British Nuclear Group’s Sellafield management company (BNGSL) is to be taken to court by the Nuclear Installations Inspectorate over the leak from primary containment of 83m3 of highly radioactive liquor that occurred at the Thermal Oxide Reprocessing Plant (Thorp). The plant was shut down upon discovery of the problem on 20 April 2005.
The liquor leaked into a heavily shielded cell and caused no harm to either workers or the public, but operators BNGSL are alleged to have broken three conditions of their site licence which required it to: ensure safety systems were in good working order; ensure radioactive material was contained, and, if leaks occurred, they would be detected and reported.
According to a report prepared for plant owners the Nuclear Decommissioning Authority, final design changes to the accountancy process meant that a feed pipe carrying spent nuclear fuel dissolver fluid was under unplanned-for stress. After 11 years of operation it began to fracture and, over a period of at least eight months, a crack developed unknown to operators allowing the liquor to accumulate in the sump of a sealed cell. Operations staff then failed to act appropriately to consequent off-normal conditions. The report concluded that a ‘new plant culture’ existed at Thorp, which was simply not expected to have problems.
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