Continued Operations Safety Reports for BNFL Sellafield
We were commissioned by BNFL to play a major part in renewing the criticality safety cases for both the B311 Fuel Handling Plant and the B205 Magnox Fuel Separation Plant.
This work required existing criticality safety analyses to be updated from a traditional contingency based approach to the BNFL Design Basis Accident Analysis (DBAA) methodology, with the provision of both deterministic and, where required, probabilistic safety arguments. Achieving this required detailed investigations and analyses of plant processes and hardware in order to evaluate potential plant mal-operations. This enabled us to revise the criticality Operating Rules, Operating Instructions and Operating Assumptions in these plants as well as taking credit for safety-critical and safety-related Structures, Systems and Components within the respective Safety Cases. The work also required the formulation and recommendation of ALARP measures to ensure further defence in depth against potential fault sequences.