Office for Nuclear Regulation

Torness - Planned intervention

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake Licence Condition (LC) compliance inspections at EDF Nuclear Generation Limited’s Torness  power station in line with the planned inspection programme contained in the Torness Intervention Plan 2015/16. The compliance inspection and information exchange meetings were carried out by a specialist Structural Integrity Inspector, a specialist Civil Engineering Inspector and by a Project Inspector.

Interventions Carried Out by ONR

We undertook a safety case informed System Based Inspection [SBI-01] of Torness’ Civil Structures focused mainly on the Pre-stressed Concrete Pressure Vessel and the Sea Defences which are important civil structures for nuclear safety. The inspection sampled compliance against several LCs, namely LC10 (training), LC23 (operating rules), LC24 (operating instructions), LC27 (safety mechanisms, devices and circuits), LC28 (examination, maintenance, inspection and testing) and LC 34 (leakage and escape of radioactive material and radioactive waste). Following review of the system, it was judged that the civil structures considered during the inspection were not applicable for inspection against the requirements of LC34 as none of them are associated with the containment or disposal of radioactive waste or material.

The objective of the inspection was to determine whether the licensee’s arrangements for plant operational limits, plant maintenance schedules, staff training requirements and inspection plans were adequate in accordance with the relevant safety case requirements.

Explanation of Judgement if Safety System Not Judged to be Adequate

We judge that the arrangements and their implementation associated with the Civil Structure systems inspected met the requirements of the associated safety case and are adequate.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

From an LC10 perspective, staff training records and profiles were judged to be in accordance with the relevant post training profile requirements and Torness operates under the corporate accredited training system. Torness reported on-going improvements in its arrangements to address a previous ONR finding relating to the appointment of system engineers. It was reported that new arrangements are in the process of being formalised for the nomination of system engineers. Prompt remedial action of this issue at Torness is welcomed and in view of the improvements we assigned the LC10 element of this inspection an Integrated Intervention Strategy (IIS) rating of 3 – Adequate.

From an LC23 and LC24 perspective, based on the evidence sampled during this inspection the implementation of the technical specifications, commentaries, and schedules were judged to be consistent with the claims presented within the Torness Station Safety Report (SSR) for the Pre-stressed Concrete Pressure Vessel and the Sea Defences systems. The licensee demonstrated adequate knowledge and understanding in the areas of the safety case and how they relate to the operating rules and instructions in place for the Pre-stressed Concrete Pressure Vessel. We therefore assigned the LC23 and LC24 elements of this inspection an IIS rating of 3 - Adequate.

From an LC27 and LC28 perspective, Torness demonstrated that there are adequate processes, procedures and records in place for the examination, inspection, maintenance and testing of nuclear safety significant areas of plant. The inspection of LC27 focused on the Pre-stressed Concrete Pressure Vessel tendons which are essential element of the system to ensure that it performs as required.  The inspection sampled the measures in place to ensure that these are performing as expected. Several samples were taken and suitable records were produced for each sample. We judged the LC28 compliance element of this inspection to be adequate and assigned  an IIS rating of 3 - Adequate.

The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.

Conclusion of Intervention

From the evidence sampled, witnessed and collected during this system based inspection of Civil Structures against LCs 10, 23, 24 and 28, the inspection concluded that the operation and maintenance of the system meet the requirements of the safety case and its implementation is considered adequate.

A number of observations were made as a result of this system based inspection and are considered to be of minor nuclear safety significance. Therefore, we are content that they will be addressed by the licensee in accordance with their own arrangements. There are no findings from this inspection that could significantly undermine nuclear safety.