The purpose of the study is to evaluate the availability and accuracy of existing methods for predicting fission product, cladding-mutant, and actinide concentrations and isotopic ratios in discharged reactor fuel elements after various irradiation and co...

Isotopic labeling of food has been widely used for the measurement of Fe absorption in determining requirements and evaluating the factors involved in Fe bioavailability. An extrinsic labeling technique will not accurately predict the total Fe absorption from foods unless complete isotopic exchange ...

This report describes the Spherical Particle Exchange Model (SPEM), which simulates exchange of one hydrogen isotope by another hydrogen isotope in a spherical metal hydride particle. This is one of the fundamental physical processes during isotope exchange in a bed of spherical metal particles and is thus one of the key components in ...

A comparison of experimental isotope shifts around neutron number 90 with theoretical predictions using accurate values of nuclear parameters shows discrepancies of the order of one standard volume shift. Nuclear quadrupole polarization by the valence electron is calculated and found to account for only a fraction of the ...

... Title : A METHODOLOGY FOR ACCURATELY PREDICTING DEMAND FOR AIRLIFT OF MILITARY CARGO TO OVERSEAS DESTINATIONS,. ...

The process of dissociative attachment of electrons to molecular hydrogen and its isotopes in the energy range at approximately 14 eV is investigated. The dissociative electron attachment cross sections for all six hydrogen isotopes are calculated over an extended range of electron energies using the local complex potential model with the excited Rydberg ...

We present a new method for the prediction of the equilibrium properties of dense gases containing hydrogen isotopes. The proposed approach combines the Feynman-Hibbs effective potential method and a deconvolution scheme introduced by Weeks et al. The resulting equations of state and the chemical potentials as functions of pressure for each of the hydrogen ...

The stable isotope composition of carbon can be used to provide information on the origin of carbon in soil organic matter. This study looks at the effect of decreasing temperature and atmospheric pressure (altitude) on the carbon-isotope composition of soil organic carbon from forests and grasslands in tropical regions. Investigators examine whether a ...

Fourier trasform ion cyclotron resonance (FTICR) mass spectrometry time domain signals from multiply charged biopolymer ions exhibit characteristics and predictable beat patterns due to the closely spaced cyclotron frequencies of the various isotopic constituents. Isotope beat frequencies can readily and accurately ...

We perform extensive magnetic Feshbach spectroscopy of an ultracold mixture of fermionic {sup 40}K and bosonic {sup 87}Rb atoms. The magnetic-field locations of 13 interspecies resonances are used to construct a quantum collision model able to predict accurate collisional parameters for all K-Rb isotopic pairs. In particular, we ...

The determination of the provenance of 'unknown' plutonium material is demonstrated through a simulation study based on an isotopic fingerprinting approach. Plutonium of known provenance was considered as the 'unknown' nuclear material in order to evaluate the potential of the approach and verify its predictive capabilities. Factor analysis was used to ...

The neutral muonic helium atom may be regarded as the heaviest isotope of the hydrogen atom, with a mass of ~4.1 atomic mass units ((4.1)H), because the negative muon almost perfectly screens one proton charge. We report the reaction rate of (4.1)H with (1)H(2) to produce (4.1)H(1)H + (1)H at 295 to 500 kelvin. The experimental rate constants are compared with the ...

The masses of six neutron-deficient rare holmium and thulium isotopes close to the proton drip line were determined with the SHIPTRAP Penning trap mass spectrometer. For the first time the masses of the proton-unbound isotopes {sup 144,145}Ho and {sup 147,148}Tm were directly measured. The proton separation energies were derived from the measured mass ...

... Title : Fast and Accurate Prediction of Windborne Contaminant Plumes for Civil Defense in Cities. Descriptive Note : Conference paper. ...

... Accession Number : ADD200835. Title : An Accurate Prediction of Natural Frequencies of Laminated Plates by a Higher Order Theory. ...

We discover several magnetic Feshbach resonances in collisions of ultracold 39K atoms, by studying atom losses and molecule formation. Accurate determination of the magnetic-field resonance locations allows us to optimize a quantum collision model for potassium isotopes. We employ the model to predict the magnetic-field dependence of ...

The occurrence of coexisting amphiboles in rocks and the likelihood of concurrent isotope closure allows equilibrium oxygen isotope fractionations among the amphiboles to be recovered from natural samples. Oxygen isotope analyses of mineral separates using laser fluorination show that coexisting amphiboles increasingly partition {sup ...

The stable hydrogen (?²H) and oxygen (?¹⁸O) isotope ratios of organic and inorganic materials record biological and physical processes through the effects of substrate isotopic composition and fractionations that occur as reactions proceed. At large scales, these processes can exhibit spatial ...

Definite identification has been made of an isotope of the element with atomic number 98 [californium]. The chemical separation and identification of the new element was accomplished through the use of ion exchange adsorption methods employing the resin Dowex-50. The element 98 isotope appears in the eka-dysprosium position on elution curves containing ...

It is now well established that accurate relative values of the rms nuclear charge radius for light atoms can be extracted from a comparison between high-precision theory and experiment for the isotope shift in atomic transition frequencies. Results are available for isotopes of helium and lithium. This paper reviews and updates the ...

238U projectile fragments have been created at the entrance of the fragment separator FRS, spatially separated in flight within 0.45 ?s and injected into the storage-cooler ring ESR at 7.9 Tm corresponding to about 70% light velocity. Accurate new mass values and lifetime information of the stored exotic nuclei in the element range from platinum to uranium have been obtained ...

This research endeavors to present the first-ever coupling of an isotopic regional climate model (RCM) with an isotopically-enabled hydrological model. This work seeks to improve the reliability of mesoscale (large domain) hydrological prediction while simultaneously assessing mesoscale hydrological variability induced by climate ...

The key to weather prediction lies in accurately measuring these variables and feeding the data into numerical models that can predict changes in the ...

We have developed a simple, yet accurate theoretical method for calculating the reduced isotope partition function ratio (RIPFR) for hydrogen of water at elevated pressures. This approach requires only accurate equations of state (EOS) for pure isotopic end-members (H2O and D2O), which are available in the ...

Three different sets of nuclear pairing energies (b) are used to predict the (n,p) cross sections at 14.5 Mev of the isotopes of iron, copper, and zinc. It is shown that the two values sigma /sub Z/ = 1.7 and sigma /sub N/ = 2.5 Mev yield more accurate predictions than the other two sets (wherein sigma ...

The higher-actinide isotopes of {sup 237}Np, {sup 241}Am, and {sup 243}Am are fissionable nuclides formed in reactor fuels and, if separated, could conceivably be used in a nuclear explosive device. Recently, the International Atomic Energy Agency Board of Governors tasked the Secretariat with maintaining oversight of these Np and Am nuclides, or alternate nuclear materials ...

An assemblage theory of matter is presented that depicts elementary particles and atomic nuclei as assemblages of point-line discontinuities in a quanrized nuclear field. On the basis of the theory, new particles are predicted; it is argued that the proton and neutron are simply different energy;tates of the same assemblage. The mean life of the neutron was ...

CE-TOFMS is a powerful method for profiling charged metabolites. However, the limited availability of metabolite standards hinders the process of identifying compounds from detected features in CE-TOFMS data sets. To overcome this problem, we developed a method to identify unknown peaks based on the predicted migration time (t(m)) and accurate m/z values. ...

Correct prediction of the fission products inventory in irradiated nuclear fuels is essential for accurate estimation of fuel burnup, establishing proper requirements for spent fuel transportation and storage, materials accountability and nuclear forensics. Such prediction is impossible without accurate knowledge ...

Human activities at local and regional scales impact the functioning of ecological processes. Integrating these activities requires spatially-explicit models that depend on both accurate input data, as well as a mechanistic understanding of the processes being modeled. Stable isotope ratios of several elements have been used successfully as both recorders ...

One of the recently established methods for monitoring a Comprehensive nuclear Test Ban Treaty (CTBT) is the collection and analysis of radioxenon isotopes as collected and measured by International Monitoring System (IMS) stations. Radioxenon isotopes are produced from several sources including nuclear power generating stations, medical ...

Astration of heavy elements by the stars of the Milky Way forms a fossil record which may preserve spacial distribution of the mass function for the stars in the galaxy. Sulfur is among the last common element for which the relative abundance of its various isotopes have yet to be completely measured within our galaxy. Explosive oxygen burning in massive stars is thought to be ...

We present the performance characteristics of a time-of-flight secondary ion mass spectrometer designed for 157 nm laser postionization of sputtered neutrals for high sensitivity elemental and isotopic analyses. The instrument was built with the aim of analyzing rare element abundances in micron to submicron samples such as interstellar grains and cometary dust. Relative ...

... of an isotope of element ... Descriptors : *ISOTOPES, *CALIFORNIUM, PREDICTIONS, SOLUTIONS ... HELIUM, IRRADIATION, GADOLINIUM, DECAY ...

The Fast Grain Boundary (FGB) model for interdiffusion provides the first model for accurately quantifying the dependence of stable isotope closure temperatures and diffusion profiles on grain size, grain shape, cooling rate, and mineral abundance. Calculations of oxygen isotope exchange for a variety of igneous and metamorphic rock ...

... Title: An Efficient and Accurate Method of Estimating Substrate ... This thesis presents a Z-parameter based model to predict the substrate ...

The regulation of Earth's climate and its ability to sustain life are critically linked to water as it exists in all three of its phases (gas, liquid, and solid). Earth's water cycle, its movement between the hydrosphere, biosphere, and the atmosphere, and how it undergoes phase changes, is incredibly complex. While we continue to gain insight into the water cycle, there remains considerable ...

We analyzed Nd and Sr isotopic compositions of Neogene fossil fish teeth from two sites in the Pacific in order to determine the effect of cleaning protocols and burial diagenesis on the preservation of seawater isotopic values. Sr is incorporated into the teeth at the time of growth; thus Sr isotopes are potentially valuable for ...

Proxy-based climate reconstructions suggest the existence of a strongly reduced equator-to-pole temperature gradient during the Azolla interval in the Early/Middle Eocene, compared to modern. Changes in the hydrological cycle, as a consequence of a reduced temperature gradient, are expected to be reflected in the isotopic composition of precipitation (?D, ?18O). The ...

Operations and material control and accountancy requirements for the Fuel Conditioning Facility demand accurate prediction of the mass flow of spent EBR-II driver fuel into the facility. This requires validated calculational tools that can predict the burnup and isotopic distribution in irradiated Zr-alloy fueled ...

Microcanonical variational theory with a semiclassical adiabatic ground-state transmission coefficient predicts the thermal rate constant for collinear H + Cl/sub 2/ within 6% for 200 to 1000 K and the kinetic isotope effect k/sub H/k/sub D/ within 6 or 9% (depending on the detailed assumptions in the transmission coefficient) over the same temperature ...

The isotopic method of determining absolute age is the most accurate and .... Another method of relative age dating involves the relative abundance of ...

Some of these compounds have isotopic signatures that are characteristic of ... can be definitely detected and a very accurate abundance determined. ...

This seminal paper contains the results of the mass spectrographic determination of the relative abundances of the uranium isotopes, U�238, U�235, and U�234. No other isotopes of uranium were observed. The half�lives of the isotopes were also reported. These were the most accurate measurements of ...

Double isotope dilution surface-enhanced Raman scattering (double IDSERS) is qualified as a method for accurate and precise determination of biomarkers in human blood serum. Providing a full evaluation of the measurement uncertainty as well as traceability to a reference material sets the procedure in line with the requirements of a primary ratio method. ...

Relativistic multi-configuration Dirac Fock (MCDF) wavefunctions coupled to good angular momentum J have been calculated for low lying states of Ba I and Ba II. These wavefunctions are compared with semi-empirical ones derived from experimental atomic energy levels. It is found that significantly better agreement is obtained when close configurations are included in the MCDF wavefunctions. ...

Ultrasensitive wavelength-dependent laser-ionization mass spectrometry is applied to spectroscopic studies of argon-benzene van der Waals molecules and isotopically substituted benzene molecules. Argon-benzene fragments either in its /sup 1/B/sub 2u/ excited electronic state or subsequent to being ionized. Substitution of a single /sup 13/C atom in the benzene monomer ring ...

Yoshimura et al. [2008] completed 30-year Reanalysis-"nudged" isotope-incorporated AGCM simulation. In their method, large scale forcing was taken from NCEP/DOE Reanalysis 2, and water isotopes were fully predicted, including their sources and sinks, without utilizing any water isotope observations. Several direct ...

The new neutron-rich rare-earth isotopes {sup 159}Pm, {sup 162}Sm, and {sup 166}Gd produced in the proton-induced fission of {sup 238}U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of {sup 159}Pm, {sup 162}Sm, and {sup 166}Gd were determined to be 1.5 {+-} 0.2, 2.4 {+-} 0.5, ...

Results for elastic electron scattering by nuclei, calculated with charge densities of Skyrme forces and covariant effective Lagrangians that accurately describe nuclear ground states, are compared against experiment in stable isotopes. Dirac partial-wave calculations are performed with an adapted version of the ELSEPA package. Motivated by the fact that ...

During the Late Cretaceous, western North America was characterized by a close geographic association between the Sevier highlands and the Western Interior Seaway. In this paper, an atmospheric general circulation model (AGCM) is used to simulate the impact of this geographic association on surface pressure, wind direction, and precipitation, and it is predicted that seasonal ...

Hydrogen isotopes play an important role in energy technologies, in particular, the compression to high densities for initiation of controlled thermonuclear fusion energy. At high densities the properties of the compressed hydrogen isotopes depart drastically from ideal thermodynamic predictions. The measurement of ...

Stochastic subsurface hydrologic theory is applied to data for a hypothetical low-level radioactive waste site to demonstrate the features of the hydraulic parameter estimation process, as developed by Gelhar and others. Effective values of hydraulic conductivity, macrodispersivity, and macrodispersivity enhancement are estimated from the data in this manner. A two-dimensional saturated flow and ...

A new design for an enhanced dispersion thermal ionization multi-collector isotope ratio mass spectrometer is proposed and the results of tests with a small-scale prototype instrument are presented. The measured performance of the small-scale prototype sized for 6Li and 7Li is compared with the predictions of an ion optical model. The ion optical model is ...

The general harmonic force field of methylene chloride has been calculated without the necessity of imposing constraints, through the use of a set of 74 observables over eight isotopic species. These include vibration frequencies, 37Cl and 13C isotopic frequency shifts, and quartic centrifugal distortion constants. All force constants are well defined by ...

The accurate determination of isotope abundances by any method requires that the measuring systems be calibrated using well characterized isotope reference materials. The National Bureau of Standards (NBS) and the Central Bureau for Nuclear Measurements (...

Isotope dilution Ar analyses are reported for all samples originally analysed by neutron activation. The methods are in agreement but the more precise and accurate isotope dilution analyses are preferred.

Two advanced prototype mass spectrometers for the accurate analysis of mixtures of the hydrogen isotopes were evaluated. One, a VG-Isotopes GAZAB, was developed for the Mass Spectrometer Technical Group, a group representing ten DOE contractors. The other...

In this study quantum mechanical models are used to estimate equilibrium zinc-isotope fractionations between zinc oxide and sulfide minerals, as well as aqueous complexes. A major goal in stable isotope geochemistry and biogeochemistry is the determination of equilibrium fractionations between different phases present in typical geochemical systems. The ...

A methodology for determining alternate nuclear material ({sup 237}Np, {sup 241}Am, and {sup 243}Am) concentrations in spent nuclear fuel based on the use of various monitors was developed and validated for use with several pressurized water reactor fuels. The monitors studied included the fuel burnup, the total plutonium concentration, the {sup 240}Pu/{sup 239}Pu isotopic ...

Reaction resonances are transiently trapped quantum states along the reaction coordinate in the transition state region of a chemical reaction that could have profound effects on the dynamics of the reaction. Obtaining an accurate reaction potential that holds these reaction resonance states and eventually modeling quantitatively the reaction resonance dynamics is still a ...

Carbon isotope composition is regarded as a powerful tool in understanding carbon cycling, both as a tracer and as a process recorder. However, accurate predictions of, for example, partitioning the net carbon flux into its components or obtaining climate information from tree rings, requires a good understanding of plant metabolism ...

We determined by ICP-MS the concentrations and isotopic ratios of Fe, Cu, and Zn in the Ti-rich lunar basalt 74275, in the lunar orange glass 74220, and in up to 10 lunar soils, namely, 14163, 15231, 64501, 66041, 68841, 69941, 70011, 72501, 75081, and 76501. Two analyses of zinc in lunar basalt 74275 give ?66Zn = 0.17� and 0.75�, values within the range of those measured ...

Fluxes of carbon, nitrogen, and water between ecosystem components and organisms have great impacts across levels of biological organization. Although much progress has been made in tracing carbon and nitrogen, difficulty remains in tracing water sources from the ecosystem to animals and among animals (the "water web"). Naturally occurring, non-radioactive isotopes of hydrogen ...

Fluxes of carbon, nitrogen, and water between ecosystem components and organisms have great impacts across levels of biological organization. Although much progress has been made in tracing carbon and nitrogen, difficulty remains in tracing water sources from the ecosystem to animals and among animals (the �water web�). Naturally occurring, non-radioactive isotopes of ...

... ENGINEERING)), MATHEMATICAL ANALYSIS, RADIOACTIVE ISOTOPES, HEAT ... TEMPERATURE, NEUTRON FLUX, NUCLEAR REACTIONS. ...