To conduct a system inspection, a LC32 compliance inspection and undertake routine regulatory interactions with Sellafield Limited
- Site: Sellafield - Magnox
- IR number: 14-127
- Date: November 2014
- LC numbers: 10, 23, 24, 27, 28, 32, 34
Purpose of intervention
This intervention was undertaken on 17 – 20 November 2014 at Sellafield Limited’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.
Interventions Carried Out by ONR
The intervention comprised:
- undertaking a system inspection of system 1.07 ‘Ventilation’ within the Magnox Reprocessing Plant;
- undertaking a LC32 ‘Accumulation of Radioactive Waste’ compliance inspection within the Fuel Handling Plant; and
- routine regulatory engagement including following up recent events.
The safety significant role of the ventilation system within the Magnox Reprocessing Plant is to protect plant operators, the public and the environment by maintaining nuclear containment and limiting the spread of radioactive contamination. The system inspection sought to determine whether the ventilation system meets the requirements of the safety case and is adequate. The implementation of the licensee’s arrangements for the following LCs were tested during the system inspection:
- 10 ‘Training’
- 23 ‘Operating Rules’
- 24 ‘Operating Instructions’
- 27 ‘Safety Mechanisms, Devices and Circuits’
- 28 ‘Examination, Inspection, Maintenance and Testing’
- 34 ‘Leakage and Escape of Radioactive Material and Radioactive Waste’
LC32 requires the licensee to make and implement adequate arrangements for minimising, so far as is reasonably practicable, the rate of production of, and total quantity of radioactive waste accumulated on the site at any time and for recording the waste so accumulated. Undertaking this LC32 compliance inspection is proportionate because there is a considerable volume of radioactive waste (radwaste) interim-stored in the graphite waste store associated the Fuel Handling Plant. The inspection sought to determine whether the accumulation of radwaste within the Fuel Handling Plant was compliant with the requirements of LC32.
Explanation of Judgement if Safety System Not Judged to be Adequate
N/A. Based on sampling inspection, the ventilation system of the Magnox Reprocessing Plant was judged to be adequate.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
For the ventilation system of the Magnox Reprocessing Plant I judged the following IIS ratings to be appropriate:
- LC10 – IIS rating 3 (adequate): A site wide ventilation awareness course is available and is of a good standard, and key individuals had completed this. Whilst noting a gap regarding the availability of mandatory ventilation system training for the Magnox Reprocessing Plant (whose ventilation systems are complex), I confirmed that arrangements are in place to roll out a tailored course during 2015. I therefore judged an IIS rating of 3 (adequate) to be justified.
- LC23 – IIS rating 3 (adequate): I confirmed that the safety case specifies limits and conditions with respect to the operation of the ventilation system in an operating rule, and that these limits and conditions are clearly specified in appropriate instructions. The trail for the operating rule from the safety case through instructions to plant check sheets was clear. Based on my sample, I judged an IIS rating of 3 (adequate) to be appropriate against LC23 ‘Operating Rules’. I did not judge a higher IIS rating to be justified however because compliance with the operating rule is not determined by a directly measurable parameter but is based on analysis of a filter, which can incur a time delay of several days.
- LC24 – IIS rating 2 (good standard): I sampled a range of operating instructions, maintenance instructions and emergency instructions. I judged these to be clear and unambiguous, and relevant to ensuring compliance with the limits and conditions derived from the safety case. I judged an IIS rating of 2 (good standard) to be appropriate against LC24 ‘Operating Instructions’.
- LC27 – IIS rating 3 (adequate): I sampled a number of key Safety Mechanisms (SMs) and Safety Related Equipment (SRE). I judged an IIS rating of 3 (adequate) to be appropriate against LC27 ‘Safety Mechanisms, Devices and Circuits’ because I found the SM and SRE to be properly connected and in good working order. I did not judge a higher IIS rating to be justified however, because a number of SRE were unavailable, reducing the redundancy and diversity designed into the ventilation system.
- LC28 – IIS rating 3 (adequate): I sampled the maintenance schedule, maintenance instructions and maintenance records for key components of the ventilation system. I judged an IIS rating of 3 (adequate) to be appropriate against LC28 ‘Examination, Inspection, Maintenance and Testing’ because I found the maintenance arrangements to be in order for my sample. The adequacy of the maintenance routines is being assessed through an ongoing programme of work; when this is further progressed a higher IIS rating is likely to be justified.
- LC34 – IIS rating 2 (good standard): I sampled the arrangements in place to detect any escapes of radioactivity from the ventilation system, including those to detect escape of radioactive condensate, and found no deficiencies. I examined a selection of the visible sections of the ventilation systems and noted no evidence of leaks. I judged an IIS rating of 2 (good standard) to be appropriate against LC34 ‘Leakage and Escape of Radioactive Material and Radioactive Waste’ because adequate arrangements are in place to prevent leakage of radioactive materials, and to detect any leakage that does occur.
- Based on sampling inspection, I judged that operation of the ventilation system is consistent with safety case requirements, the key equipment that verifies this is available and appropriately maintained, those responsible for operations are suitably trained and that appropriate written instructions are available. I conclude the ventilation system meets the requirements of the safety case.
- In the Fuel Handling Plant I judged a rating of 2 (good standard) to be appropriate against LC32 ‘Accumulation of Radioactive Waste’. A number of housekeeping and radwaste management initiatives are being implemented that are reducing the volume of radwaste generated and making use of the waste hierarchy. The storage arrangements in the graphite waste store are to a good standard. The backlog of radwaste stored in cells is being reduced systematically through an existing work programme to characterise and manage the waste making use of available routes.
- No issues of regulatory concern arose from my follow up of recent events.
Conclusion of Intervention
One minor issue was raised as a result of this intervention, relating to how SL is managing its filters. I will manage its close out as part of normal regulatory interactions with the licensee. 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.