Initial Report for the Aquifer Background Study: Summary of Uranium and Plutonium Data from INEEL Groundwater Samples (original) (raw)
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VARIATIONS IN sup234sup 234sup234U CONCENTRATION OF NATURAL URANIUM
1969
This report was prepared as an account of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commission: A. Makes any warranty or representation, expressed or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus, method, or process disclosed in this report. As used in the above, "person acting on behalf of the Commission" includes any employee or contractor of the Commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any information pursuant to his employment or contract with the Commission, or his employment with such contractor.
Global distribution of Pu isotopes and 237Np
Science of The Total Environment, 1999
Inventories and compositions of Pu isotopes and 237Np in archived soil samples collected in the 1970s from 54 locations around the world were determined to provide regional baselines for recognizing possible future environmental inputs of non-fallout Pu and Np. As sample sizes used in this work were small (typically 1 g), inhomogeneities in Pu and Np concentrations were easily recognizable
Radioprotection, 2012
The uranium isotopes 238 U, 235 U and 234 U are found naturally in the environment. 238 U and 235 U are parent nuclides of two independent decay series of isotopes, while 234 U is a member of the 238 U decay chain. When decay series occur in a closed system the series tends to reach, with time, the state of secular equilibrium in which the activities of all series members are equal to the activity of its first nuclide. The activity ratio 234 U/ 238 U in natural uranium may vary as a consequence of decay chain disequilibrium due to alpha recoil and biogeochemical processes. A study based on measurement of uranium concentration and 234 U/ 238 U activity ratios in soil samples collected from Nalgonda district, Andhra Pradesh, India, a proposed mining site, was carried out to find the spatial distribution of uranium and the state of secular equilibrium of 234 U/ 238 U to examine the possibility of applying uranium concentration and uranium isotopic activity ratios to detect any hydrogeochemical changes in the environment during/post-operation. Soil samples were collected and analyzed for uranium concentration using the conventional UV fluorimetric method, showing a uranium concentration in the range of 0.7 ± 0.2 ppm to 7.9 ± 0.4 ppm with an average of 3.4 ppm, and 234 U/ 238 U activity ratios were estimated using the alpha spectrometry technique, showing an activity ratio in the range of 0.92 ± 0.11 to 1.02 ± 0.11. The 234 U/ 238 U activity ratio obtained indicated that these two uranium isotopes are in the state of secular radioactive equilibrium. The percent activity ratio of 238 U/total U and 234 U /total U is observed to vary from 47.94 ± 4.83 to 50.76 ± 4.87 and 45.80 ± 3.83 to 49.14 ± 3.99, respectively.
Characterization of uranium isotopic abundances in depleted uranium metal assay standard 115
Journal of Radioanalytical and Nuclear Chemistry, 2012
Certified reference material (CRM) 115, Uranium (Depleted) Metal (Uranium Assay Standard), was analyzed using a TRITON Thermal Ionization Mass Spectrometer to characterize the uranium isotope-amount ratios. The certified 235 U/ 238 U ''major'' isotope-amount ratio of 0.0020337 (12) in CRM 115 was determined using the total evaporation (TE) and the modified total evaporation (MTE) analytical techniques. In the MTE method, the total evaporation process is interrupted on a regular basis to allow correction of background from peak tailing, internal calibration of the secondary electron multiplier detector versus the Faraday cups, peak-centering, and ion source re-focusing. For the ''minor'' 234 U/ 238 U and 236 U/ 238 U isotopeamount ratio measurements using MTE, precision and accuracy comparable to conventional analyses are achieved, without compromising the quality of the 235 U/ 238 U isotopeamount ratios. Characterized values of the 234 U/ 238 U and 236 U/ 238 U isotope-amount ratios in CRM 115 are 0.000007545 (10) and 0.000032213 (84), respectively. The 233 U/ 238 U isotope-amount ratio in CRM 115 is estimated to be\5 9 10-9. The homogeneity of the CRM 115 materials is established through the absence of any statistically significant unit-to-unit variation in the uranium isotope-amount ratios. The measurements leading to the certification of uranium isotope-amount ratios are discussed.
In Uranium Minerals and Standards
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2000
We have recently extended our accelerator mass spectrometry (AMS) system to the detection of actinides for geophysical applications, taking 236 U as an interesting test case for this class of nuclides. We report on the development of the experimental setup and on preliminary measurements of 236 U in minerals and uranium standards. The isotopic abundance sensitivity is 1 Â 10 À11 . The natural 236 U abundance of ®ve U-rich minerals were measured to be between 1 and 33 Â 10 À11 . 236 U is expected to be produced in situ by neutron capture on 235 U. Three uranium standards material were measured and showed a large 236 U contamination. Ó
International Journal of Mass Spectrometry, 2014
Certified reference material (CRM) 116-A, uranium (enriched) metal assay and isotopic standard, was analyzed using TRITON and MAT261 thermal ionization mass spectrometer (TIMS) instruments to characterize the uranium isotope-amount ratios. The certified n(238 U)/n(235 U) "major" ratio in CRM 116-A was determined using a combination of two analytical techniques: total evaporation (TE) and modified total evaporation (MTE). The "minor" isotope-amount ratios n(234 U)/n(235 U) and n(236 U)/n(235 U) in CRM 116-A were characterized using a combination of MTE and conventional analysis techniques. For the n (234 U)/n(235 U) and n(236 U)/n(235 U) ratios, both the MTE and conventional analysis routines incorporate an internal mass bias correction using the measured n(238 U)/n(235 U) ratio as well as corrections for peak tailing from 235 U to 238 U. The abundance of 233 U, present in CRM 116-A at trace levels, was characterized using a conventional analysis technique that incorporates a secondary electron multiplier (SEM) equipped with an energy filter. CRM 116-A isotope-amount ratios are traceable to the national measurement base and to the International System of Units (S.I.). The measurements leading to the certification of the uranium isotopic abundances in CRM 116-A are discussed. 2014 Published by Elsevier B.V. 5 10 statement of metrological traceability" [1]. CRMs are used by 11 analytical laboratories for: (i) calibration and testing of analytical 12 equipment, (ii) qualification of analytical methods, (iii) evaluation 13 of the performance of routine measurement methods, (iv) 14 establishing uncertainty limits achieved by analytical procedures 15 and measurement equipment, (v) establishing traceability of the 16 measurement results with the S.I. units, and (vi) for preparation of 17 working standards for routine use [2,3]. CRMs traceable to the S.I. 18 units and to the national/international reference base are used to 19 ensure that measurement systems are free of bias as well as to 20 establish accuracy and precision achieved through measurement 21 methodologies used by nuclear analytical laboratories. Only 22 reference standards with assigned quantity values can be used 23 for calibration or "measurement trueness control" [4]. The Department of Energy's (DOE) New Brunswick Laboratory (NBL) is the US certifying authority for CRMs used in the nuclear fuel cycle. This paper describes the isotopic characterization analysis of a high enriched uranium metal reference material (CRM 116-A) that will be used as a replacement of NBL CRM 116 [5]. Sale of CRM 116 was halted due to a planar parting observed in the metal pieces that resulted in inconsistent uranium amount content values.
AMS of natural 236U and 239Pu produced in uranium ores
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2007
The rare isotopes 236 U and 239 Pu are produced naturally by neutron capture in uranium ores. Here we measure 236 U and 239 Pu by accelerator mass spectrometry (AMS) in the same ore samples for the first time. To ensure efficient extraction of both elements and isotopic equilibrium between the 239 Pu in the ore and a 242 Pu spike, we developed a new sample preparation protocol. AMS has clear advantages over previous methods because it achieves better discrimination against molecular interferences with higher sensitivity and shorter counting times. Measurements of 236 U and 239 Pu hold considerable promise as proxy indicators of neutron flux and uranium concentration.
For the direct gamma-ray spectrometric measurements of uranium concentrations in the samples, the use of 1001 keV peak of Pa, second daughter of U is emphasized. This " clean " peak is well resolved by HPGe detectors and gives accurate indication of uranium concentration in the samples without any self-absorption correction. The 1001 keV peak of Pa in the U chain is selected because it does not include any contribution from any other gamma emissions and does not have any interference with other peaks in the high-energy region even if the samples contain high amounts of thorium. The activity of Pa is determined by calibrating a HpGe detector with uranium standards. The measurement of 1001 keV gamma-ray emission from Pa by high-resolution gamma-ray spectrometry provides the basis for a reliable determination of U in the samples. The results obtained from the 63.3 keV peak of Th and those of the 1001 keV peak from Pa in the U chain for the uranium standards are compared with the certified values of the same samples. The results obtained from the measurements of 1001 keV peak from Pa agreed to within 2—5% with the certified activity values of U in the samples with uranium content ranging from 0.014 to 1.02 wt%. The results indicate that the uranium concentrations in the samples can be determined to within 5% error by about 14 h counting in a HpGe detector system.
Ultra-low level plutonium isotopes in the NIST SRM 4355A (Peruvian Soil-1)
Applied Radiation and Isotopes, 2009
For more than 20 years, countries and their agencies which monitor radionuclide discharge sites and storage facilities have relied on the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 4355 Peruvian Soil. Its low fallout contamination makes it an ideal soil blank for measurements associated with terrestrial-pathway-to-man studies. Presently, SRM 4355 is out of stock, and a new batch of the Peruvian soil is currently under development as future NIST SRM 4355A. Both environmental radioanalytical laboratories and mass spectrometry communities will benefit from the use of this SRM. The former must assess their laboratory procedural contamination and measurement detection limits by measurement of blank sample material. The Peruvian Soil is so low in anthropogenic radionuclide content that it is a suitable virtual blank. On the other hand, mass spectrometric laboratories have high sensitivity instruments that are capable of quantitative isotopic measurements at low plutonium levels in the SRM 4355 (first Peruvian Soil SRM) that provided the mass spectrometric community with the calibration, quality control, and testing material needed for methods development and legal defensibility.
Radioanalytical approach to determine 238Pu, 239+240Pu, 241Pu and 241Am in soils
Journal of Radioanalytical and Nuclear Chemistry, 2008
The simultaneous determination of multiple actinide isotopes in samples where total quantity is limited can sometimes present a unique challenge for radioanalytical chemists. In this study, re-determination of 238 Pu, 239+240 Pu, and 241 Am for soils collected and analyzed approximately three decades ago was the goal, along with direct determination of 241 Pu. The soils had been collected in the early 1970's from a shallow land burial site for radioactive wastes called the Subsurface Disposal Area (SDA) at the Idaho National Lab (INL), analyzed for 238 Pu, 239+240 Pu, and 241 Am, and any remaining soils after analysis had been archived and stored. We designed an approach to reanalyze the 238 Pu, 239+240 Pu, and 241 Am and determine for the first time 241 Pu using a combination of traditional and new radioanalytical methodologies. The methods used are described, along with estimates of the limits of detection for gamma-and alpha-spectrometry, and liquid scintillation counting. Comparison of our results to the earlier work documents the ingrowth of 241 Am from 241 Pu, and demonstrates that the total amount of 241 Am activity in these soil samples is greater than would be expected due to ingrowth from 241 Pu decay.