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 Office for Nuclear Regulation (ONR) investigation, ONR issued Sellafield Ltd (SL) with an Improvement Notice (IN) for apparent contravention of Licence Conditions 27 (Safety mechanisms, devices and circuits), 28 (Examination, inspection, maintenance and testing, EIM&T) and 34 (Leakage and escape of radioactive material and radioactive waste). ONR also attached a Schedule to the IN requiring improvements to the Line 3 Vitrification and Breakdown Cell containment boundary.

The purpose of this intervention was to monitor SL's progress against the IN Schedule and to clarify any further work required to adequately close out the IN before its due date of 31st October 2014.

Interventions Carried Out by ONR

We conducted this intervention using the IN Schedule as a basis for the agenda and systematically inspected SL's delivery against each section.

Explanation of Judgement if Safety System Not Judged to be Adequate


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

Based on the evidence sampled, we judge SL's approach to closing out the IN is adequate. We judge SL has already met the following sections of the IN Schedule:

    1. for inlet HEPA filters - All filters have been replaced and adequate airflows measured across them.
    2. for penetrations and airlock doors - These items have adequate EIM&T instructions, which are identified on the Plant Maintenance Schedule (PMS).
    1. Through continued engagement, the ONR electrical specialist has confirmed SL has met the requirements of the IN.
    2. SL has implemented a plant modification (termed the stack effect) to minimise the consequences of loss of ventilation; This modification has previously been permitted by ONR via a derived power Licence Instrument.
  1. SL is in the process of implementing the safety case in the clearance certificates and cascading this through to the operating level documents.

Based on the evidence sampled, we advised SL that it needs to complete its proposed programme of work in the following areas to close out the IN:

Conclusion of Intervention

Based on the evidence sampled, we judge SL's approach to closing out the IN is adequate. SL was able to adequately demonstrate it had satisfied a number of sections of the IN Schedule. SL needs to complete its programme of work in a number of areas to close out the IN. We agreed with SL to maintain weekly dialogue and undertake a proportionate follow-up inspection of the containment boundary as detailed in the IN Schedule and gain assurance of final IN close out. This will be conducted before 31 October 2014.