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News article13 April 2021

New certified material and half-life measurement for Americium isotope

A unit of IRMM-0243
A unit of IRMM-0243
© European Atomic Energy Community, 2017

The JRC and the Commissariat à l’énergie atomique et aux énergies alternatives (CEA) have collaborated in the production of the first certified americium isotope (243Am) reference material for the quantification of americium by isotope dilution mass spectrometry (IDMS).

The material was produced in response to an urgent need in the fields of nuclear safeguards and security, nuclear forensics, and accountability in the nuclear fuel cycle. It contains a mixture of 241Am (12%) and 243Am (88%) and has been characterised for the amount content of americium by IDMS, using an 241Am spike produced from highly enriched 241Pu material, and for the n(241Am)/n(243Am) isotope amount ratios by thermal ionisation mass spectrometry (TIMS). In addition, absolute 243Am + 241Am and relative 243Am/241Am radioactivity measurements were performed as a redundancy check of the certified values.

By combining the unique JRC facilities at Geel site for standardisation of radioactivity with mass spectrometry, the JRC was also able to present a new value for the 243Am half-life. It has been precisely measured by an absolute and a relative method, i.e. by determining the specific activity of 243Am and the specific activity ratio with 241Am. Accurate values for the decay constant or half-life of trans-uranium nuclides are required for accounting of nuclear material, assay of targets used in nuclear physics experiments, and characterisation of isotopic mixtures for radioanalytical purposes.

Moreover, this project provided a unique opportunity for the mass spectrometry community to assess the current state of practice for americium measurements. To this end, an 243Am inter-laboratory comparison (ILC) was organised in parallel to the certification campaign by CETAMA, using the same material.

measured_dots_and_fitted_lines_alpha_spectrum_of_the_243241am_material.png
Figure 1. Measured (dots) and fitted (lines) alpha spectrum of the 243,241Am material, with interference peaks from 238Pu and tailing from other nuclides at higher energy (bottom). Residuals to the fit (top)
© Journal of Radioanalytical and Nuclear Chemistry (2020) 326:1785–1793

Additional information can be found on the articles 243Am certified reference material for mass spectrometry and Absolute and relative measurement of the 243Am half-life on springer.com

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Publication date
13 April 2021