EDF Energy - Nuclear Generation Ltd - Hunterston B planned Intervention
- Site: Hunterston B
- IR number: 15-117
- Date: November 2015
- LC numbers: 30
Purpose of intervention
The purpose of this intervention was to undertake Licence Condition [LC] compliance inspections at EDF Energy Nuclear Generation Ltd’s [NGL’s] Hunterston B power station, in line with the planned inspection programme contained in the Hunterston B Integrated Intervention Strategy [IIS] for 2015/16.
Interventions Carried Out by ONR
This intervention included planned compliance inspections against the following specific Licence Condition:
Licence Condition 30 – periodic shutdown.
We attended the start-up meeting for Reactor 3 currently shutdown for its statutory outage; this was preceded by a walkdown of various work-faces. We reviewed the station’s progress against planned maintenance schedule activities and other plant modifications, with particular focus on the results of graphite core and in-vessel inspections.
Explanation of Judgement if Safety System Not Judged to be Adequate
No system based inspection was undertaken during this intervention.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
During the pre-start-up meeting plant walkdown we made the following observations:
- Evidence of significant investment in the cooling water system, notably improvements to drum screen performance that will enhance management of marine ingress, and also to the main cooling water pumps;
- A successful replacement of the three generator transformer phases, a complex work site that has been managed safely and to a high standard;
- Effective management of various competing work-faces at the Reactor 3 pilecap.
Summary observations from the start-up meeting are listed below:
- The planned programme of 31 fuel channel inspections in the graphite core is complete and all results sentenced appropriately through the station’s graphite assessment panel. ONR specialist inspectors are continuing to review the results from these inspections which will inform ONR’s consideration for consent to return to service;
- There has been minimal deviation in outage scope so far which ensures confidence that the full scope of planned outage activities will be undertaken. This will be re-examined during consideration for consent;
- The station appears to have been successful in applying learning from incidents which occurred during the periodic shutdown of Reactor 4 during 2014. Human performance training has been delivered to a large number of personnel interfacing with plant with in-the-field observations indicating that human performance tools are being used to good effect;
- In-vessel inspections of the first two boiler quadrants have led to a number of repairs which are within the expectations of the station. The results of the other boiler quadrants were not available at the time of the meeting;
- The station appears to have been successful in minimising positive pressures in the ventilation systems as a result of a range of improvements to procedural control;
- It is evident that management of worker fatigue is more proactive through targeted risk assessments undertaken for staff and contractors working long hours. The station reports NGL intends to embed this practice more widely across the fleet and integrated into company arrangements. This shifts emphasis beyond straightforward compliance with the requirements of the working time directive;
- The enhanced role of area safety coordinators in coaching staff and contractors on industrial safety matters [notably hot-work and working at height] is judged to have been successful in addressing shortfalls in standards early-on in the outage;
We undertook discussions with the station on aspects relating to the return to service safety case. At the time of writing these discussions are ongoing in order to inform ONR’s consideration of an application for consent to return to service.
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
I have allocated an IIS rating of ‘2 – Good Standard’ for LC30 – Periodic Shutdown, in light of a generally well-executed statutory outage, minimal deviation in scope and so far a good safety record.
There are no findings from this inspection that could significantly undermine nuclear safety and, at present, no additional regulatory action is needed over and above the planned interventions of Hunterston B power station as set out in the Integrated Intervention Strategy, which will continue as planned.