Implementation of a new gamma spectrometry device on the VERDON CET loop to measure iodine release kinetics

The VERDON laboratory located in the LECA-STAR facility is devoted to the monitoring of fission products release andtransportation during severe accidents. In the recent context of the Fukushima events, a new key issue has been identified the impact ofcontrol rod degradation on the release of volatile fission products (FP). A higher than expected fraction of gaseous iodine might havebeen released during the accident due to the reaction of boron with CsI. A test was performed on high burn-up UO2 fuel to address thisnew issue and consolidate the database on the source term assessment. For this purpose a new gamma spectrometry device wasimplemented directly in the VERDON hot cell to record the iodine deposit kinetics on a dedicated filter. It completes the on-line gammastations of the VERDON CET loop focused on the fuel sample, the first hot leg of the CET, the aerosol FP filter and gaseous FP release.