Thorp Feed Clarification Cell Latest Update

British Nuclear Group has continued to make good progress with the work necessary to get Thorp reprocessing facility fully operational again.

John Clarke, Director of Thorp, said: “The Thorp team has been carrying out a comprehensive programme of work aimed at getting the plant safely up and running again. Before restarting the plant we will need to assure ourselves that we have done everything necessary to address the issues that led to the current outage and prevent future similar events. We then need to demonstrate to the Nuclear Installations Inspectorate (NII) that we have strengthened our operating regime sufficiently to give them confidence to allow the plant to restart. The decision to restart is one for the Nuclear Decommissioning Authority (NDA) in conjunction with the DTI.”

The plant ceased production in April 2005 following a CCTV camera inspection which identified that approximately 83m3 of liquor had escaped into the secondary containment of a purpose built, thick walled concrete cell lined with stainless steel through a fracture in the pipe feeding one of the accountancy tanks. Recovery of all the liquor was successfully completed in June 2005 and this is currently stored in buffer storage tanks prior to being processed

The secondary containment is specifically designed for failure of primary containment and a release of liquid in quantities significantly greater than in this event. It is fitted with engineered systems to pump liquid from the cell floor back into primary containment tanks within the cell. This equipment was used for the recovery of the escaped liquor. The event caused no harm to any individuals and did not release any radioactivity to the environment.

A Board of Inquiry (BOI) was convened and the report published at the end of June 2005, which highlighted the root causes and made eighteen recommendations. Eleven of the recommendations principally addressed the issues relating to cell instrumentation (which would indicate a plant abnormality) and the operating practices within the plant. Four of the recommendations concerned metal fatigue assessments and design issues.