NNB Generation Company (HPC) Ltd (NNB GenCo), the licensee for Hinkley Point C (HPC) has contracted Framatome to deliver the reactor coolant circuit who, in turn, sub-contract work to other manufacturers. In general, NNB GenCo performs supplier assessments of their tier 1 contractors but not of sub-contractors below tier 1. One of the key findings from an Office for Nuclear Regulation (ONR) Chief Nuclear Inspector’s (CNI) inspection at Framatome Creusot-Forge in October 2017, stated that:
This element of the CNI inspection (Creusot Forge) identified potential risks with NNB GenCo’s oversight and assurance arrangements for work sub-contracted by their Tier 1 suppliers. I have challenged NNB GenCo to ensure that their approach is commensurate with risk arising from the product supplied, rather than being focussed on the activities of their Tier 1 suppliers. This issue was examined further as a cross cutting theme during the other elements of this inspection.
During a level 4 meeting with the licensee on 20 June 2018, ONR noted that Framatome are sub-contracting the manufacture of the pressuriser to ENSA (Spain) and, by way of example, asked the licensee what, if any, supplier audits it planned to undertake of ENSA. In response the licensee explained that it had no plans to undertake any quality management audits; instead the licensee gained confidence in ENSA’s overall ability to manufacture pressurisers through other means.
The purpose of the intervention described here is to understand and judge the adequacy of the licensee’s arrangements for evaluating the ability of its sub-tier 1 suppliers to deliver nuclear steam supply system (NSSS) components of the appropriate quality.
License Condition (LC) 19 requires that “Where the licensee proposes to construct or install any new plant which may affect safety the licensee shall make and implement adequate arrangements to control the construction or installation”. This intervention focussed on the licensee’s arrangements for assuring itself of the capability of the supply chain to deliver NSSS pressure boundary components of the appropriate quality.
The intervention was conducted at the licensee’s headquarters, Bridgewater House, Bristol. The intervention comprised of discussions, where the licensee provided information in response to specific questions raised by the ONR inspectors. This was combined with a review of relevant documents provided by the licensee prior, and subsequent to, the meeting.
This was not a system-based inspection.
The implementation of NNB GenCo’s plan for assessing the NSSS supply chain appears to have been constrained by resource. The audits/assessments, identified in NNB’s plan for 2018 relating to the pressure boundary parts of the NSSS, had not been conducted. There was no evidence that NNB GenCo had rescheduled these audits/assessments.
NNB GenCo did not appear to be systematically identifying NSSS suppliers based upon risk; consequently it is not evaluating the ability of sub-tier 1 suppliers to deliver items of the appropriate quality. The soon to be issued revised NNB GenCo document on supply chain evaluation will not include any risk based evaluation.
The intervention focussed on the example of ENSA which has been selected by Framatome to fabricate the pressuriser. NNB GenCo appears to be relying on Framatome’s assessment (without reviewing this assessment) and EDF Direction industreille’s (DI) supplier evaluation (without reviewing this evaluation). NNB GenCo are generally content if there is no adverse operational experience (OPEX) about a supplier.
NNB GenCo appeared to be highly reliant on Framatome’s evaluation of its sub-contractors without completing its assessment of Framatome’s arrangements. NNB GenCo had undertaken an initial visit to understand Framatome’s arrangements but had not implemented any of the significant recommendations made as a result of this visit.
Most of the NSSS pressure boundary components are assigned a high integrity component (HIC) classification and consequently require a very high demonstration of structural reliability. In general, this involves measures to be taken in design and through manufacture (in addition to those considered in the design and safety case) above those that might be considered for non-HICs.
OPEX over recent years has identified shortcomings in the organisations that are involved in supplying and controlling the NSSS components for HPC. It is therefore expected that, as found during the CNI inspection, the licensee shall have arrangements for providing greater assurance of NSSS components based upon risk.
For these reasons and from the findings of the intervention an Amber rating has been given. ONR will seek improvement of the licensee’s arrangements through a level 3 regulatory issue ‘Develop risk-based assurance of the supply chain for the Hinkley Point C NSSS’. Appropriate actions to close this issue will be developed following further discussions with the licensee.