The purpose of this intervention was to undertake Licence Condition (LC) compliance inspections at Hunterston B power station in line with the planned inspection programme contained in the Hunterston B Integrated Intervention Strategy (IIS). The compliance inspections were carried out by two ONR Inspectors and Scottish Environment Protection Agency (SEPA) site inspector. Additionally an ONR specialist inspector conducted a readiness inspection of the reactor 4 nitrogen hold-down project modifications.
As part of this intervention, we carried out compliance inspections against Licence Conditions (LC) 28: Examination, inspection, maintenance and testing; LC27: Safety mechanisms, devices and circuits; and LC34: Leakage and escape of radioactive material and radioactive waste (with the SEPA site inspector). Additionally an ONR specialist inspector conducted a readiness inspection of the Reactor 4 nitrogen hold-down project modifications under the requirements of LC22: Modifications or experiment on existing plant. Our inspections were based on sampling of the arrangements in place and their implementation. We held pre- and post- inspection meetings with the site management where the inspection agenda was discussed and contents of this report were communicated.
Our readiness inspection of the reactor 4 nitrogen hold-down project modifications revealed no issues that were considered unacceptable and we judged that Hunterston B had made adequate preparations for these modifications in line with the requirements of licence condition 22.
Our inspection of arrangements made under licence condition 27 focused on the suitability, and maintenance regime, of the station’s moisture monitoring systems. These systems are used to warn the operators of excessive moisture in reactor coolant gas. Based on the evidence witnessed and information collected during the inspection we judged that these systems were suitable for performing the safety functions required of them by the plant’s existing safety case, and that the station was adequately complying with the requirements of LC27.
Our inspection of arrangements made under licence condition 28 focused on the adequacy of the maintenance regime of the chloride ingress protection systems. Based on the evidence witnessed and information collected during the inspection we were able to judge that the maintenance requirements associated with the chloride ingress protection system have been adequately implemented. We identified one point for improvement to include tolerance bands for indicated measurements in the work instruction covering testing of the chloride ingress protection system.
Our inspection of arrangements made under licence condition 34, jointly carried out with the SEPA site inspector, focused on the fuel storage pond. Based on the evidence witnessed and information collected during the inspection we were able to judge that the arrangements have been adequately implemented. We requested the licensee to inform us of the progress made with the recommendations in the last fuel storage pond structural integrity report.
The sample inspections undertaken against LCs 27, 28 and 34 found that in the main Hunterston B’s arrangements were adequate and were being implemented appropriately.
Discrepancies/issues were identified during the inspection, and two actions were placed on the licensee to rectify them. Their rectification will be tested at future inspections.
There are no findings from this inspection that could significantly undermine nuclear safety.
Two actions were placed on the licensee to rectify a discrepancy found during the inspection and provide information concerning recommendations made in a report.
The planned interventions set out in the Integrated Intervention Strategy for Hunterston B remain valid and will be followed for future inspections.