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Results for “Radiation Chemistry”

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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

New loading method for high precision Sm isotope analysis of nuclear materials using thermal ionization mass spectrometry

This work demonstrates an analytical protocol for high precision Sm isotope analysis by thermal ionization mass spectrometry (TIMS) using a Pt activator. Here, the method permits precise measurements of small aliquots (1–20 ng) of Sm on single Re filament using a modified static-total evaporation technique. This study represents the first attempt to use such protocols for Sm isotope analyses while reducing the loading size of Sm for TIMS. The method could potentially be deployed to study geological, meteorites and lunar samples containing low Sm concentrations, to monitor neutron irradiation exposure based on 149,150 Sm, or to measure Sm isotopic composition in other types of nuclear samples.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Exploring the use of thorium isotope compositions and concentrations as nuclear forensic signatures for uranium ore concentrates

This interlaboratory study measured thorium concentrations and isotope compositions in uranium ore concentrates from different geographical locations to examine whether thorium impurities may be useful forensic signatures for uranium ore concentrates found out of regulatory control. Measured 230 Th/ 232 Th in fifteen uranium ore concentrates record over three orders of magnitude of compositional variation. Results demonstrate that 230 Th/ 232 Th used in combination with U/Th ratios resulted in a unique signature for individual uranium ore concentrates from different processing locations. Data presented here suggest potential for 230 Th/ 232 Th and U/Th to be used as comparative signatures to investigate the provenance of seized uranium ore concentrates.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Large-scale dissolution of sintered Mo disks

Non-uranium production of 99 Mo via neutron capture or by photonuclear reaction using an electron accelerator is receiving considerable attention. For commercial production of 99 Mo, post-irradiation processes must incorporate a robust design for easy scale-up. Once developed, large-scale chemical processes must be optimized for hot-cell operations and potential automation. In this work, we present experimental results on the large-scale dissolution of sintered Mo disks using three 50% hydrogen peroxides from different suppliers. Dissolution rates obtained for 600-g Mo batches and potential reasons for different dissolution behaviors is discussed.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Rapid dissolution of PuO 2 analytical samples using mediated electrochemical oxidation

Current methods for quantitative dissolution of solid PuO 2 involve lengthy dissolution times. The adaptation of mediated electrochemical oxidation, which uses an electrochemically produced oxidizing agent to catalyze dissolution, has been explored for radiochemical analysis scale dissolutions of PuO 2 . The effects of temperature, electrode material, and electrocatalyst on the dissolution kinetics were explored. Under conditions examined in this study, complete dissolution of tens of milligrams of solid PuO 2 can be achieved in less than 1 h at ambient temperature. Overall, this methodology could be adapted to dissolve other metal oxides.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Extraction of radium and actinium with Pb resin and Rose Bengal

The extraction of radium and actinium with Eichrom Pb resin and Rose Bengal has been studied. Radium and actinium both show a strong affinity (k’ > 10,000) for the resin at intermediate pHs (~ 5–7) from solutions with Rose Bengal. The pH range and magnitude of uptake for both radium and actinium is significantly increased by the presence of Rose Bengal compared to basic solutions without this counter ion. Additionally, radium uptake is extremely fast from basic solutions with and without Rose Bengal; actinium uptake is slower, particularly in solutions without Rose Bengal. Column studies show that despite the similar behavior of actinium and radium in this system, separations of these two elements with Pb resin and Rose Bengal solutions are possible with reasonable yields due to the differences in uptake kinetics.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Multifractal detrended fluctuation analysis of soil radon ( 222 Rn) and thoron ( 220 Rn) time series

In this paper, we present results of Multifractal Detrended Fluctuation Analysis (MF-DFA) of soil Radon ( 222 Rn) and Thoron ( 220 Rn) time series to examine the scaling and multifractal features. Data consists of 15,692 measurements taken each over forty-minute interval. RTM 1688-2, 222 Rn/ 220 Rn electronic device has been used for measurement purposes. Seasonal periodicities have been removed from the data and MF-DFA was employed on de-seasonalized data. Original 222 Rn and 220 Rn time series have been converted into surrogate and shuffled time series. MFDFA has also been applied to the surrogate and shuffled series to examine the multifractality nature. Results of the study show that $^{222}_{Orig}Rn$, $^{222}_{Surr}Rn$ and $^{220}_{Orig}Rn$, $^{220}_{Surr}Rn$ time series are longrange positively correlated and an increase or decrease in either of radionuclide concentrations will be followed by another increase or decrease of concentrations in future measurements. The $^{220}_{Shuff}Rn$ time series has an independent or short-range dependent structure called white noise and the shuffled time series exhibit a very weak multifractality.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Thermal impacts on nondestructive analysis measurements of uranium hexafluoride

A series of nondestructive assay measurements were performed before, during, and after localized heating of an industrial standard 12B cylinder of uranium hexafluoride to replicate dose variations previously observed on commercial 30B cylinders. While cylinders represent a closed system, enrichment measurements may be impacted by altered uranium and daughter product distributions due to sublimation. A series of measurements were performed to examine localized heating impacts on dose rates, ratios of uranium and daughter product distributions, and measured 235 U enrichment as calculated by two different approaches. The less complex enrichment meter approaches were found to be more robust and less prone to deviation than isotope ratio approaches such as FRAM, but the impact can be minimized by using observable dose changes to avoid impacted areas.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Separation of zirconium and hafnium from early actinides and rare earth elements with eichrom’s pb resin in HCl

The separation of zirconium and hafnium isotopes from the early actinides and rare earth elements (REE) with Eichrom’s Pb resin has been studied. Batch studies were performed to characterize the behavior of actinium, thorium, zirconium, hafnium, lutetium, and yttrium on Pb resin from HCl solutions (0.001 M to 11 M). The early actinides and REE had no affinity for the resin at any concentration of HCl, but zirconium and hafnium showed a moderate uptake at high concentrations of HCl with a maximum extraction at 11 M HCl. Several column separations were tested, including with only tracer isotopes and with mass. Rapid, simple separations of zirconium from actinium, thorium, protactinium, and the REE with high yields and low elution volumes are presented with applications for tracer isotope production and fission product separations. Furthermore, the resin is less suitable for hafnium separations as hafnium tends to bleed off the resin even at high concentrations of HCl.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Extraction of gold, mercury and lead on CL resin in HCl

The uptake behavior of 197 mHg, 194 Au and 212 Pb in HCl on CL resin (Triskem) was studied. The extraction of mercury and gold is high (D w > 5,000) at all concentrations of HCl, with a maximum extraction of gold at 4 M HCl (D w ~ 53,000) and maximum extraction of mercury at 0.01 M HCl (D w ~ 44,000). Lead has moderate uptake on CL resin (D w ~ 100) from lower concentrations of HCl (0.001 to 0.05 M) and no uptake on the resin in concentrations ≥ 0.4 M. The uptake kinetics are similar for all three isotopes with high weight distribution ratios (>1,000 for 197 mHg, 194 Au and > 100 for 212 Pb) in ~ 30 s and equilibrium established at ~ 5 min. A column study was performed to demonstrate that 197m Hg, 194 Au and 212 Pb could be retained on CL resin in dilute HCl and 212 Pb eluted in 1 M HCl with no detectable 197m Hg or 194 Au. Elution of 197 mHg and 194 Au was performed with concentrated HNO 3 , but with significant losses to the column, particularly for 194 Au.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

National nuclear forensics libraries: a case study on benefits and possibilities for identification of sealed radioactive sources

A National Nuclear Forensic Library (NNFL) is a useful nuclear forensics tool which consists of information and subject matter expertise on radioactive and nuclear (RN) materials produced, used or stored within a State. If RN material is found out of regulatory control the NNFL can be used as part of a nuclear forensics investigation to help identify whether or not the material is consistent with a country’s national holdings. In previous work, a number of signatures which can be useful to identify sealed sources of 241 Am were investigated. To validate the measurement results, an official query concerning information about two of the previously investigated 241 Am sources was sent to the United States Department of State, the international point-of-contact (POC) for the U.S. NNFL. The aim of this work is to show how data obtained in a characterization of a radioactive source can be used in conjunction with an NNFL to investigate the history of a source out of regulatory control.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Direct uranium enrichment assay in gaseous uranium hexafluoride with laser induced breakdown spectroscopy

A set of eleven U atomic emission lines, between 421.099 and 421.460 nm, were characterized for direct enrichment assay of gaseous UF 6 samples with laser induced breakdown spectroscopy (LIBS). Several iterative, multivariate nonlinear spectral-fitting algorithms were evaluated for their efficacies to extract the enrichment information from the measured LIBS spectra. Furthermore, wavelength-dependent weight factors, which take into consideration of the spectral-line position in the fitting model, the determined isotopic ratio, and the isotopic shift of the emission line, are essential for the spectral-fitting model to function adequately. The analytical accuracies and precision were typically within 0.5% in absolute [ 235 U/( 235 U + 238 U)] ratios.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Extraction of 197 mHg with TIBPS in HNO 3 and HCl media

Here, the extraction of no carrier added mercury by tri-isobutyl phosphine sulfide (TIBPS) was characterized in HCl and HNO 3 media. The extraction of 197 mHg as a function of acid concentration was similar in both acids over a large acid concentration (0.001 M to conc.) with high extraction (D ~ 1000) at low concentrations and decreasing extraction for higher concentrations (≥ 4 M). The kinetics of extraction were rapid (~ 5 min.) in both acids. Speciation experiments indicated that the extraction mechanism is 1:2 ( 197 mHg:TIBPS) in HCl and 1:1 in HNO 3 .

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Age determination of a 75 Se gamma radiography source for nuclear forensics

Here, two methods were used to evaluate the age of 75 Se sealed source material. Both methods utilized gamma spectroscopy to determine the quantity of parent 75 Se present, but they differed in the technique used to determine the quantity of daughter 75 As. In one method, 75 As was quantified using inductively coupled plasma-mass spectrometry (ICP-MS) after using chromatographic techniques to separate the parent and daughter isotopes. In the other method, total As was measured using optical emission spectroscopy (OES), which did not require separation prior to measurement. The OES method was faster and gave slightly lower uncertainties, but required more daughter material to be present because of higher concentration requirements, making it unsuitable for young material. Both methods are hampered by the monoisotopic nature of As, but still gave reasonable model ages that were in agreement with each other.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Column separation of tetravalent cerium fission products from trivalent rare earth radio-isotopes

Rapid and efficient isolation of individual rare earth element (REE) radioisotopes from complex mixtures is necessary to support the fields of nuclear forensics, medical isotope production and nuclear physics measurements. The separations must be robust and generate sufficiently high purity samples for subsequent radiological analysis. Current methodologies utilize a laborious two step Ce(IV)-iodate precipitation followed by Ce(IV)-nitrate di-(2-ethylhexyl)phosphoric acid/n-heptane extraction. This work reports an alternative method to isolate Ce fission product isotopes equilibrated with milligrams of cold carrier, from the remaining REE’s using a Ce(IV)/LN-resin (Eichrom Technologies) based separation. Optimization of Ce(IV) loading, REE(III) elution volume and subsequent Ce(III) stripping step utilized 166m Ho tracer. Mixed fission product experiments provided a further test of this LN-resin method, with analysis of purified 141/144 Ce, 147 Nd and 91 Y. Overall, while decontamination factors were lower for the LN-resin method, (vs. the combined precipitation/extraction) the simplicity of the technique and the satisfactory fission product analysis results point to the efficacy of this method.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Extraction of radium and actinium with dibenzo-21-crown-7 resin and Rose Bengal

The extraction of 224 Ra and 228 Ac with dibenzo-21-crown-7 resin was studied in solutions with Rose Bengal and identical solutions without Rose Bengal (blanks) from pH 3 to 12. Batch studies demonstrated that actinium is extracted at high pH (> 10) from both solutions but with a significantly higher extraction from the Rose Bengal solutions (maximum extraction ~ 60,000) than the blank solutions (maximum extraction ~ 2,000). In the Rose Bengal solutions, there was a weak extraction of actinium at lower pH (4–10) as well. There was no uptake of radium from the blank solutions, and a weak extraction at all pH levels from the Rose Bengal solutions. Kinetics studies were performed for actinium only, as radium had no significant extraction. Two column studies are demonstrated for the separation of radium from actinium. These separations are moderately effective with ~ 78% of the actinium recovered with no detectable radium.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

International interlaboratory compilation of trace element concentrations in the CUP-2 uranium ore concentrate standard

Herein, a nuclear forensics investigation involving a uranium ore concentrate relies on accurate and precise analysis of impurities. Analytical data defensibility requires the use of reference materials as part of quality control. This study presents a compilation of trace element concentration results of the CUP-2 Uranium Ore Concentrate Standard measured by 11 different laboratories. The laboratories employed various dissolution methods, analytical preparation methods, and instrumental platforms. The data presented here contain concentrations of 66 impurities with up to 138 individual data points for each impurity. Consensus values have been assigned to each impurity following a statistical analysis of the data set.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Collaborative Study for Certification of Trace Elements in Uranium Ore Concentrate CRMs UCLO-1, UCHI-1, and UPER-1

Trace impurity patterns are important nuclear forensic signatures in uranium ore concentrates (UOCs) and Certified Reference Materials (CRMs) are used to validate the analysis methods employed by end users. Herein, we discuss the certification campaign for three new UOC CRMs from the National Research Council Canada: UCLO-1 (https://doi.org/10.4224/crm.2020.uclo-1), UCHI-1 (https://doi.org/10.4224/crm.2020.uchi-1), and UPER-1 (https://doi.org/10.4224/crm.2020.uper-1). This study involved 15 laboratories from 10 countries, using sector-field and (triple) quadrupole inductively-coupled plasma mass spectrometry to analyze 64 trace element impurities. We discuss the importance of the acids used for sample digestion, difficulties analyzing in a high uranium matrix, and data combination and uncertainty evaluation for this large dataset.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Survey of Additive Manufacturing Signatures for the Prevention of Nuclear Proliferation

Improvements in additive manufacturing technologies will enable multiple-material and advanced material capabilities, creating opportunities to improve and expand the nuclear fuel fabrication process. Additive manufacturing can allow fuel to have complex geometries and contain composites of materials that would otherwise be difficult or impossible to make with traditional manufacturing methods. This opportunity also has implications for nuclear proliferation, as nuclear parts may be printed and more easily acquired. Here, we present a survey of additive manufacturing technologies and relevant signatures that could be used to identify processes, materials, or part properties.

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