Abstract: A method for increasing the resistance of zirconium alloy tubing to nodular corrosion by applying a protective anneal at a temperature within a clearly defined temperature range. Also, a zirconium alloy tubing having such protective anneal is disclosed. The protective anneal comprises heating exposed surfaces of zirconium tubing to a temperature range bounded at its lower limit by the temperature Tc, Tc being the temperature which at equilibrium conditions a critical concentration of solute exists in &agr;-matrices of the zirconium alloy to resist nodular corrosion, and bounded at its upper limit by the maximum temperature at which precipitates exist in association with the &agr; and &bgr; matrices in the particular zirconium alloy. In respect of Zircalloy-2 containing zirconium and the following metals by weight, namely 1.2-1.7% tin, 0.13-0.20% iron, 0.06-0.15% chromium, and 0.05-0.08% nickel, the lower temperature limit Tc is approximately 840 C and the upper limit is approximately 855 C.

Abstract: A method for increasing the resistance of zirconium alloy tubing to nodular corrosion by applying a protective anneal at a temperature within a clearly defined temperature range. Also, a zirconium alloy tubing having such protective anneal is disclosed. The protective anneal comprises heating exposed surfaces of zirconium tubing to a temperature range bounded at its lower limit by the temperature T.sub.c, T.sub.c being the temperature which at equilibrium conditions a critical concentration of solute exists in .alpha.-matrices of the zirconium alloy to resist nodular corrosion, and bounded at its upper limit by the maximum temperature at which precipitates exist in association with the .alpha. and .beta. matrices in the particular zirconium alloy. In respect of Zircalloy-2 containing zirconium and the following metals by weight, namely 1.2-1.7% tin, 0.13-0.20% iron, 0.06-0.15% chromium, and 0.05-0.08% nickel, the lower temperature limit T.sub.

Abstract: A method for determining the susceptibility of a sample of Zircaloy alloy to nodular corrosion. A specimen of such Zircaloy sample is annealed at a temperature within a temperature range bounded at its upper limit by the temperature T.sub.c being the temperature at equilibrium wherein sufficient solute would exist in the (.alpha.-matrix of the particular zircaloy to resist nodular corrosion, and bounded by a lower temperature, such temperature being the temperature of the (.alpha.+precipitate)/(.alpha.+.beta.+precipitate) transus for the particular Zircaloy sample. For Zircaloy-2, such temperature range is from approximately 825.degree. C. to 841.degree. C. The specimen is maintained at such selected temperature within such temperature range for a measured period, and subsequently exposed to steam at a fixed temperature and pressure for a fixed time.

Abstract: A zirconium-based alloy with a reduced ahoy content is described that has resistance to both uniform and nodular corrosion comparable to present zirconium-based alloy compositions, such as Zircaloy-2. The alloy represents in essence a modified or diluted Zircaloy-2 or Zircaloy-4. The alloys of this invention are also expected to have improved uniform corrosion resistance at under high burn-up conditions The alloy comprises 0.05-0.09 weight percent of iron, 0.03-0.05 weight percent of chromium, 0.02-0.04 weight percent of nickel, 1.2-1.7 weight percent of tin and 0-0.15 weight percent oxygen, with a balance of zirconium. The iron chromium and nickel alloying elements form precipitates in the alloy matrix. The alloy is suitable for use as a cladding material for a fuel element housing fissionable nuclear materials in water cooled nuclear fission reactor.