REQUIREMENTS OF TRITIUM BREEDING RATIO FOR EARLY FUSION POWER-REACTORS

Requirements of tritium breeding ratio and the initial inventory of tr itium for early fusion power reactors were investigated with a calcula tion model. The results of calculated time-dependence of tritium inven tory were examined, in particular from the following three points of v iew; the doubling time of tritium inventory in the storage system to p rovide the initial inventory of the next plant, the recovery time in w hich the tritium inventory in the storage system recovers to the initi al value and the minimum tritium storage required during the operation . The following limits were adopted to evaluate the results, i.e., the doubling time shorter than 3 years, the recovery time shorter than 1 year and the minimum storage larger than the tritium for 50 days burn up. For a reference case, which assumes reasonable performance paramet ers of the fuel processing subsystems, the requirements for the tritiu m breeding ratio and the initial tritium inventory were estimated to b e 1.10 and 27.6 kg, respectively. If a poor tritium processing system is assumed, the requirements become inevitably higher. On the other ha nd, mitigation of the requirements is not conspicuous even with a good processing system. The obtained results suggest that the high perform ance tritium processing is indispensable, but still insufficient for a chievement of tritium self-sufficiency. From the point of view of trit ium fuel supply, a blanket system with high tritium breeding ratio is also indispensable in early stage of fusion power reactor development, in order to introduce fusion reactors at a reasonable pace.