Study on the structural integrity of beam window for TEF target

TEFターゲットビーム窓における構造成立性に関する研究

武井 早憲   ; 大林 寛生  ; 岩元 大樹   ; 粉川 広行  ; 佐々 敏信   

Takei, Hayanori; Obayashi, Hironari; Iwamoto, Hiroki; Kogawa, Hiroyuki; Sasa, Toshinobu

J-PARC第2期計画として検討している核変換実験施設(TEF)において、鉛ビスマスターゲットのビーム窓の構造成立性を評価するために、熱流動解析及び熱応力解析を行った。解析では、(1)ビーム窓に入射する陽子ビームの電流密度と形状、(2)鉛ビスマスの流量と入口温度、(3)ビーム窓の厚さを変化させた時のビーム窓の温度と熱応力を求めた。その結果、電流分布がガウス分布、ピーク電流密度が20A/cm、鉛ビスマス流量がのリファレンスケースの場合、トレスカ応力の最大値は制限値より小さくなり、ビーム窓として構造的に成立することがわかった。

The objective of this study is to evaluate the feasibility of a designed beam window of TEF target by the numerical analysis with a 3D model. The analysis was performed by considering (1) the peak current density and shape of the incident beam, (2) the thermal-fluid behaviour of LBE around the beam window as a function of the flow rate and inlet temperature, (3) the material and the thickness of the beam window, (4) the structural strength of the beam window. In the reference case, the peak current density and the profile of the proton beam were 20 A/cm and a Gaussian shape, respectively. The flow rate of LBE and temperature at the inlet were 1 and 350 C. The material of a beam window was type SUS316 stainless steel with the 2 mm thick. In this reference case, the maximum velocity of LBE and the maximum temperature located at the top of the beam window were about 1.2 m/sec and 477 C. By increasing the flow rate of LBE up to 4 , the maximum temperature of a beam window was reduced around 420 C. The maximum tresca stress was 190 MPa, which was observed at the center on the outside surface of a beam window. The analyzed stress in the reference case was lower than the tolerance level of the stress strength of the material, and hence the feasibility of a designed beam window was confirmed.