Introduction to the Physics of Thorium Molten Salt Fast Reactor (MSFR) Concepts

Recent conceptual developments on fast neutron spectrum molten salt reactors (MSFRs) using fluoride salts have kindled renewed interest in molten salt reactors. This concept, operated in the thorium fuel cycle, may be started either with 233U, enriched U, and/or transuranic elements as the initial fissile load. This paper describes some studies and developments around the MSFR concept based on the thorium fuel cycle. MSFRs are seen as a long-term alternative to solid-fueled fast neutron systems thanks to their unique potential, which includes large negative temperature and void coefficients, lower fissile inventory, no initial criticality reserve, a simplified fuel cycle, waste reduction, etc. They have been selected as one of the reference reactors of the Generation IV International Forum.