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At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Degradation of Nylon 6,6 Fire-Suppression Casing from Plutonium Glove Boxes Under Alpha and Neutron Irradiation

Nylon 6,6 tensile specimens, conforming to the casing for self-contained fire extinguisher systems, have been irradiated using both an accelerator He ++ ion beam and a 5-Ci PuBe neutron source to model the radiation damage these systems would likely incur over a lifetime of operation within glove boxes. Following irradiation, these samples were mechanically tested using standard practices as described in ASTM D638. The results of the He ++ study indicate that the tensile strength of the nylon specimens undergoes some slight (<10%) degradation while other properties of the samples, such as elongation and tangent modulus, appear to fluctuate with increasing dose levels. The He ++ -irradiated specimens also have a noticeable level of discoloration corresponding to increasing levels of dose. The neutron-irradiated samples show a higher degree of mechanical degradation than the He ++ -irradiated samples.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Opening the Plutonium-Beryllium Neutron Sealed-Source RGMA1002-113

The radiograph of the PuBe neutron sealed-source was useful in determining dimensions and identifying construction details. This information gives the engineer and machinist a better idea of where to breach the outer container. It would be advantageous to use a higher energy radiography system to provide information about inner container dimensions, construction details, and nuclear material location to facilitate disassembly. Characterization of the inner and outer container materials would be useful for selecting proper cutting inserts to provide more efficient and cleaner cuts. A real-time, in-line method for qualitatively identifying metal compositions such as handheld x-ray fluorescent (XRF) may prove sufficient. The disassembly of PuBe sealed-sources generally involves numerous attempts to pry a lid or plug from the innermost container. The forces involved make it impractical to hold the source so this attempt must take place with the container held horizontally in the collet. The horizontal orientation risks the flow of PuBe materials out of the container when the plug is freed as occurred in this disassembly. To mitigate this risk, it was agreed that a small vise should be introduced into the glovebox to hold the container firmly in a vertical orientation for attempts to pry off lids or plugs. The vise should hold cylindrical containers firmly without inflicting scratches or gouges into sealed-source metal surfaces. Documentation of PuBe neutron sealed-source disassembly is effectively recorded with a series of professional photographs as presented in this report. Unfortunately, the prevalence of metal surfaces and materials combined with uneven, low light conditions reduce the contrast between disassembled parts and background. To improve the photographic record of disassembly, colored liner materials should be identified and introduced as a staged background for PuBe component pictures.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2012

Opening the Plutonium-Beryllium Neutron Sealed-Source RGMA1002-468/67

The Foreign Material Characterization Project requires that PuBe neutron sealed-sources be opened to determine the chemical and physical characteristics of the PuBe materials produced for source manufacture. In order to provide an accurate and thorough evaluation of PuBe materials, the sealed-sources must be opened with care so that all PuBe material is retained in the innermost sealed-source container and free from the transfer of nuclear material previously processed in the glovebox.

Isotope & Radiation Sources(07)↗
DOE OSTI2013

Multirecycling of Plutonium from LMFBR Blanket in Standard PWRs Loaded with MOX Fuel

It is now well-known that, from a physics standpoint, Pu, or even TRU (i.e. Pu+M.A.), originating from LEU fuel irradiated in PWRs can be multirecycled also in PWRs using MOX fuel. However, the degradation of the isotopic composition during irradiation necessitates using enriched U in conjunction with the MOX fuel either homogeneously or heterogeneously to maintain the Pu (or TRU) content at a level allowing safe operation of the reactor, i.e. below about 10%. The study is related to another possible utilization of the excess Pu produced in the blanket of a LMFBR, namely in a PWR(MOX). In this case the more Pu is bred in the LMFBR, the more PWR(MOX) it can sustain. The important difference between the Pu coming from the blanket of a LMFBR and that coming from a PWR(LEU) is its isotopic composition. The first one contains about 95% of fissile isotopes whereas the second one contains only about 65% of fissile isotopes. As it will be shown later, this difference allows the PWR fed by Pu from the LMFBR blanket to operate with natural U instead of enriched U when it is fed by Pu from PWR(LEU)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2013

The Use of Non Destructive Assay Measurements to Estimate Burnup and Plutonium Inventory in Pressurized Water Reactor Spent Fuel Assemblies

One of the overarching goals of the Next Generation of Safeguards Initiative (NGSI) Spent Fuel (SF) Non-Destructive Assay (NDA) Project is to determine the Pu mass in spent fuel assemblies with NDA instruments.1 Other goals include verifying initial enrichment, burn-up and cooling time of declaration, detecting diversion or replacement of pins, and/or determining heat emitted from an assembly (not a safeguards goal but important nonetheless). In pursuit of these goals, various NDA instruments of interest need to be built, tested, and then calibrated. Ideally simple calibration sources can be used such as isotopic sources or fresh assemblies. However, given the fact that many of the measured signals are influenced by the complex, energy-dependent interaction of neutrons with a range of isotopes, the connection between the measured signals and the Pu mass is difficult to make.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Impact of Fission Products Impurity on the Plutonium Content of Metal- and Oxide- Fuels in Sodium Cooled Fast Reactors

This short report presents the neutronic analysis to evaluate the impact of fission product impurity on the Pu content of Sodium-cooled Fast Reactor (SFR) metal- and oxide- fuel fabrication. The similar work has been previously done for PWR MOX fuel. The analysis will be performed based on the assumption that the separation of the fission products (FP) during the reprocessing of UOX spent nuclear fuel assemblies is not perfect and that, consequently, a certain amount of FP goes into the Pu stream used to fabricate SFR fuels. Only non-gaseous FPs have been considered (see the list of 176 isotopes considered in the calculations in Appendix 1 of Reference 1). Throughout of this report, we define the mixture of Pu and FPs as Pu FP . The main objective of this analysis is to quantify the increase of the Pu content of SFR fuels necessary to maintain the same average burnup at discharge independently of the amount of FP in the Pu stream, i.e. independently of the Pu FP composition. The FP losses are considered element-independent, i.e., for example, 1% of FP losses mean that 1% of all non-gaseous FP leak into the Pu stream.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

New Synthetic Methods and Structure-Property Relationships in Neptunium, Plutonium, and Americium Borates. Final report

The past three years of support by the Heavy Elements Chemistry Program have been highly productive in terms of advanced degrees awarded, currently supported graduate students, peer-reviewed publications, and presentations made at universities, national laboratories, and at international conferences. Ph.D. degrees were granted to Shuao Wang and Juan Diwu, who both went on to post-doctoral appointments at the Glenn T. Seaborg Center at Lawrence Berkeley National Laboratory with Jeff Long and Ken Raymond, respectively. Pius Adelani completed his Ph.D. with me and is now a post-doc with Peter C. Burns. Andrea Alsobrook finished her Ph.D. and is now a post-doc at Savannah River with Dave Hobbs. Anna Nelson completed her Ph.D. and is now a post-doc with Rod Ewing at the University of Michigan. As can be gleaned from this list, students supported by the Heavy Elements Chemistry grant have remained interested in actinide science after leaving my program. This follows in line with previous graduates in this program such as Richard E. Sykora, who did his post-doctoral work at Oak Ridge National Laboratory with R. G. Haire, and Amanda C. Bean, who is a staff scientist at Los Alamos National Laboratory, and Philip M. Almond and Thomas C. Shehee, who are both staff scientists at Savannah River National Laboratory, Gengbang Jin who is a staff scientist at Argonne National Lab, and Travis Bray who has been a post-doc at both LBNL and ANL. Clearly this program is serving as a pipe-line for students to enter into careers in the national laboratories. About half of my students depart the DOE complex for academia or industry. My undergraduate researchers also remain active in actinide chemistry after leaving my group. Dan Wells was a productive undergraduate of mine, and went on to pursue a Ph.D. on uranium and neptunium chalcogenides with Jim Ibers at Northwestern. After earning his Ph.D., he went directly into the nuclear industry.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗