- Site: RRSL
- IR number: 21-167
- Date: March 2022
- LC numbers: 8, 10, 12, 23, 24, 28
Executive summary
Purpose of Intervention
This intervention, conducted at Rolls Royce Submarines Ltd.’s (RRSL’s) Nuclear Fuel Production Plant (NFPP) licensed site on 23 and 24 March 2022, was undertaken as part of a series of planned cross-site criticality inspections performed by the Office for Nuclear Regulation (ONR). The inspection team is known throughout this record as “we”.
Interventions Carried Out by ONR
The intervention was conducted by a walkdown of the production line of the NFPP (including the chemical plant, contact shop, clean shop and Dreadnought Production Facility (DPF)), discussions with key plant personnel, and sampling of the licensee’s criticality safety documentation, training records, maintenance schedules/records and on-site signage (e.g., criticality notices).
Explanation of Judgement if Safety System Not Judged to be Adequate
Not applicable.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
The key findings against each Licence Condition (LC) are recorded below. For the observations that we made, which were all minor, the licensee received the points positively and agreed to action improvements.
LC8 (Warning Notices) – Rating = Green (including plant walkdown observations)
Limits and conditions on plant are captured in Operator Working Limit (OWL) certificates, which are the lowest tier of safety limits on plant. Those inspected on plant were clear and easy to read. Use is made of operator aids on specific items of equipment, e.g., tables, but there is as yet no formal mechanism for ensuring that these are kept up to date when OWLs are changed. One OWL we inspected specified a concentration limit, but there was no way of directly verifying the concentration (it had to be inferred from upstream values). The licensee was able to do this when asked, but it was still an inferred result.
The licensee has a ‘one-stop shop’ of all criticality-related certification which includes expiry dates and location details. This is maintained by a dedicated officer. We considered this good practice.
We judged that the inspection against this LC merited a rating of ‘Green’.
LC10 and LC12 – Training and Duly Authorised and Other Suitably Qualified and Experienced Persons – Rating = Green
Whilst Duly Authorised Person (DAP) and general operator training records and competency matrices were detailed and comprehensive, we considered the detail for the criticality competencies to be light compared to other licensees, although we have confidence in RRSL’s criticality Suitably Qualified and Experienced Persons (SQEPs) based on previous interactions.
We judged that the inspection against this LC merited a rating of ‘Green’.
LC23 and LC24 – Operating Rules and Operating Instructions– Rating = Green
We considered the use of operator aids related to the OWL certificates was good practice, provided the licensee puts in place a formalised process for ensuring they are adequately maintained. Changes to OWLs are disseminated to operators via signed-off ‘toolbox talks’ facilitated by a criticality SQEP.
Under the LC22 modification arrangements, changes to the limits on OWL certificates is not done under a formal modification (the higher Criticality Control Certificate (CCC) limits, however, are). Further, there is no formal requirement for the Safety Case Owner (SCO) to be informed of changes to OWLs (although they are informed anyway, this relies on the professionalism of staff rather than a defined process). We recommended to the licensee that this was formalised in an appropriate manner.
We judged that the inspection against these two LCs merited a rating of ‘Green’.
LC28 – Examination, Inspection, Maintenance and Testing (EIMT) – Rating = Green
We considered that, in general, maintenance records were of a good standard, with evidence of dual sign-off e.g. if an engineer in training completes a maintenance task supervised by a SQEP engineer. However, we noted one instance of a recent maintenance record (using a template dated 2016) which had ‘red pen’ corrections.
We judged that the inspection against this LC merited a rating of ‘Green’.
Conclusion of Intervention
This criticality inspection focussed on criticality aspects of LCs 8, 10, 12, 23, 24 and 28 on the RRSL’s NFPP nuclear licensed site. Inspection findings against these LCs led to a rating of ‘Green’ in all cases, with no significant areas of concern.