@article{oai:repo.qst.go.jp:00048656,
 author = {朝倉, 伸幸 and 星野, 一生 and 鈴木, 哲 and 徳永, 晋介 and 染谷, 洋二 and 宇藤, 裕康 and 工藤, 広信 and 坂本, 宜照 and 日渡, 良爾 and 飛田, 健次 and 清水, 勝宏 and 江里, 幸一郎 and 大野, 哲靖 and 上田, 良夫 and 朝倉 伸幸 and 星野 一生 and 鈴木 哲 and 徳永 晋介 and 染谷 洋二 and 宇藤 裕康 and 工藤 広信 and 坂本 宜照 and 日渡 良爾 and 飛田 健次},
 issue = {12},
 journal = {Nuclear Fusion},
 month = {Oct},
 note = {Power exhaust to the divertor and the conceptual design have been investigated for a steady-state DEMO in Japan with 1.5 GW-level fusion power and the major radius of 8.5 m, where the plasma parameters were revised appropriate for the impurity seeding scenario. A system code survey for the Ar impurity seeding suggested the volume-averaged density, impurity concentration and exhaust power from the main plasma of Psep = 205-285 MW. The divertor plasma simulation (SONIC) was performed in the divertor leg length of 1.6 m with the fixed exhaust power to the edge of Pout = 250MW and the total radiation fraction at the edge, SOL and divertor (Prad/Pout = 0.8), as a first step to investigate appropriate design of the divertor size and geometry. At the outer target, partial detachment was produced near the strike-point, and the peak heat load (qtarget) at the attached region was reduced to ~5 MWm-2 with appropriate fuel and impurity puff rates. At the inner divertor target, full detachment of ion flux was produced and the peak qtarget was less than 10 MWm-2 mostly due to the surface-recombination. These results showed a power exhaust scenario and the divertor design concept. An integrated design of the water-cooling heat sink for the long leg divertor was proposed. Cu-ally (CuCrZr) cooling pipe was applicable as the heat sink to handle the high heat flux near the strike-point, where displacements per atom rate was estimated to be 0.5-1.5 per year by neutronics calculation. An arrangement of the coolant rooting for Cu-alloy and Reduced Activation Ferritic Martensitic (RAFM) steel (F82H) pipes in a divertor cassette was investigated, and the heat transport analysis of the W-monoblock and Cu-alloy pipe under the peak qtarget of 10 MWm-2 and nuclear heating was performed. The maximum temperatures on the W-surface and Cu-alloy pipe were 1021 and 331C. Heat flux of 16 MWm-2 was distributed in the major part of the coolant pipe. These results were acceptable for the plasma facing and structural materials.},
 pages = {126050-1--126050-12},
 title = {Studies of Power Exhaust and Divertor Design for a 1.5 GW-level Fusion Power DEMO},
 volume = {57},
 year = {2017}
}