Conceptual design of a liquid metal limiter/divertor system for the FFHR-d1

A new liquid metal divertor system named the REVOLVER-D (Reactor-oriented Effectively VOLumetric VERtical Divertor) is proposed for the helical fusion reactor FFHR-d1. The REVOLVER-D is composed of molten tin shower jets stabilized by internal flow resistances of wire/tape/chain. These shower jets are inserted into the ergodic layer surrounding the main plasma. Tin is selected as the liquid metal because of its low melting point, low vapor pressure, low material cost, and high safety. The liquid metal pumps, cryopumps, and turbo molecular pumps are installed in the central vacuum vessel connected to the main vacuum vessel via 10 inner ports equipped with maze neutron shields. Central solenoid coils made of high-temperature superconductors are installed inside the central vacuum vessel to shield the pumps from the strong magnetic field. The REVOLVER-D has a good possibility to satisfy important characteristics required for the divertor system in a fusion reactor, that is, high heat load tolerance, high maintainability, sufficient vacuum pump speed, high level of safety, and a small amount of radioactive wastes

Maintainability of the Helical Reactor FFHR-c1 Equipped with the Liquid Metal Divertor and Cartridge-type Blankets

The maintenance scheme in the compact helical fusion reactor, FFHR-c1, equipped with the liquid metal divertor, REVOLVER-D (Reactor-oriented Effectively VOLumetric VERtical Divertor) and the cartridge-type molten salt blankets, CARDISTRY-B (CARtridges Divided and InSerTed RadiallY − Blanket), is investigated. The magnetic configuration of the compact variant FFHR-c1 is similar to that of the Large Helical Device (LHD), while the device size is 2.8 times enlarged from LHD and a strong magnetic field strength of ∼8 T at the plasma center is adopted. The maintenance of the REVOLVER-D is simpler than that of the helical divertor with a complicated structure as seen in the LHD. In the REVOLVER-D, showers of molten tin are injected into the ergodic layer at 10 inner ports. To circulate the molten tin, 10 sets of the shower system including a liquid metal pump, ducts, a showerhead, a pool, and a heat exchanger, are installed. These can be replaced with simple up/down motions. The CARDISTRY-B consists of 320 tritium breeding blanket cartridges, which are toroidally segmented every two degrees. These cartridges are maintained by using heavy manipulators with a simple 4DOF motion at a constant toroidal angle

筑後変成岩の岩石学的研究

The Chikugo metamorphic rocks are mainly composed of black schists, sandstone schists, green schists, small amounts of quartz schists and metamorphosed gabbroic intrusive rocks. No conglomerate and calcareous schists are found. The metamorphic rocks are gently folded and have two pairs of anticlinal and synclinal axis plunging from 5 to 7 degrees to the east. The Chikugo metamorphic rocks are intruded by granitic rocks of the Cretaceous age into their anticlinal parts and affected by the contact metamorphism. Four zones of metamorphism, A_1, A_2, B_1, B_2, are distinguished in the metamorphic area. Some ambiguitities, however, are present in defining the zone B2, because the rock of this zone may be affected by the granitic intrusions. There is no critical fact to distinguish them from the regional metamorphism. The zone A1 is confined to the gabbroic intrusions, characterrized by the presence of clinopyroxene, brown hornblende, pumpellyite and alkali amphibole. Mineral assembrages, epidote-pumpellyite-actinolite-diopside and chlorite-actinolite-epidote-brown hornblende, and a limited occurrence of alkali amphiboles to the central part of the northern half of the gabbroic intrusions, indicate water deficient conditions of this zone comparing to its neibouring schistose area. The zone A_2 is distinguished from the zone A_1 by the absence of clinopyroxene and brown hornblende, and from the zone B_2 by the presence of pumpellyite. The zone B_2 is characterized by the relatively wide occurrence of biotite in pelitic and samitic schists. The distribution of the metamorphic zones indicates that the metamorphic grade increases to the north. The occurrences of alkali amphiboles and the sporadical distribution of biotites in the whole metamorphic area indicate a water deficient condition. The zonal structure of alkali amphiboles with actinolite, that is, in the zone A_1 alkali amphibole occurs at the periphery and in the zone B_1 at the core, seems to indicate that the water pressure increases towards the north. Pressure-temperature conditions of the metamorphic rocks are limited by the stable occurrence of albite and also may be indicated by the widespread occurrence of biaxial calcite

福岡県杷木町地方に露出する花崗閃緑岩のRb-Sr年令

Rb-Sr age determinations have been made on four biotite samples from a single granodiorite body exposed in the Sangun metamorphic rocks. This granodiorite is one of successive intrusions of Cretaceous granites in North Kyushu. Ages are 104±4, 110±4, 123±6and 128±4m. y. These ages are older than K-Ar ages reported from the granitic rocks of North Kyushu, where the successive granitic intrusions have occurred

花岡岩の黒雲母のRb-Sr年令，粒径，と包有鉱物

Biotite crystals separated from a rock sample of the Haki granodiorite were split into eight classes of different grain size and then analyzed for major elements to see the relationship between the chemistry and the grain size. Rb and Sr contents, and Sr isotopic composition were also determined before and after the elimination of mineral inclusions to see their effect on Rb-Sr radiometric dating of biotite. Biotite samples free from the mineral inclusions show, independently of their grain size, the same age of 95 ±2m. y. This age is younger by about 10 to 43 m. y. than those of biotite samples with the mineral inclusions. The relative amount to the present Rb87 of radiogenic *Sr^87 lost during a period of cooling after the solidification of the rock is constant and independent on grain sizes of biotite. This is due to the fact that the radiogenic *Sr^87 was trapped by the inclusions in biotite. The inclusions are apatite, chrolite, epidote and zircon. The proportion, K, of the radiogenic *Sr^87 captured by the inclusions to the whole radiogenic *Sr^87 generated during the cooling period is dependent on the grain size of biotite. This proportion increases with the increase of the grain size and is tentatively expressed to be K=K_0{1+3.69exp (-6.94xl0^6/r^3)}. The grain size dependent variation of K allows us to estimate the minimum cooling period during which the radiogenic *Sr^87 in biotite was subjected to diffusion. The minimum period is about 120 m. y., which corresponds to a time of 80 % of the whole rock age (156 m. y.)