Progress of the ST-VNS study

Progress is given on the investigation of a low cost, scientifically attrac tive, and technologically feasible volumetric neutron source (VNS) based on the spherical torus (ST) concept. The ST-VNS has a major radius of 1.07 m, an aspect ratio of 1.4, and a plasma elongation 3. It can produce a neutro n wall loading ultimately up to 5 MW/m(2) averaged over the outboard test s ection when the fusion power reaches 380 MW. Initial operation of this devi ce can be at a level of I MW/m2 or lower. Higher performance blanket compon ents can be developed to raised the neutron wall loading. Using staged high wall loading operation scheme and optimistic availability projected for th e VNS device, a neutron fluence of more than 30 MW-y/m(2) can be expected t o accumulate within 20 years of operation. Assessments of lifetime and reli ability of fusion core components will thus be allowed in a power reactor r elevant environment. A full-function testing of fusion core components may also become possible because of the high neutron wall loading capability. I ntegrated testing of tritium breeding in such a full scale power reactor re levant VNS device can be very useful to verify the self-sufficiency of fuel cycle in candidate power blanket concepts.