SAFETY CHARACTERISTICS OF THE SCNES CORE

The core concept of the Self-Consistent Nuclear Energy System (SCNES) and its safety characteristics have been investigated from the view po int of the elimination of recriticality. The recriticality potential c an be eliminated based on characteristics of self-controllability to p revent the core damage and self-terminability to Limit the propagation of core disruption. These two characteristics are simultaneously achi eved by the radial heterogeneous two region core with different height . This core consists of leading and driver zones where hybrid metallic fuels with different melting point are installed. The self-controllab ility can be achieved by decreased coolant density effect due to the a bove core sodium plenum at the leading zone. The self-terminability is achieved by the Controlled Material Relocation (CMR), which is essent ially the preceding downward in-pin fuel relocation selectively genera ted at the leading zone. U-Pu-1Zr alloy is used to the leading zone fu el due to lower melting point (900 degrees) than the driver fuel of U- Pu-10Zr(1100 degrees C). Based on the quantitative investigations, it was emphasized that the recriticality potential can be eliminated by t he in-pin fuel CMR even for severe unscrammed events such as a total p ump stick for the primary coolant system and a total control rods with drawal. (C) 1997 Published by Elsevier Science Ltd.