Office for Nuclear Regulation

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System Based Inspection (SBI) of National Nuclear Laboratory (NNL) Central Laboratory Nuclear Ventilation System (INF06) at Sellafield

Executive summary

Purpose of intervention

The Office for Nuclear Regulation (ONR) undertakes all regulatory interaction with the Sellafield site licensee (Sellafield Limited, SL) against a strategy defined by ONR’s Sellafield, Decommissioning Fuel and Waste Programme. In accordance with that Strategy, a System Based Inspection (SBI) of SL’s tenant National Nuclear Laboratory (NNL) Central Laboratory was planned and conducted in November 2016. The purpose of this inspection was for ONR to examine whether safety case claims in respect of this system that are important to safety have been adequately implemented.

My inspection targeted NNL’s nuclear ventilation systems. These comprise a plenum supply system; a general extract system and two specific active extract systems. These systems are important to nuclear safety as they enhance the confinement afforded by the plant, equipment and the building. Specifically, they remove airborne particles from discharged air to ensure emissions comply with the site’s aerial discharge limits and are as low as reasonably practicable, as well as providing a suitable working environment for personnel and equipment.

The continued safe operation of the Central Laboratory is also important in supporting SL’s overall hazard and risk reduction activities across the Sellafield site.

ONR’s SBI process examines evidence to determine compliance against six key Licence Conditions (LCs). These LCs (listed below) have been selected in view of their relevance to ensuring nuclear safety and in providing a structured approach to determining whether the safety case has been implemented adequately through the system being inspected.

Interventions Carried Out by ONR

LC10 requires SL to make and implement adequate arrangements for suitable training of those who have responsibility for any operations that may affect safety.

LC23 requires SL to produce adequate safety cases to demonstrate the safety of operations on the site, and to identify and implement operating conditions and limits necessary in the interests of safety.

LC24 requires SL to make and implement adequate arrangements for the provision of suitable written instructions for undertaking any operation that may affect safety.

LC27 requires SL to ensure that, before a system is operated, inspected, maintained or tested, all safety mechanisms, devices and circuits are properly connected and in good working order.

LC28 requires SL to make and implement adequate arrangements for the regular and systematic examination, inspection, maintenance and testing (EIM&T) of all plant which may affect safety.

LC34 requires SL to ensure that radioactive material and radioactive waste on the site is at all times adequately controlled and contained, and that no leak or escape of that material or waste can take place without being detected.

I conducted this SBI of National Nuclear Laboratory Central Laboratory nuclear ventilation system over the course of two days looking at compliance with these six LCs. I was assisted by technical support from an external consultant with expertise in the field of mechanical engineering. I was also supported on this inspection by SL staff from its internal regulatory organisation. The inspection comprised discussions with both SL and NNL staff, physical viewing and inspections of targeted structures, systems and components, and review of NNL’s records and other safety documentation.

Explanation of Judgement if Safety System Not Judged to be Adequate

I judge the safety case supporting this system to be adequately implemented. I did however note some areas for improvement as described below.

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

From the areas I targeted and the evidence I examined during this inspection, I consider that NNL has adequately implemented those safety case claims that relate to its nuclear ventilation systems.

Through the course of my inspection I did not identify any significant concerns with the adequacy of the licensee’s safety case for this system that would necessitate an earlier than planned assessment by ONR.

I am of the opinion that SL, as the licensee, provides an adequate level of assurance to its management and control of its tenant. In addition, NNL provides an adequate level of assurance to ownership and implementation of its safety case.

Nevertheless, I awarded an Amber inspection rating (seek improvement) against LC 10 – Training – as I consider NNL needs to update its training arrangements to ensure full LC compliance in a timely manner. This is in light of shortfalls I observed in regard to maintaining training records of Duly Authorised Persons up to date.

I consider NNL provided an adequate level of assurance and evidence to demonstrate compliance with LC 23 - Operating rules.

My inspection identified a number of minor deficiencies and anomalies against LC 24 - Operating instructions, LC 27 –Safety mechanisms, devices and circuits, and LC 28 - Examination, Maintenance, Inspection and Testing (EMI&T). However, I consider the significance of these deficiencies to be low and will not be seeking improvements. As such I awarded inspection ratings of Green (No formal action) against LCs 23, 24, 27 and 28.

However, I awarded an Inspection rating of Amber (seek improvement) against the LC 34 as I consider NNL needs to establish and implement adequate disposal arrangements for solid radioactive waste that I observed to be inappropriately stored.

In contrast, during the course of my inspection I identified several examples of NNL demonstrating good practice. One specific example is its implementation of condition-monitoring arrangements for a number of key safety mechanisms in addition to its extant EIM&T arrangements.

Conclusion of Intervention

My inspections findings were shared and accepted by the NNL and the licensee as part of normal inspection feedback.

I consider NNL adequately demonstrated ownership and implementation of its nuclear ventilation systems safety case. In addition, it demonstrated an adequate understanding of its arrangements to ensure and maintain the safety of its nuclear ventilation system.

I have however raised two regulatory issues as a result of the Amber ratings awarded for this inspection, to track NNL’s updates to its LC 10 and 34 arrangements to ensure full compliance in a timely manner.