Office for Nuclear Regulation

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Heysham 1 - SBI 15 inspection

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake a multi-disciplinary system based inspection (SBI) at EDF Nuclear Generation Limited’s (NGL’s) Heysham 1 power station in line with the relevant site inspection plan. The inspection was led by myself, a fault studies inspector. I was supported by a further fault studies inspector, a fuel and core inspector, a control and instrumentation inspector, and the nominated site inspector (partial). The aim of this SBI was to confirm that the safety case functional requirements have been adequately implemented in the HY1 back end fuel route facilities, including the associated operating instructions and maintenance schedule.

Interventions carried out by ONR

The system based inspection of the fuel route (back end) was conducted against compliance with the following licence conditions (LCs):

The Heysham 1 arrangements for monitoring the health of the fuel route systems were examined. A plant walk-down of key areas associated with the fuel route was conducted. This included the additional fuel storage facility (AFSF), the irradiated fuel dismantling facility (IFDF), and the fuel ponds and flasks areas (P&F). Inspections were conducted, on a sample basis, of the implementation of arrangements against each of the above licence conditions.

In addition to the safety inspectors, an ONR safeguards inspector also attended. This was to afford ONR safeguards an opportunity to understand HY1’s back end fuel route arrangements from a safeguards perspective. The safeguards inspector focussed on implementation of components 6 and 7 of NGL’s nuclear material accountancy and control (NMAC) system, as defined in Schedule 2 of The Nuclear Safeguards (EU Exit) Regulations 2019. As the safeguards activities were not part of the formal SBI, further detail of these aspects is reported separately in CM Ref. 2020/85566.

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

Based on the sample, I judged that for some plant areas, the compliance with licence condition 28 was not adequate. This was principally due to the failure to perform equipment reliability reviews for all fuel route facilities, and examples of individuals’ acceptance of readings which are outside of specification, during plant surveillance activities. As such an amber rating has been assigned for LC 28.

The operating rules arising from safety cases for the fuel route systems had been identified by EDF NGL, and were adequately implemented in the plant operating instructions and other documentation listed on the administrative control sheets.

Key findings, inspector's opinions and reasons for judgements made

From the intervention conducted, I summarise the following judgements for each of the licence conditions inspected:

The following observations were raised with the station during the inspection:

Conclusion of intervention

From the sample inspected, it is judged that compliance against LC 10, 23, 24 and 27, met the required standard; therefore a 'Green' rating was given for these licence conditions. It is judged that compliance against LC 28 did not meet the required standard; therefore an ‘Amber’ rating was given for this licence condition. Following application of ONR’s enforcement management model, an enforcement decision record was completed (ONR-EDR-19-051), resulting in the decision to raise a new L3 Regulatory Issue #7983 and send an enforcement letter to the licensee. The EDR noted that it was unlikely that ageing related failures would result in significant or serious consequences, due to there being other mechanisms in place to identify ageing plant and due to the redundancy and diversity implemented in the safety measures. It was therefore considered not to be proportionate to take more stringent enforcement action at this point in time. 

The back-end fuel route systems are in-general judged to meet the safety case requirements; however there is a significant shortfall associated with LC 28 compliance, which should be addressed in an appropriate time frame by satisfactory resolution of RI #7983.