Office for Nuclear Regulation

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To conduct LC28 and LC34 compliance inspections at the Sellafield site

Executive summary

Purpose of intervention

This intervention was undertaken on 17 - 18 June 2015 at the Fuel Handling Plant (FHP) on Sellafield Limited’s (SL’s) Sellafield nuclear licensed site in Cumbria.

Inspection of Licence Condition (LC) compliance at nuclear licensed sites forms a significant part of ONR’s activities.  ONR’s Sellafield Programme has defined a programme of system inspections and LC compliance inspections to be undertaken on the Sellafield site; this is a key aspect of ONR’s regulatory strategy (for the Sellafield site).  Undertaking this intervention is consistent with this strategy, and is identified on ONR’s PP4 inspection plan which covers Sellafield Limited’s Magnox Operating Unit.

This intervention forms part of a programme of work being undertaken by ONR to gain assurance that fuel from the legacy ponds at Sellafield can be safely stored in FHP without compromising the plant’s operability in either the short or the long term..

Interventions Carried Out by ONR

The primary focus of this inspection was to gain assurance that the FHP fuel storage pond structure can fulfil its safety functions for the entirety of the period for which spent fuel is expected to be stored, including those parts of FHP that will be needed to remove the spent fuel at the end of the storage period.

LC28 ‘Examination, inspection, maintenance and testing’ requires the licensee to make and implement adequate arrangements for regular and systematic examination, inspection, maintenance and testing of all plant that affect safety. 

LC34 ‘Leakage and escape of radioactive material and radioactive waste’ requires the licensee to ensure, so far as is reasonably practicable, that radioactive material and radioactive waste is at all times adequately controlled or contained so it cannot leak or otherwise escape.  The licensee is also required to ensure, so far as is reasonably practicable, that no such leakage or escape can occur without being detected. 

Accompanied by an ONR civil engineering specialist inspector, I completed the planned LC compliance inspections (which comprised office-based discussions and two plant walk downs) against LC28 and LC34 in accordance with the following ONR guidance:

Explanation of Judgement if Safety System Not Judged to be Adequate

N/A.  This was not a safety system inspection.

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

Overall, I concluded that the FHP fuel storage pond was designed and constructed to a high standard, has been well maintained and is in good condition.  Based on the evidence I obtained in this intervention I have no concerns that the pond structure will not be capable of fulfilling its safety functions for the entirety of the storage period that spent fuel is expected to be stored within it.

I undertook a LC28 compliance inspection within the FHP supported by a civil engineering specialist inspector.  I confirmed that the licensee is undertaking regular and systematic inspection of the fuel storage pond on an annual basis.  The licensee’s arrangements for undertaking this inspection met my expectations in that it is undertaken by Suitably Qualified and Experienced Persons (SQEPs) and in accordance with the scope and periodicity specified in the Plant Maintenance Schedule (PMS).  The licensee is reviewing and sentencing recommendations from the annual civil inspections classified as ‘essential maintenance’ in accordance with its arrangements for civil EIMT.  However, I found no evidence to confirm the licensee is similarly reviewing and sentencing recommendations classified as ‘considerations’.  This is not in accordance with site arrangements for civil EIMT.  Based on the evidence from this inspection, I do not judge this shortfall to be significant in terms of nuclear safety.   However the licensee should undertake a review to sentence these recommendations appropriately. 

My inspection also revealed instances where SL’s monthly under-pond inspections had not been undertaken in accordance with the relevant arrangements.  Given these two shortfalls, I judge an IIS rating of 4 (below standard) to be appropriate against LC28: whilst the licensee is meeting the fundamental requirements of ONR’s guidance for LC28, there are some failures to follow the LC compliance arrangements.  I have placed a Regulatory Issue to rectify these shortfalls.

I also undertook a LC34 compliance inspection within the FHP, again supported by a civil engineering specialist inspector.  I judge that the design of the pond facilitates maintaining containment of pond water and minimises the potential for leakage and escape (with any pond water that does escape being captured by the secondary containment).  The Licensee understands that managing the temperature of the pond water within a narrowly-defined range is a critical aspect of minimising leakage from the pond. There is also an engineered leak detection system in the form of sumps fitted with level probes in the secondary containment.  In consequence, I am satisfied that the licensee is doing all that is reasonably practicable to prevent leakage and escape, and would detect any leakage or escape that may occur.  I therefore judge that the arrangements meet the requirements of ONR’s guidance for LC34 and have awarded an IIS rating of 3 (adequate).  I nevertheless identified a small number of potential minor improvements for the licensee’s consideration.

Conclusion of Intervention

I will progress the above Regulatory Issue through my normal regulatory engagements.  Based on the evidence gathered, no significant matters have been identified that are likely to impact on nuclear safety on the Sellafield site at this time.