Summary of Lessons Learnt during Generic Design Assessment


Office for Nuclear Regulation

An agency of HSE

Summary of Lessons Learnt during Generic Design Assessment (2007 – 2013)

ONR-GDA-SR-13-001 Revision 0

September 2013







Office for Nuclear Regulation

An agency of HSE


The purpose of this document is to provide a summary of the key lessons learned by the

Office for Nuclear Regulation (ONR) and the Environment Agency (EA) during the

Generic Design Assessment (GDA) work conducted during the period 2007 to 2013.

ONR, an agency of HSE, and the EA developed the GDA process in response to a request from the Government following its 2006 energy review. ONR and EA’s initial guidance on the GDA process was published in January 2007 (References 1, 2, 3 and 4).

Whilst these have been updated since 2007, the requirements for GDA have remained largely unchanged.

Initially, four reactor designs were accepted for GDA, and work on each began in July

2007. Of these designs, only the UK EPR™ has achieved a Design Acceptance

Confirmation (DAC) from ONR and a Statement of Design Acceptability (SoDA) from EA, both of which were granted in December 2012. We were asked by the Requesting

Parties (the vendor companies that asked for a GDA of their design) to halt our assessment of the other designs, at various stages through the process. Completion of

GDA for UK EPR™ was achieved in March 2013 with the publication of all the technical assessment reports.

As we have completed the first GDA, it is timely to review the work done and to consider what worked well, and where there is room for improvement. This short report summarises the lessons learned during the period 2007 to 2013. We are in the process of revising and updating our guidance documents to take these lessons into account.

This report focuses the lessons learned about the management of the GDA process, it does not consider the detailed technical matters.

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An agency of HSE











The objective of GDA was to enable the nuclear regulators to get involved at an early stage in the development of proposals for new nuclear power stations. It allows the technical assessments to be conducted before commitments are made to construct the reactors, meaning that regulatory questions and challenges can be addressed while the designs are still “on paper”. The reports we wrote to support the UK EPR™ DAC and

SoDA decisions (References 5 and 6) demonstrate that we have achieved this objective.

A number of safety improvements were identified as a result of our assessment and these are being incorporated into the UK EPR™ design long before any construction work starts at a UK site.

The guidance for GDA (References 1, 2, 3 and 4) has proven to be clear and robust.

However, ONR and EA provided some additional guidance documents as GDA progressed (for example References 7 and 8). These documents should be reviewed, updated and collated into a single document for any future GDA.

At a late stage in our Step 4 assessment the accident at Fukushima occurred. The key impact on GDA was a six month delay in publishing our Step 4 reports while we awaited the HM Chief Inspector of Nuclear Installations’ report on the implications of Fukushima.

GDA did however, prove to be flexible and ONR was able to introduce an additional GDA

Issue to ensure that the lessons learnt from Fukushima were taken into account before the DAC and SoDA were issued.

A feature of GDA has been the clear programme and administration arrangements that we put in place to ensure efficiency and joint working between ONR and the EA. These arrangements were set out in an Interface Protocol between the regulators and the

Requesting Party at the beginning of GDA. All correspondence, technical issues and contacts have been managed in accordance with this Interface Protocol through a single

Joint Programme Office and this has proven to be particularly effective.

During GDA the regulators used a tiered system for the identification of regulatory challenges, allowing the possibility of escalation from Technical Query to Regulatory

Observation, to Regulatory Issue. Each matter was uniquely identified, tracked, and closed-out in a clearly defined manner. This basic process should be retained.

We have also made extensive use of programme working to manage the progress of our assessments within GDA. As part of this, we have published plans, progress reports and performance metrics. These were effective in helping to identify key areas on which to focus resource and we should continue to use and publish them for any future GDA.

We made extensive use of technical support contracts (TSCs), placing around 170 support contracts throughout GDA. This was an efficient way for ONR to bolster the specialist analytical resources available to it. Unfortunately, however, it took over a year from the start of GDA to have a contracting framework in place, which did slow down the pace of our work. For future GDAs we will continue to use TSCs and we will seek to improve our planning so that TSCs can be used early in GDA. To help ONR manage these contracts effectively, we employed specialist contract managers to support ONR’s inspectors. This worked well and similar contract managers should be used in future.

From the outset we have been committed to conducting GDA in an open and transparent manner and we believe we have achieved this. We have published a lot of information on our websites, including regular progress reports, detailed technical assessment reports, and overall summary reports. In addition, the Requesting Party safety cases have been published on their websites and we invited public comment on these. We have also attended and spoken at many events throughout GDA to publicise our work. We believe

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Office for Nuclear Regulation

An agency of HSE that this openness has helped raise awareness of, and public confidence in, the robust and thorough work that was undertaken.

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Office for Nuclear Regulation

An agency of HSE











Completion of GDA Steps 1 to 4 took over four years, which is longer than originally envisaged. The reasons for this are diverse and include the impact of Fukushima, a lack of ONR resource in the early stages, and the spreading of this resource to assess four reactor designs in parallel until Step 3. Future GDA projects should not start until ONR has secured appropriate resource.

Understanding the UK regulatory approach and expectations for presentation of safety case claims, arguments and evidence was a challenge for the Requesting Parties towards the beginning of GDA. This partly arose from differences between each country’s regulatory frameworks. In future, additional effort should be expended by the Requesting

Parties and ONR to help address this lack of understanding.

Delivery of documents on time and with sufficient technical content was a challenge for the Requesting Parties at certain stages of the process, which in turn created difficulties with planning our assessment and the support work of our TSCs which inevitably led to delays and the requirement for time consuming contract variations. To make the GDA process as efficient as possible, it is important that delivery schedules are agreed and adhered to.

A further difficulty was dealing with protectively marked material that originated from outside the UK. This presented logistical difficulties and delays throughout the programme. This is likely to remain an issue for future assessment of overseas designs and needs to be planned for accordingly.

For efficient working, significant GDA dedicated technical, project and administrative resource was needed in the Requesting Party’s organisation, together with dedicated

GDA offices. These need to be adequately staffed from the outset of GDA.

Although the tiered system for the identification of regulatory challenges (Technical

Query, Regulatory Observation, Regulatory Issue) worked well, there is room for improvement. On reflection we believe that we should have raised a larger number of

Regulatory Observations because some of the responses to Technical Queries became more complex than was originally intended for that level of comment. Equally we now think that it would have been more effective to have raised more Regulatory Issues to help draw attention to some significant technical problems. So for future GDAs we may raise more Regulatory Observations and Regulatory Issues but this should not be interpreted as an indication of an increased number of major ‘problems’ with the design.

While we view the openness of GDA as a success, there is always scope for improvement. Many detailed technical issues were raised during GDA but only the

Regulatory Issues and GDA Issues were individually published, with information about the other technical issues being contained within the detailed reports published for Steps 2, 3, and 4, and GDA Issue Closure. Therefore one improvement would be to extend the scope of publication throughout GDA to include all the Regulatory Observations (ROs) and the Requesting Party response plans for these.

Writing, reviewing and publishing our GDA reports took significant time and effort, and this diverted resource from assessment activities, particularly at the end of Step 3. We believe that we can improve efficiency, while being more open, by, as noted above, publishing all the Regulatory Observations at the time they are raised, rather than waiting to include them within our Step 2, 3 or 4 reports. This would then remove the need to publish detailed ONR technical assessment reports at the end of Step 3, because the relevant information would already be in the public domain. Any additional context

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Office for Nuclear Regulation

An agency of HSE




25 required can be included in the quarterly progress reports, and we would still publish an overall Step 3 summary report.

Experience shows that both regulators and Requesting Parties started the various GDA

Steps without really being fully ready to do so, for example at the start there was neither sufficient resource nor mature plans in place. To help address this in future we will introduce Requesting Party readiness reviews and regulator commencement decision gates at the start of each assessment Step.

One of the significant obstacles to progress that emerged was the difficulty of clear communication, with correct understanding, between the regulators and the Requesting

Parties. This difficulty was primarily due to language and cultural differences of the

Requesting Parties, who were all from outside the UK. Sometimes the communications problems were subtle and hard to detect with the result that where we thought we had good understanding there later turned out to be a mis-understanding such that time was lost or nugatory effort was expended. It took some time for us to develop strategies to manage this effectively (such as three-way communication, and the sharing and comparing of progress metrics) but for future GDAs we will be able to adopt these good practices from the outset.

Related to communication problems, we found that our engagements with Requesting

Parties were not always as effective as we would have wished. But with experience we developed some ‘principles for engagement’ which included things such as: ensuring relevant experts and appropriate decision-makers attend meetings; sharing of meeting notes and agreement of actions arising; promoting a questioning attitude; ensuring all relevant information is provided; ensuring open discussions take place with an objective of ‘no surprises’. We will take forward these principles into future GDAs.

Finally, although this report is about lessons learned for the management of the GDA process, we did also learn lessons about identification of technical matters, for example ensuring clarity in the questions we put to the Requesting party. The topic specific lessons learned will be covered within the individual assessment plans for those technical areas. In general, we raised many technical challenges throughout GDA but it took time for us to identify some of the most important matters. With the benefit of this experience we believe that we may be able to identify some of these key technical challenges at an earlier stage in our assessment, for example by drawing upon the Regulatory

Observations, Regulatory Issues, and GDA Issues identified in previous assessments.

We will use this experience to help draw out technical challenges at as early a stage as possible.

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Office for Nuclear Regulation

An agency of HSE


1. Nuclear power station generic design assessment – guidance to requesting parties, Version 1

HSE January 2007

2. Guidance document for generic design assessment activities (Version 2) Office for Civil Nuclear

Security 201206 January 2007

3. New nuclear power stations. Generic Design Assessment. Guide to the regulatory processes

Version 1 January 2007 HSE and Environment Agency

4. Process and Information Document for Generic Assessment of Candidate Nuclear Power

Plants, Guidance from the Environment Agency, Version 1, January 2007

5. Summary of the GDA Issue close-out assessment of the Electricité de France SA and AREVA

NP SAS UK EPR™ nuclear reactor, ONR, 13 December 2012

6. UK EPRTM nuclear power plant design by Electricité de France SA and AREVA NP SAS,

Supplement to decision document, EA, December 2012

7 New nuclear power stations. Generic Design Assessment. Guidance on the management of

GDA outcomes Version 1 June 2010 HSE

8. Paper on the required level of design waste plants for new build reactors in the Generic Design

Assessment HSE Nuclear Directorate 19 May 2009

The latest versions of the reports are available at: and

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