Office for Nuclear Regulation

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Dounreay Site Restoration Ltd (DSRL), supply chain arrangements 

Executive summary

Purpose of Intervention

To evaluate the adequacy and implementation of Dounreay Site Restoration Ltd (DSRL), supply chain arrangements related to the welding development at Langfields to support Dounreay Un-irradiated Fuel Sub-Assemblies Project in relation to the safe transport to, and the storage of radioactive material at Sellafield.

To evaluate the adequacy and implementation at Langfields in the development of the suitability of the welding design, procedures and processes to ensure that the Un-irradiated Fuel Container (UFC) meets the transport safety case requirements.

This inspection supports the ONR transport permissioning of the Design and Shipment Approvals for the ongoing assessment of the GB/4469 (M4-12) to be used to support Dounreay Exotics Consolidation Programme (DECP).

Purpose of Intervention

The purpose of the inspection was to:

Intervention Carried Out by ONR

The inspection reviewed various documents and inspectors witnessed a welding operation. The inspection also examined the management and oversight arrangements carried out by DSRL, Wood’s and SL oversight of the development of the welding process.

The intervention focused on the following areas;

Explanation of Judgement if Safety System Not Judged to be Adequate

            N/A.

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

There appears to be good communication between all the parties and an understanding of the importance of meeting the welding trials tight timescales required. People also understood the safety significance of the UFC for the safe interim storage of the contents. It was noted that the weekly telecom were used to good effect to reduce the time needed to respond to technical queries and questions, this had minimised the potential delay to the programme.

ONR witnessed a welding trial, and had chance to speak to two of the Welders who will be used on the actual closure of the UFC. From these discussions, the welders were confident they could meet the weld requirements and had been informed and understood the safety significance of the welds.

ONR questioned the approach of producing the Welding Procedure Qualification Record (WPQR) prior to the finalisation of the development trials. Langfields stated that whilst development was on-going, the parameters would be within ‘code’ requirements, and the ‘Mark III UFC Closure Welding Specification’ (L1195.1.2-ENG-1699). ONR would reserve judgement until the review of the requested documentation.

ONR informed the duty-holders what the expectations were for the Package Design Safety Case and associated evidence and that it should be able to demonstrate that the closure welds met the declared Mark III UFC Closure Welding Specification.

Conclusion of Intervention

The inspection concluded that, the current arrangements are deemed to be adequate to support the transport permissioning process for the GB/4469 package.