Regulation of the First British Power Reactor to Enter into an Extended Period of 'Care and Maintenance' - 18028
All eleven of the British first-generation Magnox nuclear power plants have now ceased operating and are in various stages of decommissioning. The Magnox reactors were graphite moderated, using carbon dioxide as the primary coolant. The reactor cores are contained in steel reactor pressure vessels, except for the last two stations which have pre-stressed concrete pressure vessels. All but two of the Magnox reactor stations have been completely de-fueled. The spent fuel removed has been despatched for reprocessing at Sellafield in the north-west of England. On behalf of the UK government the Nuclear Decommissioning Authority (NDA) is responsible for cleaning up the majority of the civil nuclear legacy. The current NDA decommissioning strategy is to prepare the Magnox reactor sites for an extended period of Care and Maintenance (C and M), during which quiescent safe storage will take place (also known as safe enclosure), whereby the cores and associated structures will accrue the benefits of radioactive decay over a period of decades. This will reduce the radiation doses to workers during final dismantling and site clearance. The two Magnox rector units at the Bradwell licensed nuclear site in the south-east of England are the first scheduled to enter this quiescent safe-storage period. This is planned to commence in the second-half of 2018, and is scheduled to last for around 70 years. The Office for Nuclear Regulation (ONR) is the independent regulatory body, responsible for enforcing safety and security requirements at nuclear installations in Great Britain (GB). This paper outlines the national strategic context and how ONR's regulatory regime is applied to nuclear power plant decommissioning. It addresses some of the specific challenges posed at Bradwell during the preparatory works for entry to C and M and how ONR has addressed these. It describes how this will culminate in a regulatory decision on the acceptability of the safety and security of the Bradwell site to enter this new stage of its life cycle. Over the last few years ONR has assessed and inspected various safety aspects of decommissioning, radioactive waste management and other preparations for Bradwell's entry into C and M. Some of the operator's proposals have provided challenges to ONR, particularly where there have been changes to established approaches taken at other sites, as the licensee seeks to minimise its costs. These have included how far to remove redundant structures, systems and components prior to C and M; how to define interim and end-states for fuel cooling ponds and other contaminated areas; and how to treat and store Intermediate Level Waste (ILW), for which there is no geological disposal facility yet available. ONR has begun its final assessment of safety and security justifications supplied by the site licensee, Magnox Ltd (ML). ONR is using its legal powers conferred to it under the site licence conditions to authorise this first-of-a-kind transition into a 70 year period of safe storage. (authors)