The Atomic Weapons Establishment (AWE) has been served with a formal warning letter and enforcement notice by a government environmental watchdog after increases in levels of tritium – a radioactive form of hydrogen – were found in the Aldermaston Stream.
The warning letter – issued by the Environment Agency in August 2013 – was sent after investigations were conducted to establish why unusual levels of tritium had been detected in the North Ponds drainage system at AWE Aldermaston, where the UK's nuclear weapons are manufactured and maintained.
The North Ponds discharge effluent into the Aldermaston Stream, which flows through Aldermaston village into the River Kennet and eventually into the River Thames.
Studies by AWE established that the tritium increase had been caused by a ventilation fan being switched off during modification works in a radioactive waste store at the Aldermaston site. Stopping the fan resulted in tritium discharged from the waste store accumulating on the roof, and then being washed by rainfall into surface water drains rather than being dispersed into the atmosphere as would normally be the case.
Following an investigation, the Environment Agency concluded that the event should not have happened and that AWE's management processes had failed to protect the environment. Although the increased levels of tritium in the discharge did not represent an environmental hazard, AWE had failed to adequately assess the impact of the modification works on the environment and the decision to switch off the fan had exposed a number of failures in AWE's management systems.
The Environment Agency has served an enforcement notice on AWE ordering the company to undertake a series of actions to ensure that modification work at other facilities has not overlooked environmental protection issues, and that its management arrangements are adequate to ensure that the environment is protected in the future. The company has until the end of February 2014 to complete the enforcement actions, and the Environment Agency will conduct a series of inspections to ensure that the company makes progress in completing them.
Hunting Brae Ltd, the former operators of the AWE Aldermaston site were fined for illegally discharging tritium into the Aldermaston Stream in 1999, resulting in the current monitoring and control arrangements for the discharge from the North Ponds.