@misc{oai:repo.qst.go.jp:00072771,
 author = {Asakura, Nobuyuki and Hoshino, Kazuo and Uto, Hiroyasu and Someya, Yoji and Tokunaga, Shinsuke and Suzuki, Satoshi and Ezato, Koichiro and Seki, Yoji and Kudo, Hironobu and Shimizu, Katsuhiro and Sakamoto, Yoshiteru and Hiwatari, Ryoji and Tobita, Kenji and Ohno, Noriyasu and Ueda, Yoshio and 朝倉 伸幸 and 星野 一生 and 宇藤 裕康 and 染谷 洋二 and 徳永 晋介 and 鈴木 哲 and 江里 幸一郎 and 関 洋治 and 工藤 広信 and 清水 勝宏 and 坂本 宜照 and 日渡 良爾 and 飛田 健次},
 month = {Oct},
 note = {Power handling and the divertor design has been investigated in steady-state Japan DEMO concept of 1.5 GW-level fusion power (Pfus) and the major radius of Rp = 8.5m. System code survey suggested to increase the plasma elongation (k95) from 1.65 to 1.75, loading to increasing Ip and ne, in order to obtain Pfus larger than 1.5 GW in the impurity seeding scenario, where the radiation power in the main plasma (Pradmain) is 180 MW (Pradmain/Pheat = 0.41, where Pheat= 430 MW), impurity concentration in the main plasma, (nAr/ne)core, of 0.5-0.75%. Design of the divertor size and geometry for the power exhaust parameter (Psep/Rp) of 29 MWm-1 was investigated by the divertor simulation (SONIC), where the outer leg lengths of 1.6 and 2.0 m were compared for a high radiation fraction (Praddiv/Pheat = 0.44). For the shorter leg divertor, the peak qtarget at the attached region (Tediv ~20 eV, Tidiv ~30eV) in the partial detached divertor was ~5 MWm-2 and it was also ~5 MWm-2 mostly due to the surface-recombination in the inner divertor (Tediv = Tidiv ~1eV). The longer leg divertor was preferable to reduce qtarget since the partial detachment extended to the outer flux surface, while the size of the vessel and TFC become larger. It was found that Cu-ally (CuCrZr) cooling pipe is applicable as the heat sink to handle the high heat flux near the strike-point, where displacements per atom (DPA) rate on Cu-alloy was estimated to be 1-2 per year from neutronics calculation. Coolant rooting for Cu-alloy and RAFM steel pipes and the flow velocities were determined to handle the peak qtarget of 10 MWm-2 level and the total thermal and nuclear heat removal of 300 MW and 118 MW, respectively. Heat transport and thermomechanical analyses of the W-monoblock and Cu-alloy pipes were performed. The maximum temperature of the Cu-ally pipe was 331C at the side surface. Heat flux of 16 MWm-2 is distributed in the major part of the interlayer side, while the maximum heat flux of 25 MWm-2 was localized near the poloidal side surface of the monoblock, which was acceptable level. The physics and engineering results were consistent for an integrated DEMO divertor design, which can handle the peak qtaret of 10 MWm-2 level. The integrated design of the two different water-cooling heat sinks for the divertor with Ldiv = 1.6m was shown., 26th IAEA Fusion Energy Conference},
 title = {Physics and Engineering Design Studies on Power Exhaust and Divertor for a 1.5 GW Fusion Power DEMO},
 year = {2016}
}