Characteristics of a Mixed Thorium - Uranium Dioxide High-Burnup Fuel

Conference · Tue Jun 01 00:00:00 EDT 1999

OSTI ID:911390

Herring, James Stephen; Mac Donald, Philip Elsworth

Future nuclear fuel must satisfy three sets of requirements: longer times between refueling; concerns for weapons proliferation; and development of a spent fuel form more suitable for direct geologic disposal. This project has investigated a fuel consisting of mixed thorium and uranium dioxide to satisfy these requirements. Results using the SCALE 4.3 code system indicated that the mixed Th-U fuel could be burned to 72 MWD/kg or 100 MWD/kg using 25% and 35% UO2 respectively. The uranium remained below 20 % total fissile fraction throughout the cycle, making it unusable for weapons. Total plutonium production per MWD was a factor of 4.5 less in the Th-U fuel than in the conventional fuel; Pu-239 production per MWD was a factor of 6.5 less; and the plutonium produced was high in Pu-238, leading to a decay heat 5 times greater than that from plutonium derived from conventional fuel and 40 times greater than weapons grade plutonium. High decay heat would require active cooling of any crude weapon, lest the components surrounding the plutonium be melted. Spontaneous neutron production for plutonium from Th-U fuel was 2.3 times greater than that from conventional fuel and 15 times greater than that from weapons grade plutonium. High spontaneous neutron production drastically limits the probable yield of a crude weapon. Because ThO2 is the highest oxide of thorium, while UO2 can be oxidized further to U3O8, ThO2- UO2 fuel may be a superior wasteform if the spent fuel is ever to be exposed to oxygenated water. Even if the cost of fabricating the mixed Th-U fuel is $100/kg greater, the cost of the Th-U fuel is 13% to 25% less than that of the fuels using uranium only.

• Research Organization: Idaho National Laboratory (INL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC07-99ID13727
• OSTI ID: 911390
• Report Number(s): INEEL/CON-99-00141
• Conference Information: ANS 1999 Annual Meeting,Boston, MA,06/06/1999,06/10/1999
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
direct geologic disposal
NEUTRONS
nuclear fuel
NUCLEAR FUELS
OXIDES
PLUTONIUM
PRODUCTION
PROLIFERATION
refueling
spent fuel
SPENT FUELS
spontaneous neutron production
THORIUM
thorium and uranium dioxide
URANIUM
URANIUM DIOXIDE
URANIUM OXIDES U3O8
WASTE FORMS
wasteform
WATER
WEAPONS
weapons proliferation