Office for Nuclear Regulation

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Research Sites Restoration Ltd (RSRL) – Harwell – Planned Intervention

Executive summary

Purpose of intervention

This was a planned inspection at Research Sites Restoration Ltd’s (RSRL’s) Harwell site, undertaken as part of the planned intervention strategy for the Harwell site for 2014/15.

Interventions Carried Out by ONR

We (nominated site inspector and ONR mechanical inspector) completed a planned System Based Inspection (SBI) “HVAC to Support Containment or for Plant Control Rooms”, referred to as S4.3, at the B462 Complex.  The objectives of a SBI are to confirm that the relevant safety systems and structures are able to meet the safety functional requirements defined in the safety case and to test implementation of the Licence Condition (LC) arrangements for:  LCs 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).

In relation to Licence Condition 2 (LC2) “marking of the site boundary” I considered two topics.  The first was RSRL’s LC2 compliance arrangements whilst the second was implementation of these at the Harwell site.  I selected these topics since I was not familiar with RSRL’s LC2 arrangements and I needed to check the marking of the site boundary as part of the relicensing of the Harwell site to Magnox Limited.

I undertook planned information gathering, including following up two incidents on the site.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable.

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

In relation to the LC10 element of the SBI, we concluded that personnel were adequately trained for the HVAC maintenance tasks sampled.  We noted that engineering support was in place to support the B462 HVAC system.  From the information sampled we noted that adequate arrangements were in place to assess the training needs for maintenance activities related to their safety significance, which feed into the training needs of individuals.  All personnel that we interviewed demonstrated a good level of competence.  Taking these factors into account, we assigned an Integrated Intervention Strategy (IIS) rating of 3 (adequate) to LC10.

In relation to the LC23 element of the SBI, we noted that safety case shortfalls were being identified and appropriately managed and that RSRL had also recognised the need to re‑baseline the safety cases considered during this SBI.  We observed that conditions and limits necessary in the interests of safety “operating rules” were comprehensively identified, with clear links to safety cases.  Evidence of compliance with one operating rule sampled was provided.  Evidence of compliance with contingency arrangements for B462 Complex HVAC plant in the event of unavailability was sampled and provided. Use of RSRL’s modifications process to control changes to safety related HVAC plant was sampled and provided.  An item was raised relating to RSRL investigating the vulnerability of cabling to a fireman’s panel in the event of a substantial fire (this panel could be used to control fire dampers in the HVAC system in the event of a fire).  This item was captured as one part of a single ONR issue relating to this SBI.  Taking these factors into account, we assigned an IIS rating of 2 (good standard) to LC23.

In relation to the LC24 element of the SBI, we considered the main operating and maintenance instructions sampled to be clear and unambiguous with RSRL identified improvements to a number of the instructions sampled well underway.  Three items were raised relating to further improving instructions in three specific areas.  These items were captured as one part of a single ONR issue relating to this SBI.  Taking these factors into account, we assigned an IIS rating of 3 (adequate) to LC24.

In relation to the LC27 element of the SBI, we raised an ONR issue relating to RSRL’s LC27 arrangements since RSRL’s approach to identifying Safety Mechanisms, Devices and Circuits is not consistent with ONR guidance.  Since this issue relates to RSRL’s generic LC27 arrangements, it is not regarded as an improvement area relevant to SBI4.3 since SBIs focus on implementation of existing Licence Condition arrangements.  We concluded that RSRL’s implementation of its existing arrangements meet the requirements of the safety case and the required safety standard in relation to the safety mechanisms, devices and circuits relevant to this system.   Taking these factors into account, we assigned an IIS rating of 3 (adequate) to LC27.

In relation to the LC28 element of the SBI, we raised an ONR issue relating to RSRL’s LC28 arrangements since RSRL’s approach does not allow a ready identification of all plant which may affect safety.  Since this issue relates to RSRL’s generic LC28 arrangements it is not regarded as an improvement area relevant to SBI4.3 since SBIs focus on implementation of existing Licence Condition arrangements.  In terms of RSRL’s existing LC28 arrangements, we noted that a ventilation equipment maintenance strategy was in place.  We also noted that required maintenance sampled had been undertaken at the required periodicity and that comments and observations are being noted by maintenance personnel on relevant maintenance instructions.  We noted no plant condition issues during our inspection and that significant improvements have been made relating to improving the HVAC maintenance strategy by learning from HVAC faults.  Taking these factors into account, we assigned an IIS rating of 2 (good standard) to LC28.

In relation to the LC34 element of the SBI, we noted the HEPA filters and the fire dampers to be relevant.  We noted that an effective HEPA filter management system is now in place and that required examination, inspection, maintenance and testing is being undertaken on the HEPA filters and the fire dampers.  We noted that contingency arrangements are in place relating to the fire dampers.  Taking these factors into account, we assigned an IIS rating of 3 (adequate) to LC34.

In relation to LC2, I noted that RSRL had made significant improvements to their arrangements for marking and properly maintaining the site boundary.  I inspected the marking of the main Harwell site boundary and its physical condition and, based on this and evidence provided by RSRL, I have now closed an existing ONR issue “Improvements to Harwell Site Boundary”.  I identified several matters that were not related to the physical condition of the main Harwell site boundary (e.g. relating to marking the site boundary rather than the security fence when these do not coincide).  I also inspected the marking and physical condition of the Liquid Effluent Treatment Plant part of the Harwell site boundary, which encloses a small area separate from the area surrounded by the main Harwell site boundary.  I did not consider that this part of the site boundary was consistent with RSRL’s improved arrangements.  I raised a single ONR issue to capture 7 items from this inspection that need to be resolved prior to the relicensing of the Harwell site to Magnox Limited.  Taking all these factors into account, with particular emphasis on the significantly improved arrangements and physical condition of the main Harwell site boundary, I assigned an IIS rating of 3 (adequate) to LC2.