No abstract available

[en] Electrical properties of ceramic candidate materials for the next-generation nuclear fusion devices under relevant irradiation conditions are reviewed. A main focal point is placed on the degradation behavior of the electrical insulating ability during and after irradiation. Several important radiation induced effects play important roles: radiation induced conductivity, thermally stimulated electrical conductivity, radiation induced electrical charge separation, and radiation induced electromotive force. These phenomena will interact with each other under fusion relevant irradiation conditions. The design of electrical components for the next-generation fusion devices should take into account these complicated interactions among the radiation induced phenomena

No abstract available

[en] Reliable plasma diagnostics systems are key elements for an efficient operation of future fusion reactors. They represent a major challenge, as existing systems must be upgraded to the harsh environment of a burning plasma and to the stringent requirements of real-time control actions. Radiation effects bring in this respect specific constraints. The front ends of most of the diagnostics systems are inside the vacuum vessel, and therefore subject to intense neutron and γ radiations. These systems use particular components, such as ceramic insulators, dielectric and optical windows, optical fibres and complete sensor assemblies. Studying radiation effects for these components requires particular attention to the material choice and a specific methodology. The paper makes a review of the research performed worldwide on this subject and discusses the state of the art and the future priorities to be set

[en] Actinides are attracting keen interests in research fields of solid state physics and are expected to reveal interesting electromagnetic properties. However, most of actinide isotopes are very hazardous α radioactively. Also, they perform the experimental works for actinides physics and chemistry. In this paper, we will describe the facility developed in Tohoku university for the handling actinide elements and will show some preliminary results obtained on the study of electromagnetic properties

[en] Radiation effects on functional materials used in the plasma heating system and the plasma diagnostic system of D-T reactors are overviewed. They include insulating ceramics, covering and insulating materials of electrical cables, silica and sapphire as vacuum window materials, optical fibers and coats on mirrors. As examples, the radiation induced electrical degradation of insulators and coloring of optical glasses are given. Promising radiation-tolerant materials for use in D-T reactors are discussed. (T.I.)

[en] This paper presents the current status of utilization of overseas reactors for study of radiation effects in materials as joint use research at International Research Center for Nuclear Materials Science, Institute for Materials Research (IMR), Tohoku Univ. (IMR-Oarai Center). Japan Materials Testing Reactor (JMTR) which had been mainly utilized for material irradiation at IMR-Oarai Center since 1970 was shut down in August 2006. Since then an overseas reactor, BR2 at SCK/CEN in Belgium, has been used in order to continue our irradiation programs and perform advanced material irradiation in collaboration with SCK/CEN for development of new irradiation techniques in BR2. In this paper, the features of irradiation facilities/devices in BR2 such as CALLISTO, MISTRAL, ROBIN and BAMI and the irradiation programs in 2006-2008 with use of each facility/device are described

[en] This paper outlines the present status of in-situ studies of radiation effects on materials. In-situ studies in fission reactors are indispensable, particularly to the development of nuclear fusion functional ceramics. In addition, they promise new possibilities for the advancement of studies of radiation effects on materials. Circumspect developments of radiation techniques comprise the initial phase of establishing fusion neutron engineering. (author)

[en] Degradation of electrical insulating ability of ceramic insulators is attracting keen attention especially in fusion reactor developments. A permanent increase of the electrical conductivity of the ceramic insulators has been observed recently in certain irradiation conditions, which is called the radiation induced electrical degradation (RIED). Its nature and mechanism are still controversial, but recent experimental results are confirmative to support the existence of the phenomenon causing the degradation of the bulk electrical conductivity of some ceramic insulators under certain irradiation conditions. The paper will review the recent experimental results and discuss the nature and the mechanism of the degradation. (author)

[en] Development of a system for optical measurements in a nuclear reactor has been progressing to investigate dynamic changes in a material caused by heavy irradiation. In such system, transfer of optical signals to out-pile measuring systems is being attempted by the use of optical fibers. In this report, the characteristics of optical fibers in the heavy irradiation field were summarized. It has been known that amorphous silica might produce radiolysis and structural defects by the exposure to ionizing radiation. The effects of heavy irradiation on molten silica were extremely complicated. A large intensity of visible light absorption occurred from an early time during start-up of the reactor. The absorption range was limited below 700 nm for the radiation associating fast neutron and the absorption was mostly attributed to non-bridging oxygen hole center. The depletion of optical transferring capacity under the radiation might be related to the internal stress. Therefore, it seems desirable to use optical fibers in the conditions without leading too much stress. (M.N.)