- Site: Dounreay
- IR number: 21-082
- Date: September 2021
- LC numbers: 22
Executive summary
Purpose of Intervention
The purpose of this readiness review inspection at Dounreay Site Restoration Limited (DSRL) was to assess the site’s arrangements for the Advanced Transition Works for Shaft & Silo to confirm that the licensee is controlling its hazards and complying with its statutory obligations.
The Shaft & Silo Decommissioning Project is required to retrieve, process and package waste currently stored in the Shaft & Silo. To enable the retrieval, processing and packaging of waste from the Shaft, a new facility (D3300) is to be constructed over the Shaft structure. To minimise the risks in constructing this facility, DSRL decided to implement a programme of work called Advanced Transition Works (ATW). This would construct part of the facility directly above the shaft and re-locate existing services to the Shaft.
The ATW will construct a reinforced concrete structure that will form the central Process Cell of D3300. These walls will form the main shielding barrier and will be designed to withstand a hydrogen deflagration. Consequently, a regulatory Hold Point was placed on the commencement of concrete pouring.
Interventions Carried Out by ONR
This readiness inspection focussed on DSRL’s implementation of its LC 22 (Modification) arrangements and safety case relating to the modification. This inspection comprised discussion with licensee staff, examination of documentation and records and a plant inspection.
This readiness inspection was undertaken to confirm that DSRL is prepared to implement its safety case modification and to commence construction of the walls surrounding the shaft.
I also held several other meetings to discuss progress on further decommissioning projects at Dounreay.
Explanation of Judgement if Safety System Not Judged to be Adequate
N/A
Key Findings, Inspector's Opinions and Reasons for Judgements Made
I determined that the licensee is outside of its own arrangements regarding issuing of the Safety Working Party minutes. Furthermore, several of the DSRL licence condition arrangements are outside of their review period. This is to be addressed further by the Site Inspector.
I assessed the licensee’s arrangements for management of explosive gases. I determined that the contractor had not supplied documentation of how these were to be implemented. Nevertheless, I confirmed that DSRL would follow their own arrangements in confirming the safety case requirements.
I assessed the licensee’s arrangements for continuation of Shaft services. I identified that DSRL planned to minimise risk to the project by planning and performing additional activities. I viewed this as meeting good practice.
I examined the Project Quality plan and identified that there is a shortfall in quality management when judged against good practice. Furthermore, the licensee could not provide information on how the quality of certain construction items met the safety case requirement. Consequently, I determined that the Internal Assurance representative should review this document, when it is available. Overall, I judged that the project should have a further inspection focussing on quality management in financial year 2022/23.
I examined the licensees’ arrangements in relation to its Construction (Design and Management) Principal Contractor role. I determined that there were shortfalls in its monitoring and control of the workforce based on the hand arm vibration evidence. I also determined that there were shortfalls in the Risk Assessment and Method Statements and Lifting Plans. Overall, I judged that the project should have a further inspection focussing on Construction (Design and Management) regulation compliance in financial year 2022/23.
I also reviewed some of the construction management arrangements. I witnessed the day-to-day contractor management and that the training provided was adequate.
Conclusion of Intervention
I informed DSRL that based on the evidence presented, I am recommending releasing the ONR hold point and permissioning the activity (wall construction). However, in accordance with the licensee’s own arrangements, I am recommending that the Internal Assurance representative confirms that the project surveillance plan is adequate.
Furthermore, I stated that I am recommending performing a further inspection on the project in financial year 22/23. It will focus on the quality management and Construction (Design and Management) regulations, to confirm that the improvements identified have been addressed.