Eddy Current Testing of Zirconium Wires

FUEL bundles for Rajasthan Atomic Power Reactor, as per the design, consist of a cluster of 19 elements held together by zircaloy end plates and spaced by wire
helices on the six elements of the inner ring and alte-rnate elements of the outer ring. Each element is a zircaloy-2 tube 495 min long,1524 mm in diameter and of 0.4 nom wall thickness containing the nuclear fuel in
the form of sintered uranium dioxide pellets and sealed
at both ends. In order to provide the required spacing between the elements, zircaloy wire of 1.25 mm dia. is spot-welded around the elements in the helix form. The wire helices serve to separate the elements to maintain the dimensions of the coolant sub-channels between them
and to increase the mixing of coolant between inner and
outer sub-channels. Zircaloy wire of 1.63 mm dia. is
spot-welded on the outer elements so as to provide
bearing surfaces for the bundle when it moves through
the fuel channels in the coolant assemblies.