Office for Nuclear Regulation

This website uses non-intrusive cookies to improve your user experience. You can visit our cookie privacy page for more information.

Heysham 2 - Systems Based Inspection 29 - Diverse Shutdown Systems

Executive summary

Purpose of Intervention

The main purpose of this intervention was to conduct a system based inspection (SBI) of EDF Energy Nuclear Generation Ltd's (NGL) Heysham 2 Power Station in relation to the diverse shutdown systems (known as the secondary shutdown (SSD) system).

This intervention was undertaken as part of a series of planned interventions that are listed in the Heysham 2 Integrated Intervention Strategy 2017/2018. The inspections were undertaken by the ONR nominated site inspector and two ONR nuclear specialist inspectors for structural integrity and fault studies, which for the purpose of this intervention report shall be referred to as "I".

Interventions Carried Out by ONR

I performed a safety case informed SBI of the SSD systems. Through examination of these systems, compliance inspections were performed against the following Licence Conditions (LC):

The objective of the inspection was to determine whether the licensee's arrangements were adequately implemented and in accordance with the systems' safety case requirements. The SSD system provides an alternative means for safe shutdown of the reactor.

In addition to the SBI of the SSD system compliance inspections against LC10 (Training) and LC11 (Emergency Arrangements), were also undertaken by the nominated site inspector.

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

Explanation of Judgement if Safety System Not Judged to be Adequate

From the system based inspection, I judge that overall the SSD system meets the requirements of the safety case.

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

Based on the areas sampled during this system based inspection, I consider that Heysham 2 has met its legal requirements that ensure that the SSD system is maintained and operated in accordance with the safety case and the station's arrangements.

In summary, the outcome of the SBI of the SSD system was:

I, the nominated site inspector observed the first of several shift exercises at the Heysham 2 focusing on the station's LC 10 and 11 arrangements. I elected to observe the Access Control Point for the full duration of the exercise to assess as to whether Heysham 2 had improved on the shortfalls identified within ONR's letter to the station from exercise "Kingfisher".

From my observations, I considered that the shift exercise was challenging for the individuals involved and overall I judge that the arrangements for compliance against LC10 and LC11 warrant a rating of "GREEN" (no formal action). However, in terms of addressing the shortfalls that were observed for exercise "Kingfisher" earlier in the year; the licensee still has some areas to address to meet the expected standard.

The Heysham 2 site inspector met with the Heysham 2 Independent Nuclear Assurance (INA) Group Head. This was a routine interaction with the internal regulator and was an opportunity to share information from the shift exercise and SBI. It was also an opportunity for INA to share its view of the performance of the site. This engagement was also used to discuss future interventions and surveillance activities.

In addition to the above, the site inspector undertook routine engagements at the site including, routine meetings with site staff, ONR issues update and incident notification follow-up.

Conclusion of Intervention

After considering all the evidence examined during the sample inspection undertaken against LCs 10, 23, 24, 27 and 28, I considered that the requirements of the safety case have been adequately implemented at Heysham 2, with a rating of green assigned against licence conditions 10, 23, 24, 27 and 28.

From my observations I considered that the shift exercise was challenging for the individuals involved and overall I judge that the arrangements for compliance against LC10 and LC11 warrant a rating of "GREEN" (no formal action).

There are no findings from this inspection that could significantly undermine nuclear safety. At present, no additional regulatory action is needed over and above the planned interventions of Heysham 2 power station as set out in the Integrated Intervention Strategy, which will continue as planned.