Nuclear power plants in France, the most nuclear dependent country in the world, are vulnerable to the catastrophic effects of a major natural disaster such as that which hit the Japanese plant at Fukushima in March. That is the conclusion of a stress-test study of the country's 58-strong reactor fleet carried out by the French radioprotection and nuclear safety institute, the IRSN, presented Thursday by the national nuclear safety agency, the ASN, which warned that "massive investment" is required for the recommended safety upgrades. Jade Lindgaard reports on the findings.
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The equipment failures and meltdowns at Japan's Fukushima nuclear power plant earlier this year, triggered by an earthquake and tsunami that hit the north west of the country on March 11th, led to a major U-turn in the approach of nuclear safety experts in France, the world's most nuclear-reliant country which derives around 75% of its electric energy production from nuclear plants.
Following the disaster in Japan, the French radioprotection and nuclear safety institute, l'Institut de radioprotection et de sûreté nucléaire (IRSN), undertook a stress-test study of the country's 58 reactors and also a new generation reactor under construction in north-west France, imagining what was hitherto considered the unimaginable; major natural disasters.
The results are contained in a 500-page report that was presented before the press on Thursday by the IRSN and the supreme nuclear safety watchdog, l'Autorité de sûreté nucléaire(ASN), which will now decide what, if any, new measures should be implemented.
The study by the IRSN, essentially the technical arm of the ASN, was carried out with the cooperation of nuclear plant operators, including EDF, Areva and the CEA, and is one of several similar reviews in other European countries.
It concluded that all of the French nuclear reactors must upgrade safety to avoid a catastrophe in the event of natural hazards such as earth tremors and flooding and major industrial accidents. It found that, in "a number of extreme scenarios", current safety precautions ensuring all or part of the essential safety functions "could be cancelled out by external aggressions of major proportions." It underlined that the risk of a terrorist attack had not even been considered in the drawing up of safety measures currently in practice.
The report noted the danger of a prolonged electricity black-out - which is what happened at Fukushima - or a delay in the provision of cooling sources, which are indispensable for reducing temperature in the reactor and the spent fuel pools. It cited the example of the depressurisation and filtration equipment surrounding reactor buildings which are to serve as a buffer, in the event of a meltdown of the core, stopping the release of radioactive cesium. These, noted the IRSN report, "are not currently designed" to cope with a major earthquake.
"There is a need to add a layer to protect safety mechanisms in reactors that are vital for the protection of the reactor such as cooling functions and electric powering," said Jacques Repussard, IRSN director-general, in an interview Thursday with Reuters news agency.
"For example, it is necessary that each reactor has at least one protected independent diesel generator positioned out of the way which does not fail even in case of an extremely violent earthquake," he said.
"All reactors have to survive much more violent events than what they were built to resist," he added, giving the examples of an earthquake in the southern city of Nice, which lies close to a faultline, or a multiple collapse of dams that would cause massive floods.
'We face massive investment'
In short, the institute found that the French nuclear power industry would face the same shortcomings as its Japanese colleagues in the event of an improbable, major natural disaster like the combined quake and tsunami which hit Fukushima. It slammed the reasoning that lies behind such ill-preparation, which it said was the belief that "a serious accident cannot be caused by a natural cause from outside the plant".
None of France's nuclear plants, it reported, faced an imminent danger. "Safety is not static, we cannot say that, because we call for new measures, that the plants were not safe beforehand," said IRSN head Repussard. But the report called for a new approach that considered the risk of extreme, however improbable, dangers to the reactor cores as valid, and which required the extra protection of a small amount of essential equipment.
"Small failings that appear to be anodyne can have serious consequences," warned Repussard, referring to the lessons of Fukushima. One example here was the back-up diesel-powered generators to be used as an alternative supply of electricity in the case of a black-out, and which would be essential for cooling a reactor, but which have insufficient fuel reserves. Another was the nuclear fleet's reserve reactor batteries, which are not water-resistant and which would fail in cases of flooding.
Repussard said "these are not major faults, but in the event of a serious situation they would make the plant fragile" by reducing the margin of manouevre.
Philippe Saint-Raymond, who chairs an ASN permanent committee of experts responsible for overseeing safety in nuclear laboratories and manufacturing plants, reported that "on every site we note problems of conformity [with regulations], both small or more important". He found that while the Areva-run plants, which include La Hague and Melox which produce Mox, had adequate crisis management systems in place, they were not sufficiently "robust".
The report underlined that control rooms across France's nuclear power plants would not resist a quake and that "the risk of toxic chemicals [emissions] is not sufficiently taken into account".
The independent French association that monitors the country's nuclear industry from a highly critical stance, l'Observatoire du nucléaire, gave the report a scathing reception. "For the IRSN, the nuclear power plants can continue to operate, despite their safety failures," it commented in a communiqué.
Repussard said plants specifically needing improvements to protection from earthquakes were Bugey (in south-east France), Fessenheim (in the east) and Civaux (in the south-west). Those reactors most requiring improvements to protection from flooding were Fessenheim, Chinon (western France), Cruas and Tricastin (in the south-east), and Saint-Laurent (central France).
The ASN, which is the only authority with the power to impose new measures on the industry, will now study the report and render its conclusions by early next year. ASN chairman Claude Lacoste warned Thursday that the required improvements meant "we face massive investment" and would "take years" to implement.
A Europe-wide report on the safety of nuclear power plants, based on the findings of similar stress test studies by EU national nuclear safety watchdogs, is to be published in June 2012.
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