Office for Nuclear Regulation

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THORP, Sellafield, inspection of the control of radioactive sources

Executive summary

Purpose of intervention

This intervention was undertaken on 5th June 2015 in the THORP facility on Sellafield Limited’s nuclear licensed site in Cumbria. Its objective was to examine the facility’s arrangements and their implementation for compliance with the Ionising Radiation Regulations 1999, particularly those aspects associated with the control of radioactive sources. This joint inspection involving both nuclear safety and security inspectors was prompted by a recently reported event involving a radioactive source.

Interventions Carried Out by ONR

IRR99 regulations 28 and 29 require the licensee to make and implement adequate arrangements for the accounting, keeping and movement of radioactive substances.

This intervention in THORP examined the adequacy of SL’s arrangements and their implementation for the control of radioactive sources with regard to the management of both radiological and security risks. The opportunity was also taken during the inspection to collect evidence to inform an opinion on whether an appropriate safety and security culture was evident in the THORP workforce. I was accompanied on my inspection by the THORP Site Inspector, a Radiological Protection Specialist Inspector and a Security Specialist Inspector.

This intervention inspected the arrangements and their implementation in place at the time of the intervention and did not seek to specifically investigate the circumstances involved with the recent event as we had been informed that SL was not yet in a position to present the findings of its Apparent Cause Investigation.  Nevertheless, the intervention did sample some of the arrangements pertinent to the incident in order to provide assurance that they are now adequate.

Explanation of Judgement if Safety System Not Judged to be Adequate

N/A. This was not a safety system inspection.

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

It was my opinion, based on the sample evidence inspected during this intervention, that THORP is compliant with IRR99 regulations 28 and 29. In particular, I consider that radioactive sources are currently stored in suitable stores and subject to adequate accountancy arrangements. I did, however identify some opportunities for improved compliance regarding the consistency of supervision between stores, daily mustering of sources etc. These matters have been captured in recommendations made to SL.  ONR will monitor the implementation of these improvements as part of normal regulatory business. Taking these factors into account, I consider that an IIS rating of 3 (adequate) is appropriate against IRR99 regulations 28 and 29.

Conclusion of Intervention

It is my opinion that the arrangements for the control of radioactive sources within THORP were adequate at the time of the inspection. The recently reported event regarding the control of sources is a significant concern. It is my intention to write formally to SL to ensure that their arrangements regarding the control of radioactive sources in line with the expectations of IRR99 are adequately implemented across site.