Office for Nuclear Regulation

DRDL - SBI Refit support equipment

Executive summary

Purpose of Intervention

This System Based Inspection (SBI), conducted at the Devonport Royal Dockyard Limited (DRDL) Devonport licensed site, was undertaken as part of the 2018/19 intervention plan and propulsion sub-division strategy.

The SBI targeted the refit support equipment primarily used in 9 dock; sampling the high and low set pressure relief valve rigs, main isolation valve blanks and the pressure control and protection panels, to confirm the adequacy of implementation of the licensee’s safety case in respect of the identified equipment.

Interventions Carried Out by ONR

The SBI covered the following Licence Conditions (LCs):

The inspection assessed the applicable nuclear safety case claims for the refit support equipment through a combination of document reviews, discussions with DRDL, and facility inspections to determine compliance against the selected LCs.

For LC 34 it was identified that while some of the equipment had a safety function to maintain the level of primary coolant, there was insufficient specific evidence to make a judgement on the arrangements for leakage and escape of radioactive material, therefore a decision was made to not assess LC34 during the inspection.

Explanation of Judgement if Safety System Not Judged to be Adequate

The licensee has demonstrated that the Safety Systems, Structures and Components (SSCs) that have been sampled as part of the refit support equipment, are able to fulfil the safety functional requirements adequately, in line with the safety case.

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

There were no safety significant shortfalls identified with the arrangements and their implementation for the management of the refit support equipment that ONR sampled. 

Throughout the inspection there were a number of shortfalls which the licensee had self-identified and would be seeking to address.  ONR commended the licensee on their openness on these issues.   

Whilst some minor shortfalls were observed against LCs 23, 24, 27 and 28; these items were not considered to have a nuclear safety significance and were fed back to the licensee during the intervention. These were raised as actions to be followed up through routine regulatory interventions. As such, inspection ratings of Green were awarded for these Licence Conditions.

Conclusion of Intervention

From the evidence gathered during this SBI; noting the minor shortfalls identified, the ONR inspection team judged that the refit support equipment meets the requirements of the safety case, and their implementation is deemed adequate.

One regulatory issue is to be raised to progress the resolution of the actions identified to address the range of minor shortfalls.