Flow measurement in high temperature liquid metal by using electro-magnet probe

電磁石流速計を用いた高温液体金属の流動計測

有吉 玄  ; 大林 寛生  ; 斎藤 滋   ; 佐々 敏信   

Ariyoshi, Gen; Obayashi, Hironari; Saito, Shigeru; Sasa, Toshinobu

液体重金属を核破砕ターゲットおよび冷却材として利用する核変換施設の建設には、液体重金属の流動特性を事前に明らかにしておくことが重要となる。鉛ビスマス共晶合金(LBE)は、加速器駆動システムや高速炉等の革新的原子力システムにおける核破砕ターゲットや冷却材の候補材料とされており、J-PARCではLBEを利用した核破砕ターゲットシステムの構築に向けた技術開発を推進している。通常、LBEの流動特性は汎用数値流体力学(CFD)コードを用いて予測・把握されるが、このようにCFDコードが多用される一つの要因は、高温液体重金属流れに対する計測手法の確立が不十分なことである。そこで原子力機構では、小型電磁石を使用した局所流速計を開発した。開発した流速計は480CのLBEへ適用され、誘導起電力と流速の良好な相関が得られることが実証された。

To clarify the flow characteristics of heavy liquid-metal (HLM) is important to achieve the construction of nuclear transmutation facility that utilizes HLM as a spallation target and coolant. At present, lead-bismuth eutectic (LBE) spallation target plans to be installed in Japan proton accelerator research complex (J-PARC). LBE is also selected as one of the candidate media of a spallation target and a coolant for innovative nuclear systems such as accelerator-driven system (ADS) and LBE-cooled fast reactor, due to its adequate physical/chemical properties. The characteristics of LBE flowing inside the target are usually clarified with computational fluid dynamics analysis since the measurement techniques for the HLM flow are not well established, especially for high temperature region over 450C that is delivered from ADS's criteria. Therefore, the objective of this study is to develop measurement method for flow characteristics in the high temperature LBE. A miniature electro-magnet is introduced to electro-magnetic probe to overcome the limitation caused by a curie temperature of permanent magnet. To evaluate performance of the new probe, experimental apparatus equipping annular rotating vessel were also manufactured. The new probe was applied to high temperature LBE up to 480C. As a result, proportional induced voltage to the rotation speed of LBE were clearly observed, where excitation currents of the miniature electro-magnet were 0.2 A or 1 A. In this paper, configuration and performance of the newly developed electro-magnet probe to the high temperature LBE will be presented.