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In situ calibration of the neutron activation system on the Large Helical Device (LHD) was performed by using an intense 252Cf neutron source. To simulate a ring-shaped neutron source, we installed a railway inside the LHD vacuum vessel and made a train loaded with the 252Cf source run along a typical magnetic axis position. Three activation capsules loaded with thirty pieces of indium foils stacked with total mass of approximately 18 g were prepared. Each capsule was irradiated over 15 h while the train was circulating. The activation response coefficient (9.4 ± 1.2) x 10-8 of 115 In(n, n')115mIn reaction obtained from the experiment is in good agreement with results from three-dimensional neutron transport calculations using the Monte Carlo neutron transport simulation code 6. The activation response coefficients of 2.45 MeV birth neutron and secondary 14.1 MeV neutron from deuterium plasma were evaluated from the activation response coefficient obtained in this calibration experiment with results from three-dimensional neutron calculations using the Monte Carlo neutron transport simulation code 6. [ABSTRACT FROM AUTHOR]

Abstract: Quartz glasses of KU-1 and KS-4V are candidate window materials for the ITER optical diagnostics in UV and visible range. The temperature dependence of the radiation-induced transmission losses in UV range has been investigated under γ-ray irradiation for the KU-1 and KS-4V quartz glasses up to 10MGy. The KU-1 and KS-4V quartz glass samples were irradiated at room temperature, 100, 200 and 300°C. Dose rate was 0.46–1.1MGy, and 2.6Gy/s from 1.1 to 10.4MGy. It was confirmed that there is no significant loss in wavelength range longer than 350nm for both window materials. Transmission loss in KU-1 is larger than that in KS-4V under temperature below 200°C. KU-1 has large temperature dependence. On the other hand, temperature dependence is not clear in KS-4V above 100°C. Prominent recover of the transmission loss was not observed after irradiation for each sample. From the transmission loss point of view, KS-4V is better window material than KU-1 at temperature below 200°C. KU-1 is available at 300°C. [Copyright &y& Elsevier]

Irradiation tests of a mica substrate bolometer were carried out at the Japan Materials Testing Reactor up to the fast neutron fluence of 0.1 dpa. A performance of the bolometer was investigated during the irradiation. Significant increase of the meander resistance from 275 to 446 Ω was observed in the fast neutron fluence of 0.06 dpa. In the post-irradiation examination (PIE), it was confirmed that the gold meander contained 46% mercury which was produced by the nuclear transmutation reaction of 197Au(n, γ) 198Au→198Hg+β−. The bolometer sensitivity was measured by the change of the meander resistance for the input power. The sensitivity decreased slightly at constant reactor power. There was not significant change in the bolometer response time. During the cool down phase of the first cycle all connections went open circuit. Some recovered on start-up of the second cycle, however, all connections went open circuit again near the end of the second cycle. They were not recovered any more at the third cycle. Breaks of the gold meander were observed in the PIE. The use of gold meanders might be problematic in ITER. [Copyright &y& Elsevier]

Examines the irradiation effects on potential diagnostic materials and components of the International Thermonuclear Experimental Reactor. Radiation-induced electrical damage and conductivity in potential insulators; Radiation-induced absorption and radio luminescence in potential optic materials; Changes to reflectivity and surface properties of bulk metal mirrors.

Abstract: This paper summarizes the proposals and findings of the IFMIF Specification Working Group established to update the users requirements and top level specifications for the facility. Special attention is given to the different roadmaps of fusion pathway towards power plants, of materials R&D and of facilities and their interactions. The materials development and validation activities on structural materials, blanket functional materials and non-metallic materials are analyzed and specific objectives and requirements to be implemented in IFMIF are proposed. Emphasis is made in additional potential validation activities that can be developed in IFMIF for ITER TBM qualification as well as for DEMO-oriented mock-up testing. [Copyright &y& Elsevier]

In order to evaluate neutron activation of materials relevant to the liquid blankets such as Lithium/vanadium-alloy and Flibe/vanadium-alloy blankets, irradiation experiments have been performed using the fusion neutronics source (FNS) at JAEA. Specimens of Er, Teflon (CF2=CF2) and NIFS-HEAT-2 (V–4Cr–4Ti) were selected in the experiments for the evaluations of the activation of Er in the MHD coating (Er2O3), F in Flibe (LiF–BeF2) and V, Cr, Ti in the structural materials, respectively. The irradiation experiments were performed with two kinds of neutron field: D–T neutrons and Be moderated neutrons for the purpose of reaction with high and low energy neutrons, respectively. The neutron spectra calculations were carried out using Monte Carlo transport codes MCNP-4C and JENDL3.3 files. The neutron-induced activity measured with a high purity Ge detector was compared with calculations carried out by the FISPACT-2001 codes and EAF-2001 files. The results showed that the calculated activities of most of products through reaction with high energy neutrons are in agreement with the experiments within 20% uncertainty. [Copyright &y& Elsevier]

Abstract: In order to investigate the activation performance of prospective materials of the IFMIF facility, we have carried out irradiation experiments with the AVF cyclotron in the TIARA facility of the Japan Atomic Energy Research Institute (JAERI). We measured the production cross sections of the nuclides Cu-61, Cu-64, Zn-62 and Zn-63 by deuterons irradiation of copper with natural isotope abundance (natCu) in the energy range of 22–40MeV. The obtained cross sections were compared with data from the ACSELAM library and with previously measured cross section data. The comparisons revealed that some of the ACSELAM cross section data are different from the experimental data and have to be improved. [Copyright &y& Elsevier]

A shutdown dose experiment was conducted by using the FNS at JAERI under the ITER R&D Task T-426, in order to evaluate the accuracy of the shutdown dose evaluation method. The activation and the delayed gamma-ray distribution after passing through the straight duct were simulated in the experiment. The experiment was conducted at the 80° beam line of the FNS and the irradiation was carried out over 6 days. The experimental analyses were carried out by using the new direct one step Monte Carlo method that is used as the design tool to estimate shutdown dose of the ITER/FEAT. The nuclear data packages, FENDL-2/MC and FENDL-2/A, were compared through the analysis of the experiment. As a result, the following facts were found for the accuracy of the shutdown dose evaluation: (1) the C/E values of the shutdown dose at around 106 s after the irradiation were 0.92–1.07; (2) the shutdown dose rate could be evaluated by the new direct one-step Monte Carlo method within the experimental error, and the accuracy of the method is sufficient for shielding design of the International Thermonuclear Experimental Reactor (ITER). [Copyright &y& Elsevier]