ASN considers reactor 1 at the Tricastin Nuclear Power Plant fit for ten more years of operation after thirty years in service

On 4 November 2010, ASN approved continuing operation of reactor 1 at the Tricastin Nuclear Power Plant (NPP) for an additional ten years after thirty years in service.

 At the same time, ASN is requiring EDF to implement technical instructions setting new operating conditions for reactor 1 of the Tricastin NPP to gradually raise the safety level.

 As part of its ongoing responsibilities, ASN will continue monitoring of the operation of reactor 1 of the Tricastin NPP.

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Continued operation of reactor 1 at the Tricastin Nuclear Power Plant

 In France, the operating license for a nuclear reactor does not set a limit for service life. On the other hand, article 29 of the Transparency and Nuclear Safety Act (13 June 2006) requires that the operator of a nuclear reactor perform a safety review of the facility every ten years.

The safety review is the occasion for an in-depth assessment of the facility to verify that it is in compliance with applicable rules and to improve its safety level by comparing applicable requirements with those in effect at facilities with more recent safety objectives and practices and taking into account advances in knowledge and national and international operating experience feedback.

Reactor 1 at the Tricastin NPP is the first reactor in the French nuclear fleet to be subject to a safety review thirty years after its initial divergence. EDF submitted the safety report for the facility on 19 February 2010. It had previously been subject to a third ten-year inspection from 2 May until 30 August 2009, during which ASN performed five inspections and supervised the requalification hydrotest on the reactor coolant system.

 The safety review of reactor 1 at the Tricastin NPP included two phases, a compliance examination and a safety review, in addition to specific tests to monitor aging and renew skills.

Compliance Examination

As part of the safety review of reactor 1 at the Tricastin NPP, EDF performed a compliance examination intended to provide an in-depth assessment of the state of the facility to verify that it is in compliance with all applicable rules, including construction approval, ASN instructions and current safety reference framework.

After the compliance examination, ASN finds the measures taken by EDF to be satisfactory. Although the Tricastin NPP is currently protected against a flood corresponding to the design basis flow rate of the Donzère – Mondragon water project, ASN notes that work must be performed to provide adequate protection from the risk of flooding in case of a maximum, thousand-year flood.

Safety Review

As part of the safety review of reactor 1 of the Tricastin NPP, EDF also performed a safety review intended to evaluate safety at the facility and to improve it in view of requirements for facilities with more recent safety objectives and practices, new developments and national and international operating experience feedback.

After examining work carried out by EDF and changes made as part of the safety review of reactor 1 at the Tricastin NPP, ASN considers that the new safety reference framework applicable to the reactor following its third ten-year inspection is satisfactory with regard to its initial objectives for the safety review.

Monitoring aging and updating skills

During the safety review of reactor 1 at the Tricastin NPP, EDF was required to demonstrate that the reactor could be operated under acceptable safety conditions for a minimum period of ten years after its third ten-year visit. On 20 September 2010, ASN considered that EDF had provided proof that the 900 MWe reactor vessels are fit for up to forty years of operation.

Finally, ASN notified EDF that specific phenomena may hinder its ability to maintain its facilities in compliance with updated safety requirements over time, particularly with regard to keeping skills up to date. On this point, ASN considers that the responses provided by EDF are on the whole satisfactory.