Inspections carried out by France's nuclear safety authority the Autorité de Sûreté Nucléaire (ASN) in March 2017 and 2018 to examine how safety regulations relating to the risk of explosions at four of the country's nuclear power stations plants are implemented highlight lapses in procedure and equipment, Mediapart can reveal. They show that in the power plants at Chinon, Flamanville, Penly and Paluel, operators EDF have failed to respect what are known as the ATEX rules on controlling potentially explosive atmospheres and have underestimated the risks of explosions at these centres. These findings, which Mediapart has seen, did not however feature in a recent Parliamentary report which called for improvements in safety in France's nuclear industry.
Since 1999 an European Union directive has required all businesses to evaluate the risks of an explosion on their premises and to implement regulations to avoid them. As far back as 2008 the ASN put EDF on formal notice to ensure that the nuclear plant at Cruas in southern France complied with the rules. Several lapses had been spotted at the plant, in particular in pipes in which an explosion could have led to the dispersal of radioactive material into the plant, or even the surrounding area.
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EDF's underestimation of the risk had more serious consequences elsewhere. On May 23rd, 2014, at the Tricastin nuclear plant in south-east France, an explosion occurred in a sampling area situated in the main area of the plant, known as the nuclear island. One employee, who was carrying out measurements on gas pipes to check for radioactivity, was injured. A leak from a connection and a build-up of hydrogen caused the explosion. Neither the ASN nor state-back utility company EDF made the incident public.
Four years later, at the nuclear power station at Paluel, in northern France, an ASN inspector noticed faults identical to those that had caused the explosion at Tricastin. They warned EDF: “The still very incomplete nature of explosion risk control in the sampling areas, even though it's close to four years after the accident that occurred on May 23rd, 2014 at the CNPE [editor's note, nuclear power station] at Tricastin … shows that the way in which explosion risk has been understood up to now is not clear and must urgently be reconsidered.”
The rest of the assessment about Paluel is damning. It says that several zones where an explosive atmosphere could form, particularly involving hydrogen, have not been regarded by EDF as 'ATEX zones', in other words risk zones. In one room containing several pipes carrying hydrogen, no leak detection measure had been installed, nor was there equipment to ensure toxic gases could be evacuated. Yet the risk of such a leak is very real, as one occurred at the nuclear plant in November 2017.
In certain zones staff have to intervene when the concentration of hydrogen is above the authorised limit. Here, again, there was no warning system provided to tell them to leave in case of danger. The 2018 report demands that EDF sort out this situation as soon as possible.
And in those cases where hydrogen detection measures were in place, the ASN inspector found that they were regularly out of order.
Ventilation systems are crucial in order to avoiding all risk of explosion in such zones. They help avoid a build up of potentially dangerous gases in the atmosphere. On this the ASN inspector at Paluel notes: “The ventilation systems could not be inspected as your representatives told me that they had no reference manual or operating instructions.” In other words, no one knows if these safety measures are enough and if the equipment is maintained. The inspector told EDF that these failings could have consequences for safety at the facilities.
Another way of reducing the risk of explosion in such areas is for staff to wear specific antistatic outfits and for them to avoid using certain objects and equipment. But the ASN inspection revealed that no instructions had been given to the staff. As a result, the report said, this could lead to “the introduction of unsuitable materials” that could cause an explosion.
Finally, EDF has a duty to give staff and all subcontracting companies a document informing them of the dangerous zones and of the particular safety rules to follow to avoid risk of an explosion. In particular this includes crucial instructions on how to access certain areas, the equipment to avoid and the places where the level of risk is especially high. This document is supposed to be kept up to date regularly but the inspection report at Paluel shows that this had not been done for four years. In the nuclear plant at Chinon in western France, this safety document had not been updated for ten years.
The observations of the inspectors at the nuclear plants at Paluel, Flamanville, Penly and Chinon are similar in nature. “One observes the designation non dangerous for places where the risk of explosion has been demonstrated,” says one. “The evaluations of risk as presented do not take account of the possibility that sources of combustion could be present nor of the extent of the consequences of an explosion,” is another comment. “The training given to management staff is not appropriate to the risks,” says one inspector. While another comments: “The preventative measures and the precautions implemented for each zone were not shown to the workers.” On occasions this dysfunctionality was noticed by ASN inspectors two years ago and had not been put right by EDF.
Because of the number and seriousness of breaches in the safety rules, the inspector in charge of the inspections at Penly, Flamanville and Paluel nuclear power stations told EDF that he was considering issuing a formal notice. This letter was sent in March 2018. Mediapart asked the ASN what follow up actions had been taken, but has had no response. EDF did not make any comment.
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- The French version of this article can be found here.
English version by Michael Streeter