Measurement of actinides in environmental samples by photon-electron rejecting alpha liquid scintillation

Cadieux, J.R.; Clark, Sue B.; Fjeld, Robert A.; Reboul, S.; Sowder, Andrew

doi:10.1016/0168-9002(94)91716-7

Cited by 22 publications

(13 citation statements)

References 2 publications

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“…We obtained total alphaand ct-PHA analyses and PERALS analyses of the product phases. 2 Counting radioactivity of these product phases did not assist us in the quantitative analyses, ct-PHA spectra confirmed the removal of 241Am and 244Cm components, but were not able to discern the Pu isotopics. Total alpha measurements on duplicate plates had poor agreement even on the standard addition samples, and the pulse shape liquid scintillation spectra were still triggering on 90y events as alpha events.…”

Section: Methodsmentioning

confidence: 84%

“…For several samples we obtained measured total alpha-content by a-plate counting and by PERALS analysis. 2 We discuss these comparisons in the Results section. For three samples we were able to obtain a direct measure of absolute 239pu content by ICP-MS. All of these comparisons are very favorable and are also discussed in the Results section.…”

Section: Introductionmentioning

confidence: 97%

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Plutonium measurements in Hanford DOE site waste samples

Dewberry

Boyce

1999

J Radioanal Nucl Chem

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This paper describes development work to prepare a method to measure absolute 239pu content and Pu-isotopics by 1CP-MS in acidified Hanford DOE-site samples which are very high in 9~ 99Tc, and 137Cs radioactivity and which are frequently high in organic carbon content. Samples with very large 9~ and 137Cs contents have historically been difficult to analyze for Pu content by each of three alpha-counting techniques in use at SRS, and analysis by ICP-MS in these samples is complicated by the high organics content. We report an ion exchange chemical preparation to obtain fraction of Pu that does not contain any fission product contribution and no interfering organics to allow measure of absolute 239pu and of 239pu through 241pu isotopics by ICP-MS. The method uses a 242pu spike to measure Pu recovery and is demonstrated in this paper with three distinct commercially available resins and with over 300 samples. Measured absolute 239pu contents in sixty-three spiked/unspiked duplicates have agreed within 15% precision. Overall 242pu recoveries were near 90% with 25% precision. Comparisons of absolute 239pu contents measured directly on three samples agreed within the quoted 25% uncertainty. IntroductionIn this paper we describe development and implementetion of a chemical separation for analysis of 239pu and Pu-isotopics by ICP-MS in Hanford DOE-type samples which are high in ~37Cs content and in organic carbon content and which originate from five distinct species of waste. Historically at the Savannah River Site (SRS) high salt content samples have complicated radioactive counting methods to the extent that sample self-absorption becomes an unmanageable uncertainty in ~x-plate counting, l Very high I]-decay activities fequently introduce significant uncertainty into instrumental discrimination against 13-decay events when using direct PERALS (photo-electron rejecting alpha liquid scintillation) spectroscopy 2 or direct pulse shape discrimination liquid scintillation counting 3,4 to determine Pu or total alpha. We have observed that the 137Cs conversion electron and the high energy 90y daughter ~-decay events will very often be electronically misinterpreted as alpha events. The difficulties with each of the three counting techniques as well as attempts to correct for the uncertainties are described in detail in Reference 1.We report in this paper the successful development of an ion exchange purification method to obtain a purified fraction of Pu suitable for determination of absolute 239pu content and for determination of 24~ isotopics by ICP-MS. The technique was developed and used with over three hundred samples from five distinct envelopes of sample species and with three distinct ion exchange or ion chromatography resins. In the chemical treatment, Pu is reduced to the +3 oxidation state and then oxidized to +6 with NaNO 2 and with concentrated HNO 3 for loading onto the ion resins in concentrated HC1. Most of the organics content, which would soil the ICP-MS cones and require additional maintenance, are hydrolyz...

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Section: Methodsmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 97%

Plutonium measurements in Hanford DOE site waste samples

Dewberry

Boyce

1999

J Radioanal Nucl Chem

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“…Alpha liquid scintillation with alpha/beta discrimination seems to be a promising technique for the determination of alpha emitters, and therefore actinide elements in environmental samples, due to a high sensitivity, a fast sample preparation and cheap analytical costs [1][2][3][4][5][6][7][8]. However, this technique suffers from a lack of resolution leading in some cases to the impossibility to resolve two adjacent peaks, as for 241 Am/ 243 Am and 210 Po/ 208 Po.…”

Section: Introductionmentioning

confidence: 99%

Deconvolution of alpha liquid scintillation spectra for quantitative analysis of actinide elements in water samples

Aupiais¹

2004

Radiochimica Acta

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The reliability and accuracy of actinide measurement in environmental samples strongly depend on the α-spectrum deconvolution process used to identify all radionuclides present in the sample, and the necessity to take into account internal conversion is demonstrated. In this process, all actinides can be resolved as the sum of three peaks: the main alpha transition and two sum peaks for which the additional α ray is merged with the internal conversion on L-shell peak and with all other conversions on M-shell, N-shell, etc.The intensity of the internal conversions for thorium, uranium, plutonium and americium have been calculated and normalised to the intensity of the main alpha transition. These data can be used to determine the activity of any above-mentioned actinide by alpha liquid scintillation with alpha/beta discrimination. The quantitative analysis and the isotopic ratio determination of several certified solutions of actinides demonstrate the validity of this approach.

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“…After the phases were separated the oxygen was purged to reduce quenching and improve energy resolution. Tests of the two-step extraction on water samples with known actinide activities have shown recoveries higher than 95% with a precision of 2% to 3% (Cadieux et al 1994). In our case we found recoveries of 95% for the first extraction and about 80% for the second one with a precision of 5%.…”

Section: Liquid Scintillation Alpha Spectrometry Using Fast Digital Cmentioning

confidence: 99%

“…When samples contained silicate material, hydrofluoric acid was required, and repeated evaporation of the sample www.intechopen.com dissolved in acid was needed to remove the silicates as silicon tetrafluoride. For the general case of samples without significant amounts of thorium or iron a two-stage extraction is a fast, simple separation procedure (Cadieux et al, 1994;McDowell, 19869). A first extraction from 0.8M nitric acid separated U and Pu into the organic phase.…”

Section: Liquid Scintillation Alpha Spectrometry Using Fast Digital Cmentioning

confidence: 99%