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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Maintaining Continuity of Knowledge on Nuclear Waste Destined for Geological Repositories. A Case Study of Plutonium Shipments to the Waste Isolation Pilot Plant (WIPP)

This study examines methods that can help maximize confidence in maintaining Continuity of Knowledge (CoK) on plutonium-bearing wastes, from a final safeguards-verification measurement through emplacement underground. The study identifies Containment and Surveillance (C/S) measures that can be applied during packaging of plutonium wastes at the Savannah River Site (SRS) in South Carolina, USA, through shipment to, and receipt and disposal at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico, USA. Results of this study could apply to countries with a Comprehensive Safeguards Agreement (CSA) that plan to dispose in a geological repository plutonium or other non-fuel nuclear materials that are under international safeguards.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Mechanical Metallurgy of Plutonium Metal, Alloys, and Allotropes [Slides]

This talk will highlight the mechanical properties of plutonium, but with some discussion of the governing (and often unusual!) underlying metallurgical fundamentals In the interest of time, this talk will focus on unalloyed plutonium metal, its temperature allotropes, and plutonium alloyed to stabilize the delta phase Most of the featured work is taken from the literature; references are provided for both attribution and further reading.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Mobile Plutonium Facility (MPF) Calorimeter Measurement Uncertainty

The Department of Energy’s (DOE) National Nuclear Security Administration (NNSA), specifically the Office of Material Management and Minimization (NA-23), is responsible for removing and/or securing special nuclear materials from around the globe that pose a threat to the U.S. and international community. Part of this responsibility requires developing the means to rapidly de-nuclearize weapons programs in foreign countries. The Savannah River Site (SRS) has been tasked by NA-23 to support efforts by establishing a Rapid Response Plutonium Team (RRPT) and developing/procuring the necessary equipment to accomplish the goal of removing plutonium from foreign nations. This includes development of a Mobile Plutonium Facility (MPF) with the overall objective of ensuring the operating crew’s safety while fulfilling the mission to stabilize, package, and ship special nuclear material in the most expeditious manner possible. One piece of equipment supporting this mission is a calorimeter that is to be used in the characterization of the nuclear material. This document provides an investigation of measurements conducted utilizing the MPF calorimeter with the purpose of estimating the uncertainty of its measurements. The evaluations conducted as part of this investigation have identified three sources of variation that are to be integrated into an estimate of the overall uncertainty of measurements provided by the MPF calorimeter. The sources of variation and each of their associated percent relative standard deviations (%RSDs) are base readings with a %RSD of 0.44%, electrical heat standard (EHS) measurements with a %RSD of 1.7157%, and environmental conditions with a %RSD of 0.7984%. Combining these standard deviations in quadrature yields an estimate of the %RSD for overall uncertainty of 1.943%. Note that is a one-sigma expression for the MPF calorimeter measurement uncertainty.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Rossi-α Measurements on a System Consisting of Weapons Grade Plutonium Moderated by Polyethylene [Poster]

A series of experiments nicknamed "TEX," standing for Thermal-Epithermal eXperiments, were performed at the National Criticality Experiments Research Center (NCERC) on the Planet critical assembly. The TEX experiment campaigns are a collaboration between Los Alamos National Laboratory (LANL) and Lawrence Livermore National Laboratory (LLNL) and funded by the Nuclear Criticality Safety Program (NCSP). The TEX experiment consists of several campaigns; this work specifically discusses measurements made on one series of TEX experiments designed to examine the thermal scattering law (TSL) for polyethylene. This series consisted of two different critical configurations which contain plutonium fuel. The plutonium plates are 2 in. by 3 in. by 0.125 in. Zero Power Physics Reactor (ZPPR) plates and are placed in a tray in an array of 6 plates by 4 plates wide creating a 12 in. by 12 in. square. These trays of plutonium are interleaved between polyethylene plates. These measurements differ from previous TEX experiments in that they examine a more thermal neutron spectrum than previously examined by interleaving much thicker interstitial moderating plates than the previous measurements. The two configurations differ in the thickness of polyethylene between the fissile material. While the experiment was designed to examine the TSL, this work only examines the results of Rossi-α measurements on the two different configurations. For both configurations, Rossi-α measurements were performed to experimentally validate the neutron spectrum.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Integral Experiment Final Design for Thermal/Epithermal eXperiments (TEX) Plutonium Additional Mixed Spectrum Configurations

This report presents the final design (CED-2) for three additional mixed-spectra configurations for plutonium Thermal/Epithermal eXperiments (TEX) to target the intermediate energy region (IER-553). The baseline cases of IER-184 (PU-MET-MIXED-002 [2]) spanned the entire fission energy spectrum. Case 3, which had a median fission energy (MFE) of approximately 6E-5 MeV and had a fission fraction of about 42% in the intermediate energy range, resulted in a $k_{eff}$ overestimation of 1.1%. Compared to 749 previous ICSBEP plutonium benchmarks, the baseline cases accurately predicted the experiments in the thermal and fast regions where the majority of benchmarks inhabit. The benchmarks in the intermediate energy region to date are sparse and overestimate $k_{eff}$ with an average C/E between 1.02 and 1.03. The additional proposed configurations span the whole of the intermediate energy region. The experimental design utilizes the plutonium/aluminum metal alloy Zero Power Physics Reactor (ZPPR) Plutonium-Aluminum No-Nickel (PANN) plates with varying polyethylene moderator thicknesses to span the intermediate fission energy region. Each of the cases have varying fractions of thermal, intermediate, and fast fissions. The designs were chosen to maximize the intermediate energy fraction. The experiment will take place on the universal critical assembly machine, Planet. The layers will be split as equally as possible between the lower platen and the upper stationary platform of Planet. The upper half of the experimental configuration will also have an upper reflector of polyethylene of specified thicknesses to achieve criticality when the lower platen is raised fully. The previous IER-184 configurations, specifically Case 3, were used to determine the configurations for the additional experiments and neutronics calculations were used to fine-tune the configurations to ensure criticality. The quadrature sum uncertainty in Δ$k_{eff}$ for Case 3 in PU-MET-MIXED-002 was found to be 0.00219. Section 3.8 gives a detailed description of the uncertainties calculated. The additional configurations, which are based directly on Case 3, are expected to have similar uncertainties. However, it is possible to reduce the overall uncertainty of Δ$k_{eff}$ for the additional configurations using the knowledge obtained from the calculations in the benchmark.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Plutonium Oxidation State Distribution under WIPP Relevant Conditions (Rev. 2)

The oxidation state of plutonium in the Waste Isolation Pilot Plant (WIPP) environment has been a topic of interest since the initial compliance certification application. Plutonium (Pu) was initially expected to be present primarily as Pu(IV), but since the presence of Pu(III) could not be ruled out, it was also included in performance assessment (PA) calculations. The redox of the other variant actinides, uranium (U) and neptunium (Np), are also coupled to the plutonium redox. This led to a position in performance assessment calculations that is commonly referred to as “50/50”. In which half of the PA realizations assume solubility is dominated by the low oxidation state [U(IV), Np(IV), Pu(III)] and the other half assume solubility is dominated by the higher oxidation state [U(VI), Np(V), Pu(IV)]. Recently, a joint group of WIPP project participants from Los Alamos National Laboratory (LANL), Sandia National Laboratories (SNL), and the Department of Energy’s Carlsbad Field Office (DOE-CBFO) agreed on a new path forward for the oxidation state model in PA which will decouple the redox active actinides and will instead consider their redox as a function of E h . This will take the current binary approach and turn it into a system with four possible redox states.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1969

Gamma radiation characteristics of plutonium dioxide fuel

Investigation of plutonium dioxide as an isotopic fuel for Radioisotope Thermoelectric Generators yielded the isotopic composition of production-grade plutonium dioxide fuel, sources of gamma radiation produced by plutonium isotopes, and the gamma flux at the surface.

Gingo, P. J.↗
DOE OSTI2013

Characterizing surplus US plutonium for disposition

The United States (US) has identified 61.5 metric tons (MT) of plutonium that is permanently excess to use in nuclear weapons programs, including 47.2 MT of weapons-grade plutonium. Surplus inventories will be stored safely by the Department of Energy (DOE) and then transferred to facilities that will prepare the plutonium for permanent disposition. The Savannah River National Laboratory (SRNL) operates a Feed Characterization program for the Office of Fissile Materials Disposition (OFMD) of the National Nuclear Security Administration (NNSA) and the DOE Office of Environmental Management (DOE-EM). SRNL manages a broad program of item tracking through process history, laboratory analysis, and non-destructive assay. A combination of analytical techniques allows SRNL to predict the isotopic and chemical properties that qualify materials for disposition through the Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF). The research also defines properties that are important for other disposition paths, including disposal to the Waste Isolation Pilot Plant (WIPP) as transuranic waste (TRUW) or to high-level waste (HLW) systems.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

ESTIMATING IMPURITIES IN SURPLUS PLUTONIUM FOR DISPOSITION

The United States holds at least 61.5 metric tons (MT) of plutonium that is permanently excess to use in nuclear weapons programs, including 47.2 MT of weapons-grade plutonium. Surplus inventories will be stored safely by the Department of Energy (DOE) and then transferred to facilities that will prepare the plutonium for permanent disposition. The Savannah River National Laboratory (SRNL) operates a Feed Characterization program for the Office of Fissile Materials Disposition of the National Nuclear Security Administration and the DOE Office of Environmental Management. Many of the items that require disposition are only partially characterized, and SRNL uses a variety of techniques to predict the isotopic and chemical properties that are important for processing through the Mixed Oxide Fuel Fabrication Facility and alternative disposition paths. Recent advances in laboratory tools, including Prompt Gamma Analysis and Peroxide Fusion treatment, provide data on the existing inventories that will enable disposition without additional, costly sampling and destructive analysis.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

TRACKING SURPLUS PLUTONIUM FROM WEAPONS TO DISPOSITION

Supporting nuclear nonproliferation and global security principles, beginning in 1994 the United States has withdrawn more than 50 metric tons (MT) of government-controlled plutonium from potential use in nuclear weapons. The Department of Energy (DOE), including the National Nuclear Security Administration, established protocols for the tracking of this "excess" and "surplus" plutonium, and for reconciling the current storage and utilization of the plutonium to show that its management is consistent with the withdrawal policies. Programs are underway to ensure the safe and secure disposition of the materials that formed a major part of the weapons stockpile during the Cold War, and growing quantities have been disposed as waste, after which they are not included in traditional nuclear material control and accountability (NMC&A) data systems. A combination of resources is used to perform the reconciliations that form the basis for annual reporting to DOE, to U.S. Department of State, and to international partners including the International Atomic Energy Agency.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2019

Initial Testing of Mediated Electrochemical Oxidation for Inclusion in the Plutonium-238 Production Program

Oak Ridge National Laboratory is currently restarting the United States’ capability to produce kilogram quantities of 238Pu annually for space power applications. This involves the purification of 238Pu from neutron-irradiated 237Np targets and conversion to heat-source plutonium oxide product for shipment to Los Alamos National Laboratory. Dissolution of the plutonium oxide product material is required to obtain an isotopic assay and impurity analysis of the product material. In addition, any off-specification product will need to be dissolved for re-purification. An electrochemical method that produces highly oxidizing ions in solution is currently being investigated as a rapid method for dissolving these plutonium oxide samples.

Myhre, Kristian↗
DOE OSTI2025

Custom Equipment Development for Processing of Surplus Plutonium

The Strategic Laboratory Assessment (SLA), a collaborative team of SRNL and ORNL personnel, has been established to advance the objectives of the Surplus Plutonium Disposition (SPD) Project, by identifying and developing technologies to accelerate disposition, reduce life cycle costs, minimize worker radiation exposure, improve worker safety, and minimize Surplus Plutonium Disposition Program risks. [1] The SLA team has identified can cutting and plutonium (Pu) oxide size reduction as two glovebox processes where technology enhancements would be valuable. The DOESTD-3013 package currently in use for Pu downblending requires cutting two nested cans before the inner convenience can that holds the Pu oxide may be accessed for further processing. A rotary tubing-style cutter is used for opening the 3013 packages within the glovebox. Collet changeouts are required between cutting of the outer and inner cans. The SLA team is currently developing and testing an adjustable-clamp can cutter design that eliminates collet changeouts and allows cutting of the outer and inner can at the same time, resulting in significant reduction of radiological dose and process time, as well as improved ergonomics. To meet the Pu oxide particle size requirement, size reduction of Pu oxide agglomerations must be performed within the process gloveboxes. The SLA team has identified jaw crushing technology as an alternative to the currently employed rotary mill. Jaw crusher advantages include reduced dust within the glovebox, increased batch sizes, and easier integration with other glovebox processes due to the flow-through nature of jaw crushing. Commercially manufactured jaw crushers are either too large and/or too heavy for implementation in the SPD gloveboxes, so the SLA team is developing and testing a custom jaw crusher to meet the needs of the SPD Project.

Krementz, Daniel [Savannah River National Laborato↗
DOE OSTI2025

Non-Destructive Plutonium Assay in Pyroprocessing Bulk Materials with a 3D Boron-Coated-Straw Detector Array

Assessment of plutonium content through all the processing steps is needed and is a challenging task. While several destructive assay methods have been developed for nuclear material accountability, a nondestructive assay (NDA) system for the assessment of plutonium in bulk materials is still needed. This system should withstand pyroprocessing harsh environments and have consistent sensitivity and accuracy despite different fuel form factors. We aim to enable the accurate assessment of the plutonium content of nuclear material during pyroprocessing to improve the separation process and enhance its proliferation resistance. We plan to achieve this goal by developing and demonstrating a new 3D boron-coated-straw neutron detector array (3D-BCSDA) with high efficiency and spatial resolution.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Complex Method of Non-Destructive Measurements of Plutonium Composition and Mass

A complex method of performing non-destructive measurements of the isotopic composition and mass of plutonium that does not require external data on {sup 242}Pu content is described. The method includes a set of measurements performed by means of γ-spectrometry, calorimetry, and neutron multiplicity. Determinations of the metrological characteristics showed that in terms of accuracy it greatly surpasses the existing analogues, approaching the coulometric and isotopic dilution methods. The method is recommended for use in the industrial production of mixed uranium-plutonium fuel.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Utilization of non-weapons-grade plutonium and highly enriched uranium with breeding of the {sup 233}U isotope in the VVER reactors using thorium and heavy water

A method for joint utilization of non-weapons-grade plutonium and highly enriched uranium in the thorium–uranium—plutonium oxide fuel of a water-moderated reactor with a varying water composition (D{sub 2}O, H{sub 2}O) is proposed. The method is characterized by efficient breeding of the {sup 233}U isotope and safe reactor operation and is comparatively simple to implement.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2017

Natural Transmutation of Actinides via the Fission Reaction in the Closed Thorium–Uranium–Plutonium Fuel Cycle

It is shown for a closed thorium–uranium–plutonium fuel cycle that, upon processing of one metric ton of irradiated fuel after each four-year campaign, the radioactive wastes contain ~54 kg of fission products, ~0.8 kg of thorium, ~0.10 kg of uranium isotopes, ~0.005 kg of plutonium isotopes, ~0.002 kg of neptunium, and “trace” amounts of americium and curium isotopes. This qualitatively simplifies the handling of high-level wastes in nuclear power engineering.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

The Potential of Plutonium as a Fuel in Near-Thermal Burner Reactors

Here, the influence of plutonium as a fuel constituent on burner reactor behavior is examined. Both the SM-1 and the Shippingport seed lattices are investigated. It is found that the decrease in the effective absorption cross section of Pu 240 with fuel burnup gives the plutonium the characteristic of a self-compensating fuel, thereby leading to the extension of core life with minimum shim control requirements. The illustrated behavior is similar to that which was previously shown to be possible for converter-type reactors.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2015

Design of the Laboratory-Scale Plutonium Oxide Processing Unit in the Radiochemical Processing Laboratory

This report describes a design for a laboratory-scale capability to produce plutonium oxide (PuO 2 ) for use in identifying and validating nuclear forensics signatures associated with plutonium production, as well as for use as exercise and reference materials. This capability will be located in the Radiochemical Processing Laboratory at the Pacific Northwest National Laboratory. The key unit operations are described, including PuO 2 dissolution, purification of the Pu by ion exchange, precipitation, and re-conversion to PuO 2 by calcination.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗