19 Sep (NucNet): Inspections in August at the Tihange-2 and Doel-4 nuclear power plants in Belgium have shown concrete degradation in the ceilings of bunkerised buildings that house backup safety systems for the plants, the nuclear regulator has said.
The Belgian Federal Agency for Nuclear Control (Fanc) said analysis is being carried out to make a precise diagnosis of the problem before repair work begins. The results of the analysis and the potential method of repair will be discussed by Fanc and its Bel V technical subsidiary.
At Tihange-2, indications of concrete degradation had already been noted during previous inspections and repair work was already planned before the most recent inspections.
The issue first came to light in 2017 when, during planned shutdowns of the Tihange-3 and Doel-3 plants, operator Engie Electrabel noted deterioration in the concrete ceilings and walls of similar bunkerised buildings.
At the time, Fanc said the other plants likely to have been affected, Tihange-2 and Doel-4, would need to be inspected during their next scheduled shutdowns.
Repair work has been completed at Doel-3 and Fanc gave the go-ahead for its restart in July 2018. Tihange-3 remains offline while repair work is being carried out.
The various buildings house safety equipment including emergency pumps, diesel generators and equipment used to rapidly reduce the steam pressure in a primary or secondary cooling loop if normal pressure reduction systems are too slow or not available.
At Doel-3 inspection showed the degradation was caused by continuous exposure of the concrete to hot and humid conditions.
At Tihange-3 the degradation was attributed to the exposure of the concrete ceiling to a jet of high temperature steam released during a test of one of the valves.
