Uranium, plutonium and cesium isotopic ratios in saline medium

NUSIMEP-5 Uranium, plutonium and caesium isotopic ratios in saline medium

NUSIMEP-5 continues the programme of external quality control campaigns for traces of nuclear materials in the environment. In this campaign four samples of a saline solution containing certified amounts of uranium ranging from depleted to low enriched and very low amounts of Pu and Cs, were supplied. Each of the four samples had a different isotopic composition of uranium. Two of the solutions contained about 1 Bq Pu per sample and the other two contained about the same activity of Cs.

Participating laboratories were asked to measure the isotope ratios:

• n(²³⁴U)/n(²³⁸U),

• n(²³⁵U)/n(²³⁸U),

• n(²³⁶U)/n(²³⁸U),

• n(²³⁸Pu)/n(²³⁹Pu),

• n(²⁴⁰Pu)/n(²³⁹Pu),

• n(²⁴¹Pu)/n(²³⁹Pu),

• n(²⁴²Pu)/n(²³⁹Pu) and/or the α-activity ratio ²³⁸Pu/(²³⁹Pu + ²⁴⁰Pu), and

• γ-activity ratio ¹³⁴Cs/¹³⁷Cs.

Over 40 laboratories registered for participation and 39 laboratories sent back their measurement results. The values of all the parameters to be measured were certified at IRMM and these values were sent to each laboratory after receiving their results.

Many laboratories showed they could measure such environmental types of samples well and it was possible to see clearly differences in performance between the different measurement techniques.

The results of this campaign are published in two reports, one putting together the results of all laboratories and other setting out the preparation and certification work done at IRMM.