UK regulator reports 'slippage' in assessment of AP1000 design

08 January 2016

There has been some program "slippage" in a number of topic areas for the generic design acceptance (GDA) of the Westinghouse AP1000 nuclear reactor design, the UK's Office for Nuclear Regulation (ONR) said in its latest quarterly report on GDAs issued yesterday. Westinghouse is working to "re-baseline the overall program", ONR said, "with the objective of enabling regulators to make decisions" about issuing a Design Acceptance Confirmation (DAC) and Statement of Design Acceptance Confirmation (SoDA) in January 2017, as per the current schedule.

The report provides information on the work that ONR has been carrying out on the GDA of Hitachi-GE's UK Advanced Boiling Water Reactor (UK ABWR), and the closure phase of the GDA project for the Westinghouse AP1000 reactor design, during the period July to October 2015. The period of the report was extended to include the end of ONR's Step 3 for the UK ABWR project.

The UK regulators - ONR and the Environment Agency - began assessing Westinghouse's AP1000 reactor design in September 2007. They granted interim GDA approval in December 2011. At that time, Westinghouse requested a pause in the GDA process and signalled that it would not proceed to address GDA issues until the design had been selected for a project in the UK.

NuGeneration Limited (NuGen) - a 60%/40% joint venture between Toshiba and GDF Suez - in 2014 confirmed plans to build three Westinghouse AP1000 pressurized water reactors at Moorside by the end of 2026 with a total capacity of 3.4 GWe. The first unit is expected to begin operating by the end of 2024. A final investment decision is expected to be taken by the end of 2018.

In August 2014, Westinghouse recommenced GDA in order to address the 51 outstanding GDA issues which must be resolved before ONR and the Environment Agency would consider granting a DAC and SoDA.

Westinghouse announced in March last year that the regulators and the company had begun the closeout phase of the GDA process for the AP1000 "with a review timeline that supports milestones for developing the three-unit Moorside project in northwest England."

ONR says in the latest GDA report that assessment of the AP1000 "gathered pace" in the reporting period and progress was being made in a number of areas. "The vast majority of GDA Issues are being progressed in a timely manner and there is convergence on the specific requirements for closure of the GDA Issue," it said.

Westinghouse has also reported an increase in resource throughout its GDA organisation; at the leadership level, project management and technical team levels. It is also increasing its UK support team, which combined with its in-house reactor expertise is "driving improvements in submission quality", ONR said.

The regulator also welcomed "additional oversight" that has been put in place at executive level in Westinghouse, "as this provides confidence that additional resource can be secured if required, and that the program delivery is routinely challenged".

Mechanical Engineering

Within the reporting period the issues relating to the release of information on the initiator element of the squib valves for Mechanical Engineering Issue-01 have been resolved, ONR said.

"This allows the GDA Issue to progress, although Westinghouse is continuing to work on recovering the schedule for ME-01. This latter point is proving difficult for Westinghouse and we will work with them on developing a credible schedule for ME-01 that aims to maintain the overall DAC and SoDA date as far as possible," it added.

There have also been a number of GDA Issue "resolution plan schedule re-baselines" by Westinghouse. This is concerning, the ONR said, as it is entering the final year of the program, "when high quality delivery at pace is paramount". The regulator said it will continue to monitor the overall program and report its views on the likelihood of completion in early 2017.

There are also instances, it said, where there is lack of convergence on what is required to close the GDA Issue and negotiations have been "protracted". It proposes a meeting before the end of the year to finalise the discussions to enable the project "to move forward at pace", it said.

"We continue to stress to Westinghouse the importance of right first time, on-time submissions if it is to maintain their desired DAC and SoDA date. The coming period will require an increase in pace and activity, and an absolute focus on GDA Issue closure through enhanced management attention and oversight," ONR said. "There are technical issues emerging, which is to be expected as we are now into detailed assessment. However, early agreement on the way forward and a focus on delivery is required to resolve issues as they arise."

The standard AP1000 plant design has continued to develop, partly in response to construction experience in China and the USA. As a result, Westinghouse has proposed a number of design changes to the UK plant and many of these have been submitted for the regulators' consideration as a revision to the Design Reference Point (DRP).

The DRP had previously been fixed, following acceptance of earlier batches of design changes in September 2010 during Step 4 of the GDA process, ONR said. The most significant - in terms of potential consequences for the safety or environment cases - design changes can only be accepted into the scope of GDA by agreement of the regulators.

ONR and the Environment Agency are currently considering the batch of design changes included in the proposed revised DRP and will provide a response to Westinghouse "as soon as practicable", according to the ONR report.

Over the coming months the regulator will focus on resolving the program issues relating to GDA Issue ME-01 and "converging on those GDA Issues where agreements have not yet been reached".

"The challenges in regards to ME-01 and slippage of the delivery program continue," the report says. "A number of Regulatory Queries have been extended, with one RQ date now extending beyond 12 months from the time of issue. Recovery of these timescales (now approximately seven months for the project scope) will be very difficult," ONR said. "Westinghouse is in the process of developing a revised recovery schedule, although we are concerned that this Issue may impact the overall DAC and SoDA date."

There is also slippage in the delivery of ME-02, "albeit relatively small and partly due to ONR availability, however, the trend is now beginning to show in this area which is concerning", the report says. "Equally, in ME-03 we understand that resources have been removed from this area to meet demands in ME-01 and other Westinghouse projects, and hence there is an increasing potential that this will impact delivery and agreed submission dates."


During the reporting period, ONR completed its assessment of Hitachi-GE's submissions for GDA Step 3 of the UK ABWR project. As part of its governance, ONR undertook a "gateway review" to consider the regulators' and Hitachi-GE's readiness to move to Step 4. The review concluded that sufficient progress had been made by Hitachi-GE, and that the regulators had the resources available to progress to Step 4, which commenced on 2 November.

The Environment Agency and Natural Resources Wales are continuing on Step 3 (detailed assessment) of their GDA process for the UK ABWR. This has a longer duration than ONR's Step 3 and concludes when the environmental regulators begin consulting on their preliminary findings at the end of that step.

Over the coming months the ONR said it will move into the detailed technical assessment of Step 4; secure additional resource both internally and through the supply chain to ensure that it is able to meet Hitachi-GE's program; undertake a "cross-cutting workshop in Japan across involving multiple disciplines"; and focus on influencing the development of a "holistic fuel route safety case" for the UK ABWR.

The reporting period coincided with the UK and Chinese governments' announcement of a Statement of Cooperation in the Field of Civil Nuclear Energy 2015 and a Strategic Investment Agreement between EDF and its partner China General Nuclear Corporation (CGN).

The agreement sets out the terms of the companies' partnership for the Hinkley Point C project and their proposed collaboration at the Sizewell and Bradwell sites. The agreement expects that a Chinese designed reactor will be submitted for GDA in 2016.

ONR said regulators plan to begin this GDA in 2016 when requested by the UK government.

Researched and written
by World Nuclear News