ASN lifts its reservations regarding the I&C architecture of the Flamanville 3 EPR

ASN considers that the changes EDF has made to the instrumentation and control (I&C) architecture of the Flamanville 3 EPR are satisfactory and enable it to lift the reservations it expressed in October 2009. This position is based on the analysis by its technical support organisation, IRSN, and the opinion of the Advisory Committee for nuclear reactors.

 I&C^[1] consists of a range of systems which, in a nuclear facility, automatically take measurements and perform control or protection functions. The I&C for the Flamanville 3 EPR reactor comprises two associated platforms (see diagram):

• the Téléperm XS platform, specifically developed for the nuclear industry and dedicated to reactor protection in incident or accident situations;
• the SPPA T2000 platform, which is a "conventional" industrial system, used for functions linked to normal reactor operations and for certain reactor protection operations in incident or accident situations.

On 15th October 2009, ASN informed EDF that the safety of the "SPPA T2000" platform could not be confirmed. ASN in particular asked EDF to provide additional justifications and examine a different design for the I&C of the Flamanville 3 EPR reactor.

On this point, ASN - together with the regulators from Great Britain (ONR, formerly HSE) and Finland (STUK) - published a joint position statement on the design of the EPR reactor's instrumentation and control system, on 2nd November 2009.

Since then, EDF has been carrying out considerable work to comply with the ASN requests and finally, as requested by ASN, has implemented an I&C architecture modification designed to improve robustness and enable the SPPA-T2000 platform to be used for the Flamanville 3 EPR reactor. This modification consists in duplicating some of the SPPA T2000 platform's reactor protection functions on the Téléperm XS platform. The aim is to improve I&C robustness in the event of failure of the SPPA-T2000 platform combined with certain accident situations.

Following the IRSN analysis of these modifications and the 16th June 2011 opinion from the Advisory Committee for nuclear reactors, ASN considers that the I&C architecture of the EPR reactor proposed by EDF is such as to be able to guarantee the safety of the systems used to manage incident or accident situations and their independence from the control systems used for normal operation of the plant. EDF may thus continue with deployment of this system, the detailed design of which will be analysed by ASN prior to the commissioning authorisation.

 ASN presented its conclusions at a meeting of the MDEP^[2] in January 2012, particularly with the safety regulators from the United States (NRC), Great Britain (ONR) and Finland (STUK), who stated that they would continue their technical analysis of this subject.

[1] The term instrumentation and control (I&C) covers the following elements:

• temperature, pressure, etc. sensors;
• devices which, based on a certain number of input data, produce automatic orders to maintain parameters within authorised limits, or to trigger protection measures such as reactor emergency shutdown;
• the operator interfaces in the control room (control consoles, alarms, etc.).

 Because they perform functions that are important for reactor safety, these elements are subject to particularly strict requirements.

[2] MDEP: Multinational Design Evaluation Program, a multinational initiative which aims to pool the knowledge of the safety regulators with statutory responsibility for evaluating new reactors.