This was a planned Systems Based Inspection (SBI) conducted at EdF Nuclear Generation Ltd (NGL) Hinkley Point B (HPB) power station, undertaken as a part of the planned intervention strategy for the Operating Reactors sub-programme of the Office for Nuclear Regulation’s (ONR) Civil Nuclear Reactors Programme (CNRP).
I (as a specialist ONR, fuel performance inspector), together with ONR’s nominated Site Inspector for HPB, conducted a planned SBI of “fuel assemblies”, i.e. safety systems grouping SBI 15.
The objectives of an SBI are to confirm that the relevant safety systems and structures meet the safety functional requirements defined in the safety case and to test implementation of the Licence Condition (LC) arrangements for: LCs 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”).
LC 10 (Training) – We examined the role profile and training records for a sample of the Fuel Route Duly Authorised Persons (DAP) at HPB and found these to be in order. All Fuel Route DAPs sampled were fully up to date with their required training and the training records were in accordance with the post training profile requirements.
We also examined criticality awareness training for station staff (including ONR’s expectation that personnel, working in areas subject to criticality control, would receive an enhanced level of criticality awareness training). Finally, we discussed the licensee’s arrangements for ensuring that contract staff during outages receives a suitable and sufficient level of criticality training. From the information provided by the licensee, we judged that the licensee is providing an adequate level of criticality awareness training to all station staff (including contractors) and that for persons working in areas under criticality control, a suitably enhanced level of training is provided. On the basis of all the information we sampled we judged the LC 10 element of our inspection warranted an Integrated Intervention Strategy (IIS) rating of 3 – Adequate.
LC 23 (Operating Rules) – The licensee’s Operating Rules (OR) are defined within its Technical Specifications (Tech Specs). The Tech Specs contain a number of required ‘surveillances,’ (e.g. for fuel builds) which are conducted on the station via a number of Station Operating Instructions (SOI) and Plant Item Operating Instructions (PIOI). We chose to sample compliance with the ORs, via sampling of a randomly chosen sample of recent fuel build records i.e. to ensure that the ‘surveillances’ conducted during fuel build fully met the requirements of the licensee’s SOIs etc. All fuel build records we examined were found to be in order and accordingly, in our opinion, the LC 23 element of this inspection merited an IIS rating of 3 – Adequate.
LC 24 (Operating Instructions) – We chose to sample compliance with the lower level SOI, PIOIs etc. again via sampling of a number of randomly chosen fuel build records e.g. to ensure that the correct paperwork was being accurately completed and signed off as required during new fuel build. All fuel build records sampled were found to be in order and accordingly, in our opinion, the LC 23 element of this inspection merited an IIS rating of 3 – Adequate.
LC 27 (Safety Mechanisms, Devices and Circuits) – A common definition of Safety Mechanisms Devices and Circuits (SMDC) is still under development between EdF NGL and ONR. Consequently, we found little to examine in this area. However, in our opinion we judged that the gamma detectors and interlocks (on the doors to the New Fuel Cell) provide a safety function (since they protect operators from potential high radiation exposures in the cell). Accordingly, we examined the maintenance requirements and records for both the gamma detectors and the door interlocks, finding these to be in order. Although our inspection was limited in scope in this area, we nonetheless judged that an IIS rating of 3 – Adequate was appropriate.
LC 28 (Examination, Inspection, Maintenance and Testing) – Picking a number of key items of equipment (as identified from the living safety case documentation) in the new fuel areas of the plant, we sampled required maintenance activities and recent Work Order Cards (WOC), maintenance records etc. Generally the maintenance records we sampled were in good order, although we did identify some components of the Gaseous Activity Monitoring System (GAM) where the licensee conceded that it needs to give additional consideration to future maintenance routines. However, overall on the basis of the evidence presented and due to the licensee’s willingness to consider additional maintenance requirements on this system, we were content that an IIS rating of 3 – Adequate was appropriate for this LC.
LC 34 (Leakage and Escape of Radioactive Material and Radioactive Waste) – Concentrating on the detection of failed fuel in the reactor core, we found the station’s Burst Can Detection (BCD) equipment to be in good order. However, the GAM system is recognised to be subject to some potential vulnerability and accordingly it will be subjected to extensive refurbishment in early 2016. In the interim we accept the licensee’s position that the BCD system could act as a fall-back, along with gas bottle sampling. Although, the licensee accepted that it needs to reconsider the As Low As Reasonably Practicable (ALARP) justification for the off-site analysis of the gas bottle samples. The licensee is already considering the introduction of a potential on-site analysis capability and so willingly accepted this ONR advice. Again, on the basis of the totality of the evidence presented by the licensee, it was our opinion that the LC 34 element of the inspection merited an IIS rating of 3 – Adequate.
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 systems based inspection and these were brought to the attention of the licensee, who readily undertook to address the findings within timescales we judged to be appropriate. However, there were no findings from this inspection that could significantly undermine nuclear safety and accordingly no issues were raised during the inspection.