The purpose of this intervention was to conduct an inspection to establish the adequacy of arrangements implemented under the site corrosion management programme. The work was carried out as part of the Office for Nuclear Regulation (ONR) planned intervention task sheet TS027 – “Management of Corrosion - Concealed and Buried Systems” and task sheet TS023 – “Management of Storage Tanks and Vessels”.
I carried out this inspection accompanied by the ONR Hartlepool site inspector and two additional Inspectors within the Structural Integrity and Fault Analysis specialisms. The inspection took place from the 12th to the 13th of December 2018, and involved discussions with a number of EDF Energy Nuclear Generation Limited’s (NGL) employees responsible for the operation and safety of the plant. A targeted plant walk down of the systems selected for sampling was also undertaken.
The primary aim of the inspection was to perform a review the adequacy of the licensee’s arrangements for managing plant material condition of storage tanks and buried pipework that are important for safety, against the requirements of licence condition (LC) 28 – Examination, Maintenance, Inspection and Testing (EMIT).
From the information that I have sampled I judge that the deployment of the corrosion management programme at HRA to be well managed and mature in its understanding of corrosion degradation. Good progress has been made at Station in addressing the corrosion issue and the current status appears to be in line with the licensee’s plans. There remain a number of outstanding corrosion related activities and these are planned to be completed during 2019. This includes completion of; CV3 and CV4 corrosion management tasks, implementation of appropriate maintenance schedules and training as well as the remediation of several systems. I am content that the licensee is appropriately managing these outstanding tasks.
Errors have been found in the living safe case documentation for the high pressure back-up cooling water system, however, I do not deem this to be significant in terms of nuclear safety since this document is not referred to in the event of a nuclear safety issue. However, I have requested that the licensee make the necessary amendments.
I consider that there is a shortfall in the licensee maintenance arrangements of the gas turbine exhaust system which during our inspection was in a visibly deteriorated condition compared with other systems located at site. The last inspection records for the gas turbine exhaust tasks completed in April 2016 reported areas of corrosion and cracking, and was followed by a large number of recommendations of low and intermediate concern including the re-coating of the exhaust stack and addressing the degradation found. However, I was unable to secure evidence to suggest that the licensee had acted upon (or justified non-action) of the recommendations provided within those reports. Consequently, I have raised two Level 4 Regulatory Issues (RI6909 and RI6916) to be addressed by the licensee. I consider this to be proportionate enforcement in relation to risks to nuclear safety. Although there is potentially a high hazard consequence resulting from a stack collapse with respect to nuclear and conventional safety I currently judge that there is a low likelihood of an exhaust stack failure occurring. This judgement is based on the most recent GT5 inspection report not raising immediate concerns of the structural integrity of this system.
I judge that, against the requirements of LC28, a rating of GREEN in accordance with ONR inspection rating guidance (TRIM 2016/118606) is appropriate. This is based on overall good performance of the licensee in managing degradation of systems and components subject to corrosion. However, ONR is seeking improvement from the licensee with respect to the GT exhaust stacks including the lack of evidence of appropriate sentencing of 3rd party inspection results and recommendations. In my opinion, the process of sentencing and recording of 3rd party inspection results and recommendations is fundamental to underpin an effective EMIT programme and demonstrate that risks are being reduced to as low as reasonably practicable. At the time of my inspection, the licensee was unable to demonstrate this. Consequently, I have raised two Level 4 Regulatory Issues (RI6909 and RI6916) for the licensee to demonstrate the adequacy of its systems and processes to ensure nuclear safety and have defined timescales that I judge to be proportionate to the exposure to risk in the intervening period. My judgement has also taken cognisance of previous regulatory engagement where there was a similar failure to appropriately consider 3rd party inspection results and recommendations, though not in relation to the GT stacks.