Office for Nuclear Regulation

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Heysham 1 - SBI15 Fuel Assemblies

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake licence condition (LC) compliance inspections at EDF Energy Nuclear Generation Limited’s (NGL) Heysham 1 (HYA) Power Station, in line with the inspection programme contained in ONR’s Operational Facilities Division intervention strategy 2017-18.

Interventions Carried Out by ONR

We performed a System Based Inspection (SBI) to confirm the implementation of safety claims made on reactor fuel assemblies. This inspection was undertaken by the ONR site inspector and two ONR specialist inspectors. During this intervention we examined NGL’s compliance with the following nuclear site Licence Conditions (LC), which are applicable provisions of the Energy Act 2013:

In addition, the ONR site inspector also undertook an information gathering meeting with the licensee independent nuclear assurance to review regulatory matters and topics.

The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.

Explanation of Judgement if Safety System Not Judged to be Adequate

Following a SBI of the fuel assemblies system, we judge that overall this system fulfils the requirements of the safety case.

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

System based inspection - fuel assemblies

From the areas targeted and the evidence examined during this inspection, we consider that NGL has implemented those safety case claims that relate to the reactor fuel assemblies. The inspection identified several areas of good practice including the arrangements used to train and assess the competence of Fuel Route Engineers and Criticality Specialists; and the arrangements implemented at the Work Execution Centre (WEC) to ensure adequate control of the condition of plant with respect to fuel assemblies.

We identified minor shortfalls with regards to the general management and traceability of documentation, and identified minor improvements that may be made to maintenance documentation. We also asked NGL to review the risks associated with charging battery powered pallet trucks in the Additional Fuel Build Facility (AFBF).

Presently the primary circuit activity level is not an explicit Limiting Condition of Operation (LCO).  However, it was explained by NGL that the Iodine at risk derived from the Gas Activity Monitoring (GAM) system output will become an explicit LCO under the pending Category 1 safety case for management and detection of failed fuel (NP/SC 7653). We placed an action to be tracked via a regulatory issue that appropriately rigorous arrangements for surveillance of such limits be included as part of the implementation of NP/SC 7653.

We also found that progress with delivery of a replacement for the GAM system is behind the original site installation plan and there is a lack of clarity in the current programme. The GAM system monitors the primary circuit activity and therefore the integrity of the fuel pin cladding. The system is subject to a planned upgrade in response to obsolescence issues for which the fleet wide programme has suffered ongoing delays.  On further examination of the GAM system we challenged the current regime for calibration of the system and subsequently requested a review to be undertaken of this.  These items are to be tracked by actions under a regulatory issue.

NGL has acknowledged these areas for improvement and raised actions to address them. An ONR regulatory Level 4 issue has been raised (issue 5699) to monitor completion of these actions.

Overall we judged that the arrangements for the erection, inspection, and online monitoring of the integrity of reactor fuel assemblies generally met relevant good practice and therefore we have given an intervention rating of ‘Green’ in relation to compliance with LCs 10, 23, 24, 27, 28 and 34.

The discussion with independent nuclear assurance was open and constructive and provided confidence that the site INA provides a robust oversight function.  No matters of significant concern were discussed that we consider require a regulatory action or issue to be raised at this time.

Conclusion of Intervention

From the evidence sampled during this inspection, we consider that the reactor fuel assemblies met the requirements of the safety case.

There are no findings from this inspection that could significantly undermine nuclear safety.  At present, no additional regulatory action is needed over and above the planned interventions at HYA Power Station.