Planned intervention - Hunterston B
- Site: Hunterston B
- IR number: 14-133
- Date: August 2014
- LC numbers: 32
Purpose of intervention
The purpose of this intervention was to undertake Licence Condition [LC] compliance inspections at the EDF Nuclear Generation Limited (NGL) Hunterston B (HNB) power station in line with the planned inspection programme contained in the HNB Integrated Intervention Strategy (IIS).
Interventions Carried Out by ONR
As part of this intervention, I undertook a compliance inspection against Licence Condition 32 - Accumulation of radioactive waste. I undertook this inspection jointly with the Scottish Environmental Protection Agency [SEPA] site inspector to ensure efficient use of respective resource on a topic of mutual regulatory interest. The overall intent of the inspection was to secure assurance that station has adequately addressed or demonstrably progressed shortfalls in compliance against LC32, identified during a 2013 specialist-led inspection.
Explanation of Judgement if Safety System Not Judged to be Adequate
No safety case informed system based inspection was undertaken during this intervention.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
During this joint ONR-SEPA inspection I made the following observations and judgements:
- The station is making good progress against its accelerated waste reduction plan against regulatory concerns expressed by ONR specialists in 2013 and has developed clearer through-life strategies for individual waste streams.
- Station measures performance against the fleet Radioactive Waste Focus Index [RWFI]; this is influenced by several weighted variables including waste inventory; availability of a through-life plan; station resources and regulatory issues. I judged the RWFI to be a useful tool in focussing station efforts to manage and expedite waste management. Based on the sample taken, I was content the metric is used to aid decision-making rather than a direct tool to influence all decisions on priority.
- I examined through-life plans for three historically difficult waste streams [tritiated waste oil; low-level waste sludges and short-lived ILW waste]. Progress against these waste streams is only partially under station's direct control. This is in-part due to the embargo imposed by LLWR [Low Level Waste Repository] in 2012 on receiving non-homogeneous waste packages [i.e. short-lived ILW waste items diluted within LLW packages]. In the absence of a clear timetable for resolution, station is developing an interim safety case to justify continued on-site storage of short-lived ILW in the form of an LC22 Engineering Change [EC], pending a clear through-life management plan. I emphasised to station the need for expeditious implementation of this EC to ensure it remains demonstrably compliant with LC32 in light of external factors outside of NGL's control.
- I sought evidence that Station has responded to 2013 regulatory concerns associated with inadequate tracking and traceability of waste. There is clear evidence of improved audit processes for tracking individual waste bin inventories [isotopic compositions] through to disposal inventories. This has been enhanced recently by use of a comprehensive inventory tool, linked to the Company KPI process.
- Control and minimisation of waste incidental to the statutory outage at Reactor 4 appears to be robust; the efforts made towards inventory reduction in LLW have ensured the outage has not led to undue accumulations in the much-improved LLW store.
Overall there has been substantial and encouraging progress made to minimise accumulation of waste at Hunterston B, and to manage legacy holdings. There are certain factors such as unavailability of LLWR that are outside EDF's direct control. I advised station to consider opportunities to be more strategic in its through-life management plan for difficult waste streams; the approach to end of operating life, currently anticipated for 2023, may be a valid factor to consider in future for packages such as short-lived ILW where there is no obvious disposal route available.
In the interim, it is essential that an adequate safety case is developed to justify continued on site storage of such items pending the availability of a suitable disposal route.
I recommend the closure of the ONR regulatory issue in light of the findings from this inspection.
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 judged the licensee to have demonstrably improved compliance with its arrangements under Licence Condition 32, with significant progress towards improving its performance against NGL's Radioactive Waste Focus Index. An IIS rating of '3 - Adequate' is awarded to reflect the good progress made towards reducing low level waste inventories; a higher rating was not justified because progress on orphan waste streams [i.e. those without a defined disposal route] is still at an early stage.