Office for Nuclear Regulation

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System Based Inspection of the Sea Discharge Treatment Plant

Executive summary

Purpose of Intervention

The Office for Nuclear Regulation (ONR) undertakes all regulatory interaction with the Sellafield site licensee (Sellafield Limited, SL) against a strategy defined by the ONR Sellafield Sub Division.

In accordance with that Strategy, a system based inspection (SBI) of the Site Ion Exchange Effluent Plant (SIXEP) within the Magnox East River facility (MER) was planned.  The purpose of this planned inspection was for ONR to confirm the adequacy of implementation of the licensee’s safety case claims in respect of this system.

As part of each SBI, ONR examines evidence of the adequate implementation of six pre-defined licence conditions.  These licence conditions (listed below) have been selected because of their importance to nuclear safety, and are defined within the ONR’s formal process for delivery of an SBI.

Interventions Carried Out by ONR

LC 10 requires SL to make and implement adequate arrangements for suitable training of those who have responsibility for any operations that may affect safety.

LC 23 requires SL to produce adequate safety cases to demonstrate the safety of its operations, and to identify the operating conditions and limits necessary in the interests of safety.

LC 24 requires SL to make and implement adequate arrangements for the provision of suitable written instructions for undertaking any operation that may affect safety.

LC 27 requires SL to ensure that, before a system is operated, inspected, maintained or tested, there are suitable and sufficient safety mechanisms, devices and circuits properly connected and in good working order.

LC 28 requires SL to make and implement adequate arrangements for the regular and systematic examination, inspection, maintenance and testing of all plant which may affect safety.

LC 34 requires SL to ensure that radioactive material and radioactive waste on the site is at all times adequately controlled and contained, and that no leak or escape of that material or waste can take place without being detected.

The inspection was conducted on-site over the course of two-days. The Sea Discharge Treatment Plant (SDTP) is within the Site Ion Exchange Effluent Plant (SIXEP) which is part of the Magnox East River facility (MER), which is part of the Magnox OU.  The inspection comprised discussions with SL staff, plant walk downs and reviews of plant records and other documentation.

Explanation of Judgement if Safety System Not Judged to be Adequate

Based on the sampling undertaken, the Sea Discharge Treatment Plant was judged to be adequate.

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

Whilst some minor opportunities for improvements were identified, I found LCs, 23, 24, and 27 to be adequately implemented in relation to the systems inspected. Consequently, it is my opinion that for this system based inspection a rating of GREEN (no formal action) is appropriate for LCs 23, 24, and 27.

For LC 10 (Training), whilst there were some minor opportunities for improvement, I judged that there was also a significant shortfall against relevant good practice with regard to the observed operator performance in following an Alarm Response Instruction.  I noted that only one operator was tested in the sample, nonetheless, the shortfall was significant and a candidate Level 3 Regulatory Issue has been raised to track progress by the licensee to address this shortfall. Therefore, I judged a rating of Amber (Seek Improvement) to be appropriate.

For LC 28 (Examination, Inspection, Maintenance and Testing), whilst there were some minor opportunities for improvement, I judged that there was also a significant shortfall with regard to the Obsolesce/Degradation Strategy. In my opinion there is a risk of a significant outage period of SDTP if certain obsolete or made to order equipment or safety mechanisms fail, which would impact site wide hazard and risk reduction. A candidate Level 3 Regulatory Issue has been raised to track progress by the licensee to address this shortfall. Therefore, I judged a rating of Amber (Seek Improvement) to be appropriate.

For LC 34 (Leakage and escape of radioactive material), I judged this LC not to be applicable to this SBI. 

Conclusion of Intervention

From the evidence sampled during the inspection, I judge that SL has adequately implemented the relevant claims in the safety case and that the formal arrangements for LCs 23, 24, and 27 are being adequately implemented. I judge LC 34 not to be applicable to this inspection.

Regarding LC 10, a candidate Level 3 Regulatory Issue has been raised which the Magnox OU Site Inspector will use to track actions to address the identified shortfall.

Regarding LC 28, a Level 3 candidate Regulatory Issue has been raised which the Magnox OU Site Inspector will use to track actions to address the identified shortfall.

Additionally, I have raised a number of level 4 Regulatory Issues in relation to minor shortfalls observed during the inspection.

Overall, I judge that the safety system is adequate and fulfils the requirements of the safety case.