The purpose of this intervention was to undertake a system based inspection of the carbon dioxide storage and distribution plant at EDF Nuclear Generation Limited’s (NGL’s) Heysham 2 power station in line with the planned inspection programme contained in the Heysham 2 Integrated Intervention Strategy (IIS) for 2015/16.
As part of this intervention, I, the ONR Nominated Site Inspector, and two Structural Integrity Specialist Inspectors performed a System Based Inspection (SBI) of the CO2 storage and distribution system to judge the system performance against its safety function. Through examination of this system and associated sub-systems we performed compliance inspections against Licence Conditions (LC) 10 (Training), LC23 (Operating rules), LC24 (Operating instructions), LC27 (Safety mechanisms, devices and circuits) and LC28 (Examination, inspection, maintenance and testing). The inspections were based on sampling the implementation of the arrangements in place at the station against each licence condition.
The standard consideration of licence conditions during system based inspections includes LCs 10, 23, 24, 27, 28 and 34, with conditions added or excluded depending on their applicability. In this case, LC 34 that relates to leakage and escape of radioactive material and waste is not applicable to the operational aspects of the CO2 storage and distribution system and therefore deemed not applicable to the inspection.
Also, as part of this intervention I also undertook licence compliance inspections against LC8 (Warning Notices) and LC9 (Instructions to Persons on the Site).
From the inspection, we judge that overall the carbon dioxide storage and distribution plant meets the requirements of the safety case and is adequate. During the inspection, several observations were noted and fed back to the licensee and two level 4 issues were raised and recorded on the ONR regulatory issues database.
The LC8 inspection involved inspection of the arrangements for LC8, which I considered to be adequate. From my sampled inspection of the implementation of the arrangements at Heysham 2, I judged that the implementation of the LC8 arrangements is adequate and, therefore, have rated this element of my inspection through the IIS as 3 (adequate).
The LC9 inspection involved inspection of the arrangements for LC9, which I considered to be adequate. From my sampled inspection of the implementation of the arrangements at Heysham 2, I judged that the implementation of the LC9 arrangements is adequate and, therefore, have rated this element of my inspection through the IIS as 3 (adequate).
During the course of the licence compliance inspections I observed activities that were being undertaken by third party contractors that I judged were not adequately controlled. I have therefore raised an ONR issue on the ONR issues database to monitor the station’s actions to address it.
In summary, the outcome from the SBI of CO2 storage and distribution system was;
We were satisfied that the licensee had implemented adequate arrangements for suitable training for staff responsible for the operation and maintenance of the carbon dioxide storage and distribution plant. We gave an IIS rating of 3 (adequate) against LC10.
We were satisfied that the safety case conditions and limits have been correctly identified and where necessary have been incorporated into technical specifications. We gave an IIS rating of 3 (adequate) against LC 23.
We were satisfied that adequate operating instructions were in place to support plant operations that may affect safety. We gave an IIS rating of 3 (adequate) against LC24.
Evidence was provided to demonstrate that examination, inspection, maintenance and testing activities had been conducted on the carbon dioxide storage and distribution plant, and that there had been a significant programme of maintenance work completed within the last two years to improve plant reliability and material condition. However, at the time of the inspection, the licensee could not provide suitable evidence to demonstrate that the full scope of inspection requirements listed in the plant maintenance schedule had been met. In association with this, the licensee could not demonstrate a clear identification of plant items that are important for nuclear safety from the safety case, therefore, could not demonstrate that the plant is being operated with safety mechanisms, devices and circuits in good working order. It is our opinion that this is a shortfall against the requirements of LC27 and LC28. Therefore an IIS rating of 4 (below standard) was appropriate for both licence conditions. An ONR issue has been raised for the licensee to review the historic maintenance records and address any identified shortfall (see Section 1.5 below).
The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.
From my sampled inspection of the implementation of the arrangements at Heysham 2, I judged that the implementation of the arrangements for LC8 and LC9 were adequate
A Level 4 issue has been taken out by the nominated site inspector for Heysham 2 relating to the Control of 3rd party contractors on site following an observation made during the LC compliance inspection.
After considering all the evidence examined during the sample inspection undertaken against LCs 10, 23, 24, 27 and 28, we considered that the requirements of the safety case have been adequately implemented at Heysham 2.
An ONR issue has been raised to address concerns associated with the adequacy of the plant maintenance schedule and written schemes of examination for identifying pipework important for nuclear safety.
From the evidence gathered during this intervention, I do not consider there to be any matters that have the potential to impact significantly on nuclear safety.