Temperature distribution in nuclear fuel rod and variation of the neutronic performance parameters in (D–T) driven hybrid reactor system

Abstract

Temperature distribution in nuclear fuel rod and variation of the neutronic performance parameters are investigated for different coolants under various first wall loads (Pw=2, 5, 7, 8, 9, and 10 MW m−2) in (D, T) (deuterium and tritium) driven and fueled with UO2 hybrid reactors. Plasma chamber dimension, DR, with a line fusion neutron source is 300 cm. The fissile fuel zone is considered to be cooled with four different coolants with various volume fractions, the volumetric ratio of coolant-to-fuel [ε(Vm/Vf) = 1:2, 1:1, and 2:1], gas (He, CO2), flibe (Li2BeF4), natural lithium (Li), and eutectic lithium (Li17Pb83). Calculation in the fuel rods and the behavior of the fissile fuel have been observed during 4 years for discrete time intervals of Δt=15 days and by a plant factor (PF) of 75%. As a result of the calculation, cumulative fissile fuel enrichment (CFFE) value indicating rejuvenation performance has increased by increasing Pw for all coolants and ε. Although CFFE and neutronic performance parameter values increase to the higher values by increasing Pw, the maximum temperature in the centerline of the fuel roads has exceeded the melting point (Tm>2830°C) of the fuel material during the operation periods. However, the best CFFE (11.154%) is obtained in gas coolant blanket for ε=1:2 (29.462% coolant, 58.924% fuel, 11.614% clad), under 10 MW m−2 first wall load, followed by flibe with CFFE=11.081% for ε=2:1 (62.557% coolant, 31.278% fuel, 6.165% clad), under 7 MW m−2, and flibe with CFFE=9.995% for ε=1:1 (45.515% coolant, 45.515% fuel, 8.971% clad), under 7 MW m−2 during operation period without reaching the melting point of the fuel material. While maximum CFFE value has been obtained in fuel rod row#10 in gas, natural lithium, and eutectic lithium coolant blankets, it has been obtained in fuel rod row#1 in flibe coolant blanket for all ε and Pw. At the same condition, the best neutronic performance parameter values, tritium breeding ratio (TBR)= 1.4454, energy multiplication factor (M)= 9.2018, and neutron leakage (L)= 0.0872, have been obtained in eutectic lithium coolant blankets for the ε=1:2, followed by gas, natural lithium, and flibe coolant blankets. The isotopic percentage of 240Pu is higher than 5% in all blankets for Pw⩾7 MW m−2, so that plutonium component in all blankets can be never reach a nuclear weapon grade quality during the operation period.