FRANCE’S 900 MW FLEET | COVER STORY


Above: Four 900 MW reactors are located at the Cruas Nuclear Power Station on the Rhône River Photo credit: Ralf Liebhold/Shutterstock.com


ASN said that to justify the scenario planners must justify


life extension to 60 years – “with sufficient margins for dealing with major or generic unexpected scenarios” and with back-up plans that would allow at least 15 years to take an alternative route in order not to compromise safety.


Broad concerns More broadly, ASN said whatever France’s energy policy, it will “imply a considerable industrial effort, in order to tackle the industrial and safety challenges. If nuclear power is needed for 2050, the nuclear


sector will have to implement a ‘Marshall Plan’ to make it industrially sustainable and have the skills it needs. It warned that “Quality and rigour in the design,


manufacture and oversight of nuclear facilities… were not up to the required level in the latest major nuclear projects conducted in France”. It also warned that more work was also needed in fuel


chain facilities. It said a series of events “is currently weakening the entire fuel cycle chain and is a major strategic concern for ASN requiring particularly close attention”. Most urgent is a build-up of radioactive materials and delays in construction of a centralised spent fuel storage pool planned by EDF to address the risk of saturation of the existing pools by 2030. The need for the pool was identified back in 2010, but work has not begun. ASN said the combination of shortcomings between fuel cycle and nuclear plants meant the electricity system “faces an unprecedented two-fold vulnerability in availability”. New vulnerabilities like the discovery of stress corrosion cracking mostly “stem from the lack of margins and inadequate anticipation,” ASN said, and “must serve as lessons for the entire nuclear sector and the public authorities.” However, at the same time ASN noted that nuclear was


more needed than ever and acknowledged that given demand growth, France “will have to carefully weigh its decision to shut down an additional 12 reactors by 2035”. Alongside that decision it will have to consider, by the end of the decade at the latest, whether or not to continue reprocessing spent fuel after 2040, to allow for refurbishment or alternative solutions. An energy policy comprising a long-term nuclear


component “must be accompanied by an exemplary policy for the management of waste and legacy nuclear facilities,” ASN said.


The winter of 2021-2022 was marked by low availability


of EDF’s nuclear fleet and the lack of anticipation of that was also mentioned by ASN. “This was for a number of reasons, some of which could be foreseen, others less so”, ASN said. EDF would have known about the delayed commissioning of the EPR at Flamanville, the shutdown of two units at Fessenheim and the schedule – set up in 2018 - of major overhauls. “This lower availability has been predictable since 2018, ASN said”. The impact of the Covid-19 pandemic was unforeseeable, the authority admitted (Covid restrictions meant maintenance and refuelling operations took longer, reducing output). ASN also made further comment on the discovery


of stress corrosion cracking in reactors (which is still keeping reactors offline this winter). Sounding a note of exasperation, ASN said the build-up of events “illustrates the absolute need – as ASN has pointed out to the public authorities and nuclear sector stakeholders numerous times – to maintain design-basis margins for the electricity system and the installations, in order to deal with unexpected events and avoid having to resort to a trade-off between the safety of installations and the availability of electricity supply.” ■


Hardened core Following the Fukushima Daiichi accident, France has aimed to implement a so-called ‘hardened nuclear core’ of material and organisational provisions at French reactors. The aim is to limit fuel melt accidents and large-scale radiological releases and aid the operator in the event of an emergency. The most important measures include:


● a new makeup pump to the primary system; ● new means of injecting borated water into the primary system at high pressure;


● fixed backup water supply systems for the steam generators and fuel storage pool;


● an extra fuel pool cooling system ● an ‘ultimate containment cooling system’ to prevent opening of the filtered vent on this containment in a severe accident;


● a so-called ‘core catcher’ on the basemat in case of reactor vessel melt- through;


● a backup I&C system


www.neimagazine.com | November 2022 | 17


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