Office for Nuclear Regulation

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SBI 19 - Irradiated Fuel Dismantling Facility

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake a System Based Inspection (SBI) at EDF Nuclear Generation Limited’s (NGL’s) Hinkley Point B power station in line with the planned 2018-19 Intervention Strategy for the site . The inspection was undertaken by two fuel performance Inspectors, a C&I Inspector and the nominated Site Inspector and concentrated on the Irradiated Fuel Dismantling Facility (IFDF) and associated intermediate waste vaults. The aim of the inspection was to confirm that the IFDF, with its associated operating instructions and maintenance schedule, is able to meet the safety case functional requirements.

Interventions Carried Out by ONR

The system based inspection of the IFDF was conducted against compliance with the following Licence Conditions (LCs):

The inspections were based on sampling the implementation of arrangements for the IFDF against each licence condition.

Explanation of Judgement if Safety System Not Judged to be Adequate

From our inspection, we judged that overall the IFDF system met the requirements of the safety case and was adequately safe. However, a significant shortfall was identified with respect to LC10 in relation to adequacy of training in response to a revision to the Station Operating Instructions (SOIs) brought about by an Interim Justification for Continued Operation (IJCO).  A new level 3 regulatory issue will be raised to bring about an improvement in the arrangements and to ensure that requirements of the IJCO are appropriately implemented.

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

LC 10 (Training) - In order to examine LC10 compliance the training records of a number of fuel route staff who work on the IFDF were sampled against their role profile. Overall, the fuel route staff came across as well trained and a significant volume of training material was observed. The classroom material and on the job training mentor guides for IFDF operation were sampled and found to be of a good quality.  However, when examining the training material supporting the recent IJCO we found that there were a number of shortfalls against the requirements of the safety case. These shortfalls were identified through discussion with the operators regarding their understanding of the expected response to dropped stringer faults. It was also unclear that the directed reading used to deliver training on the changes in the SOIs required by the IJCO was an effective and appropriate delivery method in this instance. We judge that this is a shortfall against relevant good practice and the established standard. Therefore, it is appropriate to rate LC10 as AMBER and seek improvement through formal regulatory action.

LC 23 (Operating Rules) - The Technical Specifications and associated surveillance records were sampled, including those held in the central control room (CCR). We found that the limits and conditions of operation (LCOs) were appropriately specified and that the operators were able to demonstrate a clear understanding of the governance arrangements. We identified an opportunity to improve clarity regarding the recording of the confirmation of fuel irradiation limits for the IFDF but this was a minor observation and not a compliance shortfall.   Therefore, based on our sample, we judge that a rating of Green for LC 23 is appropriate.

LC 24 (Operating Instructions) - We sampled a number of station operating instructions (SOIs) with particular focus on Dropped Stringer faults. This included sampling the implementation of an IJCO in revised SOIs. During the plant walkdown we noted a strong use of procedures and place-holding, which is a good practice. Although the SOIs themselves were found to be of a good standard, shortfalls were identified in the training related to dropped stringer SOIs and their availability at the point of work as required by the recent IJCO.   However, since the SOIs themselves were of and adequate standard we judged it to be proportionate to resolve the issue concerning the implementation of the IJCO under LC10. Therefore, we have assigned a rating of GREEN for LC 24.

LC 27 (Safety Mechanisms, Devices and Circuits) - Based on the areas sampled in our inspection of LC 23, LC 24 and LC 28, we were satisfied that suitable and sufficient safety mechanisms, devices and circuits (LC 27) are connected and in working order to meet the requirements of the safety case and identified operating limits and conditions. We also considered that NGL have implemented arrangements to actively address ageing and obsolescence of plant. Therefore we assigned a rating of GREEN to LC 27.

LC 28 (Examination, Inspection, Maintenance and Testing) - A sample of records of recent maintenance activities, functional tests, work order cards and the closure of previous inspection findings from 2016 concerning the application of LOLER (Lifting Operations and lifting Equipment Regulations) for fuel route was examined. We found that activities related to the application of LOLER were completed and overall we were satisfied that the equipment was being adequately maintained. Opportunities for improvements were identified with regards to calibration of instrumentation and pass/fail criteria for relays. However, these did not represent a shortfall in safety.  We therefore judged that a rating of GREEN to LC 28 is appropriate.

LC 34 (Leakage and Escape of Radioactive Material and Radioactive Waste) - We sampled the records of the materials disposed of to the vaults and that EDF NGL maintains adequate accountability of their contents. We therefore assigned a rating of GREEN to LC 34.

Based on the inspection of the physical IFDF plant and equipment the facility was judged to be in good condition. 

The inspection has highlighted a significant shortfall in the safety case implementation through the training arrangements under LC10 in terms of operator response to dropped fuel. However, after considering all of the evidence presented by NGL we concluded that in general the arrangements in place associated with the IFDF met the requirements of the safety case and that an overall rating of GREEN is appropriate.

Conclusion of Intervention

After considering all of the evidence presented by NGL we concluded that the arrangements and their implementation, associated with the IFDF system met the requirements of the safety case and were deemed to be adequate.

However, due to the amber rating under LC10 and in accordance with ONR processes the finding will be considered against the Enforcement Management Model (EMM) which may result in formal enforcement action.