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Time and frequency domain measurements for plutonium metal rings

Description: The {sup 252}Cf-source-driven noise analysis method was used to measure the neutron multiplication factor for subcritical systems and to identify fissionable materials and configurations. These measurements with the moderator-ring configuration have shown that the {sup 252}Cf-source-driven noise methods, both in the time and frequency domain, can be used to identify and distinguish the {sup 242}Pu from the {sup 239}Pu ring. Signatures for each ring can be used to track and confirm the presence of these two types of Pu rings. Because of the sensitivity of these signatures to mass, these measurements can also confirm the Pu mass. These preliminary measurements have not yet explored the full range of capability of this method for this application.
Date: September 1996
Creator: Mihalczo, J. T.; Pare, V. K.; Blakeman, E. D.; Valentine, T. E.; Vessard, S. & Pruvost, N. L.
Partner: UNT Libraries Government Documents Department

Determination of the 242Pu Branching Ratio via Alpha-Gamma Coincidence

Description: When the burn-up is high, the {sup 242}Pu isotopic content becomes more important. The traditional correlation method will fail. The {sup 242}Pu isotopic content in the sample plays an essential role if the neutron coincidence method is used to quantify the total amount of plutonium. In one of the earlier measurements we had a chance to measure an isotopic pure (> 99.95 %) {sup 242}Pu thick sample and realized that the difference in the branching ratio (BR) value among current nuclear data3) for the two important gamma-rays at 103.5-keV and 158.8-keV. In this study, the thick sample was counted on a 15% ORTEC safeguards type HPGe to further improve BR determination of the 159-keV gamma-ray. Furthermore, we have made a thin {sup 242}Pu sample from the thick sample and performed alpha-gamma coincidence measurements. Our preliminary gamma-ray BR results are 4.37(6) E-4, 2.79(8) E-5, and 2.25(8) E-6 for 44.9-keV, 103.5-keV, and 158.9-keV, respectively.
Date: May 24, 2012
Creator: Wang, T F
Partner: UNT Libraries Government Documents Department

{sup 242}Pu CRITICAL MASS

Description: Large amounts of {sup 242}Pu (0.3 to 0.8 mg/g UO{sub 2}) are present in spent nuclear reactor fuel with more being produced on a daily basis. For stabilization and reprocessing of spent fuel, criticality safety data are needed to ensure that {sup 242}Pu is handled safely. The calculated bare critical mass of {sup 242}Pu is 85.80 {+-} 3.46 kg at a density of 19.86 g/cm{sup 3}. This critical mass was derived based upon calculations of critical experiments that used up to 24 kg {sup 242}Pu. The previous critical mass derivation should be reasonably accurate until such time that integral data can be obtained.
Date: June 1, 1999
Creator: BREWER, R.
Partner: UNT Libraries Government Documents Department

Laser ablation of silicate glasses doped with transuranic actinides

Description: Direct sampling laser ablation plasma mass spectrometry (DS-LAMS) was applied to silica glasses doped with {sup 237}Np, {sup 242}Pu or {sup 241}Am using a unique instrument recently installed into a transuranic glovebox. The primary goal was to assess the utility of mass spectrometry of directly ablated ions for facile evaluation of actinide (An) constituents of silicate glass immobilization matrices used for encapsulation of radionuclides. The instrument and general procedures have been described elsewhere. Three high-purity silicate glasses prepared by a sol-gel process (SG) and one conventional high-temperature (HT; melting point {approx} 1,450 C) borosilicate glass were studied. These glasses comprised the following constituents, with compositions expressed in mass percentages: Np-HT {approx} 30% SiO{sub 2} + 6% B{sub 2}O{sub 3} + 3% BaO + 13% Al{sub 2}O{sub 3} + 10% PbO + 30% La{sub 2}O{sub 3} + 8% {sup 237}NpO{sub 2}; Np-SG {approx} 70% SiO{sub 2} + 30% {sup 237}NpO{sub 2}; Pu-SG {approx} 70% SiO{sub 2} + 30% {sup 242}PuO{sub 2}; Am-SG {approx} 85% SiO{sub 2} + 15% {sup 241}AmO{sub 2}.
Date: October 1, 1998
Creator: Gibson, J. K. & Haire, R. G.
Partner: UNT Libraries Government Documents Department

Feasibility study of plutonium and uranium measurements in input dissolver solutions

Description: We are studying the isotope dilution gamma-ray spectrometry (IDGS) technique for the simultaneous measurements of concentrations and isotopic compositions for both plutonium and uranium in spent-fuel dissolver solutions at a reprocessing plant. Previous experiments have demonstrated that the IDGS technique can determine the elemental concentrations and isotopic compositions of plutonium in dissolver solutions. The chemical separation and recovery methods for just plutonium were ion-exchange techniques using anion exchange resin beads and filter papers. To keep both plutonium and uranium in the sample for simultaneous measurements, a new sample preparation method is being studied and developed: extraction chromatography. The technique uses U/TEVA{center_dot}Spec resin to separate fission products and recover both uranium and plutonium in the resin from dissolver solutions for measurements by high-resolution gamma-ray spectrometry.
Date: October 1, 1995
Creator: Li, T.K.; Kitagawa, O.; Kuno, Y. & Kurosawa, A.
Partner: UNT Libraries Government Documents Department

Non-destructive assay of {sup 242}Pu by resonance neutron capture

Description: For the accurate assay of plutonium by neutron correlation measurements, especially for material derived from high-burnup reactor fuel, the content of {sup 242}Pu in a sample must be determined. Since {sup 242}Pu has a long half-life (387,000 yr) and decays to {sup 238}U by alpha particle emission with the accompanying emission of only weak, low-energy gamma rays, gamma-ray spectrometry methods which are ordinarily employed to determine the isotopic composition of a plutonium sample are not feasible for {sup 242}Pu. The existence of a resonance in the neutron capture cross section of {sup 242}Pu at an energy of 2.67 electron volts (eV) with a large (72, 000 barn) cross section affords the possibility for the quantitative assay of this isotope by epithermal neutron capture. Essential for this purpose is an appropriately designed geometry of neutron moderators and absorbers which will provide maximum flux in the eV region while suppressing thermal neutron capture by the fissile plutonium isotopes. Signatures for neutron capture in {sup 242}Pu include the decay of {sup 243}Pu (4.9 hr), prompt capture gamma rays (total energy 5.034 MeV), and the decay of an isomeric state (330 nanosecond). Experiments to determine the feasibility of this approach are currently in progress.
Date: August 1, 1995
Creator: Kane, W.R.; Lu, Ming-Shih; Aronson, A.; Forman, L. & Vanier, P.E.
Partner: UNT Libraries Government Documents Department

HIGH FLUX ISOTOPE REACTOR--A GENERAL DESCRIPTION

Description: The High Flax lsotope Reactor (HFIR) is being planned for construction at Oak Ridge National Laboratory as a supporting facility in the program of investigation of the properties of the transplutonium elements. The reactor will be a flux-trap reactor consisting of a berylliumrefiected, light-water-cooled annular fuel region surroundin g a light-water island. An irradiation sample of 200 to 300 g of Pu/sup 242/ will be placed in the island where a thermalneutron flux of approximately 3 x 10/sup 15/ n/cm/sup 2//sec can be achieved on the average during an irradiation period of about 1 year. It is estimated that more than 100 mg of Cf/sup 252/ will be produced by such an irradiation. In addition to the central irradiation facility for heavy-element production, the HIKIR will have eight hydraulic rabbit tubes located in the beryllium refiector and four beam holes for basic research. Preliminary design of the reactor was based on the results of a parametric study of the dimensions of the island and fuel region, heat-removal rates, and fuel loading on the achievable thermal-neutron fluxes in the island and reflector. A research and development program ding critical experiments, heat transfer, corrosion, a clufuel element studies has been in progress to verify the important parameters used in the design. The present design results in an average power density of 2.2 Mw/l in the active core and requires a maximum heat-transfer rate from fuel-plate surfaces of 1.5 x 10/ sup 6/ Btu/ft/sup 2//hr. This heattransfer rate is achieved by flowing H/sub 2/ O, at an inlet temperature of 120 F, and a pressure of 600 to 900 psig, through the 0.05-in. coolant channels at a velocity of 40 fps. A preliminary analysis of the hazards brought on by a reactor core meltdown shows that a controlled-leakage, filter-scrubber, stack release system of ...
Date: March 1, 1960
Creator: Cole, T E
Partner: UNT Libraries Government Documents Department

Alpha-n and spontaneous fission sources and spectra from individual plutonium isotopes in PuF{sub 4} and PuO{sub 2}

Description: Plutonium-containing compounds vary widely in isotopic content, and as a result, the dose as function of isotopic content also varies considerably. Determination of the dose from neutrons, decay and capture gammas from plutonium in the form of compounds thus requires that the spontaneous fission and ({alpha},n) source and spectra from each individual isotope be known. To facilitate dose calculations from plutonium-containing compounds, we have calculated the spontaneous fission and ({alpha},n) sources and spectra for 1 g of each of the plutonium isotopes in the form of either PuF{sub 4} or PuO{sub 2}. As {sup 241}Am is often a component in a mixture of plutonium isotopic compounds, the source and spectra from 1 g of {sup 241}Am mixed with PuF{sub 4} or PuO{sub 2} has also been determined. Using these results, the neutron source and spectra may be determined for any sample composition. 2 refs., 3 tabs.
Date: October 1996
Creator: Perry, R. T. & Wilson, W. B.
Partner: UNT Libraries Government Documents Department

Actinides at the crossroads: ICP-MS or alpha spectrometry?

Description: The report contains viewgraphs only that summarize the following: Why turn to mass spectrometry for radiochemical measurements; What might be some advantages of using ICP mass spectrometry; Sensitivity of ETV-ICP-MS relative to decay counting (versus half-life); ICP-MS instrument detection limits for dissolved actinide isotopes; Effect of dissolved solids on USN-ICP-MS analysis; Polyatomic ion interferences in ICP-MS actinide measurements; Effect of operating conditions on uranium and protonated uranium signal; ICP mass spectrometry performance in actinide determinations; Determination of actinide elements in soil; Leachable Th-230 and Pu-239 in soil as determined by ICP-MS and alpha spectrometry; Leachable U-234 and U-238 in soil by ICP-MS and alpha spectrometry; Determination of uranium isotopic composition on smears; Activity ratios (U-234/U-238) as determined by mass spectrometry and alpha spectrometry; Uranium isotopic abundances as determined by TIMS and ICP-MS; and Comparison of uranium atom percentages determined by TIMS and ICP-MS. It is concluded that isotope dilution and radiochemical preparative techniques work well in radioanalytical applications of ICP-MS; radioanalytical ICP-MS data are equivalent to data from standard methods (TIMS, alpha spectrometry); and applications in radiation protection and earth sciences are certain to expand further.
Date: December 31, 1995
Creator: Crain, J.S.; Yaeger, J.S.; Smith, F.P.; Alvarado, J.A.; Smith, L.L.; Kiely, J.T. et al.
Partner: UNT Libraries Government Documents Department

Unsafe Coulomb excitation of {sup 240-244}Pu.

Description: The high spin states of {sup 240}Pu and {sup 244}Pu have been investigated with GAMMASPHERE at ATLAS, using Coulomb excitation with a {sup 208}Pb beam at energies above the Coulomb barrier. Data on a transfer channel leading to {sup 242}Pu were obtained as well. In the case of {sup 244}Pu, the yrast band was extended to 34{h_bar} revealing the completed {pi}i{sub 13/2} alignment, a ''first'' for actinide nuclei. The yrast sequence of {sup 242}Pu was also extended to higher spin and a similar backbend was delineated. In contrast, while the ground state band of {sup 240}Pu was measured up to the highest rotational frequencies ever reported in the actinide region ({approximately}300 keV), no sign of particle alignment was observed. In this case, several observable such as the large B(E1)/B(E2) branching ratios in the negative parity band, and the vanishing energy staggering between the negative and positive parity bands suggest that the strength of octupole correlations increases with rotational frequency. These stronger correlations may well be responsible for delaying or suppressing the {pi}i{sub 13/2} particle alignment.
Date: February 4, 1999
Creator: Ahmad, I.; Amro, H.; Carpenter, M. P.; Chowdhury, P.; Cizewski, J.; Cline, D. et al.
Partner: UNT Libraries Government Documents Department

Unsafe coulomb excitation of {sup 240-244}Pu.

Description: The high spin states of {sup 240}Pu and {sup 244}Pu have been investigated with GAMMASPHERE at ATLAS, using Coulomb excitation with a {sup 208}Pb beam at energies above the Coulomb barrier. Data on a transfer channel leading to {sup 242}Pu were obtained as well. In the case of {sup 244}Pu, the yrast band was extended to 34{h_bar}, revealing the completed {pi}i{sub 13/2} alignment, a ''first'' for actinide nuclei. The yrast sequence of {sup 242}Pu was also extended to higher spin and a similar backbend was delineated. In contrast, while the ground state band of {sup 240}Pu was measured up to the highest rotational frequencies ever reported in the actinide region ({approximately} 300 keV), no sign of particle alignment was observed. In this case, several observables such as the large B(E1)/B(E2) branching ratios in the negative parity band, and the vanishing energy staggering between the negative and positive parity bands suggest that the strength of octupole correlations increases with rotational frequency. These stronger correlations may well be responsible for delaying or suppressing the {pi}i{sub 13/2} particle alignment.
Date: December 1, 1998
Creator: Wiedenhoever, I.
Partner: UNT Libraries Government Documents Department

Diffusive release of radionuclides into saturated and unsaturated tuff

Description: In the proposed Yucca Mountain repository, packages of high-level waste are separated from surrounding unsaturated rock by a 2-cm air-gap annulus. If a waste package contacts the surrounding rock, if the annulus becomes filled with rock and rubble, or if the rock becomes saturated, there can exist pathways for release of dissolved radionuclides by liquid diffusion. We have applied the analytical solutions for time-dependent mass transfer of dissolved species through porous rock to predict the time-dependent release rates of key radionuclides. The expected ground-water velocities are so low that mass-transfer is predicted to occur predominantly by molecular diffusion in pore liquid. Conservatively, we neglect mass-transfer resistance from fuel cladding and failed metal containers. 6 refs., 3 figs.
Date: January 1, 1990
Creator: Sadeghi, M.M.; Lee, W.W.L.; Pigford, T.H. & Chambre, P.L.
Partner: UNT Libraries Government Documents Department

Proposal for experiments with actinide elements

Description: An analytical study was conducted in which critical masses for some actinide isotopes were calculated with the Monte Carlo Neutron Photon (MCNP) Transport computer code. Different spherical computer models were used for even- and odd-neutron nuclides. Critical masses obtained are tabulated for Np-237, Pu-242, Am-241, Am-243, Pu-241, and Am-242m, together with indirect experimental data. Experimental data are needed for actinides with odd number of neutrons.
Date: June 1, 1994
Creator: Sanchez, R. G.
Partner: UNT Libraries Government Documents Department

High spin states in neutron rich nuclei from spontaneous fission

Description: One fragment-{gamma}-{gamma} and three {gamma}-{gamma} coincidence measurements of the prompt {gamma}-rays from the fragments produced in the spontaneous fission (SF) of {sup 252}Cf and very recently of {sup 242}Pu were carried out with a 20 Ge detector ball at HHIRF. With our high statistics, {gamma}-{gamma}-{gamma} coincidences where the two gates are on transitions in the two partner fragments were extracted. Comparing the {sup 252}Cf and {sup 242}Pu data allowed unique placements of many transitions. New, higher spin states were observed in many nuclei, up to 16{sup +} in some of the heavy partners. Levels in several nuclei were observed for the full time. Studies of the fission process included measured relative branchings to the 1n to 6n channels. Much data remains to be analyzed. These data provide new insights into the changing structures at higher spins of many neutron-rich nuclei and the fission process.
Date: December 31, 1992
Creator: Butler-Moore, K.; Zhu, S.; Zhao, X.; Hamilton, J. H.; Ramayya, A. V.; Lu, Q. et al.
Partner: UNT Libraries Government Documents Department