FANC, the Belgian nuclear regulator, is examining every available aspect of material science as it seeks to understand the reasons for the corrosion that compromised its reactor pressure vessels at Doel 3 and Tihange nuclear power plant (pictured).
Nele Scheerlinck, spokesperson for FANC, told Power Engineering International late Thursday evening that there is still a lot of uncertainty about what damage hydrogen flakes are causing but also pointed out that the recommendation made by their director general wasn’t new, FANC having issued the same declaration in 2012.
“What we don’t know yet is to what extent these hydrogen flakes affect the robustness of the RPV’s steel wall in case of a thermal shock. Since we are entering uncharted territory here, we convened an international review board of material scientists to help us analyse the data that Electrabel is providing us with. So far, these experts have come to no conclusion other than that it is still way too early for any conclusions.”
Scheerlinck also told PEi that additional research being carried out by two academics was also being taken into consideration.
“Walter Bogaerts from Leuven University and Digby Macdonald from the University of California, both corrosion experts (material scientists) say that there is still another phenomenon (in short: hydrogen atoms getting trapped in microvoids (flakes) in the steel without possibility to escape) that might occur in nuclear reactors showing hydrogen flakes (or other flaws) and that might lead to the tearing of the RPV’s steel wall.”
“We have asked them to send us the paper in which they present this hypothesis, so that we might check if it contains any elements that should be taken into consideration in the Doel 3/Tihange 2 dossier. It should be noted here that Macdonald has stated explicitly that he doesn’t know for sure if this phenomenon really poses a problem, but that he thinks that it should at least be examined – and as a nuclear regulator, we agree.”