RECOVERY FROM FEEDING UNCONDITIONED FEED TO PART OF THE SOLVENT EXTRACTION PROCESS IN THORP

摘要

A recent event in the Thorp Reprocessing Plant involved unconditioned feed being sent to one of the main process solvent extraction vessels. As the feed was unconditioned the fissile material was lost to the aqueous raffinate stream. The plant was tripped and shutdown in line with the baseline criticality safety case. This paper describes the recovery option that was taken to remove the Pu from the raffinate tank and safely consign it to the downstream effluent vessels. Key assumptions that were fundamental to maintaining criticality safety throughout these operations were clearly highlighted in the supporting criticality safety assessment. Key learning points that are of relevance to the wider criticality safety assessment community are pulled out at the end of this paper.