AEC FUEL CYCLE PROGRAM EXAMINATION OF UO$sub 2$ FUEL RODS OPERATED IN THE VBWR TO 10,000 MWD/TU

ZIRCALOY-CLAD UO$sub 2$ FUEL ROD EVALUATION PROGRAM. Final Report, November 1967--June 1971.

“…An example of this mottling can be seen in Figure 17 on rod 14J-12, which later was selected for irradiation in SA-1 as rod A 18. 3 Evidence of fretting wear of the cladding caused by the single-layer wire spacers located at the middle of the V8WR assemblies was frequently noted. Some relatively severe cases of fretting wear are shown in Figure 18.…”

“…A similar phenomenon was noted during the destructive examinatio ns of Fuel Cycle Program fue l rods conducted at the conclusion of V8WR operation. 3 The thicknesses of the internal and external Zr0 2 were not related in any particular way . Specimen No.…”

“…i.e., as large as the overall average increase shown by the twelve rods that received additional irradiation in Dresden. 3 The difference between the maximum diameter and the minimum diameter at a given point along the rod axis (o.d.max -o.d·minl was as large as 0.0075 or 0.010 cm (0.003 or 0.004 in.) at some locations of some SA-1 rods, both among those that were removed after two cycles of Dresden operation and among those that operated four cycles.…”

“…The bottom of the total fuel column was 58.6 cm (23-1/16 in.) above the bottom of the reactor active fuel zone and the top of the column was :l8./ ±4.4 cm (i [1][2][3][4][5] helow the top of the reactor active fuel zone. The subassemblies were held down by a spring-loaded fixture attached to a clamp ( Figure 7) which fitted into slots in the sides of the channel near the top.…”

“…In addition , some of the samples from the first group of rods were analyzed for tritium content. Tritium, which is produced by the ternary fission of uranium and plutonium, decays by beta emission to 3 He. The degree to which it enters and is trapped by the Zircaloy cladding is of interest from the standpoint of both reactor operation and spent fuel reprocessing.…”