manele Bay, as well as higher-elevation deposits there containing reworked coral-bearing debris from two older megatsunami events. Coral clasts have been dated from all four events within the high-elevation gullies within Kaluakapo Crater on southern Lanai in this study and Moore and Moore (1988), indicating enormous runups to more than 626 m and wave heights of more than 240 m there that are in agreement with the latest hydrodynamic modeling. There is presently evidence for the 110 ka event on Hawaii, Lanai and West Maui, and for the 200 ka and 240 ka events on the islands of Lanai, Molokai and probably Hawaii. The 135 ka event has so far only been recorded on southern Lanai, but will likely turn up in future work elsewhere.

McMurtry, G. M.; Fryer, G. J.; Tappin, D. R.; Fietzke, J.

2008-12-01

429

U-series dating of Hoxnian interglacial deposits at Marks Tey, Essex, England  

NASA Astrophysics Data System (ADS)

A U-Th dating study was carried out on the authigenic carbonate component of interglacial lake sediments at Marks Tey, Essex, England. Isochron methods were necessary because of the presence of non-carbonate detritus. Calculated dates around the limit of the U-Th method were obtained for two horizons. Error limits were determined by Monte Carlo sampling from the normal distributions of errors in the isotope ratios. Comparison of the resulting empirical distribution functions with the marine oxygen isotope time-scale indicates with 87% confidence that the Marks Tey sediments correlate with OIS 11 or some older stage. As the Marks Tey deposits rest without stratigraphical break on Anglian till, and can be firmly correlated with the Hoxnian interglacial type site at Hoxne, Suffolk, England, this result implies that the Anglian glaciation took place in OIS 12 and the Hoxnian Stage of the British chronostratigraphy commenced in OIS 11.

Rowe, P. J.; Atkinson, T. C.; Turner, C.

1999-12-01

430

U-Series Chronology of Lacustrine Deposits in Death Valley, California  

Microsoft Academic Search

Uranium-series dating on a 186-m core (DV93-1) drilled from Badwater Basin in Death Valley, California, and on calcareous tufas from nearby strandlines shows that Lake Manly, the lake that periodically flooded Death Valley during the late Pleistocene, experienced large fluctuations in depth and chemistry over the last 200,000 yr. Death Valley has been occupied by a long-standing deep lake, perennial

Teh-Lung Ku; Shangde Luo; Tim K. Lowenstein; Jianren Li; Ronald J. Spencer

1998-01-01

431

U-series dating of speleothems from the Sierra del Endrinal (Grazalema Mountains, S Spain).  

PubMed

The uranium-series method is applied to date relic flowstone from karstic mountains in the south of Spain. Geomorphological mapping shows three staircased erosion surfaces with a typical karst landform. Exhumed flowstones fill the surficial palaeosinkholes and open fractures. Some of the samples analysed were impure carbonates consequently the leachate-leachate method was used to obtain activity ratios in the carbonate fraction. The ages obtained range from 34.4 ky to 266 ky and are grouped in four periods: 30-50 ky, 90-110 ky, 150 ky and 230-270 ky. All these periods are related to the warm climate oxygen isotope stages 3 and 5. Practically all locations present secular equilibrium in uranium isotopes. PMID:22854172

Alcaraz-Pelegrina, J M; Martínez-Aguirre, A; Rodríguez-Vidal, J

2012-10-01

432

1529-6466/00/0052-0001$05.00 Introduction to U-series Geochemistry  

E-print Network

4 Place Jussieu 75252 Paris cedex 05, France 2 Department of Earth Sciences Wills Memorial Building University of Bristol Bristol, BS8 1RJ, United Kingdom 3 Department of Earth Sciences University of Oxford-SERIES GEOCHEMISTRY During the last century, the Earth Sciences underwent two major revolutions in understanding

Henderson, Gideon

433

Sediment transport time measured with U-Series isotopes: Resultsfrom ODP North Atlantic Drill Site 984  

SciTech Connect

High precision uranium isotope measurements of marineclastic sediments are used to measure the transport and storage time ofsediment from source to site of deposition. The approach is demonstratedon fine-grained, late Pleistocene deep-sea sediments from Ocean DrillingProgram Site 984A on the Bjorn Drift in the North Atlantic. The sedimentsare siliciclastic with up to 30 percent carbonate, and dated by sigma 18Oof benthic foraminifera. Nd and Sr isotopes indicate that provenance hasoscillated between a proximal source during the last three interglacialperiods volcanic rocks from Iceland and a distal continental sourceduring glacial periods. An unexpected finding is that the 234U/238Uratios of the silicate portion of the sediment, isolated by leaching withhydrochloric acid, are significantly less than the secular equilibriumvalue and show large and systematic variations that are correlated withglacial cycles and sediment provenance. The 234U depletions are inferredto be due to alpha-recoil loss of234Th, and are used to calculate"comminution ages" of the sediment -- the time elapsed between thegeneration of the small (<_ 50 mu-m) sediment grains in the sourceareas by comminution of bedrock, and the time of deposition on theseafloor. Transport times, the difference between comminution ages anddepositional ages, vary from less than 10 ky to about 300 to 400 ky forthe Site 984A sediments. Long transport times may reflect prior storagein soils, on continental shelves, or elsewhere on the seafloor. Transporttime may also be a measure of bottom current strength. During the mostrecent interglacial periods the detritus from distal continental sourcesis diluted with sediment from Iceland that is rapidly transported to thesite of deposition. The comminution age approach could be used to dateQuaternary non-marine sediments, soils, and atmospheric dust, and may beenhanced by concomitant measurement of 226Ra/230Th, 230Th/234U, andcosmogenic nuclides.

DePaolo, Donald J.; Maher, Kate; Christensen, John N.; McManus,Jerry

2006-06-05

434

U-series dating of Paleolithic art in 11 caves in Spain.  

PubMed

Paleolithic cave art is an exceptional archive of early human symbolic behavior, but because obtaining reliable dates has been difficult, its chronology is still poorly understood after more than a century of study. We present uranium-series disequilibrium dates of calcite deposits overlying or underlying art found in 11 caves, including the United Nations Educational, Scientific, and Cultural Organization (UNESCO) World Heritage sites of Altamira, El Castillo, and Tito Bustillo, Spain. The results demonstrate that the tradition of decorating caves extends back at least to the Early Aurignacian period, with minimum ages of 40.8 thousand years for a red disk, 37.3 thousand years for a hand stencil, and 35.6 thousand years for a claviform-like symbol. These minimum ages reveal either that cave art was a part of the cultural repertoire of the first anatomically modern humans in Europe or that perhaps Neandertals also engaged in painting caves. PMID:22700921

Pike, A W G; Hoffmann, D L; García-Diez, M; Pettitt, P B; Alcolea, J; De Balbín, R; González-Sainz, C; de las Heras, C; Lasheras, J A; Montes, R; Zilhão, J

2012-06-15

435

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

436

Volume reduction of low-level radioactive wastes  

Microsoft Academic Search

A process is described for reducing the volume of a low-level radioactive liquid waste containing a compound of an element selected from the group consisting of I, Cs, Co and Mn. The process consists of: introducing the low-level radioactive liquid waste in the form of a finely atomized spray into a spray drying zone and contacting it with a hot

R. L. Gray; L. F. Grantham

1986-01-01

437

Institutional options for state management of low level radioactive waste  

Microsoft Academic Search

This paper concerns ''institutional'' (legal, organizational, and political) aspects of low-level radioactive waste management. Its point of departure is the Low-Level Radioactive Waste Policy Act of 1980. With federal law and political consensus now behind the policy of state responsibility for low level waste, the question becomes, how is this new policy to be implemented. The questions of policy implementation

1981-01-01

438

Low-level radioactive waste disposal facility closure  

Microsoft Academic Search

Part I of this report describes and evaluates potential impacts associated with changes in environmental conditions on a low-level radioactive waste disposal site over a long period of time. Ecological processes are discussed and baselines are established consistent with their potential for causing a significant impact to low-level radioactive waste facility. A variety of factors that might disrupt or act

G. J. White; T. W. Ferns; M. D. Otis; S. T. Marts; M. S. DeHaan; R. G. Schwaller

1990-01-01

439

Combustible radioactive waste treatment by incineration and chemical digestion  

NASA Astrophysics Data System (ADS)

Present and planned combustible radioactive waste treatment systems in the U.S. are reviewed. Advantages and disadvantages of various systems are considered. Design waste streams are discussed in relation to waste composition, radioactive contaminants by amount and type, and special operating problems caused by the waste.

Stretz, L. A.; Allen, C. R.; Crippen, M. D.

1980-05-01

440

Transporting radioactive materials: Q & A to your questions  

SciTech Connect

Over 2 million packages of radioactive materials are shipped each year in the United States. These shipments are carried by trucks, trains, ships, and airplanes every day just like other commodities. Compliance with Federal regulations ensures that radioactive materials are transported safely. Proper packaging is the key to safe shipment. Package designs for radioactive materials must protect the public and the environment even in case of an accident. As the level of radioactivity increases, packaging design requirements become more stringent. Radioactive materials have been shipped in this country for more than 40 years. As with other commodities, vehicles carrying these materials have been involved in accidents. However, no deaths or serious injuries have resulted from exposure to the radioactive contents of these shipments. People are concerned about how radioactive shipments might affect them and the environment. This booklet briefly answers some of the commonly asked questions about the transport of radioactive materials. More detailed information is available from the sources listed at the end of this booklet.

Not Available

1993-04-01

441

Environmental impact of radioactive silver released from nuclear power plant  

Microsoft Academic Search

Radioactive silver 110mAg is not a fission product, but as a contaminant originating from Chernobyl, was registered in many European countries. The environmental impact of radioactive silver was specially expressed in the process of obtaining copper and noble metals from ores originating from opencast mines. Direct consequence was contaminated metal silver in the period of several years after the Chernobyl

Ž. Vukovi?

2002-01-01

442

Continuous Recording of Bird Nesting Visits using Radioactive Tagging  

Microsoft Academic Search

IN view of the successful application of radioactive tagging in entomology in Central Africa, I have investigated the potentiality of the method as a tagging technique in ornithology. Because the detection range of small amounts of radioactive material is only of the order of feet, the method requires the close proximity of the labelled bird and the radiation detector. It

P. R. B. Ward

1967-01-01

443

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

444

Combustible radioactive waste treatment by incineration and chemical digestion  

SciTech Connect

A review is given of present and planned combustible radioactive waste treatment systems in the US. Advantages and disadvantages of various systems are considered. Design waste streams are discussed in relation to waste composition, radioactive contaminants by amount and type, and special operating problems caused by the waste.

Stretz, L.A.; Crippen, M.D.; Allen, C.R.

1980-05-28

445

TYPES AND ORE RESERVES OF CANADIAN RADIOACTIVE DEPOSITS  

Microsoft Academic Search

Figures for production of uranium in Canada and for reserves of ; radioactive ores are summarized. A revised classification and a short discussion ; of geological types of productive and nonproductive radioactive deposits are ; presented. Low-grade thorium deposits are known to occur in large tonnages, ; particularly at Blind River. The ores of this region as a whole, although

J. W. Grittith; A. H.. Lang

1959-01-01

446

Transneuronal Transfer of Radioactivity in the Central Nervous System  

Microsoft Academic Search

After injection of tritiated amino acid into the mouse eye, radioactivity appeared in the contralateral visual cortex, indicating that some material had been transferred from optic axons to lateral geniculate neurons. The radioactivity in the cortex was about 2 percent of that arriving in the geniculate, and most of it was contained in material that appeared to be protein.

Bernice Grafstein

1971-01-01

447

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

448

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

449

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

450

An Excel[TM] Model of a Radioactive Series  

ERIC Educational Resources Information Center

A computer model of the decay of a radioactive series, written in Visual Basic in Excel[TM], is presented. The model is based on the random selection of cells in an array. The results compare well with the theoretical equations. The model is a useful tool in teaching this aspect of radioactivity. (Contains 4 figures.)

Andrews, D. G. H.

2009-01-01

451

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.

452

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

453

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

454

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

455

Radioactivity concentration in soil in Jeddah area, Saudi Arabia  

Microsoft Academic Search

The level of radioactivity in soil was measured in Jeddah area. Cs concentration was determined as an indication of the degree of contamination from Chernobyl accident. Natural uranium and thorium radioactive series, as well as K concentration levels have been determined. These radioisotopes contribute to the background exposure both indoor and outdoor. The concentration of Bi a member of U

Waleed Abulfaraj

1992-01-01

456

Radioactive Liquid Waste Treatment Facility: Environmental Information Document  

Microsoft Academic Search

At Los Alamos National Laboratory (LANL), the treatment of radioactive liquid waste is an integral function of the LANL mission: to assure U.S. military deterrence capability through nuclear weapons technology. As part of this mission, LANL conducts nuclear materials research and development (R&D) activities. These activities generate radioactive liquid waste that must be handled in a manner to ensure protection

H. T. Haagenstad; G. Gonzales; I. L. Suazo

1993-01-01

457

RADIOACTIVE IMPURITIES IN THE POLONIUM PROCESS AT MOUND LABORATORY  

Microsoft Academic Search

Radioactive impurities in the polonium process at Mound Laboratory were ; investigated radiochemically. Tellurium and, to a lesser extent, selenium were ; found to be the radioactive impurities in the polonium product. At least 30 ; days' cooling time is recommended for the irradiated bismuth in order to avoid ; greater-than-tolerance amounts of Po²¹° in waste solutions. Specifications ; for

1963-01-01

458

Light radioactive nuclei capture reactions with phenomenological potential models.  

E-print Network

Light radioactive nuclei capture reactions with phenomenological potential models. V. Guimar basis. Some reactions are practically impossible to be directly measured. For instance, for light, SP, Brazil Texas A&M University-Commerce, Commerce, Texas 75429, USA. Abstract. Light radioactive

Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University

459

Issues in radioactive waste management for fusion power  

Microsoft Academic Search

Analysis of recent conceptual designs reveals that commercial fusion power systems will raise issues of occupational and public health and safety. This paper focuses on radioactive wastes from fusion reactor materials activated by neutrons. The analysis shows that different selections of materials and neutronic designs can make differences in orders-of magnitude of the kinds and amounts of radioactivity to be

R. C. Maninger; D. W. Dorn

1983-01-01

460

Page 1 of 2 Intent to Ship Radioactive Materials  

E-print Network

Page 1 of 2 Intent to Ship Radioactive Materials All shipments of radioactive materials must. Please complete this form and email it to radiation-safety@northwestern.edu with "Intent to Ship the materials to be shipped, to the Research Safety office. A tracking number will be provided to you once

Shull, Kenneth R.

461

Radioactive demonstration of the late wash'' Precipitate Hydrolysis Process  

SciTech Connect

This report presents results of the radioactive demonstration of the DWPF Precipitate Hydrolysis Process as it would occur in the late wash'' flowsheet in the absence of hydroxylamine nitrate. Radioactive precipitate containing Cs-137 from the April, 1983, in-tank precipitation demonstration in Tank 48 was used for these tests.

Bibler, N.E.; Ferrara, D.M.; Ha, B.C.

1992-06-30

462

Radioactive demonstration of the ``late wash`` Precipitate Hydrolysis Process  

SciTech Connect

This report presents results of the radioactive demonstration of the DWPF Precipitate Hydrolysis Process as it would occur in the ``late wash`` flowsheet in the absence of hydroxylamine nitrate. Radioactive precipitate containing Cs-137 from the April, 1983, in-tank precipitation demonstration in Tank 48 was used for these tests.

Bibler, N.E.; Ferrara, D.M.; Ha, B.C.

1992-06-30

463

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

464

Radioactive Ion Beam Purification by Selective Adsorption  

NASA Astrophysics Data System (ADS)

Isobaric contaminations in ISOL beams are a recurrent problem in nuclear physics experiments. Surface effects in the transfer line between target and ion source can be employed to achieve additional selectivity. Since interactions of the atoms' outer electrons with the surface determine adsorption behavior it can change drastically within an isobaric chain, introducing a chemical selectivity. Quartz transfer lines are currently applied at ISOLDE to reduce alkali contaminations [1]. We will conduct an on-line study of the adsorption behavior of fission products on a range of materials stable at high temperatures. Therefore a special target--ion source unit with a variable-temperature transfer line and interchangeable liner has been constructed in collaboration with the ISOLDE technical group. Results of first tests using new adsorption materials at the on-line separator test facility at Holifield Radioactive Ion Beam Facility, ORNL, will be presented. [1] Bouquerel et al., Europ. Phys. J. -- Spec. Top. 150, 277 (2006)

Jost, C.; Carter, H. K.; Griffith, B. O.; Reed, C. A.; Kratz, K.-L.; Stora, T.; Stracener, D. W.

2008-10-01

465

Radioactive waste disposal in thick unsaturated zones.  

PubMed

Portions of the Great Basin are undergoing crustal extension and have unsaturated zones as much as 600 meters thick. These areas contain multiple natural barriers capable of isolating solidified toxic wastes from the biosphere for tens of thousands to perhaps hundreds of thousands of years. An example of the potential utilization of such arid zone environments for toxic waste isolatic is the burial of transuranic radioactive wastes at relatively shallow depths (15 to 100 meters) in Sedan Crater, Yucca Flat, Nevada. The volume of this man-made crater is several times that of the projected volume of such wastes to the year 2000. Disposal in Sedan Crater could be accomplished at a savings on the order of $0.5 billion, in comparison with current schemes for burial of such wastes in mined repositories at depths of 600 to 900 meters, and with an apparently equal likelihood of waste isolation from the biosphere. PMID:17790523

Winogard, I J

1981-06-26

466

Radioactive Waste Disposal in Thick Unsaturated Zones  

NASA Astrophysics Data System (ADS)

Portions of the Great Basin are undergoing crustal extension and have unsaturated zones as much as 600 meters thick. These areas contain multiple natural barriers capable of isolating solidified toxic wastes from the biosphere for tens of thousands to perhaps hundreds of thousands of years. An example of the potential utilization of such arid zone environments for toxic waste isolation is the burial of transuranic radioactive wastes at relatively shallow depths (15 to 100 meters) in Sedan Crater, Yucca Flat, Nevada. The volume of this man-made crater is several times that of the projected volume of such wastes to the year 2000. Disposal in Sedan Crater could be accomplished at a savings on the order of 0.5 billion, in comparison with current schemes for burial of such wastes in mined repositories at depths of 600 to 900 meters, and with an apparently equal likelihood of waste isolation from the biosphere.

Winograd, Isaac J.

1981-06-01

467

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

468

Annual radioactive waste tank inspection program -- 1993  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site (SRS) separations processes are contained in large underground carbon steel tanks. Inspections made during 1993 to evaluate these vessels, and evaluations based on data accrued by inspections made since the tanks were constructed, are the subject of this report. The 1993 inspection program revealed that the condition of the Savannah River Site waste tanks had not changed significantly from that reported in the previous annual report. No new leaksites were observed. No evidence of corrosion or materials degradation was observed in the waste tanks. However, degradation was observed on covers of the concrete encasements for the out-of-service transfer lines to Tanks 1 through 8.

McNatt, F.G. Sr.

1994-05-01

469

Annual Radioactive Waste Tank Inspection Program - 2003  

SciTech Connect

Aqueous radioactive wastes from Savannah River Site (SRS) separations and vitrification processes are contained in large underground carbon steel tanks. Inspections made during 2003 to evaluate these vessels and other waste handling facilities along with evaluations based on data from previous inspections are the subject of this report. The 2003 inspection program revealed that the structural integrity and waste confinement capability of the Savannah River Site waste tanks remained unchanged from 2002. A total of 4249 photographs were made, 1178 visual and video inspections were performed, and 12 helium leak tests were conducted. Ultrasonic testing was performed on five High Level Waste Tanks in accordance with approved inspection plans that met the In-Service Inspection Program requirements.

WEST, WILLIAM

2004-06-03

470

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

471

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

472

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

473

The dispersion of radioactive aerosols in fires  

NASA Astrophysics Data System (ADS)

Experimental results are reported on the resuspension, due to fire, of radioactive nuclear fuel particles from a variety of substrates. Experiments were carried out both on large and small scale. In small-scale fires uranium-plutonium oxide particles were used and in the large-scale fires cerium-europium oxide particles were used. The mechanisms of particle resuspension were investigated in separate series of experiments. It was found that in small-scale fires up to 20% of the particle inventory can be resuspended and in large-scale fires up to 75%. In both cases most of the resuspended material deposits within the fire chamber and a maximum of 2% is carried into the ventilation duct at the outlet of the fire chamber. The predominant resuspension mechanisms are bubble bursting in small-scale fires and turbulence in large-scale fires.

Buijs, K.; de Dalmassy, B. Chavane; Pickering, S.

1989-07-01

474

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

475