Editing Advanced gas-cooled reactor (section)

== History ==
[[File:Dungenesspowerstation (cropped).JPG|thumb|[[Dungeness B]] AGR power station, with a different outward appearance to most AGRs, consequential to multiple build companies being used]]
There were great hopes for the AGR design.<ref name=ft-20160307>
{{cite news
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 |title= Book review: 'The Fall and Rise of Nuclear Power in Britain'
 |newspaper= Financial Times
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</ref>
An ambitious construction programme of five twin reactor stations, [[Dungeness B]], [[Hinkley Point B]], [[Hunterston B]], [[Hartlepool nuclear power station|Hartlepool]] and [[Heysham nuclear power station|Heysham]] was quickly rolled out, and export orders were eagerly anticipated.

For political reasons the CEGB was instructed to spread the 'first generation' orders between three different 'design & build' consortia and a variety of major subcontractors.  In consequence the first three CEGB stations, whilst sharing the same design concept and the same fuel pin design, were completely different in detail design. This also resulted in the three consortia having to compete for the same limited number of expert staff, the need for each design to have a unique (and very complex) safety case, and the need to support for the life of the programme three (later four) different AGR reactor designs.

The AGR stations proved to be complex and difficult to construct. Notoriously bad labour relations at the time added to the problems. The lead station, Dungeness B, was ordered in 1965 with a target completion date of 1970. After problems with nearly every aspect of the reactor design it finally began generating electricity in 1983, 13 years late.<ref name=ft-20160307/>

The following reactor designs at Hinkley Point and Hunterston, ordered a year or two later, proved to be significantly better than the Dungeness design, and indeed were commissioned ahead of Dungeness. The next AGR design, built at Heysham 1 and Hartlepool, sought to reduce overall cost of design by reducing the footprint of the station and the number of ancillary systems. However this led to difficulties in construction.

The final two AGRs at Torness and Heysham 2 returned to a modified and 'debugged' Hinkley design with much greater seismic margin, and have proved to be the most successful performers of the fleet.<ref name=dalton-20161201>{{cite news |url=http://www.dalton.manchester.ac.uk/media/eps/dalton/documents/Experience-of-Consortia-Engineering-for-Nuclear-Power-Stations.pdf |title=UK Experience of Consortia Engineering for Nuclear Power Stations |author=S H Wearne, R H Bird |newspaper=Dalton Nuclear Institute, University of Manchester |date=December 2016 |access-date=25 March 2017 |archive-url=https://web.archive.org/web/20170326135456/http://www.dalton.manchester.ac.uk/media/eps/dalton/documents/Experience-of-Consortia-Engineering-for-Nuclear-Power-Stations.pdf |archive-date=26 March 2017 |url-status=dead }}</ref> Former Treasury Economic Advisor, [[David Henderson (economist)|David Henderson]], described the AGR programme as one of the two most costly British government-sponsored project errors, the other being [[Concorde]].<ref name=nei-20130621>{{cite news|first=David|last=Henderson|title=The more things change...|website=Nuclear Engineering International|url=http://www.neimagazine.com/opinion/opinionthe-more-things-change|date=21 June 2013|access-date=23 July 2021}}</ref>

When the government started on [[Privatization of the Central Electricity Generating Board|privatising the electricity generation industry]] in the 1980s, a cost analysis for potential investors revealed that true operating costs had been obscured for many years. Decommissioning costs especially had been significantly underestimated. These uncertainties caused nuclear power to be [[British Energy|omitted from the privatisation]] at that time.<ref name=ft-20160307/>

The small-scale prototype AGR at [[Sellafield]] (Windscale) has been decommissioned as of 2010 &ndash; the core and pressure vessel decommissioned leaving only the building "Golf Ball" visible. This project was also a study of what is required to decommission a nuclear reactor safely.

In October 2016 it was announced that super-articulated control rods would be installed at [[Hunterston B nuclear power station|Hunterston B]] and [[Hinkley Point B Nuclear Power Station|Hinkley Point B]] because of concerns about the stability of the reactors' [[Nuclear graphite|graphite]] cores. 
In early 2018 a slightly higher rate of new keyway root cracks than modelled was observed in Hunterston B Reactor 3 during a scheduled outage, and EDF announced in May 2018 that the outage would be extended for further investigation, analysis and modelling.<ref name=wnn-20180503>{{cite news |url=http://www.world-nuclear-news.org/RS-New-cracks-delay-restart-of-Hunterston-B-reactor-0305184.html |title=New cracks delay restart of Hunterston B reactor |website=World Nuclear News |date=3 May 2018 |access-date=6 May 2018}}</ref>

In 2018 inspections ordered by the ONR at [[Dungeness Nuclear Power Station|Dungeness B]] showed that seismic restraints, pipework and storage vessels were "corroded to an unacceptable condition", and that would have been the state when the reactor was operating. The ONR classified this as a level 2 incident on the [[International Nuclear Event Scale]].<ref name=nei-20190124>{{cite news |url=https://www.neimagazine.com/news/newsuk-dungeness-corrosion-rated-at-ines-level-2-6952999 |title=Dungeness B corrosion rated at INES level 2 |publisher=Nuclear Engineering International |date=24 January 2019 |access-date=30 January 2019}}</ref>