This paper describes an approach to measuring extinct fission products that would allow for the characterization of a nuclear test at any time. The isotopic composition of molybdenum in five samples ...of glassy debris from the 1945 Trinity nuclear test has been measured. Nonnatural molybdenum isotopic compositions were observed, reflecting an input from the decay of the short-lived fission products 95Zr and 97Zr. By measuring both the perturbation of the 95Mo/96Mo and 97Mo/96Mo isotopic ratios and the total amount of molybdenum in the Trinity nuclear debris samples, it is possible to calculate the original concentrations of the 95Zr and 97Zr isotopes formed in the nuclear detonation. Together with a determination of the amount of plutonium in the debris, these measurements of extinct fission products allow for new estimates of the efficiency and yield of the historic Trinity test.
The isotopic composition of cadmium in nuclear debris was measured by multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS). Mass‐independent perturbations due to fission product ...decay on the isotopes of Cd were observed. Relative fission yields for masses 111, 112, 114 and 116 were determined in each sample of nuclear debris and compared with reported values found in irradiated plutonium and uranium fuels. Mass spectrometry measurements of the valley fission product endpoints are extremely challenging due to the low cumulative fission yields and small amounts of each isotope that are produced. To overcome these challenges, a new purification method for Cd was developed and validated by examination of a number of geological reference materials.
Key Points
The isotopic composition of cadmium in nuclear debris was measured by multi‐collector inductively coupled plasma‐mass spectrometry.
Mass‐independent perturbations due to fission product decay on the isotopes of cadmium were observed.
Relative fission yields for masses 111, 112, 114 and 116 were determined.
Measurements of the ruthenium isotopic composition of nuclear samples could provide information about the method of sample production, sample irradiation history, and age. To investigate the ...feasibility and applicability of this idea, this study focuses on measurements of the ruthenium isotope composition of a nominally single-isotope 106Ru radioactivity standard, where the complications of environmental mixing are eliminated. The measurements of the 106Ru standards reveal unusual stable ruthenium isotopic compositions consistent with fissiogenic ruthenium. Three different lots of the material have been investigated, and the isotopic composition is found to be different for lot 1 as compared to lots 2 and 3, indicating a longer irradiation duration incurred during the production of lot 1. Through measurements of 106Ru and its 106Pd daughter, radiochronometry can be used to infer the ages of the samples. Lot 1 is older than lots 2 and 3 and was produced 4.91(5) years before the reference date of 1/1/21, approximately 2.7 years before lots 2 and 3. In an effort to better understand the sample production pathway, the isotopic measurements are compared with nuclear reactor simulations, which suggest that the material was generated by irradiation of a low-enriched uranium target material in a light water reactor. These findings have significant implications for nuclear treaty monitoring, providing an example of the power of ruthenium isotope measurements to discern details of sample origin and history.
Compositional analysis of postdetonation fallout is a tool for forensic identification of nuclear devices. However, the relationship between device composition and fallout composition is difficult to ...interpret because of the complex combination of physical mixing, nuclear reactions, and chemical fractionations that occur in the chaotic nuclear fireball. Using a combination of in situ microanalytical techniques (electron microprobe analysis and secondary ion mass spectrometry), we show that some heavy stable elements (Rb, Sr, Zr, Ba, Cs, Ba, La, Ce, Nd, Sm, Dy, Lu, U, Th) in glassy fallout from the first nuclear test, Trinity, are reliable chemical proxies for radionuclides generated during the explosion. Stable-element proxies show that radionuclides from the Trinity device were chemically, but not isotopically, fractionated by condensation. Furthermore, stable-element proxies delineate chemical fractionation trends that can be used to connect present-day fallout composition to past fireball composition. Stable-element proxies therefore offer a novel approach for elucidating the phenomenology of the nuclear fireball as it relates to the formation of debris and the fixation of device materials within debris.
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.
An intercomparison of the radio-chronometric ages of four distinct plutonium-certified reference materials varying in chemical form, isotopic composition, and period of production are presented. The ...cross-comparison of the different 234U/238Pu, 235U/239Pu, 236U/240Pu, and 241Am/241Pu model purification ages obtained at four independent analytical facilities covering a range of laboratory environments from bulk sample processing to clean facilities dedicated to nuclear forensic investigation of environmental samples enables a true assessment of the state-of-practice in “age dating capabilities” for nuclear materials. The analytical techniques evaluated used modern mass spectrometer instrumentation including thermal ionization mass spectrometers and inductively coupled plasma mass spectrometers for isotopic abundance measurements. Both multicollector and single collector instruments were utilized to generate the data presented here. Consensus values established in this study make it possible to use these isotopic standards as quality control standards for radio-chronometry applications. Results highlight the need for plutonium isotopic standards that are certified for 234U/238Pu, 235U/239Pu, 236U/240Pu, and 241Am/241Pu model purification ages as well as other multigenerational radio-chronometers such as 237Np/241Pu. Due to the capabilities of modern analytical instrumentation, analytical laboratories that focus on trace level analyses can obtain model ages with marginally larger uncertainties than laboratories that handle bulk samples. When isotope ratio measurement techniques like thermal ionization mass spectrometry and inductively coupled plasma mass spectrometry with comparable precision are utilized, model purification ages with similar uncertainties are obtained.
Modern mass spectrometry and separation techniques have made measurement of major uranium isotope ratios a routine task; however accurate and precise measurement of the minor uranium isotopes remains ...a challenge as sample size decreases. One particular challenge is the presence of isobaric interferences and their impact on the accuracy of minor isotope
234
U and
236
U measurements. We present techniques used for routine U isotopic analysis of environmental nuclear safeguards samples and evaluate polyatomic interferences that negatively impact accuracy as well as methods to mitigate their impacts.
Glassy nuclear fallout debris from near-surface nuclear tests is fundamentally reprocessed earth material. A geochemical approach to analysis of glassy fallout is uniquely suited to determine the ...means of reprocessing and shed light on the mechanisms of fallout formation. An improved understanding of fallout formation is of interest both for its potential to guide post-detonation nuclear forensic investigations and in the context of possible affinities between glassy debris and other glasses generated by high-energy natural events, such as meteorite impacts and lightning strikes. This study presents a large major-element compositional dataset for glasses within aerodynamic fallout from the Trinity nuclear test (“trinitite”) and a geochemically based analysis of the glass compositional trends. Silica-rich and alkali-rich trinitite glasses show compositions and textures consistent with formation through melting of individual mineral grains—quartz and alkali feldspar, respectively—from the test-site sediment. The volumetrically dominant glass phase—called the CaMgFe glass—shows extreme major-element compositional variability. Compositional trends in the CaMgFe glass are most consistent with formation through volatility-controlled condensation from compositionally heterogeneous plasma. Radioactivity occurs only in CaMgFe glass, indicating that co-condensation of evaporated bulk ground material and trace device material was the main mechanism of radioisotope incorporation into trinitite. CaMgFe trinitite glasses overlap compositionally with basalts, rhyolites, fulgurites, tektites, and microtektites but display greater compositional diversity than all of these naturally formed glasses. Indeed, the most refractory CaMgFe glasses compositionally resemble early solar system condensates—specifically, CAIs.
A new thorium-229 reference material Essex, Richard M.; Mann, Jaqueline L.; Williams, Ross W. ...
Applied radiation and isotopes,
04/2018, Letnik:
134, Številka:
C
Journal Article
Recenzirano
Odprti dostop
A new reference material was characterized for 229Th molality and thorium isotope amount ratios. This reference material is intended for use in nuclear forensic analyses as an isotope dilution mass ...spectrometry spike. The reference material value and expanded uncertainty (k = 2) for the 229Th molality is (1.1498 ± 0.0016) × 10−10molg−1 solution. The value and expanded uncertainty (k = 2) for the n(230Th)/n(229Th) ratio is (5.18 ± 0.26) × 10−5 and the n(232Th)/n(229Th) ratio is (3.815 ± 0.092) × 10−4.
•New thorium-229 isotopic reference material was characterized.•Thorium-229 molality was measured by isotope dilution mass spectrometry.•Multiple thorium-232 isotopic spikes were prepared from high purity metal.•Thorium isotope amount ratios were measured with 3 multi-collector ICP-MS instruments.•Uncertainty budgets are provided for characterized reference material attributes.
New measurement and assessment techniques have been applied to the radiochemical reevaluation of the Trinity Event. Thirteen trinitite samples were dissolved and analyzed using a combination of ...traditional decay counting methods and the mass spectrometry techniques. The resulting data were assessed using advanced simulation tools to afford a final yield determination of 24.8 ± 2 kt TNT equivalent, substantially higher than the previous U.S. Department of Energy released value of 21 kt.
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