Nuclear and Thermal Analyses of Supercritical-water-cooled Solid Breeder Blanket for Fusion DEMO Reactor

Abstract

Within a design study of a fusion DEMO reactor aiming at demonstrating technologies of fusion power plant, supercritical water is applied as a coolant of solid breeder blanket to attain high thermal efficiency. The blanket has multi-layer composed of solid breeder pebbles (Li 2 O) and neutron multiplier pebbles (Be) which are radially separated by cooling panels. The first wall and the breeding region are cooled by supercritical water below and above the pseudocritical temperature, respectively. Temperature distribution and tritium breeding ratio (TBR) have been estimated by one-dimensional nuclear and thermal calculations. The local TBR as high as 1.47 has been obtained after optimization of temperature distribution in the breeder region under the following conditions: neutron wall loading of 5 MW/m 2 , 6 Li enrichment of 30% and coolant temperature at inlet of breeder region of 380 • C. In the case of the higher coolant temperature 430 • C of the breeder region the local TBR was reduced to be 1.40. This means that the net TBR higher than 1.0 could be expected with the supercritical-water-cooled blanket, whose temperature distribution in the breeder region would be optimized by following the coolant temperature, and where a coverage of the breeder region is assumed to be 70%.

Design and technology development of solid breeder blanket cooled by supercritical water in Japan

“…The nuclear heating rate and TBR have been estimated using APPLE-3 code. By using the values of nuclear heating rate obtained, one-dimensional thermal analysis has been performed to obtain the temperature distribution [6]. The net TBR is required to be more than 1.05 for stable operation and accumulation of startup fuel for the next fusion plant [7].…”

“…The net TBR is required to be more than 1.05 for stable operation and accumulation of startup fuel for the next fusion plant [7]. Figure 3 shows the distribution of the local TBR in the radial thickness direction, together with the temperature distribution in the case where 30% 6 Li-enriched Li 2 TiO 3 and Be were applied as the breeder and multiplier materials. As can be seen from this figure, the temperature of the breeder can be kept below the temperature limit of 900˚C.…”

Three-dimensional flow measurement of a water flow in a sphere-packed pipe by digital holographic PTV

“…Japan Atomic Energy Agency has been performing research, development and design of a blanket module with a water cooled ceramic breeder (WCCB) for ITER and DEMO of a nuclear fusion reactor [1][2][3][4]. Pebbles of a ceramic tritium breeder are packed in a container of the blanket.…”

Measurement of tritium production rate in water cooled pebble bed multi-layered blanket mockup by DT neutron irradiation experiment

“…The water cooled pebble bed blanket being developed by the Japan Atomic Energy Agency consists of Li 2 TiO 3 or Li 2 O small pebbles with enriched 6 Li as tritium breeder, beryllium small pebble as neutron multiplier, ferritic steel F82H as structural material and water as coolant [1]. The TBR is around 1.1 for the present DEMO reactor design, therefore a prediction uncertainty is required to be less than 10% [1,2] to guarantee the TBR more than unity. Neutronics experiments were conducted on simple mockup by using DT neutrons in the previous studies [3][4][5][6][7].…”