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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Determination of filter pore size for use in HB line phase II production of plutonium oxide

H-Canyon and HB-Line are tasked with the production of plutonium oxide (PuO 2 ) from a feed of plutonium (Pu) metal. The PuO 2 will provide feed material for the Mixed Oxide (MOX) Fuel Fabrication Facility. After dissolution of the Pu metal in H-Canyon, plans are to transfer the solution to HB-Line for purification by anion exchange. Anion exchange will be followed by plutonium(IV) oxalate precipitation, filtration, and calcination to form PuO 2 . The filtrate solutions, remaining after precipitation, contain low levels of Pu ions, oxalate ions, and may include solids. These solutions are transferred to H-Canyon for disposition. To mitigate the criticality concern of Pu solids in a Canyon tank, past processes have used oxalate destruction or have pre-filled the Canyon tank with a neutron poison. The installation of a filter on the process lines from the HB-Line filtrate tanks to H-Canyon Tank 9.6 is proposed to remove plutonium oxalate solids. This report describes SRNL’s efforts to determine the appropriate pore size for the filters needed to perform this function. Information provided in this report aids in developing the control strategies for solids in the process.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Scanning transmission x-ray microscopy (STXM) of plutonium oxide

Scanning transmission x-ray microscopy was used to examine plutonium oxide particles formed by the corrosion of δ-phase plutonium alloy under high-humidity conditions. O K-edge spectra collected from eight distinct particles displayed significant spectral differences, revealing heterogeneity in oxidation states within a single sample batch. Here, this variation suggests complex chemical environments and formation histories, which are important considerations for nuclear forensic investigations. These findings highlight both the potential of synchrotron-based x-ray microscopy for nondestructive, high-resolution analysis of nuclear materials and the need for expanded reference datasets to improve the interpretation and forensic utility of such measurements.

organic↗
DOE OSTI2024

The Role of Radiation-Induced Non-Equilibrium Plutonium Oxidation States in Solution

Plutonium plays a key role in global actinide research and nuclear fuel cycle technologies, and yet, our fundamental understanding of its inherent radiation-induced chemical behavior is limited. These radiation-induced processes cannot simply be switched off, as they are as fundamentally inherent to plutonium as the impact of relativistic effects on its f-electrons. In less chemically complex actinide systems, such as aqueous solutions of neptunium and americium, both steady-state and transient radiolysis products play a significant role in the redox cycling of their oxidation states, which ultimately impacts their chemistry and transport. However, plutonium's multiple, coexisting, and chemically active oxidation states, which comprise of bare ions and dioxo cations, provide additional redox pathways that complicate the aforementioned radiation-induced competition kinetics. Mechanistically understanding the response of these multiple oxidation states, both equilibrium and non-equilibrium, to intense ionizing radiation fields is essential for predicting the behavior of plutonium under a host of conditions that support technological innovation in global nuclear energy and non-proliferation efforts. Here, advances in radiation-induced plutonium solution chemistry will be presented, including new results from time-resolved electron pulse and steady-state gamma and alpha irradiations.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Independent Gamma Spectroscopy Analysis of a Plutonium Oxide Sample

Independent gamma spectroscopy data analysis of a plutonium oxide sample was requested on July 23, 2021. The primary request was to assess the Pu-239 activity/mass of the sample using previously collected gamma spectral data. Using the provided gamma spectral analysis report and spectral files, an independent evaluation of the data was conducted without any prior knowledge of the isotopic activity/mass of the sample.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Synthesis of Plutonium Oxide Specimens for a Statistically Designed Nuclear Forensics Study

This report describes the synthesis of plutonium oxide (PuO 2 ) samples at a bench-scale (10 g Pu) to support nuclear forensics research. The key unit operations that were performed included dissolving the PuO 2 feed material, purifying the Pu by ion exchange, precipitating as plutonium (III) oxalate, and reconverting to PuO 2 by calcination of the oxalate compound. Seventy-six PuO 2 synthetic runs were performed in execution of a statistically designed test matrix. The process parameters varied in these synthesis runs included temperature (30 or 50 °C), the Pu concentration in the feed solution (10, 30, or 50 g Pu/L), the HNO 3 concentration in the feed solution (1, 2, or 3 M), the direction of reagent addition (direct or reverse strike), the source of oxalic acid (solid or solution), and the reagent addition rate (as fast as possible, 20, or 40 minutes). This report describes the synthesis of the 76 PuO 2 specimens. The characterization of these specimens will be described in separate reports.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2015

Analysis of pressurization of plutonium oxide storage vials during a postulated fire

The documented safety analysis for the Savannah River Site evaluates the consequences of a postulated 1000 °C fire in a glovebox. The radiological dose consequences for a pressurized release of plutonium oxide powder during such a fire depend on the maximum pressure that is attained inside the oxide storage vial. To enable evaluation of the dose consequences, pressure transients and venting flow rates have been calculated for exposure of the storage vial to the fire. A standard B vial with a capacity of approximately 8 cc was selected for analysis. The analysis compares the pressurization rate from heating and evaporation of moisture adsorbed onto the plutonium oxide contents of the vial with the pressure loss due to venting of gas through the threaded connection between the vial cap and body. Tabulated results from the analysis include maximum pressures, maximum venting velocities, and cumulative vial volumes vented during the first 10 minutes of the fire transient. Results are obtained for various amounts of oxide in the vial, various amounts of adsorbed moisture, different vial orientations, and different surface fire exposures.

42 ENGINEERING↗
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↗
DOE OSTI2023

Packaging Plan for Mark-18A Plutonium Oxide

Mark-18A (Mk-18A) targets were irradiated at the Savannah River Site and have been in wet storage at the site since the 1970s. The Mk-18A Target Material Recovery Program has been established to recover the 244 Pu and heavy curium (≥50% 246 Cm and 248 Cm) in the targets at the Savannah River National Laboratory (SRNL) and ship the materials to Oak Ridge National Laboratory’s (ORNL’s) Radiochemical Engineering Development Center for programmatic use. Two products will be recovered from the Mk- 18A targets for shipment from SRNL to ORNL: a plutonium oxide stream and an oxide material that will contain the americium, curium, and lanthanides. This document presents the plan for packaging of the plutonium oxide material for shipment and storage at ORNL.

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

MIS High-Purity Plutonium Oxide Oxalate Precipitation/Calcination Product PBO-47-09-012-023 (Final Report)

A high-purity fuel-grade plutonium dioxide material from the Material Identification and Surveillance (MIS) Program inventory has been studied with regard to gas generation and corrosion in a storage environment. Sample PBO-47-09-012-023 originated from the Hanford continuous oxalate precipitation and calcination process and represents plutonium oxides from multiple processes currently stored in 3013 containers. After calcination to 950°C, the material contained 87.5% plutonium/americium with no major impurities. This study followed over time the gas pressure of a sample with nominally 0.5 wt% water in a sealed container with an internal volume scaled to 1/400 th of the volume of a 3013 container. Gas compositions were measured periodically over a three year period. The maximum observed gas pressure was 96 kPa. The increase over the initial pressure was primarily due to generation of hydrogen (5.7 kPa) and nitrogen (2 kPa) gas. Oxygen was a minor component of the initial headspace gas and was depleted. At the completion of the study, the internal components of the sealed container did not show significant signs of corrosion.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Surface area and particle size distribution of plutonium oxides derived from the direct oxidation of Pu metal (LA-UR-18-22581)

The intent of this paper is to interrogate the physical characteristics of PuO 2 powders and aggregates produced by direct metal oxidation to examine possible relationships between process parameters and the physical characteristics of the product. The majority of the PuO 2 samples considered were generated during the pre-production and production phases of the Advanced Recovery and Integrated Extraction System (ARIES) program at Los Alamos National Laboratory (LANL). Oxide formed passively on Pu metal surfaces at ambient atmospheric conditions is also characterized. Plutonium oxide powders from the ARIES Direct Metal Oxidation (DMO) furnace and muffle furnace process lines are very consistent in terms of their bulk and tapped density, specific surface area (SSA) and particle size distribution (PSD). The SSAs of calcined PuO 2 generated in the ARIES DMO-2 and muffle furnaces are between 0.1 and 0.5 m2/g. Oxides from both the DMO-2 and muffle furnaces also had similar tri-modal PSDs with maxima at 0.73–3.16 μm, 10.9–18.5 μm, and 41.3–63.0 μm. The PSDs of the oxide formed passively on Pu metal surfaces at ambient conditions were unimodal, with near-Gaussian distributions and D50 close to 1 μm. In conclusion, the oxide formed passively at ambient conditions also had significantly higher SSAs (6–8 m 2 /g).

36 MATERIALS SCIENCE↗
DOE OSTI2018

MIS High-Purity Plutonium Oxide Metal Oxidation Product BLO-39-11-14-004 (SSR132 and 132A): Final Report

A high-purity, reactor-grade plutonium dioxide material from the Material Identification and Surveillance (MIS) Program inventory has been studied with regard to gas generation and corrosion in a storage environment. BLO-39-11-14-004 is a high specific power oxide that represents Hanford process plutonium oxides from oxalate process product, oxalate precipitation of impure plutonium and pure mixed uranium/plutonium nitrate solutions, PFP NDA and impure and scrap plutonium oxides 80-85% from PFP and the 300 area. It also represents plutonium oxides from oxalate precipitation at LANL and Savannah River. After calcination to 950 °C, the material contained 80% plutonium and 7% americium with no major impurities. This study followed over time the gas pressure of a sample with nominally 0.5 wt% water in a sealed container with an internal volume scaled to 1/500th of the volume of a 3013 container. A leak occurred in the original reactor (SSR132) which was terminated after 3 years. The sample was reloaded (SSR132A) and an additional set of data was collected. Results from both loadings are discussed. Gas compositions were measured periodically over three (SSR132) and four and a half (SSR132A) year periods. The maximum observed gas pressures were 93 kPa and 94 kPa, respectively. The increase over the initial pressure was primarily due to generation of nitrogen gas. For SSR132, the maximum observed gas pressure for hydrogen was 1.2 kPa and oxygen was 9.3 kPa (includes oxygen from leak). For SSR132A, the maximum observed gas pressure for hydrogen was 5.5 kPa and oxygen was 0.9 kPa. At the completion of the study, the internal components of the sealed container showed limited signs of corrosion.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Extension of the Plutonium Oxide Nanocluster Family to Include {Pu 16 } and {Pu 22 }

Plutonium(IV) oxide nanoclusters represent an interesting scientific problem regarding structure-function relationships and are also relevant to global concerns surrounding plutonium reprocessing, the remediation of plutonium-contaminated soils, and the storage or disposal of plutonium-containing wastes. Here we report the synthesis of five unique Pu IV oxide nanoclusters containing 38,22, or 16 metal centers and capped only with inorganic ligands, such as chlorine and water, which prevent formation of the extended PuO 2 structure. The products are interrogated through single-crystal X-ray diffraction, bond valence calculations, and comparisons to other known metal-oxide nanoclusters. Of particular interest is the in-corporation of hydroxide linkages into the smaller plutonium oxide nanoclusters, which underscores previous observations and hypotheses regarding the formation of plutonium polymers and colloids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

MIS Shelf-Life Final Report for Plutonium Oxide Item 1000089 (SSR136 and SSR136A) from Rocky Flats Peroxide Precipitation and Calcination Process

A plutonium dioxide material from the Material Identification and Surveillance (MIS) Program inventory has been studied to determine the gas generation and corrosion behavior in a storage environment. Sample 1000089 represents product-quality plutonium oxides produced in the Rocky Flats peroxide precipitation process currently stored in 3013 containers. This study followed over time the gas pressure and composition of a sample with nominally 0.5 wt% water in a sealed container with an internal volume scaled to 1/500th of the volume of a 3013 container. Gas compositions had been measured periodically over almost 13 years. The maximum observed gas pressure was 204 kPa and was related to a temperature excursion. The maximum observed gas pressure from gas generation was 126 kPa. The increase over the initial pressure of 86.7 kPa was due to the generation of hydrogen, oxygen, and nitrogen. Carbon dioxide, methane and carbon monoxide were minor components of the headspace gas. The material exhibited unusual behavior in that the atmosphere reached flammable levels of hydrogen and oxygen within the first 30 days and remained flammable for the duration of the experiment. It has been determined that the sample inside the reactor was a mixture of the AR material, material calcined at 800 °C, and material calcined at 950 °C. The experiment was terminated in 2012 and unloaded in 2016. A new reactor, SSR136A, was loaded with the original sample freshly calcined at 950 °C. The total pressure inside SSR136A remained close to the initial value of 93 kPa. The total pressure is composed of He (steady levels after the reloading) and hydrogen which is 10% of the reactor’s total pressure. Nitrogen and oxygen compose trace amounts of the reactor headspace. The internal components of SSR136 were inspected in 2021, five years after it was removed from the array. The inside surfaces of the inner bucket exposed to the original sample for 4,576 days had an etched appearance, and pit-like features were observed in the microscopic analysis. No corrosion was observed on the SSR136A inner bucket that held the freshly calcined sample that was exposed for 1,303 days.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
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↗
DOE OSTI2017

Preparation and Characterization of a Master Blend of Plutonium Oxide for the 3013 Large Scale Shelf-Life Surveillance Project

A mixture of chlorine-containing, impure plutonium oxides has been produced and has been given the name Master Blend. This large quantity of well-characterized chlorinecontaining material is available for use in the Integrated Surveillance and Monitoring Program for shelf-life experiments. It is intended to be representative of materials packaged to meet DOE-STD-3013.1 The Master Blend contains a mixture of items produced in Los Alamos National Laboratory’s (LANL) electro-refining pyrochemical process in the late 1990s. Twenty items were crushed and sieved, calcined to 800ºC for four hours, and blended multiple times. This process resulted in four batches of Master Blend. Calorimetry and density data on material from the four batches indicate homogeneity.

3013 electro-refining storagage radioactive↗
DOE OSTI2015

Cleaning up the Legacy of the Cold War: Plutonium Oxides and the Role of Synchrotron Radiation Research

The deceptively simple binary formula of AnO 2 belies an incredibly complex structural nature, and propensity to form mixed-valent, nonstoichiometric phases of composition AnO 2±x . For plutonium, the very formation of PuO 2+x has challenged a long-established dogma, and raised fundamental questions for long-term storage and environmental migration. This presentation covers two aspects of Los Alamos synchrotron radiation studies of plutonium oxides: (1) the structural chemistry of laboratory-prepared AnO 2+x systems (An = U, Pu; 0 ≤ x ≤ 0.25) determined through a combination of x-ray absorption fine structure spectroscopy (XAFS) and x-ray scattering of laboratory prepared samples; and (2) the application of synchrotron radiation towards the decontamination and decommissioning of the Rocky Flats Environmental Technology Site. Making the case for particle transport mechanisms as the basis of plutonium and americium mobility, rather than aqueous sorption-desorption processes, established a successful scientific basis for the dominance of physical transport processes by wind and water. The scientific basis was successful because it was in agreement with general theory on insolubility of PuO 2 in oxidation state IV, results of ultrafiltration analyses of field water/sediment samples, XAFS analyses of soil, sediment, and concrete samples, and was also in general agreement with on-site monitoring data. This understanding allowed Site contractors to rapidly move to application of soil erosion and sediment transport models as the means of predicting plutonium and americium transport, which led to design and application of site-wide soil erosion control technology to help control downstream concentrations of plutonium and americium in streamflow.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Long-term Moisture Adsorption in Packaged Plutonium Oxide

In 2018, the Department of Energy National Nuclear Security Administration (DOE-NNSA) began implementing dilute and dispose to remove 34 metric tons (MT) of surplus weapons grade plutonium from the US stockpile. Under this plan, surplus plutonium material is converted into plutonium oxide (PuO 2 ) before being stored in metal containers and sent to the DOE Waste Isolation Pilot Plant (WIPP). The dilute and dispose project was implemented as a more cost-effective method for abiding by the Plutonium Management and Disposition Agreement (PMDA) between the USA and Russia, as compared to producing mixed oxide fuel (MOX). The PMDA was originally signed in 2000 and amended in 2010.2 The disassembly of pits and conversion to PuO 2 as part of dilute and dispose is carried out through the Advanced Recovery and Integrated Extraction System (ARIES) developed at Los Alamos National Laboratory (LANL). The dilute portion of dilute and dispose is carried out at Savannah River Site (SRS). With this program in place, it is necessary to ensure the safe, long-term storage of the PuO 2 generated during this process until final disposal at WIPP is accomplished.

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

Pressurization Analysis for Heating of a Screw Top Utility Can Loaded With Plutonium Oxide Powder by a 1273 K Fire

The documented safety analysis for the Savannah River National Laboratory (SRNL) evaluates the consequences of a postulated 1273 K fire in a glovebox. The radiological dose consequences for a pressurized release of plutonium oxide powder during such a fire depend on the maximum pressure that is attained inside the oxide storage containers. The oxide storage configuration selected for analysis is can/bag/can, comprised of oxide powder inside an 8.38 × 10 -6 m 3 stainless steel B vial inside 0.006 kg of polyethylene bagging inside a one-quart screw top utility can of the type commonly used to package solvents or rubber cements. To enable evaluation of the dose consequences, temperature and pressure transients have been calculated for exposure of a typical set of storage containers to the fire. The pressurization analysis credits venting to and from the B vial but does not credit venting or leakage from the can. Due to the low rate of venting from the B vial into the can gas space, the can pressure is nearly independent of the B vial pressure. Calculated maximum pressures are compared to the utility can burst pressure. In lieu of a structural analysis of the utility cans, burst pressures and leakage rates were measured using compressed nitrogen gas. The measured gauge burst pressure was 0.250 ± 0.043 MPa. The measured burst pressures are lower than the calculated maximum pressure due to fire exposure, indicating that the utility cans could burst during exposure to a 1273 K fire.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗