Office for Nuclear Regulation

Routine Licence Compliances Inspection at THORP covering LC 22, 28 and 36

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 core licence conditions targeted at those facilities with the potential to give rise to offsite effects to the public. This core licence condition inspection was performed to assess Sellafield Ltd.’s compliance with Licence Condition 22; Modification or experiment on existing plant, Licence Condition 28; Examination, inspection, maintenance and testing and Licence Condition 36; Organisational Capability, in the Thermal Oxide Reprocessing Plant (THORP).

Interventions Carried Out by ONR

Supported by ONR Specialist Inspectors, I carried out three consecutive one day planned compliance inspections against the following licence conditions:

Explanation of Judgement if Safety System Not Judged to be Adequate

N/A as this was not a safety systems inspection.

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

LC 22 Modification or experiment on existing plant

THORP demonstrated that it is maintaining adequate control of modifications to existing plant with appropriate categorisation and oversight, in compliance with site guidance. It was, however, evident that although THORP is expending a significant amount of effort to ensure  that it’s  temporary and permanent plant modification proposals (PMPs)  do not pass their target closure dates, there is a significant backlog which will required enhanced effort to address.

THORP were able to demonstrate adequate control of Temporary Hard Wire overrides in compliance with local arrangements.

SL and THORP have developed and implemented a robust and comprehensive process to manage and control temporary software modifications, with good oversight and control enacted by the process owner.

LC28 examination, inspection, maintenance and testing

THORP were able to demonstrate that Plant Maintenance Schedule (PMS) maintenance (the most safety significant maintenance) was being completed appropriately and that THORP had ensured effective control and oversight of its completion.

THORP has a significant back-log of maintenance that it categorises as ‘normal plant’. Following sampling of items included in this backlog, however, I conclude that it contains overdue maintenance on equipment that may affect safety and, hence, I consider that THORP should have appropriate arrangements in place to ensure that its deferral/non-completion is assessed both at an individual task level and in aggregate, to ensure that no significant nuclear safety impact exists.

It is my expectation that SL is able to demonstrate that the appropriate examination, maintenance inspection and testing is being carried out on plant and equipment that that may affect safety. Sampling of a cell inspection task identified that although inspections were being completed the underpinning justification that I would expect to be contained in the safety case and engineering schedule as to why certain features were being inspected and  the link to the inspection tasks which ensured these requirements were implemented was not clear.

LC36 Organisational capability

I noted in SL’s corporate arrangements regarding Organisational Capability some shortfalls against Relevant Good Practice with regard to categorisation of changes and the lack of a Nuclear Baseline. With one notable and significant exception, THORP was found to be compliant with these arrangements. THORP was, however, able to demonstrate a pragmatic approach which serves to partially mitigate these corporate shortfalls.

SL is implementing a new organisational management software tool to improve control of the organisational baseline. This should lead to a significant improvement in its control of the nuclear safety baseline. I do, however, note that in migrating to this new system, significant difficulties have been encountered. These difficulties have led to degradation of the information contained in the existing organisational management tool and hence this has impacted THORP’s ability to adequately justify organisational changes without reference to its own locally produced organisation charts.

THORP was found to have adequate arrangements to manage organisational capability; with all posts filled with trained individuals and the governance process was found to be robust. The change documents I inspected provided proportionate justifications of the related changes, in some areas again exceeding the corporate requirements.

The main area for concern was in the proposed reduction in staffing numbers across THORP, where THORP was unable to provide evidence that the process had been applied. I believe that, as the proposed change involves a significant >5% reduction in staff, many of whom in my opinion occupy nuclear safety implicated posts, in this case THORP has fallen significantly short of SL’s own arrangements and RGP.

Conclusion of Intervention

LC 22 Modification or experiment on existing plant

Overall, I consider that an IIS rating for LC22 of 3 (adequate) is appropriate, because whilst THORP have demonstrated that they have adequately implemented SL arrangements to ensure effective control of modifications on plant which may affect safety, there remain areas for improvement particularly with addressing the back-log of PMPs older than SL’s targets. I recognise that SL was able to demonstrate that they had a very robust process for the control of temporary software modifications.

LC28 examination, inspection, maintenance and testing

Overall, I consider that that an IIS rating for LC28 of 4 (below standard) is appropriate, because whilst THORP could demonstrate good control of maintenance required as part of the facilities plant maintenance schedule, THORP had a significant back-log of “normal plant” maintenance. Examination of this back-log identified that it contained maintenance of plant which may affect safety and SL was unable to provide appropriate evidence that this backlog was being effectively addressed or that that potential aggregate impact on safety had been assessed. Furthermore, regarding cell inspections, SL were unable to adequately justify that the appropriate examination, inspection, maintenance and testing was being completed. Although evidence was provided that cell inspections were being completed, SL was unable to demonstrate that the scope and periodicity for these inspections had been derived from the requirements of the safety case.

LC36 Organisational Capability

Overall for compliance with LC36 I judge that an IIS rating of 5 (significantly below standard) is appropriate. Whilst THORP has provided some good evidence of adequate consideration of organisational change, I consider the failure to apply the process to the proposed reduction in staffing levels to be a significant shortfall. Furthermore, THORP was unable to provide a formal, auditable, nuclear baseline, which in my opinion, indicates that one or more important requirements of LC36 have been missed And that THORP are unable to fully demonstrate maintenance of adequate human resource to ensure the safe operation of the facility.