Office for Nuclear Regulation

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System Based Inspection - SBI03 - Boiler Feed

Executive summary

Purpose of Intervention

The main purpose of this intervention was to conduct a system based inspection (SBI) of the boiler feed system at EDF Energy Nuclear Generation Ltd.’s (NGL) Hinkley Point B Power Station.

This intervention was undertaken as part of a series of planned interventions that are listed in the Hinkley Point B Integrated Intervention Strategy for 2018/2019. The inspections were undertaken by the ONR nominated site inspector and two ONR nuclear specialist inspectors for structural integrity and chemistry, 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 boiler feed system.  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 boiler feed system is the source of the secondary coolant which provides a heat sink to the primary coolant. 

In addition to the SBI of the boiler feed system, the following inspections 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 boiler feed 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 Hinkley Point B has met its legal requirements that ensure that the boiler feed system is operated and maintained in accordance with the safety case and the station’s arrangements.

In summary, the outcome of the SBI of the system was as follows:

I was satisfied that Hinkley Point B has implemented its arrangements for training staff with responsibilities for the specific operation and maintenance of the system. I consider that, based on the evidence seen during this intervention, that an inspection rating of ‘Green – no formal action’ is appropriate for LC 10.

I was satisfied that the safety case limits and conditions have been identified and where necessary have been incorporated into technical specifications. I consider that, based on the evidence seen during this intervention, that an inspection rating of Green is appropriate for LC 23.

I was satisfied that operating instructions were in place to support plant operations. I consider that, based on the evidence seen during this intervention, that an inspection rating of Green is appropriate for LC 24.

I was satisfied that suitable and sufficient safety mechanisms, devices and circuits were connected and in working order with identified operating limits and condition’s to meet the requirements of the safety case. I consider that, based on the evidence seen during this intervention, that an inspection rating of Green is appropriate for LC 27.

While I was content that the system was maintained appropriately, I identified that a number of components important to safety were captured by the lowest level of maintenance routines (therefore not mandatory). I have therefore raised a Level 4 issue for NGL to demonstrate that this is appropriate. However, I am satisfied that a rating of Green for LC 28 is appropriate.

Conclusion of Intervention

After considering all the evidence examined during the sample inspection undertaken against relevant LCs, I judge that the requirements of the safety case have been adequately implemented at Hinkley Point B. I have therefore assigned an IIS rating of green for LCs 10, 23, 24, 27 and 28.

A number of minor gaps were identified relating to maintenance hierarchy and consistency within Living Safety Case Documents.  Further, a number of observations were made and fed back to the licensee from the plant walk down. While I was satisfied these have been captured appropriately, I have captured issues relating to maintenance as a level 4 regulatory issue (6786) on ONR’s issues database to monitor progress.

There were no findings from this inspection that could significantly undermine nuclear safety. However, I judge that future interventions related to LC28(6) should be considered in future planned interventions for the Hinkley Point B power stations Integrated Intervention Strategy (IIS).