Office for Nuclear Regulation

This website uses non-intrusive cookies to improve your user experience. You can visit our cookie privacy page for more information.

System Based Inspection

Executive summary

Purpose of intervention

The purpose of this intervention was to conduct a systems based inspection (SBI) of EDF Nuclear Generation Ltd's (NGL) Heysham 2 Power Station in relation to fuel assemblies. The intervention was undertaken by the Office for Nuclear Regulation (ONR) nominated site inspector and a specialist fuel inspector and was carried out in line with the planned inspection programme for 2014/15 contained in the Heysham 2 integrated intervention strategy (IIS).

Interventions Carried Out by ONR

Systems Based Inspections (SBI) involve a 'deep slice' sample into the safety case and its supporting documentation, with a view to ascertaining the adequacy of the implementation of the licensee's arrangements as a part of licence condition compliance. These inspections are generally undertaken with the support of specialists within ONR and are informed through a review of the safety case (including supporting references and records), discussions with station specialists, plant inspection and the sampling of documents and records.

This intervention considered the arrangements in place for their receipt, storage and assembly. Through examination of this system we performed compliance inspections against Licence Condition (LC) 10 (training), LC 23 (operating rules), LC 24 (operating instructions), LC 27 (safety mechanisms, devices and circuits), LC 28 (examination, inspection, maintenance and testing) and LC 34 (leakage and escape of radioactive material and radioactive waste).

Pre and post inspection meetings were held with Heysham 2 staff, which included discussion of the inspection agenda as well as communication of the inspection outcomes.

Explanation of Judgement if Safety System Not Judged to be Adequate

This system based inspection judged that the arrangements and their implementation, associated with fuel assemblies, met the requirements of the safety case and are adequate.

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

LC 10 (Training) - we were satisfied that the licensee has a robust and well developed training programme, with good evidence of periodic reviews and updating (as necessary) of the training material. In addition good use is made of experienced plant personnel to conduct aspects of the training. All training records (3 of - sampled at random), of staff working on System 015, were found to be in order. We also sampled some of the training programme descriptions, roles and training profiles, and the Qualification Manual for Duly Authorised Persons on the station's fuel route - all documentation sampled was found to be of a good standard. We assigned an IIS rating of 2 (Good) to this inspection.

LC 23 (Operating Rules) - we sampled three of the key Technical Specifications (i.e. the licensee's operating rules) relating to System 015 and in particular the surveillances required under these Technical Specifications. To sample the surveillances, we picked fuel build folders at random and scrutinised the documents contained in each folder to ensure that the required surveillances had been fully executed as required. All documentation examined was found to be correct and in order, no anomalies were identified. We assigned an IIS rating of 2 (Good) for this inspection.

LC 24 (Operating Instructions) - we requested the licensee to provide copies of the Plant Item Operating Instructions (PIOI) referenced from the Technical Specification Surveillance documents but found two of the referenced documents had been superseded. We then chose to sample the application of a procedure for criticality control and whilst it was clear that the procedure, as sampled, was being fully complied with, we provided the licensee with some advice on the clarity of the procedure in one area. Accordingly, we assigned an IIS rating of 3 (Adequate) for this inspection.

LC 27 (Safety Mechanisms, Devices and Circuits) - whilst recognising that a common definition of safety mechanisms, devices and circuits (SMDC) is being developed between ONR and the licensee, we nonetheless examined the licensee's documentation for defeat of interlocks on the fuel route and judged this to be both robust and appropriate. We also identified two sets of devices we considered to be interlocks (i.e. gamma monitors/locks - preventing inadvertent entry of personnel into high radiation fields in the New Fuel Build Cell) and under LC 28 examined the maintenance records for these items. We assigned an IIS rating of 3 (Adequate) to this inspection.

LC 28 (Examination, Inspection, Maintenance and Testing) - we examined the maintenance records for the fuel pressure test equipment and the gamma monitors and interlocks in the New Fuel Build Cell. All documentation we examined was found to be in order and we assigned an IIS rating of 2 (Good) to this inspection.

LC 34 (Leakage and Escape of Radioactive Material and Radioactive Waste) - for this inspection we chose to look at the current condition of the station's Burst Can Detection (BCD) and Gaseous Activity Monitoring (GAM) systems for the detection of radioactive releases from failed fuel in core. We also queried the number of "dark channels" (i.e. fuel channels were there is insufficient gas flow to the BCD system to allow accurate testing for failed fuel in the channel). The licensee was able to evidence a satisfactory position, although noting that a fleet-wide project is in progress which is required to replace the GAM system due to ageing and obsolescence issues. We assigned an IIS rating of 3 (Adequate) to this inspection.

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

Conclusion of Intervention

After consideration of all the evidence witnessed during the sampling inspections undertaken against LCs 10, 23, 24, 27, 28 and 34, we consider that the arrangements and their implementation, associated with fuel assemblies, meet the requirements of the safety case and are deemed adequate.

A number of observations were made as a result of the system based inspection; however, given that they are of minor nuclear safety significance, we are content that they be addressed by NGL in accordance with their own arrangements. NGL has raised a Condition Report (CR) that captures the observations as a number of actions.

There were no findings from this inspection that could significantly undermine nuclear safety and accordingly no actions were raised during this inspection