NDTnet 1998 Aug, Vol.3 No.8

Abstract

When developing the manufacturing technologies for and during manufacture of the toroidal field conductor insert (TFCI) for the central solenoid model of the ITER superconducting magnet system it is essential to provide nondestructive testing (NDT), this being a critical engineering problem. The superconductor is a cable-in-conduit conductor (CICC) made of Nb3SN strands. The sealing conduit is made of Incoloy tubes 1 mm in thickness. The conductor is a long cylindrical item with longitudinal and circumferential welds of the jacket. It is crucial that the conductor jacket tightness should not be broken throughout the operation period Therefore, stringent requirements for no-failure operation are imposed on the jacket and particularly on welds. Besides, in the technological line of conductor jacketing and TFCI manufacture the jacket is compacted by 5%, there occur excessive bends during winding and transfer, giving rise to defects.

The report presents the NDT system used in the RF jacketing line. Concrete results are given on detection and assessment of real defects in the Incoloy908 jacket when manufacturing 800m superconductor.One of the promising NDT methods, as applied to the jacket, is ultrasound method using a computer-aided system of scanning and processing of results. The experimental sample of the developed apparatus makes it possible to detect in welds of Incoloy 1-mm-thick tubes the following defects and to produce their two-dimensional pictures

• cracks and incomplete penetration more than 0.2 mmin depth;
• pores, inclusions more than 0.3 mm in diameter;
• sagging more than 0.2 mm in height;
• edge displacement more than 0.15 mm in height

The analysis performed shows the necessity to develop the effective NDT systems for ITER.

Key words NDT, jacket, inclusions, cracks, sagging, edge displacement

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

Publication Contact:
7th ECNDT, Park Alle 345, DK-2605 Broendby, Denmark, Fax: +45 46 26 70 11, Email: 101373.3414@compuserve.com