Precision and Accuracy in the Determination of ²³⁸Pu/(²³⁹Pu+²⁴⁰Pu) α Activity Ratio by Alpha Spectrometry

Abstract

Precision /Accuracy IDetermination of^'Pu/(^^^Pu + ^^'Pu) / Alpha spectrometryO.Ol to 10 by a spectrometry and demonstrates the validity of a simple method for the analysis of a spectrum. AbstractThe evaluation of precision and accuracy in "'Pu/("'Pu+""'Pu) a activity ratio determination is of paramount importance for calculating '"Pu in plutonium samples and for exploiting Isotope Dilution Alpha Spectrometry (IDAS) to establish the concentration of plutonium in the irradiated fuel dissolver Solution. This has been achieved by preparing synthetic mixtures with a activity ratios ranging from O.Ol to 10 using '"Pu and '"Pu isotopes. Sources were prepared from these mixtures by electrodeposition in an aqueous HNO3 medium and the a spectra were recorded by employing a solid State sihcon surface barrier detector coupled to a 4 K analyser. The validity of a simple evaluation method based on the geometric progression (G. P.) decrease for the far tail of the spectrum is demonstrated in the present work. It is concluded that an accuracy of 0.5% and a precision of ± 0.2% (1 o) can be reached in the determination of "»Pu / ("' Pu+"° Pu) cx activity ratio ranging from O.Ol to 10.

Recent Analytical Chemistry of the Transplutonium Elements

“…The alpha-spectrometer with a semiconductor detector (area 1 -3 cm 2 ) has an efficiency of nearly 50% and the detection limit 10~3 Bq (in sample) [203][204]; the efficiency is 85% using two detectors [205], As the energy resolution of such detectors reaches 20-30 keV, it is possible to determine the usual mixture of americium and curium ( 241 Am, 243 Am, 242 Cm, 244 Cm) without separation of those elements. In case of complex α-spectra with superposing lines, different mathematical methods processing are used [206,207], A number of methods, based on precipitation, extraction and ion-exchange procedures have been worked out to isolate TPE from the environment, irradiated nuclear fuel industrial solutions, etc. [177,203,204,[207][208][209][210].…”

“…In case of complex α-spectra with superposing lines, different mathematical methods processing are used [206,207], A number of methods, based on precipitation, extraction and ion-exchange procedures have been worked out to isolate TPE from the environment, irradiated nuclear fuel industrial solutions, etc. [177,203,204,[207][208][209][210]. The electrodeposition of radionuclides on the backing from aqueous [211 -213] or organic solutions (ethanolic [205], iso-propanolic [214,215], iso-butanolic [216] or mixed [217] solutions) solutions) which gives the thin uniform coating on target and the high resolution under measuring α-particles, is used more often on target for aspectrometry.…”

Chemically selective polymer substrate based direct isotope dilution alpha spectrometry of Pu

“…240 Pu cannot be used as a spike for IDAS experiments since the energy of the alpha particles emitted by 240 Pu (5.168 MeV) is close to that emitted by 239 Pu (5.155 MeV). IDAS using 238 Pu as a spike and reverse-IDAS using 239 Pu as a spike were reported for the determination of Pu concentration [33,34]. However, in order to produce good quality alpha source for IDAS, electrochemical deposition of Pu was carried out which is laborious and time consuming.…”

Isotope correlations for determining the isotopic composition of plutonium

“…The overall performance of the system was checked using SRM-947 isotopic reference material of Pu. The 238 Pu/( 239 Pu + 240 Pu) alpha activity ratio was determined from purified plutonium sample using passivated ion implanted detector and employing the previously developed method [8] based on Geometric Progression (G.P.) decrease of the counts in the far tail of the alpha spectrum to account for tail contribution at low energy peak due to energy degradation of high energy alpha peak.…”