Executive summary
Date(s) of inspection: February 2024
Aim of inspection
This was a planned inspection of EDF's Sizewell B Power Station (SXB), undertaken as part of the planned intervention strategy for the Operating Facilities Division (OFD) of the Office for Nuclear Regulation (ONR). The work was carried out in accord with the planned inspection programme.
The purpose of this intervention was to gain confidence that the licensee’s current Licence Condition 17 (LC 17) Management Systems and COMAH arrangements associated with chemistry commodity purchase, delivery, storage and connection to plant are adequately implemented, effective and integrated.
Subject(s) of inspection
- COMAH - Control of Major Accident Hazards Regulations 2015 - Rating: Green
- LC17 - Management systems - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
I conducted a Licence Condition 17 (LC 17) Management Systems inspection into the arrangements for chemical commodities at Sizewell B power station (SZB). The inspection also covered arrangements in place to comply with the COMAH, conducted on behalf of the Competent Authority (CA) and focused on the control of chemical commodities in preventing major accidents.
The inspection was part of the annual intervention programme agreed with SZB. Remote engagements were carried out in advance in preparation for the site visit.
The inspection sampled four commodities: fuel oil, boric acid, hydrazine and lithium hydroxide. The key activities sampled were:
Implementation of LC17 arrangements for chemical commodities, including independent verification.
Review of the Major Accident Prevention Policy (MAPP), COMAH Inventory calculations and arrangements for receipt and offload of chemical commodities.
Regulatory judgment was based on determining compliance with LC 17 and COMAH 2015 including the associated guidance L111.
An inspection rating of green was assigned to both the LC 17 and COMAH parts of the intervention.
Conclusion
Licence Condition 17 – Management Systems
At the outset of the inspection, I noted that the development of arrangements at SZB was within the bounds of the corporate technical oversight (CTO) function. I therefore maintain several queries with respect to production of arrangements, which I intend to follow-up with the CTO function. My sample was therefore focused upon the implementation of LC17 arrangements at SZB.
With regard to implementation of LC17 arrangements, I targeted diesel fuel oil, boric acid, ammonia and hydrazine. Based on my sample, I was content with SZB arrangements within operating instructions. I did however note that the delivery notes provided for diesel fuel oil were incomplete, but during the inspection it was made clear that the diesel fuel oil tanks intended for road vehicle use on site have different surveillance requirements upon delivery. This therefore meant that not all parts of the delivery note applied to each delivery. The delivery notes have since been changed to reflect this, with a separate note for each tank. I was content with the approach taken by SZB, I did however encourage SZB to return to using one delivery note with a n/a option for the parts that do not apply to all deliveries.
Based on my sample, I was content with SZB implementation of management system arrangements with respect to chemical commodities. I therefore judge a rating of GREEN to be appropriate for LC 17 at SZB.
COMAH
Based on the sample of chemical commodities across the two-day inspection, I judged that arrangements on site for control of chemical deliveries and associated offloading and storage of chemical commodities are adequate and meet the required standard. Procedural controls were explained clearly and on the days sampled demonstrated effective control of the risks associated with delivery and handling of dangerous substances.
The requirement for a Major Accident Prevention Policy (MAPP) is under Regulation 7 of COMAH, the accompanying guidance to these regulations, L111, details the expectations for the content of and its implementation via a safety management system (SMS). The dutyholder’s demonstration of their arrangements for identifying major accident hazards and corresponding prevention and mitigation measures was not comprehensive. The methodology for the underpinning Process Hazard Review did not meet the standard expected, namely to consider unmitigated major accident scenarios prior to crediting prevention and mitigation measures. Since this approach is common across the fleet, this will be taken forwards with EDF corporate, initially at a meeting on 3 April 2024.
Several observations were noted verbally on the day and were captured as observations and advice. These were not significant shortfalls therefore I judged a regulatory issue was not required.
Based on my sample, an inspection rating of green has been assigned to the COMAH aspects of this inspection.