Office for Nuclear Regulation

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Dungeness A: SBI on Waste Remediation Projects

Executive summary

Purpose of intervention

This report covers an inspection of Magnox Ltd.'s Dungeness A nuclear licensed site on 7th to 9th March 2017. This inspection was part of a programme of planned interventions as outlined in the Dungeness A Integrated Intervention Strategy (IIS) for 2016/17

Interventions Carried Out by ONR

During this intervention, I carried out a project orientated systems based inspection on the design and construction of the Advanced Active Drying System (AVDS) plant that will dry intermediate level waste so that it is in a passive condition during storage. The inspection was comprised of Licence Condition (LC) compliance inspections to verify compliance with the following Licence Conditions:

The AVDS inspection was carried out against the requirements of LC 10, 19, 23, 24, 27 and ONR's published inspection guidance associated with these Licence Condition

I also carried out an inspection to judge safety and progress in the ponds clearance project being carried out by divers and undertook a fact finding inspection into an incident where a lump of concrete fell from height in a boiler cell.

Explanation of Judgement if Safety System Not Judged to be Adequate

The design and construction of the AVDS plant was considered adequate to deliver the safety functions in the safety case.

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

I am satisfied that the licensee's arrangements for the construction and installation of the AVDS plant meet the key requirements as defined in ONR guidance and demonstrate relevant good practice. I am satisfied that these arrangements were adequately implemented on site: I have rated compliance with Licence Conditions 10,19,23,24, and 27 as adequate (green). The plant has been designed and built by a core team of engineers drawing on previous experience with this type of plant at other sites. It is a bespoke design incorporating relevant learning from experience with previous plant and is constructed and installed to a high quality.

The ponds project is maintaining safe and efficient progress. Diving operations have moved from pond 1 to pond 2 and progress at remediating the storage skips is continuing to schedule. Identical arrangements have been implemented at pond 2 to those inspected and approved previously by HSE Offshore Safety Division specialist diving inspectors.

Suitable and sufficient arrangements have been put in place to ensure the safety of people from dropped objects in the boiler cells whilst the incident involving the fall of a lump of concrete is investigated and resolved. Non-essential personnel have been excluded from the affected area and any working station will be fitted with dropped load protection scaffolding canopies. This occurrence suggested that there may be incipient unforeseen degradation in the condition of the former operational facilities. Dungeness A gave assurance that this was not the case, and that they were monitoring the physical condition of the plant closely with particular attention to corrosion and water ingress. This will be followed up as part of routine regulatory business.

Conclusion of Intervention

From the evidence gathered during this intervention I consider that: