Office for Nuclear Regulation

Devonport - System Based Inspection (SBI) - Vessel Impact

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 2019/20 intervention plan and propulsion sub-division strategy.

The SBI targeted the systems and arrangements which prevent an external impact to a vessel in 9 Dock in excess of the design withstand of the reactor systems; sampling the dockside crane zoning system, hard wired height limit system and lifting operation arrangements to confirm the adequacy of implementation of the licensee’s safety case.  The systems and arrangements sampled were based on the higher vessel impact withstand due to the current phase of refuelling.

Interventions Carried Out by ONR

The SBI covered the following Licence Conditions (LCs):

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

SBIs would routinely include LC 34, leakage and escape of radioactive material and radioactive waste; however this SBI looked at dockside crane systems which were not involved in radioactive material or waste handling.  There was not an evident link relevant to LC 34; 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 demonstrated that the Safety Systems, Structures and Components (SSCs) and arrangements that were sampled, which provide vessel impact protection, were 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 systems or arrangements and their implementation for vessel impact protection that ONR sampled. 

The inspection found evidence of the significant improvements which had been made to the crane maintenance arrangements.  These set a standard which should be deployed across the rest of the site.   

Two observations were raised against LCs 10 and 23; these items were not considered to have nuclear safety significance and were fed back to the licensee during the intervention. One had been identified by the licensee through ongoing safety case reviews and was already being addressed. These observations will 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 observations identified, the ONR inspection team judged that the vessel impact protection systems and arrangements meet the requirements of the safety case, and their implementation is deemed adequate.