Office for Nuclear Regulation

Sizewell B - Dry Fuel Store Readiness inspection and System Based Inspection

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake inspections at EDF Energy Nuclear Generation Limited’s (NGL) Sizewell B Power Station, in line with the ONR’s Operational Facilities Division intervention strategy. The intervention was carried out by the ONR site inspector, supported by a number of specialist inspectors.

Interventions Carried Out by ONR

We performed a safety case informed systems based inspection (SBI) of Sizewell B’s Fire Protection Systems to judge the system performance against its safety function. Through examination of the system, compliance inspections were performed against the following License Conditions (LC) which are provisions of the Energy Act 2013:

We also performed an inspection to evaluate NGL’s progress in implementing learning identified during the active commissioning of the station’s Dry Fuel Store. The inspection was intended to inform ONR’s decision whether to release a regulatory hold on the implementation of the facility’s operational safety case. The inspection was  rated for compliance with LC22 (Modification or experiment on existing plant) and LC24 (Operating Instructions).

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

Explanation of Judgement if Safety System Not Judged to be Adequate

For the fire protection systems inspection, I found, based on my sample, that overall the system met the requirements of the safety case.

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

System Based Inspection

We found that the licensee had established an adequate training programme for personnel required to respond to fires and other emergencies which may occur on the site. Based on a sample inspection, we were satisfied that the limits and conditions of operation identified in the safety case had been adequately implemented in the station’s Technical Specifications and Surveillance Test Procedure Instructions. Duly Authorised persons demonstrated a sound understanding of the limits and condition for the operability of principal fire barriers to ensure nuclear safety.

We evaluated NGL’s maintenance regime for a sample of equipment forming part of the fire protection system and judged, based on this sample, that adequate maintenance regimes were in place to manage integrity in line with the principal claims within the safety case. We walked down a sample of the system and we found the equipment to be in an acceptable condition.

Overall we judged that arrangements for the fire protection system met legal requirements and awarded an intervention rating of Green in relation to compliance with LCs 10, 23, 24, 27, and 28.

Dry Fuel Store

We sampled technical queries generated during commissioning of the dry fuel store and found that where necessary, EDF had raised an Engineering Change to manage configuration of installed plant, documents and drawings in accordance with arrangements made under LC22. We sampled emergency and maintenance instructions updated following active commissioning. We found the documentation contained sufficient detail to enable a competent person to undertake the task safety. We awarded the following intervention rating for both LCs 22 and 24: Green.

The evidence gathered from this inspection confirmed that DFS commissioning had been successful and sufficient progress had been made to support the release of ONR’s hold point on implementation of the facility’s operational safety case, including establishment of a capable organisation to operate the DFS.

Conclusion of Intervention

There are no findings from this intervention that could significantly undermine nuclear safety. At present, no additional regulatory action is needed over and above the planned interventions at Sizewell B Power Station.