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Radiation effects in components and materials will be one of the most serious technological issues in nuclear fusion systems realizing burning-plasmas. Especially, diagnostic components, which should play a crucial role in controlling plasmas and understanding the physics of burning-plasmas, will be exposed to high-flux neutrons and gamma rays. Dynamic radiation effects will affect the performance of components substantially from the beginning of exposure to radiation environments, and accumulated radiation effects will gradually degrade their functioning abilities in the course of their service. High-power-density fission reactors will be the only realistic tools to simulate the radiation environments expected to occur in burning-plasma fusion machines such as the International Thermonuclear Experimental Reactor (ITER), at present. Some key diagnostic components, namely magnetic coils, bolometers, and optical fibres, were irradiation-tested in a fission reactor, to evaluate their performances in heavy radiation environments. Results indicate that ITER-relevant radiation-resistant diagnostic components could be developed in time, although there are still some technological problems to be overcome.

A `common basis' systems study of superconducting (SC) and normal conducting (NC) DT burning fusion power and materials testing reactor designs is presented. The figures of merit for power and materials testing reactors are, respectively, projected cost of electricity (COE) and direct cost. A common 0-D plasma modelling basis is used and the plasma geometry and engineering aspects of the SC and NC designs are treated in an equivalent manner that is consistent with the limitations of their respective magnet technologies. Aspect ratios A in the range 1.2≤A≤6 and plasma elongations κ in the range 1.5≤κ≤3 are explored and an MHD stability (beta limit) physics basis that accurately describes the increase of normalized beta βN and toroidal beta βT with decreasing A and/or increasing κ is incorporated. With this MHD basis taken into account and with the usual reactor geometry, physics and engineering constraints and costing bases applied, the results of the study show that for SC power reactor designs with κ = 2 the COE has a minimum for 2≤A≤3 and increases with a further increase in A(A>3). For NC power reactors the COE has minima at A≈2. For both SC and NC power reactors, the minima are more apparent with lower κ. While SC options appear to offer lower COE for power plants, the direct cost for NC test reactors with similar fusion power output is significantly lower. Within the NC category, test designs that combine modest A and maximum elongation show promise for achieving ITER-like testing capabilities at low direct cost. For example, an NC coil design with A = 2, κ = 3 could produce fusion power of 200 MW at 1.23 MW/m2 average neutron wall loading at a total direct cost of about 650 million US dollars. This NC design with a fissile blanket could also convert about 1270 kg of fission reactor waste per full power year. A possible cost effective development scenario for fusion power is identified for NC A = 2 toroidal devices for physics and material testing studies for use in the near future. The selection of the SC or NC coil option could then be made for the construction of the demonstration power reactor.

Emission monitoring of radionuclides has been performed since 1959 at the Studsvik site at the Baltic coast in the county of Södermanland, 80 km south of Stockholm. Several small nuclear reactors have been used at the site. Today only one 50 MW high-flux pool-type materials testing reactor (MTR) and one 1 MW low-power pool reactor are used. In the R2 reactor, testing of nuclear reactor fuel, production of radioisotopes for medical purposes and neutron transmutation doping of silicon are performed. A facility for boron neutron capture therapy (BNCT) for medical treatments at the R2-0 reactor will be in operation by the year 2000. The University of Uppsala has a department of neutron research at the reactor. Other types of nuclear work done at Studsvik are decontamination, incineration, melting and recycling of low-level waste. Yearly emissions are much smaller than the limit, 0.1 mSv per year to the critical group, set by the Swedish authority.

Thermal shock tests of neutron irradiated carbon fiber reinforced carbon composites (CFCs) were started with OHBIS to study the neutron irradiation effects on the erosion behavior. Specimens were one directional, two directional and three directional CFCs. These specimens were irradiated with a total neutron fluence of 0.3–0.4 dpa at 556-594 K using Japan Materials Testing Reactor. Heat load conditions were 20 MJ m-2 (800 MW m-2 × 25 ms and 500 MW m-2 × 40 ms). It was clear that the weight loss of the neutron irradiated specimens increased with neutron fluence, and that the erosion area of the neutron irradiated specimens were broader than that of the un-irradiated specimens.

Results are given of some experiments to measure the light output from NE 102 and NE 421 scintillators under neutron radiographic conditions. These are then used to interpret an experiment in which an image intensifier was used to provide immediate radiography by direct viewing of a scintillating plate placed in the Materials Testing Reactor neutron radiography unit at Dounreay.