Residual Strains in ITER Conductors by Neutron Diffraction

Abstract:

Measurements of internal strains in the superconducting constituent (Nb₃Sn phase in Nb₃Sn strand) in two cable-in-conduit conductors (CICC) for International Thermonuclear Experimental Reactor 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 strain were observed in Nb₃Sn 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. Three main results were obtained. (1) Residual strain difference before and after the cutting to 100 mm long bar was about 0.1%, (2) a large relaxation on residual thermal strain was observed at the high field zone, and (3) the large relaxation on residual thermal strain at the high field zone was found mainly in a cross sectional side where the Lorentz force coming in.

• Periodical: Materials Science Forum (Volume 777)
• Pages: 84-91
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.777.84
• Online since: February 2014
• Authors: Stefanus Harjo*, Tsutomu Hemmi, Jun Abe, Wu Gong, Yoshihiko Nunoya, Kazuya Aizawa, Takayoshi Ito, Norikiyo Koizumi, Shutaro Machiya, Kozo Osamura
• Keywords: Conductor, ITER, Nb₃Sn, Neutron, Residual Strain, Superconducting, Time-of-Flight

References

[1] M. Huguet, ITER Joint Central Team, ITER Home Teams, Nucl. Fusion 41 (2001) 1503-1513.

DOI: 10.1088/0029-5515/41/10/317

[2] J.W. Ekin, Cryogenics 20 (1980) 611-624.

[3] T. Hemmi, S. Harjo, T. Ito, K. Matsui, Y. Nunoya, N. Koizumi, Y. Takahashi, H. Nakajima, K. Aizawa, H. Suzuki, S. Machiya, H. Oguro, Y. Tsuchiya, K. Osamura, IEEE Trans. Appl. Supercond. 21 (2011) 2028-2031.

DOI: 10.1109/tasc.2010.2089770

[4] T. Hemmi, S. Harjo, Y. Nunoya, H. Kajitani, N. Koizumi, K. Aizawa, S. Machiya and K. Osamura, Supercond. Sci. Technol. 26 (2013) 084002 (6pp).

DOI: 10.1088/0953-2048/26/8/084002

[5] P. Bruzzone, A. Anghel, A. Fuchs, G. Pasztor, B. Stepanov, M. Vogel, G. Vecsey, IEEE Appl. Supercond. 12 (2002) 520-522.

DOI: 10.1109/tasc.2002.1018457

[6] Y. Nunoya, Y. Nabara, M. Yoshikawa, K. Matsui, T. Hemmi, Y. Takahashi, T. Isono, N. Koizumi, H. Nakajima, B. Stepanov, P. Bruzzone, IEEE Trans. Appl. Supercond. 21 (2011) 1982-1986.

DOI: 10.1109/tasc.2011.2178370

[7] T. Hemmi, Y. Nunoya, Y. Nabara, M. Yoshikawa, K. Matsui, H. Kajitani, K. Hamada, T. Isono, Y. Takahashi, N. Koizumi, H. Nakajima, B. Stepanov, P. Bruzzone, IEEE Trans. Appl. Supercond. 22 (2012) 4803305 (5pp).

DOI: 10.1109/tasc.2011.2178370

[8] S. Harjo, T. Ito, K. Aizawa, H. Arima, J. Abe, A. Moriai, T. Iwahashi and T. Kamiyama, Mater. Sci. Forum 681 (2011) 443-448.

DOI: 10.4028/www.scientific.net/msf.681.443

[9] R. Oishi, M. Yonemura, Y. Nishimaki, S. Torii, A. Hoshikawa, T. Ishigaki, T. Morishima, K. Mori and T. Kamiyama, Nucl. Instr. and Meth. A 600 (2009) 94–96.

DOI: 10.1016/j.nima.2008.11.056

[10] R. de Wit, J. Appl. Cryst. 30 (1997) 510-511.

[11] K. R. Keller and J. J. Hanak, Phys. Rev. 154 (1967) 628-632.

[12] T. Hemmi, unpublished work.

[13] S. Murase, H. Okamoto, T. Wakasa, T. Tsukii, S. Shimamoto, IEEE Trans. Appl. Supercond. 13 (2003) 3386 - 3389

DOI: 10.1109/tasc.2003.812331

[14] N. Mitchell, A. Devred, D. Larbalestier, P. Lee, C. Sanabria, A. Nijhuis, Electro-mechanical effects in Nb3Sn cable in conduit conductors: use of imperfect superconductors in cable in conduit conductors, presented at MEM 13, Aix-en-Provence, 12-14 March 2013.

DOI: 10.1088/0953-2048/26/11/114004

[15] A. Nijhuis and Y. Ilyin, Supercond. Sci. Technol. 19 (2006) 945–962.