JSME Construction Standard for Superconducting Magnet of Fusion Facility “Fabrication, Installation, NDE and Testing”

Abstract

For construction of TF coil, a “Fabrication and Installation” standard FM-4000, accompanying a mandatory Appendix 41 “Welded Joint” and a “Nondestructive Examination” standard FM-5000 accompanying a mandatory Appendix 51 for “Ultrasonic Examination Method” and a “Pressure and Leak Testing” standard FM-6000 have been developed, based on other JSME standards for nuclear power plant (JSME S NB1) and also ASME Sec. III ND, NF or Sec. VIII-div.2 Since TF coil structure does not include radioactive materials but is operated under high stress produced by high magnetic field, it is not safety-relevant-barrier. The requirements to construction should be relaxed in comparison with a fission reactor. The TF coil structure is mainly classified into two divisions; (1) Jacket and helium cooling pipe that is required for leak tightness, and (2) The general structure which is stressed only by the electromagnetic force. For the welded joint in the structure part (1), more severe requirements for nondestructive examination are prescribed in addition to the requirement for pressure and leak testing, based on JSME S NB1 and ASME Sec. III ND, NF or Sec. VIII-div.2. All of weld joints are classified into 6 categories depending on strength and direction of the stress induced by the magnetic field. Approved weld joint configuration and welding processes, nondestructive examinations, pressure and leak testing required and also acceptance criteria of discontinuity are defined in each category. Qualification of welding personnel and inspector are also defined, but its final responsibility is to the owner of TF coil.