Office for Nuclear Regulation

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Waste Vitrification Plant Line 3 Improvement Notice Close-Out Inspection

Executive summary

Purpose of intervention

Following loss of power to the Waste Vitrification Plant (WVP) Line 3 on the 27th November 2013 and subsequent investigation by ONR, we issued Sellafield Ltd (SL) with an Improvement Notice (IN) to secure improvements in implementation of Licence Conditions 27, 28 and 34. ONR also attached a Schedule to the IN requiring improvements to the Line 3 Vitrification and Breakdown Cell containment boundary.

ONR has undertaken a previous intervention to monitor SL’s progress against the IN schedule (Ref. ONR-SEL-IR-14-117). This identified that SL still needed complete its proposed programme of work to adequately close out the IN in view of the required 31st October 2014 compliance date. The purpose of this intervention was to undertake a proportionate follow-up inspection of the containment boundary (as identified in the IN Schedule) and gain assurance of IN compliance.

Interventions Carried Out by ONR

Our previous inspection identified areas where SL still needed to complete its proposed programme of work to adequately close out the IN. We used these areas as the basis for this inspection. We also undertook a walk-down of the Line 3 containment boundary.

Explanation of Judgement if Safety System Not Judged to be Adequate


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

As a result of our previous intervention, we judged that SL has adequately satisfied Sections 1) a) for inlet HEPA filters, 1) b) for penetrations and airlock doors, 2) a), 2) b) and 3) of the IN Schedule. 

Based on the evidence sampled during this intervention, we judge SL has adequately satisfied the following outstanding sections of the IN Schedule:

  1. for penetrations and airlock doors – SL has confirmed all penetrations and airlock doors have been sealed and successfully proof tested.
  2. for inlet HEPA filters – SL has clarified that annual inspection of airflows across the inlet HEPA filters will be undertaken to monitor filter performance. 
  3. SL adequately demonstrated the controls of modifications to non-standard penetrations. These included training, labelling, routine Examination, Inspection, Maintenance and Testing (EIM&T), the plant modification process and a newly implemented penetration defect management process.  

Conclusion of Intervention

Based on the evidence sampled, we judge SL has, So Far As Is Reasonably Practicable (SFAIRP) met the requirements of the IN and associated Schedule. We agreed that SL would formally confirm to ONR via letter that the IN scope of work was complete and the ONR inspector would respond to state the IN is now closed.