EDF and Areva’s reactor design raises concerns for UK regulator

The new reactor proposed for Britain by EDF and Areva of France, the European pressurised water reactor, (EPR) has raised concerns at the UK’s nuclear regulator, the Nuclear Installations Inspectorate, which has issued a warning about the design.

The NII wrote to EDF and Areva in April, saying the “adequacy” of the proposed control and instrumentation (C&I) systems for the EPR was “a matter of sufficient importance to raise this as a Regulatory Issue at this stage that may, if not resolved, prevent the successful outcome  [of licensing the reactor for the UK]“.

It is a significant development not only because the UK is set to be a very important nuclear market in itself, possibly the biggest of any developed country over the next decade or two, but also because the EPR’s C&I systems are currently going through licensing processes in France and Finland, where construction of the new reactors is already under way.

The NII, part of the UK’s Health and Safety Executive, has started publishing its views on regulatory issues as they come up in its Generic Design Assessment: the process of licensing reactor designs for use in the UK. Its concerns over the EPR are the first substantive issue that it has made public.

In its letter to EDF and Areva, the NII writes:

It is our regulatory judgement that the C&I architecture appears overly complex. Our judgement is based on a number of concerns; firstly, the reliance on two computer-based systems (originally developed by the same Company) and a high degree of connectivity between these two systems. Secondly, independence between the safety (Class 1) and the larger number of safety related systems (Class 2/3) appear to be significantly compromised due to the high level of interconnectivity between systems of different safety classification. Thirdly, we have serious reservations about your proposal which allows lower safety class systems to have write access (permissives etc.) to higher safety class systems (i.e. the usual UK practice of only allowing one way online communication from a safety system to systems of a lower safety class is not applied in the UK EPR design)

Other concerns include the absence of a safety class 1 display system, which EDF and Areva have included in their EPR designs for the US and Finland; the lack of “Class 1 manual controls or indications either in the Main Control Room or Remote Shutdown Station,” and EPR function categories/equipment class assignments that “do not appear to align with UK expectations.”

The NII called on the companies to submit an initial reponse by May 22, and then a full answer by the end of August 2009.

In its statement in response, Areva said it was “working with the UK Regulator to define the optimum solution for the country”, adding:

Areva is committed to ensuring the safety of the EPR reactor and to meeting the UK’s specific requirements. This process of constructive dialogue and technical explanation has just begun and the group is confident that a solution meeting UK’s requirements can be defined in the months to come.

The EPR reactor is currently being built in Finland, France and China and undergoing certification in the U.S. Areva is working closely with the different regulators to understand how the design can address specific issues in each country where it is being constructed.

In its statement, EDF says it “shares a common objective with the regulators to ensure the EPR design is safe and our aim is to meet all of the regulatory requirements so that the EPR can be built safely in the UK.”

It adds:

We believe that it is extremely important that the assessment processes are robust and thorough and in the UK we fully support the NII in their conduct of the Generic Design Assessment.

The process is designed so that the NII has a responsibility to scrutinise the design and ask questions and the applicants have a responsibility to demonstrate how their designs meets all the safety requirements of the regulator. This example is therefore evidence that the Generic Design Assessment process is working effectively.

We look forward to continuing to work with the NII on the points they have raised. These are complex matters and they will take careful consideration to resolve.

We are confident that through the GDA process these matters will be resolved to the satisfaction of all parties, leading to even better understanding of the EPR and to a safe power station.

It sounds as though the issue can be resolved. But one of the great concerns about new nuclear investment has always been that national regulators will all insist on their own specific design features, undermining the benefits of delivering a standardised reactor to a number of different markets around the world. The more regulators insist on their own idiosyncratic standards, the higher the cost of new nuclear power will be.

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