- Site: Sellafield
- IR number: 21-055
- Date: July 2021
- LC numbers: 23
Executive summary
Purpose of Intervention
In accordance with the Office for Nuclear Regulation’s (ONR’s) Sellafield Strategy, each year ONR performs a series of planned compliance inspections of selected licence conditions, targeted at those facilities with significant importance to nuclear safety. One such inspection was performed to assess the Special Nuclear Materials (SNM) Value Stream’s compliance with Sellafield Ltd’s (SL’s) corporate arrangements for Licence Condition (LC) 23 (Operating Rules) in respect to Nuclear Fire Safety. The LC inspection focussed on SNM South (S) activities.
Interventions Carried Out by ONR
On 13 July 2021, I carried out a licence condition compliance inspection of the SNM (S) facilities, namely: Sellafield MOX Plant (SMP), Sellafield Product & Residue Store (SPRS), Thorp Product Store (TPS) and Finishing Line 6 (FL6). The inspection comprised discussions with SL staff, review of plant records and other documentation, and a plant inspection. I undertook this inspection with the ONR Site Inspector for SNM and a Nuclear Safety Associate. I was also supported remotely (by telephone) by another ONR Internal Hazards Specialist Inspector. A member of SL’s Nuclear Intelligence and Independent Oversight (NI&IO) team participated in the inspection and an SNM(S) Safety representative took part in the desk-based part of the inspection.
LC 23 requires the licensee to ensure that any operations that may affect safety are at all times controlled and carried out in compliance with the conditions and limits necessary in the interest of safety. In this instance, I focused the LC 23 inspection on those Limits and Conditions arising from considering the impact of fire on nuclear safety.
As part of my preparation for the delivery of this intervention, I used the current version of ONR technical inspection guidance for LC 23, NS-INSP-GD-023 Issue 6.1, and ONR Internal Hazards Technical Assessment Guide, NS-TAST-GD-014 (Rev 6).
Explanation of Judgement if Safety System Not Judged to be Adequate
This was not a system-based inspection, and therefore no judgement has been made of the adequacy of implementation of any part of the safety case.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
During the inspection, I observed that the licensee has a good understanding of the LC 23 arrangements from a nuclear fire safety perspective. On a sample basis, evidence was seen that SNM(S) had adequately implemented required Operating Instructions (rOIs) associated with the Nuclear Fire Safety Assessments and compliance checklists were adequately completed and updated in accordance with the plant status.
I also found suitable evidence from the fire safety dashboards that equipment malfunctions were adequately monitored and resolved through condition reports. During the plant walkdown, I found that no evidence of significant damage to ablative and intumescent coatings to cablings, penetrations and fire barriers, but pointed a number of areas of minor wear in this context which SNM(S) agreed to monitor and address.
On a sample basis, I found adequate evidence that Examination, Inspection and Testing on fire barriers and dampers had been completed as planned. Consequently, I judged that no items of important to nuclear safety in the context of fire hazards were unavailable or operated under degraded conditions.
The SNM(S) team stated that it has continued to undertake bi-monthly fire surveillance audits despite the COVID-19 pandemic and throughout the intervention, I saw evidence that progress was being made on the management of combustible inventories. No major accumulations were seen in any of the areas visited.
Some minor shortfalls were noted regarding the storage of combustible materials outside designated areas which we brought to the attention of SNM(S). Specifically, this involved some storage of a small volume of packaging in a fire protected corridor, which was reported by SNM(S) as resolved immediately after the walk-down, and minor accumulation in an undesignated area of SPRS, which SNM(S) agreed to monitor and resolve through a condition report. SNM(S) recognises the need to remain vigilant and emphasised its commitment to continuing to implement the Sellafield Ltd Fire team’s recommended approach to control combustible inventories across the facilities.
SNM(S) accepted a suggestion from ONR that they review a decision not to implement the recommended segregation of extract fan cabling in the Thorp Product Store identified in the Long Term Periodic Safety Review (LTPR), given that forced extract ventilation (not natural ventilation) was the normal operational state of the facility.
Conclusion of Intervention
I judged from the evidence sampled that SL has effectively implemented its arrangements for compliance with LC 23 in respect to Nuclear Fire Safety for SNM(S) and I have assigned an inspection rating of Green (no formal action) for compliance against this LC.
One level four (i.e. lowest level) regulatory issue (RI 8853) has been raised in order to gain oversight that SNM does review the Thorp Product Store LTPR recommendation.