Office for Nuclear Regulation

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Berkeley - System inspection of the reactor buildings

Executive summary

Purpose of intervention

The intervention was part of a series of planned inspections of Berkeley licensed nuclear site during 2014-15.

Interventions Carried Out by ONR

We undertook a system inspection of the Reactor Buildings in safestore conditions and discussed emergency arrangements as requested by Berkeley.

Explanation of Judgement if Safety System Not Judged to be Adequate

The Reactor Building system inspection was found to be adequate.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

The reactor building was in good condition. There was no sign of water ingress above the pile cap and on the biological shield in general. The buildings around the base of the reactor did show signs of water ingress and this had been the case for some time. Berkeley was working on a solution to this. Also part of the basement is subject to water ingress from a small spring. The current pumping arrangement appears to be adequate but in order to reduce the need for entry into the safestore to maintain the pump Berkeley were looking at alternative locations outside the rector building for the pump.

Berkeley had developed an appropriate demonstration emergency exercise scenario that was consistent with the nuclear safety hazards remaining on the site.

Conclusion of Intervention

The reactor building (called safe-store) was adequately protecting the reactor and other irradiated components stored within it. It provides useful data for other reactors as they approach a similar safe-store stage.


I will include entry into the safe store as part of the site inspection plan for next year to see the condition of both reactors and to gain knowledge of the proposed maintenance work to be undertaken on the buildings during their safestore period.