Office for Nuclear Regulation

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Hunterson B - Planned intervention, System Based Inspection SBI-11, Fire Protection Systems

Executive summary

Purpose of Intervention

In accordance with the Office for Nuclear Regulation (ONR) Strategy, each year ONR performs a series of planned System Based Inspections (SBIs). In line with Hunterston B Integrated Intervention Strategy (IIS) for 2019/20, a planned SBI on the fire protection systems (SBI-11) at EDF Energy Nuclear Generation Limited’s (NGL’s) Hunterson B (HPB) power station was conducted on 10th – 11th September 2019. The purpose of this inspection was for ONR to determine the adequacy of implementation of the safety case claims in respect of the fire protection systems.

Interventions Carried Out by ONR

In order to determine the adequacy of implementation of the Licensee’s safety case claims in respect of the fire protection systems, ONR examined evidence to determine compliance against five key Licence Conditions (LCs), which are applicable provisions of the Energy Act 2013. These LCs (listed below) have been selected in view of their importance to nuclear safety and in providing a structured approach to determining whether the safety case has been implemented adequately through the system being inspected.

ONR assessed compliance against the following LCs using applicable inspection guidance:

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

The inspection sampled and examined the applicable safety case claims, through a combination of document reviews, discussions with plant operators and plant inspections to determine compliance against the selected LCs. In this case, the inspection plan did not cover any area where fire protection systems could lead to escape of radioactive waste and hence LC34 did not form part of this inspection.

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

From the areas targeted and the evidence examined during the SBI, ONR considers that NGL has adequately implemented those safety case claims that relate to the fire protection systems. 

Licence Condition 10 (Training) – ONR sampled the training records of a number of personnel that fulfil roles associated with the fire protection system.  This included the Fire System Engineer, a maintenance technician and external contractor involved in fire door maintenance.  ONR noted that the training records for the Fire System Engineer and contractor were complete and valid.  The training records of the maintenance technician were not up to date however, ONR noted that a dispensation was being produced on the basis of previous experience.  Overall, ONR considered NGL provided an adequate level of assurance and evidence to demonstrate compliance against LC10. As such, an inspection rating of Green (no formal action) for LC10.

Licence Condition 23 (Operating Rules) and Licence Condition 24 (Operating instructions) – For LC23 ONR sampled the limits and conditions associated with the fire protection system.  Based on the sample ONR considered the principal limits and conditions of the fire safety case were identified in the station’s technical specifications.  For LC24 ONR sampled operating and maintenance instructions associated with the fire system and considered the limits and conditions were implemented via clear working instructions.  Overall, ONR considered NGL provided an adequate level of assurance and evidence to demonstrate compliance against LC23/24. As such, an inspection rating of Green (no formal action) for LC23/24.

Licence Condition 27 (Safety Mechanisms, Devices and Circuits, SMDCs) – ONR undertook a plant walkdown which covered various fire protection equipment across the site: fire barriers within the reactor building; fire fighting pumps; fire detection suppression equipment.  ONR considered the fire protection equipment viewed on plant was properly connected and in good working order.  Overall, ONR considered NGL provided an adequate level of assurance and evidence to demonstrate compliance against LC27. As such, an inspection rating of Green (no formal action) for LC27.

Licence Condition 28 (Examination, Inspection, Maintenance and Testing) – ONR sampled the maintenance and testing records for a fire fighting pump, a nuclear significant fire damper, nuclear significant fire doors and a selection of defect tags.  Based on the sample inspection ONR considered the equipment was maintained in accordance with the safety case requirements.  Overall, ONR considered NGL provided an adequate level of assurance and evidence to demonstrate compliance against LC28. As such, an inspection rating of Green (no formal action) for LC28.

Conclusion of Intervention

From the evidence sampled during this SBI, it was judged that there were no matters that have the potential to impact significantly on nuclear safety. Consequently, an overall rating of Green was awarded for the fire protection systems as a whole. The inspection findings were shared and accepted by NGL as part of normal inspection feedback. ONR considers NGL adequately demonstrated ownership and implementation of the fire protection systems safety case to ensure and maintain nuclear safety.