France's nuclear regulator has given a conditional go-ahead for a further 10 years of operation at the country's oldest operating nuclear power reactor, Fessenheim unit 1.
The French Nuclear Safety Authority (Autorité De Sûreté Nucléaire, ASN) has ruled that Fessenheim 1 can be operated for ten more years provided it complies with requirements set down by the regulator. Chief amongst these are a requirement to strengthen the unit's concrete basemat, which must be completed before 30 June 2013, and a requirement to make improvements to systems for removing residual power in the case of a loss of cooling function, to be completed before the end of 2012.
The 1.5-metre thick concrete basemat must be strengthened to make it more resistant to corium. Corium is a mixture of molten cladding, fuel, and structural steel formed in the event of a serious accident involving the melting of fuel in the reactor, which could potentially break through the steel reactor pressure vessel.
The ASN's decision does not prejudge the findings of additional safety assessments which are to be carried out at all French nuclear power plants following on from the accident at the Fukushima Daiichi nuclear power plant in Japan, the regulator notes.
Rather than issuing an operating licence for a set period of time, French law requires that the operator of a reactor performs a review of the level of safety at the unit every ten years. This involves a compliance review, which ensures that the plant complies with applicable safety rules, and a security review. The review process also makes sure the plant incorporates the latest safety practices and sets new operating conditions for the unit, as well as verifying that any phenomena associated with plant ageing will be manageable for a minimum of ten years.
The ASN ruled in July 2009 that no generic problems had been found that would affect the ability of the 900 MWe class of French pressurised water reactor, like the two units at Fessenheim, to enjoy operating lives of 40 years, although the individual reactors must still pass their 10-yearly review. Tricastin 1, which started up in 1980, became the first such reactor to complete its third 10-yearly review in 2010.
Fessenheim 1's third 10-yearly inspection and maintenance outage took place between October 2009 and March 2010, during which the ASN carried out twelve inspections as well as supervising hydraulic tests to requalify the plant's primary circuit.
The ASN's decision makes Fessenheim 1, which started up in 1977, the second French nuclear reactor to complete its thirty-year safety review. Fessenheim 2, which started up in 1978, is currently undergoing its own third ten-yearly inspection.