THORP (Thermal Oxide Reprocessing Plant)

On 20 April 2005 a leak of highly radioactive product liquor inside a cell of the THORP plant at Sellafield was reported to HSE.  In total, approximately 83000 litres of dissolver product liquor, containing approximately 22000 kilograms of nuclear fuel (mostly uranium incorporating around 160 kilograms of plutonium), had leaked onto the floor of the cell. The leak had begun prior to 28 August 2004 and had remained undiscovered until 20 April 2005. HSE's investigation report addresses a range of human factors issues, including management of change, alarm handling, culture, procedural violations, roles and responsibilities, supervision and management oversight.