Investigation of the performance parameters and temperature distribution in fuel rod dependent on operation periods and first wall loads in fusion–fission reactor system fueled with ThO 2

Abstract

The neutronic performance parameters, fissile breeding and temperature distribution in the fuel rod are investigated for different coolants (‘He, CO 2’, ‘Li 2BeF 4’, ‘Li’, and ‘Li 17Pb 83’) in the fissile fuel breeding zone with volume ratios of V coolant/ V fuel, ε, (0.5,1,2) under various first wall loads ( P w=2–10 MW m −2) in a fusion–fission reactor fueled with ThO 2. Depending on the type of coolant in the fission zone, first wall loads and volume ratios, fusion power plant operation periods between 1 and 4 years are evaluated to achieve a fissile fuel enrichment quality between 1.2274% and 13.7305% in the above mentioned situation for intervals of half month and by plant factor of 75%. A fusion reactor with (D,T) reaction acts as an external high energetic neutron source. The fissile fuel zone, containing 10 fuel rod rows in the radial direction, covers the cylindrical fusion plasma chamber with 300 cm chamber dimension. At the end of four years, the cumulative fissile fuel enrichment (CFFE) values, indicating rejuvenation performance, increased to 10.184%, 12.218%, 9.650% and 11.089% from 0% in gas, flibe, natural lithium and eutectic lithium coolant blankets with ε=0.5 for 10 MW m −2, respectively, without reaching the melting point of the fuel material. However, for ε=1, the CFFE values increased to 10.59% (the best CFFE value for gas coolant), 11.372%, 10.414% (the best CFFE value for natural lithium coolant) and 10.963% from 0% in the above mentioned coolants for 10 MW m −2, respectively. In the same way, for ε=2, the CFFE increased to 10.181%, 13.7305% (the best CFFE value for all coolants), 9.1369% and 11.4809% (the best CFFE value for eutectic lithium coolant) for 10 MW m −2, respectively. At the beginning of the operation period, for ε=0.5, the tritium breeding ratio (TBR) values, being about 0.9092, 0.7075, 0.7921 and 0.9512 for the above mentioned coolants, respectively, at the end of four years increased to 1.2924, 1.1475, 1.0724 and 1.441 (the highest TBR value for all blankets) for 10 MW m −2. For ε=1, these increments are 1.3067, 1.2303, 1.1653 and 1.4033 for 10 MW m −2. However, for ε=2, these values are 1.2256, 0.9993, 0.9341 and 1.4069 for 10 MW m −2 without reaching the melting point of the fuel material. For ε=0.5, the blanket energy multiplication ( M) increases to 2.7349, 2.8045, 2.5685 and 2.8183 (the highest M value for all blankets) for 10 MW m −2 from 2.1534, 2.0251, 2.0918 and 2.0793 in the blankets cooled with gas, flibe, natural lithium and eutectic lithium coolants, respectively, at the end of four years. These increments become 2.6707, 2.7301, 2.4332 and 2.7812 for 10 MW m −2 from 2.1037, 1.8985, 2.004 and 1.9874, respectively, for ε=1. However, the blanket energy multiplication ( M) increases to 2.4122, 2.4573, 2.1413 and 2.3800 for 10 MW m −2 from 2.0196, 1.7323, 1.8658 and 1.8303, respectively, for ε=2. The maximum temperatures in the centerline of the fuel rods have not exceeded the melting point of the fuel material for all coolants and ε under changing first wall loads between 2 and 10 MW m −2 during the operation periods. While the maximum CFFE values have been obtained in fuel rod row#10 in the gas, natural lithium and eutectic lithium coolant blankets, it has been obtained in fuel rod row#1 in the flibe coolant blanket for all ε and P w. Therefore, the investigated hybrid blankets are self-sufficient for all coolant and volume fractions and P w=10 MW m −2. The best neutron economy has been shown by flibe.