EU project targets nuclear accident combustion risk

A project to look at hydrogen and carbon monoxide combustion risk management in the case of severe accidents at nuclear power plants has been launched.

The EU-funded Horizon 2020 project, Accident Management of the Hydrogen/CO Combustion Risk (AMHYCO), started on 1 October, and will run for four years.

Severe accidents at nuclear plants are costly and potentially dangerous to humans and the environment. Adequate accident management measures are “paramount” for preventing and/or mitigating the consequences of these accidents, says AMHYCO.

During severe accidents, combustible gases can be released, leading to a potential explosion risk in the nuclear containment building. In the 2011 Fukushima meltdown, when water in the pressure vessels of unit three evaporated, fuel rods inside the reactor were exposed and then reacted to produce hydrogen which then ignited. There were 13 hydrogen explosions at the plant. Gases, including CO and H₂, need to be managed to avoid threatening the containment integrity which can lead to releases of radioactive material into the environment, according to the release.

The main objective of AMHYCO is to propose innovative enhancements to the way combustible gases are managed in severe accidents at currently-operating reactors. To reach its objective, the project has three specific goals.

Firstly, it aims to improve Severe Accident Management Guidelines (SAMGs) with respect to combustible gases risk management, using theoretical, simulated, and experimental results. SAMGs are used to guide reactor operators on handling the response of nuclear power plants against severe accidents. They need to be regularly updated and include knowledge gained from international efforts, including recent and ongoing research projects.

AMHYCO will contribute to these efforts by improving understanding of H₂/CO combustion and incorporating this knowledge into SAMGs.

Secondly, the project will experimentally investigate phenomena that are difficult to predict theoretically. It will look at H₂/CO combustion and passive autocatalytic recombiners (PARs) behaviour under accident conditions, taking into account their interactions with safety systems. PARs are implemented in the containment of water-cooled power reactors to mitigate the risk of hydrogen combustion.

The final aim of the project is to improve the predictability of analysis tools which are used for explosion hazard evaluation inside the reactor containment and providing support to SAMGs design and development.

According to AMHYCO, previous EU and OECD (Organisation for Economic Co-operation and Development) projects have not addressed nuclear plant accident H₂/CO combustion risk.

Led by Universidad Politécnica de Madrid (UPM), Spain, the AMHYCO project will be run by an international partnership which involves 12 organisations from six European countries, and one from Canada. It will benefit from the worldwide expertise in combustion science, accident management, and nuclear safety of members of its Advisory Board.

The project has been endorsed by NUGENIA, an international organisation dedicated to research and development of nuclear fission technologies, with a focus on generation II and III nuclear reactors.