Date(s) of inspection:
- January 2023
Aim of inspection
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 undertaken to assess the Special Nuclear Materials (SNM) Value Stream’s compliance with Sellafield Limited’s corporate arrangements for Licence Condition (LC) 28 Examination, Inspection, Maintenance and Testing (EIMT). With ONR structural integrity specialist support, I undertook the inspection all day on 10 and the morning of 11 January 2023.
Subject(s) of inspection
- LC28 – Examination, inspection, maintenance and testing – Rating – Amber
Key findings, inspector’s opinions and reasons for judgement made
From the inspection sample I found that SNM had issued a document containing photographs which clearly identified the acceptable boundary for outer package features (including welds). Evidence was seen that the document took account of the claims made in the safety case for the storage and movement/ transport of Magnox SNM packages. I judged that this document should help reduce the reliance on implicit engineering judgement when assessing the condition of packages during inspections. SNM are currently revising the technical basis of examination, inspection, maintenance and testing (EIMT) to reflect the document.
I found that packages were being inspected (mainly in-situ, some ex-situ, and some limited laboratory destructive testing of all the package layers) in line with a strategy that took account of previous findings, and research into degradation modelling. SNM appear to be on target to complete the in-situ inspection of all Magnox packages ahead of the operation of Sellafield Product and Residues Store (SPRS) Retreatment Plant (SRP) targeted for 2028. This should assist SNM in prioritising packages for treatment and justifying the movement of packages. However, as recognised by SNM, currently the in-situ inspection provides only partial information on the condition of the package. Consequently, it is important that SNM continues with the plans to improve inspection techniques and methods.
SNM’s package inspection findings feed into the Sellafield Limited Magnox Package System Health Report. That report states that the Magnox Packages are in an acceptable condition and that current modelling shows no measurable degradation for 100 years.
Originally, Magnox SNM packages were substantiated without EIMT requirements and considered as consumables. Since 2016, SNM have had an inspection strategy based on the principles in LC 28. Package inspections commenced in 2017/18. For historical reasons, in part relating to the technical nature of the package inspections, for Magnox packages SNM have not yet fully implemented the Sellafield Corporate arrangements for LC 28. I sought assurance on the adequacy of SNM’s current approach in instances where it did not align with Sellafield’s Corporate arrangements. Whilst I gained assurances, for one specific aspect, I was not content that SNM(N) had adequately implemented SNM’s interim arrangements for Magnox package inspections. Specifically, I found that SNM could not demonstrate that those physically undertaking the endoscope inspections in SNM(N) Stores were under the control and supervision of a Suitably Qualified and Experienced Person (SQEP) appointed for that purpose by the licensee. In particular, this was not evident from the associated instructions and completed records for undertaking endoscope inspections in the SNM(N) Stores (LC 28(6)(b and d refer). Evidence was seen that that those undertaking the operations were SQEP for the task, and assurance provided that a SQEP Technical Specialist was present for all such inspections. I found no evidence that this shortfall had significantly impacted nuclear safety. Furthermore, sample evidence was seen that the endoscope recordings made were adequate for the SQEP Technical Specialists to evaluate the package condition.
I judged as a significant inspection finding that SNM(N) could not demonstrate that those physically undertaking the endoscope inspections in SNM(N) Stores were under the control and supervision of a SQEP appointed for that purpose by the licensee (LC 28(6)(b and d refer). I believe that this was without prejudice to overall nuclear safety objectives. Consequently, I judge that SNM(N) warrant an inspection rating of Amber (Seek Improvement) for this inspection – “specific legal requirements not met, but without prejudice to overall nuclear safety”. I will raise a Level 3 Regulatory Issue to have oversight of SNM’s progress to address the shortfall. In addition, I will raise a Level 4 Regulatory Issue to have oversight of some other aspects of EIMT package inspection SNM are looking to improve.