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Journal Articles

Evaluation of tritium behavior in the epoxy painted concrete wall of ITER hot cell

Nakamura, Hirofumi; Hayashi, Takumi; Kobayashi, Kazuhiro; Nishi, Masataka

Fusion Science and Technology, 48(1), p.452 - 455, 2005/07

Times Cited Count：2 Percentile：17.57(Nuclear Science & Technology)

Tritium behavior released in ITER hot cell has been investigated numerically. Tritium behavior was evaluated by a combined analytical methods of a tritium transport analysis with the one dimensional diffusion model in the multi-layer wall (concrete and epoxy paint) and a tritium concentration analysis with the complete mixing model by the ventilation in the hot cell under the simulated hot cell operational conditions. As the results, tritium concentration in the hot cell volume decreases rapidly from 300 DAC (Derived Air Concentration) less than 1 DAC in several days after removing the tritium release source. Tritium inventory in the wall is estimated to be about 0.1 PBq for 20 years operation. On the other hand, Tritium permeation through the epoxy painted concrete wall will be negligible. Finally, as to the effect of epoxy paint on the tritium permeation and inventory, it is found that the epoxy paint can reduce tritium inventory by about two orders of magnitude relative to bare concrete wall.

Journal Articles

Evaluation of tritium permeation from lithium loop of IFMIF target system

Matsuhiro, Kenjiro; Nakamura, Hirofumi; Hayashi, Takumi; Nakamura, Hiroo; Sugimoto, Masayoshi

Fusion Science and Technology, 48(1), p.625 - 628, 2005/07

https://doi.org/10.13182/FST05-A1003

Times Cited Count：6 Percentile：40.41(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Review of JAERI activities on the IFMIF liquid lithium target in FY2004

Nakamura, Hiroo; Ida, Mizuho*; Matsuhiro, Kenjiro; Fischer, U.*; Hayashi, Takumi; Mori, Seiji*; Nakamura, Hirofumi; Nishitani, Takeo; Shimizu, Katsusuke*; Simakov, S.*; et al.

JAERI-Review 2005-005, 40 Pages, 2005/03

JAERI-Review-2005-005.pdf:3.52MB

The International Fusion Materials Irradiation Facility (IFMIF) is being jointly planned to provide an accelerator-based Deuterium-Lithium (Li) neutron source to produce intense high energy neutrons (2 MW/m $^{2}$ ) up to 200 dpa and a sufficient irradiation volume (500 cm $^{3}$ ) for testing the candidate materials and components up to about a full lifetime of their anticipated use in ITER and DEMO. To realize such a condition, 40 MeV deuteron beam with a current of 250 mA is injected into high speed liquid Li flow with a speed of 20 m/s. In target system, radioactive species such as 7Be, tritium and activated corrosion products are generated. In addition, back wall operates under severe conditions of neutron irradiation damage (about 50 dpa/y). In this paper, the thermal and thermal stress analyses, the accessibility evaluation of the IFMIF Li loop, and the tritium inventory and permeation of the IFMIF Li loop are summarized as JAERI activities on the IFMIF target system performed in FY2004.

Journal Articles

Application of glow discharges for tritium removal from JT-60U vacuum vessel

Nakamura, Hirofumi; Higashijima, Satoru; Isobe, Kanetsugu; Kaminaga, Atsushi; Horikawa, Toyohiko*; Kubo, Hirotaka; Miya, Naoyuki; Nishi, Masataka; Konishi, Satoshi*; Tanabe, Tetsuo*

Fusion Engineering and Design, 70(2), p.163 - 173, 2004/02

https://doi.org/10.1016/j.fusengdes.2003.11.001

Times Cited Count：19 Percentile：75.17(Nuclear Science & Technology)

In order to establish the effective and conventional in-vessel tritium removal method, glow discharge methods, usually used as wall conditioning, have been applied and examined in vacuum vessel of JT-60U for tritium removal characteristics and kinetics. Release rates of all hydrogen isotopes as well as hydrocarbons from JT-60U vacuum vessel induced by Glow Discharge Cleaning (GDC) with He and H $_{2}$ were measured. Release characteristics of hydrogen isotopes were classified into three different release processes each of which is well described by a simple exponential decay with time. It was found that H $_{2}$ GDC showed the superior hydrogen isotope release characteristics than the He GDC, probably because chemical processes, such as isotope exchanges assisted by the chemical sputtering process between discharged hydrogen and hydrogen isotopes plasma facing carbon tiles are enhanced by the H $_{2}$ glow discharge. Based on the release kinetics observed in the present work, it is estimated that it will take several days to reduce tritium inventory in the surface area of JT-60U to a half by continuous H $_{2}$ GDC at 573 K.

JAEA Reports

Nuclear, thermo-mechanical and tritium release analysis of ITER breeding blanket

Kosaku, Yasuo; Kuroda, Toshimasa*; Enoeda, Mikio; Hatano, Toshihisa; Sato, Satoshi; Sato, Shinichi*; Osaki, Toshio*; Miki, Nobuharu*; Akiba, Masato

JAERI-Tech 2003-058, 69 Pages, 2003/06

JAERI-Tech-2003-058.pdf:5.86MB

The design of the breeding blanket in ITER applies pebble bed breeder in tube (BIT) surrounded by multiplier pebble bed. It is assumed to use the same module support mechanism and coolant manifolds and coolant system as the shielding blankets. This work focuses on the verification of the design of the breeding blanket, from the viewpoints which is especially unique to the pebble bed type breeding blanket, such as, tritium breeding performance, tritium inventory and release behavior and thermo-mechanical performance of the ITER breeding blanket.

Journal Articles

Design of the ITER tritium plant, confinement and detritiation facilities

Yoshida, Hiroshi; Glugla, M.*; Hayashi, Takumi; Lsser, R.*; Murdoch, D.*; Nishi, Masataka; Haange, R.*

Fusion Engineering and Design, 61-62, p.513 - 523, 2002/11

https://doi.org/10.1016/S0920-3796(02)00105-9

Times Cited Count：28 Percentile：84.11(Nuclear Science & Technology)

ITER tritium plant is composed of tokamak fuel cycle systems, tritium confinement and detritation systems. The tokamak fuel cycle systems, composed of various tritium sumsystems such as vacuum vessel cleaning gas processing, tokamak exhaust processing, hydrogen isotope separation, fuel storage, mixing and delivery, and external tritium receiving and long-term storage, has been designed to meet not only ITER operation scenarios but safety requirements (minimization of equipment tritium inventory and reduction of environmental tritium release at different off-normal events and accident scenarios). Multiple confinement design was employed because tritium easily permeates through metals (at 150 $^{circ}$ C) and plastics (at ambient temperature) and mixed with moisture in room air. That is, tritium process equipment and piping are designed to be the primary confinement barrier, and the process equipments (tritium inventory 1 g) are surrounded by the secondary confinement barrier such as a glovebox. Tritium process rooms, which contains these facilities, form the tertiary confinement barrier, and equipped with emergency isolation valves in the heating ventillation and air conditioning ducts as well as atmosphere detritiation systems. This confinement approach has been applied to tokamak building, tritium building, and hotcell and radwaste building.