On 17 September 2002 a large-scale test involving the melting of material representative of a light water reactor core was successfully carried out as part of the MASCA Project, set up at the Kurchatov Institute in Moscow under OECD Nuclear Energy Agency (NEA) auspices. The project addresses the convective molten pool of prototypic core melt material and constitutes a follow-up to the Rasplav Project. It has been designed to ensure that the results generated will be of relevance to the reactors operating in NEA member countries as well as to Russian-designed pressurised water reactors (VVER). Furthermore, the project is applicable to both current and future reactor designs.
During the test, core material was heated to over 2000°C under controlled conditions. Steel was introduced after melting of the material and the test was continued for another half hour before reaching a steady state. All measuring and engineering systems functioned normally during the experiment. The post-test examination will consist of sectioning the solidified material and performing metallographic examination to gain information yielded by the test. Complex physical and chemical phenomena have been observed in earlier MASCA tests. The knowledge gained from those tests led to accurate predictions of the behaviour of the pool during this latest test. All major nuclear safety organisations in OECD countries are actively using the results of the project to further develop computer models that will be used to assess the situation in their power reactors. There will be a conference in France in 2004 to present the results.
MASCA is the latest link in a chain of international projects aimed at refining strategies for maintaining the integrity of reactor pressure vessels in the highly improbable event of a core meltdown. Retaining the integrity of the reactor pressure vessel for such accidents, which are estimated to have a probability of occurrence of less than 1 in l0 000 years of reactor operation, will help prevent the release of radioactive material to the environment.
The MASCA Project brings together 16 NEA member countries and Russia. The participating Russian organisations are the Russian Research Centre "Kurchatov Institute", the Russian Ministry of Atomic Energy, the Ministry of Industry, Science and Technology and the Federal Nuclear and Radiation Safety Authority of Russia. The MASCA Project is a major international nuclear reactor safety undertaking which started in July 2000, and is due to end in June 2003. The experimental work is being carried out at the Kurchatov Institute; the analytical work is being done at the Institute of Nuclear Safety (IBRAE) of the Russian Academy of Sciences; and design work and some testing is being carried out by other organisations in the St. Petersburg region.