Evaluation of heat removal property in W/Cu/RAFM steel joint by using electron beam facility. (October 2022)

• Record Type: Journal Article
• Authors: Yamashita, T.; Tokitani, M.; Hamaji, Y.; Shen, J.; Noto, H.; Masuzaki, S.; Muroga, T.
• Is Part Of: Nuclear materials and energy. Volume 33(2022)
• Publication Date: 2022-10
• Subjects: W, RAFM steel -- Divertor -- Heat removal property -- Electron beam; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2022.101236
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: The durability of the W/Cu/JLF-1 joint sample fabricated by brazing was confirmed by performing steady-state and repetitive heat loading experiments. The W/Cu/JLF-1 showed excellent heat removal performance under the steady-state heat loading. A degradation of the heat removal performance was confirmed during the repetitive heat loading. The delamination which could lead to the barrier of efficient heat transfer was confirmed after the repetitive heat loading of ∼6.0 MW/m 2 . Abstract: A reliable technique for creating joints between tungsten (W) and Reduced Activated Ferritic/Martensitic (RAFM) steel with a pure-copper (Cu) interlayer (W/Cu/RAFM steel) has been explored for developing the heat removal component in the baffle and dome of a divertor. The first joint sample of W/Cu/RAFM steel was fabricated by using a brazing technique described in our previous work. In this work, to evaluate the heat removal property, a joint sample was subjected to a steady-state and a repetitive heat loading test with an electron beam facility (ACT2). In the steady-state heat loading test, a step-wised static heat load with ∼0.7, ∼1.0, ∼1.9, ∼2.7, ∼3.6, ∼4.4 and ∼6.0 MW/m 2 was applied to the joint sample. The temperatures on the W and RAFM steel showed a linear increasing tendency, as a function of the heat loading value. Also, in the repetitive heat loading test, a 30 s pulse width of 100 cycles was applied with a maximum heat loading value of ∼2.8 and ∼6.0 MW/m 2 . The obvious temperature excursion, while increasing the heat cycles, was confirmed at ∼6.0 MW/m 2 . After the heat loading, a major crack in the vicinity of the interface between the W and Cu was confirmed. This crack led to the degradation of the heat removal performance over ∼6.0 MW/m 2 .