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    Investigation of neutronic potential of a moderated (D-T) fusion driven hybrid reactor fueled with thorium to breed fissile fuel for LWRs
    (PERGAMON-ELSEVIER SCIENCE LTD, 2000) Yapici, H; Sahin, N; Bayrak, M
    The potential of a moderated hybrid reactor fueled with ThC2 or ThF4 is investigated by a PF (plant factor) 75% under a first wall fusion neutron current load of 5 MW/m(2) LWR (Light Water Reactor) fuel rods containing ThC2 or ThF4 are replaced in the fissile fuel zone of the hybrid reactor. It is considered that gas (He or CO2), or flibe (Li2BeF4), or natural lithium is the coolant. The behaviour of the neutronic potential is observed for four years. At the end of the operation period, the Cumulative Fissile Fuel Enrichment (CFFE) values varied between 3.55 and 7% depending on the fuel and coolant type. Calculations show that the best neutronic performance is obtained with Flibe, followed by air and natural lithium coolants. After 48 months, the maximum CFFE value is 7% in the ThF4 fuel and flibe coolant mode, and the lowest CFFE value 3.55% is in the ThC2 fuel and natural lithium coolant mode. Consequently, these enrichments would be sufficient for LWRs. The Tritium Breeding Ratio (TBR) values are greater than 1.05 for all investigated natural lithium coolant modes, and the investigated hybrid reactor is self-sufficient in the tritium required for the D,T fusion driver in these modes during the operation period. The blanket energy multiplication factor M, varies between 2.45 and 3.68 depending on the type of fuel and coolant at the end of the operation period. At the same time, the peak-to-average fission power density ratio decreases by similar to 25%. The lowest radial neutron leakage out of the blanket is in the blanket with the flibe coolant modes. (C) 1999 Elsevier Science Ltd. All rights reserved.
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    Neutronic performance of proliferation hardened thorium fusion breeders
    (ELSEVIER SCIENCE SA, 2001) Sahin, S; Yapici, H; Sahin, N
    Production of denaturated fissile fuel in a thorium fusion breeder has been investigated by mixing the fertile fuel with natural-UO2 and LWR (light water reactors) spent nuclear fuel. Four different coolants (pressurised helium, Flibe 'Li2BeF4', natural lithium and Li17Pb83 eutectic) are selected for the nuclear heat transfer. In order to obtain a power flattening in the fissile-fertile zone, the UO2- or the spent fuel-fraction in the mixed oxide (MOX) fuel has been gradually increased in radial direction. Power plant operation periods between 13 and 29 months are evaluated to achieve a fissile fuel enrichment similar to4%, under a first-wall fusion neutron energy current of 5 MW m(-2) (plant factor of 100%). For a plant operation over 4 years, enrichment grades between 6.0 and 11.5% are calculated for the investigated MOX fuel and coolant compositions. The U-238 component of natural-UO2 can provide a limited proliferation hardening only for the U-233 component, whereas, the homogenous mixture of ThO2 with a small quantity of (>4%) LWR spent nuclear fuel remains all-over non-prolific for both, uranium and plutonium components. (C) 2001 Elsevier Science B.V. All rights reserved.