The project goal is to prevent the risk of explosion or ignition of combustible gases produced during a nuclear reactor core meltdown accident, as demonstrated by the accident at Fukushima Daiichi NPP.
In the event of a severe accident with a nuclear reactor core meltdown, flammable gases (mainly hydrogen, but also carbon monoxide) can accumulate in the reactor building and lead to explosions that could compromise the building’s integrity, as demonstrated by the accident at Fukushima Daiichi NPP. With this in mind, IRSN initiated and now coordinate the SAMHYCO-NET research project within the support of the international association for research NUGENIA.
Among other things, improvements are expected in: the knowledge on recombiner behavior and combustion phenomena; the procedures for managing late-phase severe accidents; and the efficiency of recombiners, particularly for reactors with double-walled concrete enclosures that present a risk of explosive atmosphere formation in the interspace.
The project will involve complex explosion and recombination tests on hydrogen-carbon monoxide mixtures, at temperatures and pressures representative of those encountered in the late phases of a severe accident. Indeed, the risk of explosion happens in the third stage of an accident, after the nuclear reactor core meltdown, the break through the pressure vessel and finally the interaction between the corium and the concrete of the foundation.