The uranium OD increased about 20 mils in 97W-17 and 12 mils in 96W-18. The ID did not change. Remaining cladding thicknesses of 97W-17 were 37 mils minimum and 41 mils maximum external, and 42 mils minimum and 44 mils maximum internal, excluding the A{sub l}-S{sub i}. Remaining cladding thicknesses of 96W-18 were 35 mils minimum and 45 mils maximum external, and 36 mils minimum and 45 mils maximum internal, exclusive of A{sub l}-S{sub i}. Metallographic examination disclosed small grains to a depth of about 10 mils on the internal surface of the uranium in both elements. The spire bond in 97W-17 was cracked completely around the spire.

Nickel plated aluminum was considered as a jacketing material for nuclear fuel elements as early as 1954, and both static and dynamic corrosion tests were carried out by Argonne National Laboratories and by Atomic Energy of Canada Ltd., employing demineralized water at temperatures of from 260 to 316{degree}C. Results generally indicated that the nickel had excellent corrosion resistance; however, difficulties were experienced in achieving satisfactory continuity and adhesion of the plate; subsequent work emphasized Ni-Aluminum alloy development. At Hanford, our earliest experience employed Ni plate on aluminum-jacketed fuel elements primarily to minimize mechanical damage to the jacket surface during an irradiation test. The appearance of these fuel elements after discharge suggested that the nickel plate might also be a highly satisfactory coating for corrosion and abrasion resistance. Incentives were manifold, including reducing the incidence of in-reactor fuel element failures and permitting reduction of the aluminum jacket thickness with a concomitant increase in space available for uranium or for cooling water passage. A program has been carried out for the past three years aimed at determining various methods of employing nickel plated aluminum jacket material and testing the capabilities of high quality commercially adequate plate. Almost exclusively chemically deposited plate has …