Evaluation of the tungsten alloy vaporizing lithium first wall and blanketconcept

This paper reports the results of the second phase evaluation of the EVOLVE W-alloy first wall and blanket design cooled by vaporizing lithium. For th e transpiration-cooled first wall and blanket concept, we identify the need to further quantify the data of lithium superheat from W-alloy heated surf ace and bulk lithium slabs. For the boiling lithium blanket, we identify th e need to elucidate the impacts of magnetic field on various stable-boiling regimes. We also find that this FW/blanket concept should have no problem in achieving adequate nuclear performance. With the addition of passive coo ling loops, the concept has a strong possibility of achieving the safety re quirement of not needing a public evacuation plan under the loss of power a ccident conditions. Even though the irradiated W-alloy may be subject to em brittlement, due to the relatively low system pressure of the design, it is shown to be able to withstand a large number of cracks. The fundamental is sues of W-alloy properties under high neutron fluence irradiation and the c omponents fabrication technique remain. Preliminary investigations of W-all oy fabrication and heat flux removal through SBIR programs have begun and t he initial results are encouraging. We recommend that the investigation of critical issues of the EVOLVE concept continue since this innovative design has a good possibility of showing a way to achieve high performance and pa ssively safe designs that are necessary for the utilization of fusion power .