Proficiency testing with uncertainty evaluation for measuring activities per unit mass of 134 Cs and 137 Cs in brown rice in Japan.

In Japan, we conducted proficiency testing of activity measurement by using high-purity germanium detectors for ¹³⁴ Cs and ¹³⁷ Cs in brown rice grains. Among 176 reported results, 86 % (for ¹³⁴ Cs) and 93 % (for ¹³⁷ Cs) of the results satisfied |E _n | ≦ 1. However, 58 reports for ¹³⁴ Cs and 51 reports for ¹³⁷ Cs had some failures in their evaluations of uncertainties. The proficiency testing was effective to improve the ability of uncertainty evaluation.
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