Palladium behavior in the presence of irradiated diluent in the PUREX process

AREVA La Hague plants UP3 and UP2-800 started operations to reprocess spent nuclear fuel in 1990 and 1994 respectively. Aging equipment in these plants is a cause for concern as it could lead to process dysfunctions or production rate decrease. A few years ago, several columns had to be replaced in UP3-T4 plutonium purification facility because of clogging. Analyses revealed that TPH degradation products could be responsible for precipitating palladium compounds. 1 M NaOH solutions proved to be efficient to dissolve most of the precipitate. Therefore, several columns in both UP3 and UP2-800 are from now on washed periodically with 1 M NaOH solutions to avoid further clogging and to dissolve current precipitates. (authors)