Cracks discovered in the walls of Belgian nuclear reactors are causing unease among experts. The reason: a previously unknown phenomenon – material fatigue. There are fears that many more reactors could be affected.
Several thousand cracks have been discovered by corrosion experts in the pressure vessels of two reactors at the Belgian nuclear power stations Doel 3 and Tihange 2. Caused by a previously unknown phenomenon, material fatigue, it is feared the finding could have implications outside of Belgium.
The discovery of the cracks in the reactors “could be a problem for the entire global nuclear industry,” says Jan Bens, general director of the Belgian Federal Agency for Nuclear Control (FANC), speaking on Belgian TV.
Examination of nuclear reactors demanded
Of most concern are the cracks that have been found in the walls of pressure vessels, the part of reactors where the highly radioactive chain reaction takes place. During such a process, the vessel is under extreme stress and instability caused by the cracks could cause a potentially catastrophic release of radioactive contamination.
It is already known that pressure vessels can become fatigued as a result of stress caused by pressure, temperature and radioactive materials. But the Belgian Nuclear Research Center in Mol has only just found out “that the material is mechanically weakened through radiation much more than previously thought,” says Heinz Smital, nuclear physicist and expert at Greenpeace.
Nuclear material corrosion expert Walter Bogaerts, of Belgium’s University of Leuven says that corrosion factors have until now been “underestimated”, globally. He adds: “I would be really surprised if it had not also occurred elsewhere.”
Reactors could be shut down
Digby MacDonald, an expert in corrosion at the University of California, Berkley, analyzed the cracks together with Bogaerts and has advised nuclear reactor operators and government regulators that they should use ultrasound equipment to carefully examine reactors for cracks. “All reactor operators should be require under the leadership of regulatory authorities,” says MacDonald. He adds that the results of such detailed investigations “could be insignificant, or so strong that all the reactors must be shut down.”
According to nuclear experts, hydrogen from the reactor can penetrate the reactor wall and there in the steel increase the interior pressure causing small bubble and cracks from just a few millimeters in size “up to seven centimeters”, says Smital.
Using special ultrasound equipment, experts discovered 13,047 cracks in total in the Belgian reactor Doel 3 and 3,149 in Tihange 2. The reactors have been shut down, as a result. Whether they will once again be connected to the network is, as of yet, unclear.
Danger for the nuclear industry
The appearance of the cracks as a result of material fatigue has caused a tide of reaction. Safety checks are being demanded all over world and “could lead to a wave of reactor closures”, says Smital.
Greenpeace successfully sued the Belgian nuclear authority FANC in January following the publication of the detailed investigative documents. “It's a very delicate matter and could indeed have a huge impact on the whole nuclear industry,” says Smital. Greenpeace is demanding that all reactors worldwide are closely examined.
The German Environment Ministry has also reacted and is seeking to have immediate contact with the Belgian authorities to see whether the findings could be applicable to German reactors.
But according to Greenpeace, the Belgian findings confirm the growing threat posed by old nuclear power plants. The world’s reactors now have an average age of 29 years. “That is no longer state-of-the-art, which can be dangerous, even when you upgrade,” says Smital. “What are now needed are scenarios for a shut down of plants. Every country needs a get-out plan.”