Office for Nuclear Regulation

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Planned site inspection

Executive summary

Purpose of intervention

This was a planned visit in pursuance of ONR's plan of compliance inspection for Chapelcross.

Interventions Carried Out by ONR

The main activity at this visit was an inspection of the storage of waste arising from the Chapelcross Processing Plant, which until 2005 extracted and purified tritium generated in Chapelcross's reactors. The objective of the inspection was to decide whether the waste containers and the store fulfil one of their safety functions, namely to protect the public and workers from the residual tritium in the waste.

Since this inspection was proposed (in March), the aerial discharges of tritium from the store had increased. Magnox Ltd had carried out extensive investigations to discover the cause of the increase. These discharges are subject to a limit in an Authorisation granted by the Scottish Environment Protection Agency (SEPA), who had been discussing the issue with Magnox Ltd. ONR and SEPA therefore decided to make a joint inspection, there being a substantial area of common interest for these two regulators.

Having first assessed the licensee's safety case before the visit, we inspected the building and its equipment. We inspected and discussed the tests that Magnox Ltd has done to investigate the recent increases in discharges. I went on to inspect arrangements, instructions, and records associated with maintenance of the building and its equipment. I examined the records made to show that staff who perform and supervise this work have been suitably trained.

I had insufficient time to finish all parts of this inspection, which will be completed at a future visit.

Two inspectors from HSE's Construction Division inspected the site during my visit, looking at control of contractors, compliance with CDM regulations, and asbestos stripping. They debriefed me afterwards.

In these and other discussions the outcomes of actions previously placed were reviewed, and the actions closed where possible; new actions were also placed.

I attended the quarterly meeting of the Site Stakeholder Group, where I gave an account of ONR's recent inspection and assessment of the site.

Explanation of Judgement if Safety System Not Judged to be Adequate

This inspection remains to be completed at the next visit.

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

Despite recent increases, aerial discharges of tritium from the store have been and remain of negligible significance to health (and the environment). We found no plausible explanation for the increases. Magnox Ltd's investigations have been thorough but are still inconclusive. The discharges from the store are a small fraction of the site's total aerial discharge of tritium; nevertheless, it is desirable that both Magnox Ltd and the regulators continue to seek an explanation.

Conclusion of Intervention

I found no issues that significantly affect nuclear safety, or that require me to take further regulatory action. The inspection of waste containing tritium will be completed at the earliest opportunity.