The thorium molten salt reactor
E. D. Greaves 1*, K. Furukawa 2, H. Barros 1, L. Sajo-Bohus 1
1 Laboratorio de Física Nuclear, Universidad Simón Bolívar, Caracas, Venezuela.
2 Thorium Tech Solution Inc., Japan
Current technology, PWR and BWR, solid uranium-fuelled, nuclear power reactors suffer from a number of important shortcomings among which are the production of weapons proliferation plutonium, an inefficient 5% utilization of the energy content of the fuel requiring periodic nuclear fuel rod exchange, the production of extremely long lived, highly toxic fuel waste and the use of a high pressure vessel which constitutes a mayor accident safety issue. The Molten Salt Reactor (MSR), invented and operated during the 1960s and 1970s at Oak Ridge National Laboratory (ORNL), USA, and developed as FUJI reactor by Furukawa and collaborators  in the 1980s and 1990s, addresses all of these shortcomings. In the thorium MSR, 232Th replaces 238U as the n-capture fertile isotope for the production of fissile 233U with a fraction (~10-2) production of long-lived actinides, including troublesome 239Pu. A high temperature (550-700 oO) fluid, a fluoride of lithium and beryllium (FLIBE) with dissolved fissile 233U (or 235U or 239Pu prepared from solid spent-fuels) replaces the solid fuel elements and serves the triple function of fuel, heat transfer and waste reprocessing medium leading to high thermal efficiency (~ 44% in comparison with some 32%). A simple low pressure (0.5 MPascal or 4.93 Atm or 72,5 PSI) Ni-alloy (Hastelloy N) reactor vessel houses the graphite moderator, fluid fuel and one or two graphite control rods ensuring extremely high safety margins. The initial reactor fuel charge and conversion ratio (1,002) results in almost fuel self-sufficiency for the reactor life. At variance with the ORNL MSR, the FUJI reactor does not incorporate fuel reprocessing at the power reactor. However, it incorporates radioactive gas removal such as 133Xe and 135Xe leading to the absence of poison gas accumulation in the fuel and allowing the reactor to follow the power load. Global electric energy demand grows at an average 2.3% yearly with a doubling time of 30 years. The only non- CO2 emitting and technologically developed alternative for long term supply of this energy demand is a short doubling-time nuclear technology. The Thorium Molten Salt Reactor within the THORIMS-NES fuel cycle system meets these requirements. Additionally it has the virtue of simplicity with positive impact on capital and operating costs. As described, this technology meets 4th generation nuclear reactor safety standards, nuclear weapons non-proliferation and a partial solution to long term nuclear waste. Abundant and proven thorium resources worldwide and in particular in Brazil and Venezuela make this the technology of choice for the South American continent.
 K. Furukawa, et al., (17 coauthors) A road map for the realization of Global scale Thorium Breeding Fuel Cycle by single Molten-Fluoride Flow. Energy Conversion & Manag. 49, (2008) 1832-1845.