Sizewell B - External Hazards Safety Case
- Site: Sizewell B
- IR number: 18-003
- Date: April 2018
- LC numbers: 10, 23, 24, 26
Purpose of Intervention
The purpose of this intervention was to undertake licence condition (LC) compliance 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 an intervention to evaluate implementation of the station’s external hazards safety case focusing of claims made in the event of extreme weather. The ONR site inspector also conducted an intervention to examine standards of control and supervision with maintenance and operations teams at Sizewell B. During these interventions, inspections were performed against the following Licence Conditions (LC) which are applicable provisions of the Energy Act 2013:
- LC10 - Training.
- LC23 - Operating Rules.
- LC24 - Operating Instructions.
- LC26 - Control and Supervision
The ONR site inspector also carried out follow-up enquires into an incident reported by NGL via ONR’s INF1 notification system. This incident involved the discovery that some level instrumentation on the station’s refuelling water storage tank had been adversely affected during recent cold weather.
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
Not applicable - no system based inspections were completed during this intervention.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
- External Hazards - We performed a sample inspection of instructions provided to personnel on site who may be required to respond in the event of severe weather, focusing on severe wind and extreme ambient temperatures. We concluded that appropriate instructions were provided to staff responding to potential faults on the station’s back-up electrical generation system and reserve ultimate heat sink. Personnel’s knowledge of the external hazards safety case and implementation is maintained via a programme of training and exercises. We judged that Green inspection ratings were appropriate against LC 10, 23, and 24.
- Control and Supervision - During this intervention, I observed a number of start-of-shift briefings and observed standards of work in progress at Sizewell B. I am satisfied that the briefings observed were commensurate with expectations defined with NGL’s own arrangements and IAEA guidance. All of the tasks observed during this intervention were controlled via an appropriate safe system of work and I consider that overall, the standards of procedural use and adherence were acceptable. On this basis, I judge that the following inspection rating is appropriate: Green
- Follow-up Enquires - I confirmed that NGL has established a seasonal readiness programme which is implemented in late summer / early autumn to ensure the plant is prepared to withstand extremes of winter weather. I reviewed the licensee’s own investigation of the incident and am satisfied that it had been conducted in an appropriately thorough and systematic manner. The intervention did not identify any significant breach of site licence conditions and I am satisfied that the incident does not meet ONR’s investigation criteria.
A minor compliance shortfall was noted in relation to provision of written instructions setting out the expected response to forecast low temperatures. NGL have accepted an action to resolve this finding which will be tracked to resolution via an entry on the ONR issues database.
Conclusion of Intervention
There are no findings from this inspection 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.