A45 corrosion of ‘major’ significance, reveal FOI papers

Documents released under the Freedom of Information Act reveal that the closure last autumn of the A45 uranium components facility at the Atomic Weapons Establishment (AWE) Aldermaston was rated as an incident of “major” significance by company staff.

The facility was closed when corrosion was discovered in steel columns supporting the building structure, resulting in the serving of a formal Improvement Notice on AWE by the government's nuclear safety watchdog, the Office for Nuclear Regulation (ONR).   ONR concluded that “although the building remains safe to enter, corrosion has affected both the seismic and weathering withstand of this class 1 structure, rendering it unsafe for nuclear operations.”

AWE is now working on 'Project Phoebe' –  proposals for remedying the structural defects with the building before it can reopen.

Documents relating to the incident (available to download at the bottom of this article) were released to Nuclear Information Service by the Office for Nuclear Regulation following a request under the Freedom of Information Act.

The papers show that corrosion was first detected on a steel support column in the building following an inspection on 21 August 2012, and reported to the Office for Nuclear Regulation two days later.  AWE's engineers took the view that “there was no immediate threat” and a broader inspection programme began to establish the condition of other parts of the steel building structure.

On 10 October 2012 AWE made a second report to ONR stating that a number of columns in the building had been categorised as being in either “poor” or “bad” condition, and that fissile operations in the affected area had been suspended except for moves to reduce the inventory of fissile materials in the building.  The significance of the incident was described as “major” by AWE staff and the incident was rated as a scale 2 incident on the IAEA International Nuclear and Radiological Event Scale (INES) because of its impact on nuclear 'defence in depth' safety arrangements.

Routine operations in the A45 complex – including all production operations – were subsequently suspended and AWE began work on preparing plans for repairing the damaged columns.  ONR's permission will be required before the plans are implemented and before work in the building can begin again.  Although it is “not certain” how long the repair work will take, the regulator has required the building to have been “fully restored in respect of its nuclear safety function” by the end of 2013, and has requested AWE to use the downtime in the facility to progress other safety-related work.

Notes of a meeting between ONR and AWE observe that “This is not the first time ONR have found an AWE structure in need of repair”.


Download the documents released by the Office for Nuclear Regulation here:

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