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Heat transfer characteristics of the first wall with graphite sheet interlayer

黒鉛シート中間層を持つ第一壁構造の除熱特性

正木 圭; 三代 康彦; 櫻井 真治; 江里 幸一郎; 鈴木 哲; 逆井 章

Masaki, Kei; Miyo, Yasuhiko; Sakurai, Shinji; Ezato, Koichiro; Suzuki, Satoshi; Sakasai, Akira

$$sim$$MW/m$$^{2}$$クラスの熱負荷に対して、十分な除熱性能が得られるボルト締結第一壁構造の開発を目的として、カーボンタイルとヒートシンク間に数種類の黒鉛シートを挿入した第一壁構造に対してJEBISを用いた熱負荷試験を実施し、その除熱特性を評価した。冷却水条件を1MPa, 5m/s固定とし、1MW/m$$^{2}$$$$times$$60sの熱負荷において黒鉛シートの厚みによる除熱特性の比較を行った結果、最も熱伝導率の高いパナソニックグラファイトシート(PGS)0.1mm厚3枚を使用した場合、他の黒鉛シート(PERMA FOIL 0.2$$sim$$0.6mm)より接触熱伝達係数を大きく改善できることがわかった。さらに、PGSを用いた試験体で除熱実証試験を実施した結果、1MW/m$$^{2}$$$$times$$100sにおいてはタイル表面温度500$$^{circ}$$C(IRTV)でほぼ定常に達し、3MW/m$$^{2}$$$$times$$20sにおいても800$$^{circ}$$C程度と運転可能な範囲であることを確認した。

Steady-state research is indispensable to establish scientific and technological basis for the next fusion devices. In JT-60, long pulse operation of up to 65s (OH) with a neutral beam heating power of $$sim$$12 MW (30s) was conducted to investigate the plasma behavior in several tens of seconds. However, the structure of the JT-60U first wall, which was composed of bolted graphite tiles and backings, restricted the flexibility of the plasma operation, because the first wall was not actively cooled. To improve the heat transfer characteristics of the first wall taking into account the cost, a candidate is to insert a graphite sheet between the graphite tile and the backing plate. Aiming at a design study for next fusion devices, the heat transfer characteristics of the first wall structure were investigated with a variety of graphite sheets and fixing-bolt torque conditions. The first wall mockup used for the experiment was composed of three CFC tiles (125(L) $$times$$110(W)$$times$$24(T) mm for each tile) and a cupper-alloy heat sink (377(L)$$times$$100(W)$$times$$20(T) mm) with two cooling channels of 10 mm diameter. Four types of the graphite sheets, 0.1-mm thickness PGS (Pyrolytic Graphite Sheet; Panasoic Co., Ltd), 0.2-mm PF (Perma Foil; Toyo Tanso Co., Ltd) 0.38-mm PF, 0.6-mm PF, were examined in the experiment. The heat load tests of the mockup were performed with the heat fluxes of 1 and 3 MW/m$$^{2}$$ on the JAERI electron beam irradiation stand. The experimental results showed that the structure with 0.1-mm thickness $$times$$ 3 PGSs had the highest heat transfer performance in the experiment. The first wall structure with the PGS sheets withstood the heat flux of 1 MW/m$$^{2}$$$$times$$100s. The maximum surface temperature of the CFC tile was 500$$^{circ}$$C. Furthermore, the results indicated that the structure could be used at the steady-state condition with the heat flux of $$sim$$1 MW/m$$^{2}$$. In the paper, detail of the results will be presented and discussed.

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パーセンタイル:87.11

分野:Nuclear Science & Technology

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