Residual strains in ITER conductors by neutron diffraction

Harjo, S.   ; Hemmi, Tsutomu; Abe, Jun; Gong, W.; Nunoya, Yoshihiko; Aizawa, Kazuya  ; Ito, Takayoshi*; Koizumi, Norikiyo; Machiya, Shutaro*; Osamura, Kozo*

Measurements of internal strains in the superconducting phase in two cable-in-conduit conductors (CICC) for ITER were performed using an engineering materials diffractometer TAKUMI of J-PARC. From strain measurements in a CICC for the toroidal field magnet after a performance test of cyclic current, in 100 mm long cut bars, a peak broadening and a large relaxation on residual thermal strain were observed in NbSn phase at a portion received a high magnetic field (high field zone). Internal strain measurements were also conducted in a CICC for the central solenoidal magnets after the similar performance test, in the full-size shape as used in the performance test (3.6 m long) and in 100 mm long cut bars. From results of the measurements the performances degradations of the ITER conductors were clarified.