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Sellafield Site - Inspection ID: 52594

Executive summary

Date(s) of inspection:

May 2023

Aim of inspection

The Office for Nuclear Regulation (ONR) undertakes all its regulatory interactions with the Sellafield site licensee, Sellafield Limited, against a strategy defined by the ONR Sellafield, Decommissioning, Fuel and Waste (SDFW) Division. In accordance with this strategy, this was a planned Corporate Licence Condition Inspection (CLCI) of Licence Condition 22 (LC22) “Modification or experiment on existing plant” targeted at the classification of modifications.

Clause 4 of LC22 requires a licensee’s arrangements to “…provide for the classification of modifications or experiments according to their safety significance”.

The classification of modifications was targeted for the following reasons:

  1. Consistent and reliable classification of modifications under arrangements made to comply with Licence Condition 19 (LC19) “Construction or installation of new plant”, Licence Condition 20 (LC20) “Modification to design of plant under construction”, Licence Condition 21 (LC21) “Commissioning”, LC22 and Licence Condition 35 (LC35) “Decommissioning” is key to meeting ONR Safety Assessment Principle for Nuclear Facilities (SAP) SC.1 “Safety case production process”. This SAP states that “The process for producing safety cases should be designed and operated commensurate with the hazard, using concepts applied to high reliability engineered systems”.
  2. ONR confidence in consistent and reliable classification of modifications under arrangements made to comply with LC19, LC20, LC21, LC22 and LC35 is an important factor which ONR takes into account when deciding whether or not to place a Hold Point (HP) on LC19, LC20, LC21, LC22 or LC35 entries in the Level 3 Regulatory Interface Meeting (RIM) Hold Point Control Plan (HPCP).

Although only LC22 was rated at the end of this inspection, the inspection also sought to establish that the classification system for the safety significance of LC22 modifications is consistent with that used for: LC19; LC20; LC21; and, LC35. This is because ONR’s Technical Inspection Guide (TIG) NS-INSP-GD-022, “LC 22: Modification or Experiment on Existing Plant” states that “The licensee’s classification system for the safety significance of modifications should be consistent with that used for LC19, 20, 21 and 35”.

In some of Sellafield Limited’s documentation reference is made to categorisation rather than to classification. In the remainder of this Inspection Record, these two terms are used interchangeably.

Subject(s) of inspection

  • LC 22 - Modification or experiment on existing plant - Rating: GREEN

Key findings, inspector's opinions and reasons for judgement made

We considered that the engagement prior to and during the inspection allowed us to complete a meaningful CLCI of LC22 focussed on the classification of modifications. We considered that all the objectives of this inspection were met.

On the basis of the discussions during the inspection and the evidence sampled before and during this inspection we identified some areas of good practice relating to the delivery of the overall inspection and relating to Sellafield Limited’s LC22 arrangements and/ or their implementation. We also provided regulatory advice for potential improvements.

On the basis of the evidence sampled before and during this inspection, we identified the following regulatory findings relating to Sellafield Limited’s LC22 arrangements and/ or their implementation, representing gaps against relevant good practice:

  1. Graded approach to classification;
  2. Provision of Plant Modification Proposals (PMPs) to the Nuclear Safety Committee (NSC);
  3. Definition of operations and safety case;
  4. Radiological safety categorisation for reduced scope PMPs;
  5. Classification of modifications contributing to nuclear safety indirectly; and,
  6. The use of mitigated consequences within classification.

Full details of the areas of good practice, regulatory advice and regulatory findings are in the full Inspection Record (IR) which is shared with Sellafield Limited.

Having considered these Findings I have raised three Level 4 (the lowest level) Regulatory Issues (RIs):

  1. Graded approach to classification;
  2. Provision of modification proposals to the NSC; and,
  3. Detailed matters related to classification.

The Sellafield Limited personnel present at the hot debrief were in broad agreement with the outcomes of this inspection.

Conclusion

Two separate judgements are made:

  1. Rating for LC22; and,
  2. Use of classification in ONR decisions to set Hold Points.

Rating for LC22

Three Level 4 (the lowest level) Regulatory Issues have been raised to monitor Sellafield Limited’s progress to address the six regulatory findings relating to Sellafield Limited’s LC22 arrangements and/or their implementation identified during this inspection. These are:

  1. Graded approach to classification;
  2. Provision of modification proposals to the NSC; and,
  3. Detailed matters related to classification.

I considered that an Inspection Rating of Green (No Formal Action) for LC22 was appropriate since no significant shortfalls against relevant good practice have been identified.

Use of Classification in ONR Decisions to Set Hold Points

The first and second RIs listed above in particular will need to be addressed to improve the weight which ONR can place on Sellafield Limited’s assigned classification of LC22 modifications in ONR decisions to set Hold Points for regulatory permissioning.