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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

From early prophylaxis to delayed treatment: Establishing the plutonium decorporation activity window of hydroxypyridinonate chelating agents

The potential consequences of a major radiological event are not only large-scale external radiation exposure of the population, but also uncontrolled dissemination of, and internal contamination with, radionuclides. When planning an emergency response to radiological and nuclear incidents, one must consider the need for not only post-exposure treatment for contaminated individuals, but also prophylactic measures to protect the workforce facing contaminated areas and patients in the aftermath of such events. In addition to meeting the desired criteria for post-exposure treatments such as safety, ease of administration, and broad-spectrum efficacy against multiple radionuclides and levels of challenge, ideal prophylactic countermeasures must include rapid onset; induce minimal to no performance-decrementing side effects; be compatible with current military Chemical, Biological, Radiological, Nuclear, and Explosive countermeasures; and require minimal logistical burdens. Hydroxypyridinone-based actinide decorporation agents have shown the most promise as decorporation strategies for various radionuclides of concern, including the actinides plutonium and americium. The studies here probe the extent of plutonium decorporation efficacy for two chelating agents, 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO), from early pre-exposure time points to a delay of up to 7 days in parenteral or oral treatment administration, i.e., well beyond the initial hours of emergency response. Despite delayed treatment after a contamination event, both ligands clearly enhanced plutonium elimination through the investigated 7-day post-treatment period. In addition, a remarkable prophylactic efficacy was revealed for 3,4,3-LI(1,2-HOPO) with treatment as early as 48 h before the plutonium challenge. This work provides new perspectives in the indication and use of experimental actinide decorporation treatments.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2017

Digital pile-up rejection for plutonium experiments with solution-grown stilbene

A solution-grown stilbene detector was used in several experiments with plutonium samples including plutonium oxide, mixed oxide, and plutonium metal samples. Neutrons from different reactions and plutonium isotopes are accompanied by numerous gamma rays especially by the 59-keV gamma ray of 241Am. Identifying neutrons correctly is important for nuclear nonproliferation applications and makes neutron/gamma discrimination and pile-up rejection necessary. Each experimental dataset is presented with and without pile-up filtering using a previously developed algorithm. The experiments were simulated using MCNPX-PoliMi, a Monte Carlo code designed to accurately model scintillation detector response. Collision output from MCNPX-PoliMi was processed using the specialized MPPost post-processing code to convert neutron energy depositions event-by-event into light pulses. The model was compared to experimental data after pulse-shape discrimination identified waveforms as gamma ray or neutron interactions. We show that the use of the digital pile-up rejection algorithm allows for accurate neutron counting with stilbene to within 2% even when not using lead shielding

Bourne, M. M.↗
DOE OSTI2017

Plutonium segregation in glassy aerodynamic fallout from a nuclear weapon test

Our study combines electron microscopy equipped with energy dispersive spectroscopy to probe major element composition and autoradiography to map plutonium in order to examine the spatial relationships between plutonium and fallout composition in aerodynamic glassy fallout from a nuclear weapon test. We interrogated a sample set of 48 individual fallout specimens in order to reveal that the significant chemical heterogeneity of this sample set could be described compositionally with a relatively small number of compositional endmembers. Furthermore, high concentrations of plutonium were never associated with several endmember compositions and concentrated with the so-called mafic glass endmember. Our result suggests that it is the physical characteristics of the compositional endmembers and not the chemical characteristics of the individual component elements that govern the un-burnt plutonium distribution with respect to major element composition in fallout.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2021

Four-decade follow-up of a plutonium-contaminated puncture wound treated with Ca-DTPA

Contaminated wounds are a common route of internal deposition of radionuclides for nuclear and radiation workers. They may result in significant doses to radiosensitive organs and tissues in an exposed individual's body. The United States Transuranium and Uranium Registries' whole-body donor (Case 0303) accidentally punctured his finger on equipment contaminated with plutonium nitrate. The wound was surgically excised and medically treated with intravenous injections of Ca-DTPA. A total of 16 g Ca-DTPA was administered in 18 treatments during the 2 months following the accident. Ninety-three urine samples were collected and analysed over 14 years following the accident. An estimated 239 Pu activity of 73.7 Bq was excreted during Ca-DTPA treatment. Post-mortem radiochemical analysis of autopsy tissues indicated that 40 years post-accident 21.6 ± 0.2 Bq of 239 Pu was retained in the skeleton, 12.2 ± 0.3 Bq in the liver, and 3.7 ± 0.1 Bq in other soft tissues; 1.35 ± 0.02 Bq of 239 Pu was measured in tissue samples from the wound site. To estimate the plutonium intake, late urine measurements, which were unaffected by chelation, and post-mortem radiochemical analysis results were evaluated using the IMBA Professional Plus software. The application of the National Council on Radiation Protection and Measurements wound model with an assumption of intake material as a predominantly strongly retained soluble plutonium compound with a small insoluble fraction adequately described the data (p = 0.46). The effective intake was estimated to be 50.2 Bq of plutonium nitrate and 1.5 Bq of the fragment. Here, the prompt medical intervention with contaminated tissue excision and subsequent Ca-DTPA decorporation therapy reduced 239 Pu activity available for uptake and long-term retention in this individual's systemic organs by a factor of 38.

239Pu↗
DOE OSTI2024

Field-induced magnetization of δ -plutonium from density functional theory

Here, we present results from density functional theory (DFT) calculations of magnetization, induced by an external magnetic field, for δ-phase plutonium. The fully relativistic electronic structure accounts for Zeeman splitting effects through a Hamiltonian that couples the magnetic field to both spin and orbital magnetic moments. The electronic-structure model is further improved by an extension to DFT in terms of an orbital-orbital coupling via the conventional orbital-polarization method, as has routinely been done for plutonium. The response to the applied magnetic field is shown to be weak in the DFT model, with induced magnetic moments of the order of in magnetic fields up to 30 T. These results are in accord with recent assessments from x-ray magnetic circular dichroism measurements in magnetic field on δ-plutonium. Somewhat surprisingly, a model assuming δ-plutonium to be absent magnetic moments shows stronger response to an external static magnetic field than models allowing for antiferromagnetism or magnetic disorder.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Chelation Modeling of a Plutonium-238 Inhalation Incident Treated with Delayed DTPA

This work describes an analysis, using a previously established chelation model, of the bioassay data collected from a worker who received delayed chelation therapy following a plutonium-238 inhalation. The details of the case have already been described in two publications. The individual was treated with Ca-DTPA via multiple intravenous injections and then nebulizations beginning several months after the intake and continuing for four years. The exact date and circumstances of the intake are unknown. However, interviews with the worker suggested that the intake occurred via inhalation of a soluble plutonium compound. The worker provided daily urine and fecal bioassay samples throughout the chelation treatment protocol, including samples collected before, during, and after the administration of Ca-DTPA. Unlike the previous two publications presenting this case, the current analysis explicitly models the combined biokinetics of the plutonium-DTPA chelate. Further, using the previously established chelation model, it was possible to fit the data through optimizing only the intake (day and magnitude), solubility, and absorbed fraction of nebulized Ca-DTPA. This work supports the hypothesis that the efficacy of the delayed chelation treatment observed in this case results mainly from chelation of cell-internalized plutonium by Ca-DTPA (intracellular chelation). It also demonstrates the validity of the previously established chelation model. As the bioassay data were modified to ensure data anonymization, the calculation of the “true” committed effective dose was not possible. However, the treatment-induced dose inhibition (in percentage) was calculated.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
DOE OSTI2017

Second-order Kinetics of DTPA and Plutonium in Rat Plasma

We report that in 2008, Serandour et al. reported on their in vitro experiment involving rat plasma samples obtained after an intravenous intake of plutonium citrate. Different amounts of DTPA were added to the plasma samples and the percentage of low-molecular-weight plutonium measured. Only when the DTPA dosage was three orders of magnitude greater than the recommended 30 μmol/kg was 100% of the plutonium apparently in the form of chelate. These data were modeled assuming three competing chemical reactions with other molecules that bind with plutonium. Here, time-dependent second-order kinetics of these reactions are calculated, intended eventually to become part of a complete biokinetic model of DTPA action on actinides in laboratory animals or humans. The probability distribution of the ratio of stability constants for the reactants was calculated using Markov Chain Monte Carlo. In conclusion, these calculations substantiate that the inclusion of more reactions is needed in order to be in agreement with known stability constants.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2013

Evaluating HDEHP Based Polymer Ligand Film (PLF) for Rapid Extraction of Plutonium

A method was developed to produce a thin Polymer Ligand Film (PLF) using di(2-ethylhexyl) orthophosphoric acid (HDEHP) ligand for rapid extraction of plutonium. The ligands were incorporated into a polymer matrix to generate a thin film substrate. HDEHP is an efficient extractant for a wide variety of metal ions. It is an amphiphillic molecule with two long hydrocarbon chains and a polar end with a phosphoryl oxygen (P=O) and an acidic –OH group. The extraction of lanthanides and other +3 oxidation state elements is highly dependent on the molarity of nitric acid in liquid/liquid extraction. The distribution factors for lanthanides generally decrease as molarity of nitric acid increases. Plutonium and uranium are less dependent on the molarity of the nitric acid. Still the distribution factors are higher at lower a nitric acid concentration. The main benefit of a PLF is that it eliminates the need for extensive and time consuming chemical processes to prepare samples for analysis. PLFs were tested using 239 Pu tracer, and all of the samples were analyzed with alpha spectroscopy to measure the recovery of plutonium. The pH of the plutonium tracer solutions and exposure time were varied to study effectiveness of PLFs in different conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Rapid, autonomous analysis of HPGe gamma-ray spectra III: Plutonium identification and characterization

RadID is a gamma-ray spectrum analysis program originally written to assist in the detection of the illicit movement of nuclear material. It is specific to the rapid analysis of HPGe gamma-ray data to reveal the radionuclide signatures of interest that may be present in the spectra. It is an autonomous, rule-based heuristic system that can identify well over 200 radioactive sources in about one second. RadID does not require knowledge of the detector efficiency, the source-todetector distance, or the geometry of the inspected radiation source—including any shielding. In this third of a three-document series we discuss how RadID detects the presence of plutonium isotopes and determines a number of its characteristics, most notably: the spectral characteristics of weapons-grade plutonium, reactor-grade plutonium, and heat-source plutonium used in radioisotope thermoelectric generators.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

PUMA: Plutonium Modeling and Analysis Theory Manual Rev 1.0

The high rate of alpha decay of the plutonium-238 isotope lends the material to be used for many unique space applications where the reach of solar radiation is either too weak or unavailable. With a power density of 0.54 watts per gram, plutonium-238 has been used to power space exploration satellites from mars rovers to deep space probes. Los Alamos National Laboratory (LANL) has remained the primary location for fabrication of the plutonium oxide pellets. In an effort to apply modern techniques and tools towards supporting LANL’s fabrication responsibilities, PUMA was created under an LDRD funded program to gain understanding of plutonium oxide heat source pellets during fabrication.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Integrated Initiative for Plutonium and Actinide Missions

Recognizing the dynamic environment and challenges facing the plutonium and actinide missions at Los Alamos National Laboratory over the next decade, Laboratory leadership established Fiscal Year (FY) 2020 Laboratory Agenda Item 2.6. This agenda item calls for the development and implementation of an integrated initiative for plutonium and actinide missions at Los Alamos. Over the next decade, Los Alamos has been asked to significantly ramp up pit production to help address nuclear stockpile and nuclear deterrence needs, heat source production to support expansion in space exploration, evaluation of stockpile returns, processing operations in support of nonproliferation, and the actinide science to support all of these efforts. All of this must be accomplished while significantly increasing the size of our plutonium and actinide missions workforce and modernizing and updating critical infrastructure. Only through enhanced integration of science, technology, and engineering (ST&E), manufacturing, and mission operations will we enable achievement of these critical missions. An overall summary of the plutonium and actinide missions is included in Figure 1 on Page 3 and Figure 2 on Page 4 summarizes our goals, objectives, FY 2021 recommended actions and internal strategic priorities that are key elements of our integrated initiative.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2023

Plutonium Basket Counter Measurement Control Q3-Q4 2023

The Plutonium Basket Counter (PBC) is a spent fuel nuclear safeguards instrument that was developed to measure spent-fuel elements from MAGNOX-type research reactors and determine their plutonium content. The instrument is designed to measure fuel elements in spent fuel cooling pools through underwater operation, but it is also able to measure radiation sources in air. The PBC determines fuel plutonium content by detecting neutrons with an array of Helium-3 detectors. The electronics make use of a JSR-15 shift register for data collection and IAEA Neutron Coincidence Counting (INCC) software for data analysis. The PBC is used to determine the 240 Pu content in spent MAGNOX fuel elements grouped into basket-like bundles, thus the instrument’s name. Reactor burnup calculations can be used in conjunction with the data from the PBC to estimate the total plutonium content in the fuel.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Measurement of Plutonium Ratios for CRM 137A Recertification

This report documents the analytical methodologies used by the Chemical and Isotopics Mass Spectrometry (CIMS) Group at the US Department of Energy’s Oak Ridge National Laboratory (ORNL) for plutonium isotopic ratio characterizations on purified ~1 mg units prepared by Lawrence Livermore National Laboratory (LLNL) from a mother solution created from an existing 250 mg unit of certified reference material (CRM) 137. The analytical processes described are designed to maintain traceability of the final certified attributes and to eliminate sources of systematic bias for the measurements described. The measurands for certification are the plutonium isotope ratios: 238 Pu/ 239 Pu, 240 Pu/ 239 Pu, 241 Pu/ 239 Pu, and 242 Pu/ 239 Pu. The preparation and analytical process included the following activities: Preparation of reference materials to be used as calibrants to establish traceability to the SI unit of mass for the isotopic analyses and quality controls. For the plutonium isotopic analyses, CRM 128 (a CRM comprising equal atoms of 239 Pu and 242 Pu) was used as the primary calibrant; Each CRM 137A unit was reconstituted using dilute high-purity HNO3. From each, seven replicates were distributed for the isotopic characterizations by thermal ionization mass spectrometry (TIMS) using the total evaporation (TE) method for isotope ratio measurements and MC-ICP-MS using a dynamic peak hooping method for secondary isotope ratio measurements; Due to time delay in the analyses from the last purification of the original CRM 137 mother solution by LLNL, an aliquot of the three provided plutonium units was purified using Eichrom TEVA separation methods to remove americium in-growth and uranium impurities; Minimally corrected data were reported from each analysis using reporting templates provided by the New Brunswick Laboratory Program Office (NBL PO) for the specific methods used for isotopic measurements. In addition, a copy of the instrument exports, Excel templates for isotopic data corrections, and the uncertainty budgets completed with the GUM Workbench software package were submitted to NBL PO.

07 ISOTOPE AND RADIATION SOURCES↗
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 OSTI2014

Carcinogenesis and Inflammatory Effects of Plutonium-Nitrate Retention in an Exposed Nuclear Worker and Beagle Dogs.

The genetic and inflammatory response pathways elicited following plutonium exposure in archival lung tissue of an occupationally exposed human and experimentally exposed beagle dogs were investigated. These pathways include: tissue injury, apoptosis and gene expression modifications related to carcinogenesis and inflammation. In order to determine which pathways are involved, multiple lung samples from a plutonium exposed worker (Case 0269), a human control (Case 0385), and plutonium exposed beagle dogs were examined using histological staining and immunohistochemistry. Examinations were performed to identify target tissues at risk of radiation-induced fibrosis, inflammation, and carcinogenesis. Case 0269 showed interstitial fibrosis in peripheral and subpleural regions of the lung, but no pulmonary tumors. In contrast, the dogs with similar and higher doses showed pulmonary tumors primarily in brochiolo-alveolar, peripheral and subpleural alveolar regions. The TUNEL assay showed slight elevation of apoptosis in tracheal mucosa, tumor cells, and nuclear debris was present in the inflammatory regions of alveoli and lymph nodes of both the human and the dogs. The expression of apoptosis and a number of chemokine/cytokine genes was slightly but not significantly elevated in protein or gene levels compared to that of the control samples. In the beagles, mucous production was increased in the airway epithelial goblet cells and glands of trachea, and a number of chemokine/cytokine genes showed positive immunoreactivity. This analysis of archival tissue from an accidentally exposed worker and in a large animal model provides valuable information on the effects of long-term retention of plutonium in the respiratory tract and the histological evaluation study may impact mechanistic studies of radiation carcinogenesis.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
NASA NTRS1972

Radiation from plutonium 238 used in space applications

The principal mode of the nuclear decay of plutonium 238 is by alpha particle emission at a rate of 17 curies per gram. Gamma radiation also present in nuclear fuels arises primarily from the nuclear de-excitation of daughter nuclei as a result of the alpha decay of plutonium 238 and reactor-produced impurities. Plutonium 238 has a spontaneous fission half life of 4.8 x 10 to the 10th power years. Neutrons associated with this spontaneous fission are emitted at a rate of 28,000 neutrons per second per gram. Since the space fuel form of plutonium 238 is the oxide pressed into a cermet with molybdenum, a contribution to the neutron emission rate arises from (alpha, n) reactions with 0-17 and 0-18 which occur in natural oxygen.

Keenan, T. K.↗
DOE OSTI2013

Electrochemically Modulated Separation for Plutonium Safeguards

Accurate and timely analysis of plutonium in spent nuclear fuel is critical in nuclear safeguards for detection of both protracted and rapid plutonium diversions. Gamma spectroscopy is a viable method for accurate and timely measurements of plutonium provided that the plutonium is well separated from the interfering fission and activation products present in spent nuclear fuel. Electrochemically modulated separation (EMS) is a method that has been used successfully to isolate picogram amounts of Pu from nitric acid matrices. With EMS, Pu adsorption may be turned "on" and "off" depending on the applied voltage, allowing for collection and stripping of Pu without the addition of chemical reagents. In this work, we have scaled up the EMS process to isolate microgram quantities of Pu from matrices encountered in spent nuclear fuel during reprocessing. Several challenges have been addressed including surface area limitations, radiolysis effects, electrochemical cell performance stability, and chemical interferences. After these challenges were resolved, 6 µg Pu was deposited in the electrochemical cell with approximately an 800-fold reduction of fission and activation product levels from a spent nuclear fuel sample. Modeling showed that these levels of Pu collection and interference reduction may not be sufficient for Pu detection by gamma spectroscopy. The main remaining challenges are to achieve a more complete Pu isolation and to deposit larger quantities of Pu for successful gamma analysis of Pu. If gamma analyses of Pu are successful, EMS will allow for accurate and timely on-site analysis for enhanced Pu safeguards.

Pratt, Sandra H.↗
DOE OSTI2023

Implementation of a System of Gamma Imagers for Measuring Plutonium Holdup

The Surplus Plutonium Disposition (SPD) project is an effort to dilute and dispose of many tonsof weapons grade plutonium. This work will take place in a shielded glovebox to protect workers fromradiological dose. Accurate measurements of the holdup, or material left behind, in the gloveboxes is im-portant for Nuclear Material Control and Accountancy, worker dose minimization, criticality safety, andprocess monitoring. Shielding around the gloveboxes presents an obstacle for the traditional GeneralizedGamma Holdup (GGH) method. The uncertainties associated with that method, at around 28%, arealso detrimental since the amount of holdup must be kept below an established limit with a high level ofconfidence.Passive gamma-ray imaging provides a more complete depiction of the distribution of radioactivematerials. Recent refinement of the method has demonstrated that quantitative information can beextracted from the images with a well-characterized system. A permanently installed system of gamma-ray imagers is currently being developed to measure plutonium holdup in the SPD gloveboxes. Thispaper will report on progress with the development of this system.This application requires that the features of current commercially available instruments from H3Dand PHDS, optimized for measurement performance in a mobile application, be translated into theconstraints of the operational environment with fixed installations. The interaction between facilityconstraints and measurement capabilities will be addressed.A series of measurements with plutonium sources in a mocked-up glovebox geometry with imagersmounted above the ceiling of the glovebox have been taken. Imager performance with respect to angularresolution, minimum measurement time for quantification, and signal-to-noise ratio with a multitudeof sources will be evaluated for those measurements. A series of prototypes of user interfaces will bepresented for display of the data to its various consumers for the purposes of Nuclear Material Controland Accountancy, worker dose minimization, criticality safety, and process monitoring.

Schmitt, Kyle↗