To detect the non-bond regions an immersion ultrasonic technique has been developed using a point focussed probe for maximum sensitivity. A scanning set up has been designed and fabricated for carrying out the plate scans in a controlled and repeatable manner. A reference standard to simulate non-bond regions of varying size and at two different depths has been carefully fabricated. The signals from a fuel plate are compared with those from this reference. This gives the apparent area of non- bond. It was possible to detect a non-bond of area less than that equivalent to a circle of diamter 1.5 mm. Verification of the sensitivity was done by testing a regular fuel plate and then carrying out optical metallography on it.

In this paper we describe the technique, it's resolution and the Ultrasonic digitiser system with C-scan display developed for the detection of non-bond areas in these plate type fuels and present a few typical results. We also describe the precision X-Y stage scanner developed and fabricated for the immersion ultrasonic scanning of these fuel plates. REFERENCE:

1. C. Ganguly, G. J. Prasad, et al., "Fabrication Experience of Al-233U and Al-Pu Plate Fule for PURNIMA III and KAMINI research reactors", Nuclear Technology Vol. 96, No. 1 pp. 72-83 October 1991.