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Hunterston and Continuous Decommissioning 

 nuClear News No136 Dec 21,  Hunterston and Continuous Decommissioning    The Nuclear Decommissioning Authority’s 2021-24 Business Plan (1) says it has reviewed the Magnox reactor decommissioning strategy and endorsed a site-specific approach to Magnox reactor decommissioning which will involve a mix of decommissioning strategies. For some sites this will result in their decommissioning being brought forward whilst for others a deferral strategy will be the chosen approach. New Site-Specific Strategies will be developed for each Magnox station across Britain. These will support optimal sequencing of reactor dismantling – a rolling programme of decommissioning which will maximise the opportunity for sharing any lessons learned, developing and implementing new technologies and strengthening wider capability. 
These new site-specific decommissioning strategies are currently being defined. A timetable will be set that best suits each site and a business case developed to set out the benefits and cost and schedule impacts of any changes.  

  Reactor dismantling at the Hunterston A Magnox station, which ceased generation in 1990, is now expected to start in 2035. The previous strategy was to place the reactors into care and maintenance for up to 85 years to allow for radioactivity to decay. The current work programme which involves packaging various waste, sludges etc and placing the packages into an Intermediate Level Waste store will now take until 2030, 40 years after it ceased operation. The plant opened in 1964, so by 2030 Hunterston A will have spent longer being cleaned up than it actually spent generating electricity. Originally the current work programme was expected to be completed by 2022, but problems associated with retrieving waste in 5 bunkers has caused delays. The period between 2030 and 2035 will be spent demolishing various buildings.

 Under the old strategy the NDA was going to install a “weather envelope” around the old Magnox reactors. Work on this has now been suspended. 

  Hunterston B Meanwhile, Hunterston B – Reactor 3 switched off for final time on 26th November. The reactor was first switched on on 6th February 1976. When EDF acquired the power station it was expected to end generation in 2016. (2) Hunterston B Reactor 4 – is scheduled to shut down in January, which will see the end of power generation for the site in North Ayrshire, Scotland. (3)

 Reactor 3 and Reactor 4 were taken offline on 9 March and 3 October 2018, respectively, after cracks in their graphite cores were discovered during routine inspections. In August 2020, the UK’s Office for Nuclear Regulation (ONR) gave approval to EDF to restart Reactor 4 in August 2020 and Reactor 3 the following month. The reactors were taken offline earlier this year for further inspections of their graphite cores. In April, the ONR gave permission for the units to be    switched back on. However, it said continued operation would be for up to a total of 16.7 terawatt days for Reactor 3 and 16.52 terawatt days for Reactor 4 – about six months of operation for each reactor. Reactor 3 returned to service on 23 April and Reactor 4 on 5 June.

 In June, the UK government and EDF agreed on improved arrangements to decommission the UK’s seven AGR nuclear plants that are scheduled to close this decade. This followed an announcement by EDF that it had decided not to restart the first of the AGRs, Dungeness B, and to begin defuelling with immediate effect. (4) Each of the AGR sites will move across to the NDA on a rolling basis once defueling and fuel free verification are complete, for the decommissioning work to be overseen and managed by the NDA’s Magnox division. However, EDF’s defueling work will be supported by the NDA divisions Sellafield Ltd and Nuclear Transport Solutions (NTS) alongside other parts of the NDA group. Spent fuel from Hunterston B will be sent by train to Sellafield. (5)

 EDF has now submitted a defueling safety case to ONR. First there will be what’s called “defueling outage” which will last about 60 days – making sure everything is safe to commence defueling. Defueling is then expected to start in March 2022 and will take around 3 years.
 After defueling the NDA will take control of the AGR reactors. Under the old regime it would have taken until about 2030 to prepare the reactors for a period of care and maintenance. Now Hunterston B will develop a site-specific decommissioning strategy which should involve reactor dismantling sooner rather than later, thus providing the prospect of more continuous employment on the site.

 The NDA, EDF and Magnox have been working together to investigate the feasibility of Hunterston B sharing the use of the Hunterston A Intermediate Level Waste (ILW) store and processing facility. Seems obvious that they should, but EDF has recently been working on plans for a standalone store. EDF and NDA have now agreed to share the Hunterston A store and EDF has suspended work on a Hunterston B store. ONR & SEPA still need to be consulted and a planning application made to North Ayrshire Council (NAC). (6)


December 11, 2021 - Posted by | decommission reactor, UK

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