Isotope correlations for determining the isotopic composition of plutonium

Abstract

Isotope ratios / Plutonium / Mass spectrometry / Alpha spectrometry / CorrelationSummary. Improved correlations using the 238 Pu/( 239 Pu + 240 Pu) alpha activity ratios determined alpha spectrometrically and the different atom ratios viz. 240 Pu/ 239 Pu, 241 Pu/ 239 Pu and 242 Pu/ 239 Pu determined mass spectrometrically are presented for Pu produced in Pressurised Heavy Water Reactors (PHWRs). These correlations are useful to obtain the different atom ratios, with reasonable accuracy (1 to 10% depending upon the atom ratio), using only the 238 Pu/( 239 Pu + 240 Pu) alpha activity ratio determined alpha spectrometrically from a plutonium sample purified from 241 Am. Since the correlations involve the relative values and not the absolute values of the atom% abundance of any specific isotope, the accuracy of the data obtained using these correlations is much better. In addition, the change in the atom% abundance of 241 Pu due to the relatively short half-life of 241 Pu (14.4 yr) does not create any ambiguity in the ratio 242 Pu/ 239 Pu and hence the accuracy of data for 242 Pu is not affected by the uncertainty in the data for 241 Pu.

A novel approach for the determination of 238Pu by thermal ionization mass spectrometry (TIMS) using interfering element correction methodology

“…Accurate data on 238 Pu/ 239 Pu atom ratio is important for various applications in nuclear science and technology [4][5][6][7]. These include the development of isotope correlations, refinement of computer codes in reactor physics calculations to calculate the build-up of different Pu isotopes, the use of 238 Pu as a tracer (spike) in isotope dilution alpha spectrometry and the possibility of employing 238 Pu as a tracer (spike) in isotope dilution thermal ionization mass spectrometry (ID-TIMS), etc.…”

Determination of 241Pu/239Pu atom ratio in pressurised heavy water reactor (PHWR)-Pu samples using liquid scintillation counting

“…The limitations of the isotope correlations reported previously by us [1][2][3] for obtaining this atom ratio are circumvented since the ratio of count rates of beta and total alpha does not demand a knowledge of the irradiation and cooling history of Pu sample. Thus, it provides a method to characterise all the isotopes of Pu using isotope correlations, employing the present approach for obtaining 241 Pu/ 239 Pu atom ratio.…”

“…We have developed and reported isotope correlations [1][2][3] for the determination of atom ratios of Pu isotopes, using the data obtained by alpha spectrometry and by thermal ionization mass spectrometry. With these correlations, the atom ratios of different Pu isotopes, except for the one involving 241 Pu, could be obtained with reasonable accuracy (2-5%).…”

A comparative evaluation of 238Pu determination in NIST-SRM-947-Pu by alpha spectrometry and thermal ionization mass spectrometry

“…These include accurate determination of isotopic composition of Pu, development of reactor physics codes, development of isotope correlations for nuclear material accounting, employment of isotope dilution alpha spectrometry (IDAS) using 238 Pu as a spike for determining concentration of Pu in dissolver solution of irradiated fuel, identification of source of Pu contamination in the environment etc. [1][2][3][4][5].…”