Office for Nuclear Regulation

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Hunterston B - 2014 events follow up

Executive summary

Purpose of intervention

This intervention was held at Hunterston B Power Station (HNB).  It was a planned intervention captured in the HNB site inspection plan and contributes towards the Office for Nuclear Regulation’s (ONR) Civil Nuclear Reactor (CNRP) Operating Reactors sub-programme.

Its purpose was to follow up on progress towards implementation of corrective actions to address the findings of investigations into several events at the HNB during 2014. In particular, Nuclear Generation Limited’s (NGL’s) Significant Adverse Condition Investigations (SACIs):

Interventions Carried Out by ONR

We carried out a programme of discussions, presentations and interviews involving station management; topic specialists (human performance and continuous improvement), operations and maintenance staff to establish corrective actions taken.

We undertook a plant walk down against procedure PIOI 10.01.01 4.64A  which was implicated in the September 2014 Gas Circulator event.  We also visited the workplace where the December 2014 event was initiated.

We undertook interventions relating to Site Licence Conditions (LCs) 24 Operating Instructions and 26 Control and Supervision of Operations.

We held discussions with a member of the Station’s Independent Nuclear Assurance team and nominated safety representatives.

Explanation of Judgement if Safety System Not Judged to be Adequate

There was no safety system inspection carried out during this intervention.

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

From the evidence presented we judged that NGL had made good progress towards implementing corrective actions to address issues identified during its SACIs.  HNB management recognise the potential severity of the events experienced in 2014 and understand the root causes identified via investigations.  Station has commenced multiple initiatives aimed at preventing reoccurrence, including an extensive Human Performance (HuP) programme for ‘plan touchers’.  Station management accept that further work is required to embed the learning from these events and ensure sustained HuP in the longer term.  They are committed to developing a longer term programme of work to achieve this.

We found that the personnel questioned at all levels of the organisation had understood the key messages from recent HuP training activities.  We also observed commitment to further learning through planned self-assessments; benchmarking with other stations and identification / sharing of Fleet-wide good practice.

We judged NGL to be compliant with its arrangements under LC24 and LC26, justifying ratings of 3 – Adequate, for both LCs.

We found that the Station’s Independent Nuclear Assurance (INA) team were engaged with these improvement programmes – providing challenge and monitoring progress.  We found evidence that HNB management took due cognisance of INA input, demonstrating a healthy working relationship.

Conclusion of Intervention

We conclude that the Station has made significant progress towards implementing the programme of actions to address the findings from the recent SACIs, specifically SACI No. 896816 (Gas Circulator Protection Trip) as requested in ONR’s letter of 31st October 2014 and set out in the Station’s response letter dated 1st December 2014. We therefore conclude that no further specific regulatory action is required on this matter. ONR will continue to monitor progress in delivering HNB’s longer-term plan to confirm appropriate HuP is sustained and good practices are shared.  This will be achieved via normal regulatory interactions in relation to Procedure Quality Use and Adherence at HNB.