Development of benchmark reduced activation ferritic/martensitic steels for fusion energy applications

Tanigawa, Hiroyasu; Gaganidze, E.*; Hirose, Takanori; Ando, Masami; Zinkle, S. J.*; Lindau, R.*; Diegele, E.*

Nuclear Fusion, 57(9), p.092004_1 - 092004_13, 2017/06

https://doi.org/10.1088/1741-4326/57/9/092004

The current status of RAFM developments and evaluations, including the applicability of joining technologies, is reviewed. The technical challenges and potential risks of utilizing RAFM steels as the structural material of in-vessel components are discussed, and possible mitigation methodology is introduced. The discussion suggests that deuterium-tritium fusion neutron irradiation effects currently need to be treated as an ambiguity factor which could be incorporated within the safety factor. The safety factor will be defined by the engineering design criteria which are not yet developed with regard to irradiation effects and some high temperature process, and the operating time condition of the in-vessel component will be defined by the condition at which those ambiguities due to neutron irradiation become too large to be acceptable, or by the critical condition at which 14 MeV fusion neutron irradiation effects is expected to become different from fission neutron irradiation effects.

Actively convected liquid metal divertor

Shimada, Michiya; Hirooka, Yoshihiko*

Nuclear Fusion, 54(12), p.122002_1 - 122002_7, 2014/12

https://doi.org/10.1088/0029-5515/54/12/122002

Tungsten is considered to be the most promising material for divertor in a fusion reactor. Tungsten divertor can withstand the heat loads of ITER, but the heat loads of DEMO divertor is a challenge. Pulsive heat loads as those associated with disruption could melt tungsten targets. The surface would not be flat after subsequent resolidification, which would significantly deteriorate its heat handling capability. Furthermore, DBTT of tungsten is rather high: 400C, which would become even higher after neutron irradiation, possibly resulting in cracks in tungsten. Our proposal is to use liquid metal for the divertor target material and actively circulate it with force. A simplified analysis of mhd equation in a cylindrical geometry suggests that the engineering requirement is modest. This analysis suggests that this new divertor concept merits further investigation.

Evaluation of contact strength of LiTiO pebbles with different diameters

Tsuchiya, Kunihiko; Kawamura, Hiroshi; Tanaka, Satoru*

Fusion Engineering and Design, 81(8-14), p.1065 - 1069, 2006/02

https://doi.org/10.1016/j.fusengdes.2005.07.031

no abstracts in English

Confinement of alpha particles in a low-aspect-ratio tokamak reactor

Tani, Keiji; Tobita, Kenji; Iio, Shunji*; Tsutsui, Hiroaki*; Nishio, Satoshi; Aoki, Takayuki*

Denki Gakkai Rombunshi, A, 125(11), p.938 - 942, 2005/11

https://doi.org/10.1541/ieejfms.125.938

Studies on the loss of fusion produced alpha particles enhanced by toroidal field (TF) ripple in a low-aspect-ratio tokamak reactor (VECTOR) have been made by using an orbit-following Monte-Carlo code. The ripple loss is strongly reduced as the aspect ratio becomes low. Consequently, alpha particles are well confined in VECTOR. Thanks to the good confinement of alphas in a low-aspect-ratio system, the number of TF coils can be reduced to about 6, one half of the original VECTOR, by installing cooling systems near the outer edge of plasma and making allowances for about 30% increase in the bore diameter of TF coils.

Effects of gelation and sintering conditions on granulation of LiTiO pebbles from Li-Ti complex solution

Tsuchiya, Kunihiko; Kawamura, Hiroshi; Casadio, S.*; Alvani, C.*

Fusion Engineering and Design, 75-79, p.877 - 880, 2005/11

https://doi.org/10.1016/j.fusengdes.2005.06.063

no abstracts in English

Control of particle size and density of LiTiO pebbles fabricated by indirect wet processes

Tsuchiya, Kunihiko; Kawamura, Hiroshi; Takayama, Tomoo*; Kato, Shigeru*

Journal of Nuclear Materials, 345(2-3), p.239 - 244, 2005/10

https://doi.org/10.1016/j.jnucmat.2005.06.005

no abstracts in English

Intelligible seminar on fusion reactors, 7; Optimum materials for the realization of fusion reactor

Hasegawa, Akira*; Tsuchiya, Kunihiko; Ishitsuka, Etsuo

Nihon Genshiryoku Gakkai-Shi, 47(8), p.536 - 544, 2005/08

http://ci.nii.ac.jp/naid/10015604920

no abstracts in English

Local bonding states of ion-irradiated graphite characterized by photon-stimulated desorption (PSD) spectroscopy

Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.

Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.437 - 441, 2005/06

https://doi.org/10.1016/j.elspec.2005.01.156

no abstracts in English

Low temperature tritium release experiment from lithium titanete breeder material

Tsuchiya, Kunihiko; Kawamura, Hiroshi; Nakamichi, Masaru*; Sagawa, Hisashi

JAERI-Tech 2005-013, 56 Pages, 2005/03

JAERI-Tech-2005-013.pdf:6.4MB

no abstracts in English

Optimization study on the normal conducting center post for the low aspect ratio tokamak reactor

Song, Y.*; Nishio, Satoshi

Fusion Engineering and Design, 72(4), p.345 - 362, 2005/01

https://doi.org/10.1016/j.fusengdes.2004.08.002

This paper presents detailed optimization results and design windows for the engineering design of normal conducting (NC) center post based on the analysis of thermal-hydraulic, static stress and critical buckling. At the same time a method to reduce the stress in the center post have been proposed, which can be applied to enhance the possibility of normal conducting center post in the future power plants. When the method of improvement for reducing the stress is applied in the system of the center post, the maximum magnet field can be improved from 8.6T to 15T.