Translated using Google
Les réacteurs nucléaires ont redémarré au détriment de la sûreté
by Marie Astier (Reporterre),
January 18, 2017
Due to the cold spell, demand for electricity is at its maximum, justifying according to EDF, the re-start without delay of reactors inspected by the Nuclear Safety Authority. The association Nuclear Observatory is worried about this speed, according to it to the detriment of safety. It appealed to the courts to invalidate three restarts.
Update: The Council of State, by a decision of 18 January 2017, rejected the applications of the Nuclear Observatory Association, which challenged the legality of the authorizations for restarting the nuclear reactors Dampierre 3, Gravelines 2 and Tricastin 3, Nuclear Safety Authority at EDF. The Nuclear Observatory contested the re-launch of these reactors, which were found to be faulty (see article below). In its decision, the judge hearing the application for interim measures considers that EDF has taken the necessary precautions and in particular “precautionary measures of exploitation intended to reduce the risk of sudden rupture by making changes to the reactor operation”.
Reporterre updated his map of the nuclear fleet, detailing the central situation by power station.
To cope with the cold spell, have we rebooted some nuclear reactors too quickly, ignoring safety? Météo France announces – 6.4 ° C on average this Wednesday in metropolitan France, and the peak of 7 pm should require the call of a power of 95,000 megawatts.
Demand for electricity is at its peak, while five nuclear reactors are still stationary, compared with just one last year at the same time. Already in November, Electricity Transmission System (TEN), which is responsible for supplying energy to France, warned that the peak would be “more delicate to insure than in previous winters, by reason of unavailability of several production sites “.
Indeed, multiple stops of nuclear reactors had to be programmed during the year 2016, after the revelation in April and then in July, dozens of anomalies in the design of the parts equipping the nuclear reactors. Reporter told you in detail the whole matter. After checking, the Nuclear Safety Authority (ASN) authorizes EDF to restart the reactors one after another.
“A Fukushima-type accident is possible”
“But there was pressure on the ASN. Seeing the cold spell come, EDF has done everything possible to restart its reactors as soon as possible, “says Stéphane Lhomme, director of the association Nuclear Observatory. For him, the safety conditions are not met and “a Fukushima-type accident is possible”.
That is why his association has asked the courts to suspend three of ASN’s restarting authorizations for the Dampierre 3, Gravelines 2 and Tricastin 3 reactors. Why these three? “Because they were the first ones who were allowed to restart,” explains Stéphane Lhomme. The suspension and suspension were examined by the Council of State on Friday 13 January, which should give its decision no later than Wednesday.
The parts on which defects were discovered are the steam generators located in the reactor building. For these documents, the IRSN (the Institute for Radiation Protection and Nuclear Safety) explains that there is “exclusion of rupture”: that is, the consequences of their failure would be so great that Is not even taken into account in nuclear safety scenarios.
“In particular, the steel of the parts near the reactor must be able to withstand violent thermal shocks. At any time, it may be necessary to pour cold water onto the steam generators, “explains Stéphane Lhomme. Abnormal carbon concentrations have been identified in the steel tanks of the generators, making them potentially more fragile than expected. The maximum recommended concentration by the ASN is 0.22%, while the controls have shown that some zones in the tanks have a concentration of up to 0.39%. For the Nuclear Observatory, ASN’s authorizations to restart reactors do not comply with its own regulations and violate the precautionary principle. These are the reasons that were invoked before the Council of State.
In their defense, ASN and EDF recall that the 0.22% recommended is not included in the law, which is therefore not infringed. Especially, according to them the risk is not so high that feared the Nuclear Observatory. “The sudden rupture [of the steel] occurs in the event of the simultaneous appearance of three parameters”, indicates the ASN in its brief, which Reporterre consulted, to the Council of State: a material of “insufficient toughness” , A crack in this material and a thermal shock. The fragility of steel tanks is therefore not dangerous on its own, says the ASN.
And then, restarting the reactors is allowed with some precautions, called “compensatory measures”. Everything is done now to avoid thermal shocks, the authority reassures us. The operation of the pumps capable of pouring water abruptly onto the reactor is, for example, modified, the temperature variations during starting and stopping of the reactor are limited, etc.
“It’s DIY!” Worries Stéphane Lhomme. Initially, it is known that emergency water can be needed at any time, so a steel is resistant to thermal shocks. Henceforth, as it is no longer certain that it resists, we reverse and we do everything to avoid them. It is as if one noticed that the brakes of the car are worn, and that it was decided that now it will be the other drivers to be careful to avoid having to brake brutally! “
Another concern, as ASN indicated in its brief, is that these “compensatory measures” have become “operational measures in their own right”. In other words, “they want to continue like that for years,” Stéphane Lhomme translated. However, the resistance of these parts will continue to degrade because they are continuously subjected to radiation and thermal shocks. “
That is why, according to Stéphane Lhomme, the decision to restart the reactors would at least have been “a national debate to ask the question: are nuclear safety measures optional when it is cold? “
In its memorandum, which Reporterre consulted, in court, EDF acknowledges having already given its answer: stopping reactors with poor workmanship “in cold winter, where electricity needs are increased, would pose serious problems for the security of energy supply ‘.
Source : Marie Astier for Reporterre