Upgrading the experimental database of fission products and actinides release behaviour in the VERCORS program through chemical analysis

Fission product (FP) and actinide release behaviour from degraded fuel in the VERCORS RT7, HT2 and HT3 tests, which were not quantified by ƴ-ray spectrometry, were investigated by chemical analysis of their deposits on the components of VERCORS loops. The FP and actinide released fraction was established by dividing the FP or actinide weight evaluated using the ICP-MS results by the total FP or actinide weight calculated using the ORIGEN-2 code. The release behaviour was discussed for 13 non-ƴ-ray emitters with reference to the limited available information and thermodynamic estimations. The experimental database for Rb, Sr and U release behaviour was upgraded through the chemical analysis in terms of the effects of atmosphere. Rb shows release behaviour similar to Cs. The release of Sr, which has a significant impact for public exposure, may be enhanced for high burn-up fuel in reducing atmosphere. The release of U was significantly enhanced in a steam atmosphere, but almost all the released U remained near the fuel. The results for other FPs and actinides confirm the previous VERCORS test results. The releases of Pd and Tc confirm a semi-volatile behaviour rather similar to Mo, that is, enhanced in a steam atmosphere. The released fractions of Pr, Nd and Sm were very low, whereas that of Y was higher and almost equivalent to the low volatile FPs, such as Ce, Eu and La.JRC.G.I.3-Nuclear Fuel Safet