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Kai, Tetsuya; Harada, Masahide; Maekawa, Fujio; Teshigawara, Makoto; Konno, Chikara; Ikeda, Yujiro
Journal of Nuclear Science and Technology, 41(Suppl.4), p.172 - 175, 2004/03
In J-PARC neutron source, intense protons (3 GeV,1 MW) pass through a proton-beam window and bombard a Hg target in a target-moderator-reflector-assembly (TMRA). The SS316 target chamber is the most highly activated. Decouplers (Ag-In-Cd (AIC) alloy) are also highly activated. Some neutron extraction holes of Be and AL-coated iron reflector are lined with AIC alloy. A SS316 shield is located outer the TMRA. All these components are cooled by H
O or DO. We estimated the induced-radioactivity of the TMRA components and the cooling water using NMTC/JAM, MCNP4 and DCHAIN-SP. As results, the remote maintenance and massive shields were indispensable. For example, a 30 cm thick Fe cask for the reflector assembly was necessary to attenuate the radiation less than 1 mSv/h. The cask required a 130-ton crane. The AL-coated Fe of the reflector was adopted instead of SS316 resulting in eliminating the high activity of Ni in SS316 and reduction of the cask weight. Based on these results, shielding wall designs and maintenance scenarios of the highly activated components are developed.
Matsuda, Norihiro; Nakashima, Hiroshi; Kasugai, Yoshimi; Sasamoto, Nobuo*; Kinno, Masaharu*; Kitami, Takayuki; Ichimura, Takahito; Hori, Junichi*; Ochiai, Kentaro; Nishitani, Takeo
Journal of Nuclear Science and Technology, 41(Suppl.4), p.74 - 77, 2004/03
In high power proton accelerator facilities, concrete shield can be highly activated, which makes maintenance work quite difficult. So, a low-activationized concrete (limestone concrete) is to be partially adopted as a concrete shield for Japan Proton Accelerator Research Complex (J-PARC) aiming at reducing 
-ray exposure dose during maintenance period. A new quantity, 
Na-equivalent, was introduced as a criterion to assure effectiveness of the low-activationized concrete. In order of its verification, powdered low-activationized concrete and ordinary one were irradiated using FNS at JAERI. The measurements were analyzed by a shielding design code system being used for J-PARC, showing that the calculations reproduce the measured induced activity within a factor of 2. Furthermore, by using the same code system, -ray exposure dose was calculated for the configuration of J-PARC to find out that -ray exposure dose by the low-activationized concrete was about 10 times lower than that by the ordinary concrete in a period of less than a few days after operation.
Kai, Tetsuya; Maekawa, Fujio; Kasugai, Yoshimi; Niita, Koji*; Takada, Hiroshi; Meigo, Shinichiro; Ikeda, Yujiro
Proceedings of ICANS-XVI, Volume 3, p.1041 - 1049, 2003/07
A radioactivity calculation code system DCHAIN-SP was validated in view of the following points: (1) Activation cross section data library for the energy region below 20 MeV. (2) NMTC/JAM code for calculation of the nuclide yield induced by the high energy particles above 20 MeV. (3) DCHAIN-SP code system which treats overall nuclide yield by the high energy particles. 42 of activation cross sections and 22 tritium production cross sections were revised so that the DCHAIN-SP calculation could improve its accuracy within 30% for typical materials irradiated by 14-MeV neutrons. The NMTC/JAM code was improved to implement the GEM model for better estimation of light fragment production. Accuracy of the nuclide yield for proton induced reactions in 10 MeV - 10 GeV still remains in the level of a factor of 2 to 3. The DCHAIN-SP code system was employed for the analysis of time evolution of the radioactivity produced in the samples on a thick mercury target bombarded with 2.83 and 24 GeV protons. It is found that the code system agrees with the measured data by a factor of 2 to 3.
Kai, Tetsuya; Maekawa, Fujio; Kasugai, Yoshimi; Kosako, Kazuaki*; Takada, Hiroshi; Ikeda, Yujiro
JAERI-Research 2002-005, 65 Pages, 2002/03
JAERI-Research-2002-005.pdf:2.75MB
Reliability assessment for the High Energy Particle Induced Radioactivity Calculation Code DCHAIN-SP 2001 was carried out through analysis of integral activation experiments with 14-MeV neutrons. The following three series of experiments conducted at the D-T neutron source facility, FNS, in JAERI were employed: (1) the decay gamma-ray measurement experiment for fusion reactor materials, (2) the decay heat measurement experiment for 32 fusion reactor materials, and (3) the integral activation experiment on mercury.As a result, it was found that the calculations with DCHAIN-SP 2001 predicted the experimental data for (1)
(3) approximately within 30%, 20% and 20%, respectively. It was concluded that the activation cross section data below 20 MeV and the associated decay data as well as the calculation algorithm for solving the Beteman equation that was the master equation of DCHAIN-SP were adequate.
Harada, Masahide; Yamaguchi, Yuji; Hashimoto, Norimichi*; Ito, Taku*; Tajima, Takahiro*; Oku, Takayuki; Haga, Katsuhiro; Ikeda, Hiroshi*; Tamura, Satoshi*
no journal, ,
In Materials and Life Science Experimental Facility at J-PARC, carbon and mercury targets bombarded by 3 GeV and 1 MW proton beam produce muons and neutrons to provide to muon and neutron instruments. As the samples irradiated by muons and neutrons produce radioactive materials, an estimation of the radioactive materials produced in the irradiated samples is necessary for the stable operation and management of the facility. Therefore, a sample radio-activity evaluation code was developed using data from the DCHAIN-SP-2001 code. By selecting the irradiation conditions for each experiment and entering the information for each sample, the radio-activity of a sample can be calculated by multiplying the neutron flux by the activation cross section. The code is a servlet application, programed by JAVA, accessible on the Web, and can be used from the internal network. In the future, we will conduct activation experiments on various materials and validate this code.
Matsuda, Norihiro
no journal, ,
no abstracts in English
