Office for Nuclear Regulation

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AWE - SBI - Moguls

Executive summary

Purpose of Intervention

The purpose of this intervention was to determine AWE’s readiness to begin re-commissioning activities on electrical systems and whether necessary improvements had been implemented following the October 2015 electrical event and subsequent ONR interventions.  The structure of this intervention was based on that of a system based inspection.

The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.

Interventions Carried Out by ONR

As part of this intervention, the ONR Portfolio Inspector and ONR Electrical Specialist Inspector performed a modified system based inspection (SBI) electrical systems to judge performance against their safety function.  Through examination of the systems and their associated sub-systems, we performed compliance inspections against the normal SBI set of licence conditions LC10 (Training), LC23 (Operating rules), LC24 (Operating instructions), LC27 (Safety mechanisms, devices and circuits), LC28 (Examination, inspection, maintenance and testing).  LC34 (Leakage and escape of radioactive material and radioactive waste) was not applicable.  In addition three further licence conditions were taken into consideration, but not rated as part of this SBI, these being LC21 (Commissioning), LC22 (Modification or experiment on existing plant) and LC26 (Control and supervision of operations).  The inspection was based on sampling the implementation of the arrangements in place against each licence condition.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable.

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

Based on the areas sampled during the course of this inspection, it was found that AWE has adequate arrangements in place to ensure that the electrical systems inspected meet the requirements of the safety case.  On this basis ONR is satisfied that it is acceptable for AWE to proceed with re-commissioning those electrical systems.

In summary, the outcome from this modified system based inspection of the electrical systems is that the arrangements and the implementation for LC 10, 23, 24, 26, 27 and 28 were judged adequate.  Therefore, we have given an inspection rating of GREEN (no formal action required) for each of these LCs.  LC 34 was not applicable for this inspection.  Areas for improvement were noted for some licence conditions, but these were not sufficient to warrant a lower rating. These were communicated to the licensee during the inspection and are noted in this report.