The first version of the software simulates the formation of the explosive atmosphere, then the deflagration of the reactive mixture of hydrogen and oxygen. This type of event represents a major risk of aggravating the consequences of a core melt accident at a nuclear reactor.
The accident at the Japanese Fukushima Daiichi NPP in March 2011 proved the devastating nature of a hydrogen explosion in a reactor, particularly for the containment of radioactive material. Thus, IRSN developed its own simulation tool, the software P2REMICS, to better control the complexity of the phenomenon modeled, and the relevance of the calculations made.
Developed as part of research into the hydrogen risk associated with severe accidents, the first version of the P2REMICS software simulates the formation of the explosive atmosphere, then the deflagration of the reactive mixture of hydrogen and oxygen. It can also be used to calculate dust deposition and aerosol transport, to simulate the interaction of a spray safety system with the containment atmosphere, and to factor in the effect of the hydrogen recombiners.
P2REMICS v1.0 has been put through a verification process consisting of 16 test cases and a validation process using 25 experimental tests. It required the development of computer models as well as the construction of numerical schemes for the resolution of balance equations obtained. This work has been facilitated by the research in theoretical analysis achieved by Raphaele Herbin (Institute of mathematics of Marseille), which earned her the medal of innovation of France's national scientific research center CNRS in 2017.
The software is already being used in intercomparison work carried out nationally, such as the Mithygene research project and internationally, such as exercises run by the OECD/NEA.