Generic Design Assessment

The nuclear regulators – the Office for Nuclear Regulation (ONR) and Environment Agency – have been carrying out a new process called ‘Generic Design Assessment’ (GDA), which looks at the safety, security and environmental implications of new reactor designs before an application is made to build that design at a particular site. Initially the GDA was expected to be completed around spring 2011, when the regulators would issue statements about the acceptability of the designs.1

Four designs were originally submitted to GDA process. In March 2008 the regulators announced they had found no shortfalls – in terms of safety, security or the environment – that would prevent any of the designs from ultimately being constructed on licensed sites in the UK. The nuclear regulators published a series of reports on their findings on the four reactor types:

Atomic Energy of Canada Ltd ACR-1000

General Electric and Hitachi Ltd. Economic Simplified Boiling Water Reactor (ESBWR)

Westinghouse AP1000

Areva/EDF European Pressurised water Reactor (EPR)

The next stage was going to be a prioritisation process to reduce the number of designs to three, but Atomic Energy of Canada Ltd pulled its ACR1000 design out of the process, and General Electric and Hitachi Ltd. asked for a temporary halt to the assessment of its Economic Simplified Boiling Water Reactor (ESBWR).

In June 2010 the Environment Agency released its assessments of the two new reactor designs – EPRs and AP1000s – for consultation. This focussed on the waste which would be produced by the reactors and discharges of radioactive waste into the marine environment and the atmosphere.

The Nuclear Free Local Authorities response to this consultation is available here.

By August 2010 it started to become clear that the ONR (formerly Nuclear Installations Inspectorate) might only be able to issue “interim” approvals for the Areva EPR and Westinghouse AP1000 reactor designs at the end of the generic design assessment (GDA) in June 2011. Construction could only occur after any outstanding “GDA issues” had been resolved. This was confirmed in the final quarterly report of 2010.2

On 14th December 2011 the Regulators granted interim Design Acceptance Confirmations (iDACs) and interim Statements of Design Acceptability (iSoDAs) for the UK EPR and the AP1000 reactor designs. The Regulators also confirmed that they are satisfied with how EDF and Westinghouse plan to resolve the GDA issues identified during the process.3

The regulators also published on 14th December reports for each design summarising the basis of their decision, together with their technical assessment reports as well as documents explaining how the designers plan to resolve issues identified in a report written by the UK’s chief inspector of nuclear installations, Mike Weightman, on the Fukushima accident in Japan.4

ONR’s interim approval for the UK EPR came with a long list of caveats – 31 so-called ‘GDA Issues’. Moreover, portions of the UK EPR design were, by agreement, outside the scope of the GDA review altogether. Westinghouse’s iDAC for its UK AP1000 contained 51 GDA Issues. At this point Westinghouse decided to request a pause in the GDA process for the AP1000 pending customer input to finalizing it. Now that Westinghouse has become part of the NuGen consortium with its parent company Toshiba taking a 60% stake, the process for AP1000 has resumed, and is scheduled to be completed in January 2017 with issuance of DAC and SODA. 5

On 13th December 2012 the regulators confirmed that they were satisfied the EPR reactor meets regulatory expectations on safety, security and environmental impact and is suitable for construction in the UK.6

In January 2014 Westinghouse became a part of the NuGen consortium when parent company Toshiba bought a 60% stake. In August 2014, Westinghouse recommenced GDA in order address the 51 outstanding GDA issues which must be resolved before ONR and EA would consider granting a DAC/SoDA. The process is scheduled to be completed in January 2017.

Early in 2013 Hitachi-GE applied for GDA for its Advanced Boiling Water Reactor (ABWR), and in August 2014 the ONR and EA completed the second stage of this, and cleared it to proceed to stage 3. In 2015 the ONR and EA raised an issue regarding reactor chemistry, which Hitachi-GE is addressing, and then another regarding safety analysis. The whole GDA process was to be completed about the end of 2017. There are four operable ABWR units in Japan, while two more are under construction. (See ABWRs – one of the least realiable reactors in the world, nuClear News No.77 September 2015) Two more are being built in Taiwan and one is planned for Lithuania. The design is already licensed in Japan and the USA. It can run on a full-core of mixed-oxide (MOX) (containing weapons-useable plutonium) nuclear fuel.

John Large of Large and Associates, an expert on nuclear safety, was commissioned to develop a detailed study of the ONR and Environment Agency’s GDA of the EPR and AP1000 proposed nuclear reactor designs. His independent review of progress when there were 30 outstanding issues still to be resolved for the EPR reactor was published in June 2012.7 Large issued the second of three reports in September 2012. 8

Large’s third and final review was published in June 2013.9 This raised a number of serious issues regarding the manner and speed with which the final outstanding issues in the GDA process were being resolved by the ONR. These issues were summarised in an NFLA Press Release issued on 19th June 2013.

UK Nuclear Regulators Nuclear Reactor Assessment web-pages:

1. HSE Press Release 18th March 2008 (Applications from reactor vendors were invited in May 2007)
2. Generic Design Assessment Progress Report 1st Oct to 31st Dec 2010
3. Generic Design Assessment Progress Report 1st Oct to 31st Dec 2011
4. Platts 14th December 2011
5. World Nuclear Association 3rd Aug 2011
6. ONR Press Release 13th December 2012
7. Large and Associates, 1st Interim review of Generic Design Assessment – Outstanding Issues, June 2012
8. 2nd Interim review of the ONR Generic design Assessment Outstanding Issues, Large & Associates September 2012
9. Large & Associates, Final Report on the ONR Generic Design Assessment, June 2013


Published: 1 April 2009
Last updated: 7 September 2015