Combustion Engineering, Inc.

Satya R Pati

Anand M Garde

Lawrence V Corsetti

A stabilized alpha metal matrix provides an improved ductility, creep strength, and corrosion resistance against irradiation in a zirconium alloy containing on a weight percentage basis tin in a range of 0.4 to 1.0 percent and typically 0.5; iron in a range of 0.3 to 0.6 percent, and typically 0.46 percent; chromium in a range of 0.2 to 0.4 percent, and typically 0.23 percent; silicon in a range of 50 to 200 ppm, and typically 100 ppm; and oxygen in a range 1200 to 2500 ppm, typically 1800 to 2200 ppm. The high oxygen level assists in reducing hydrogen uptake of the alloy compared to Zircaloy-4, for example.

Zirconium alloy with superior corrosion resistance

A burnable-absorber-containing zirconium alloy is described for application to the inside surface of cladding tubes for light water nuclear reactors. The alloy comprises naturally occurring erbium in a range from a measurable amount up to about 20 wt. % or isotopically purified erbium-167 in a range from a measurable amount up to about 5 wt. %; tin in a range from a measurable amount up to about 0.5 wt. %; iron in a range from a measurable amount up to about 0.2 wt. %; chromium in a range from a measurable amount up to about 0.1 wt. %; niobium in a range from a measurable amount up to about 0.1 wt. %; silicon in a range from about 50 to about 120 parts per million ('ppm'); oxygen in a range from a measurable amount up to about 800 ppm; and the balance zirconium. Such an alloy provides an effective absorber material for reactor control, while providing adequate mechanical properties and corrosion resistance for the intended application.

Zirconium alloy absorber layer

A stabilized alpha metal matrix provides an improved ductility, creep strength, and corrosion resistance against irradiation in a zirconium alloy containing tin in a range of 0.45 to 0.75 wt. %, and typically 0.6 wt. %; iron in a range of 0.4 to 0.53 wt. %, and typically 0.45 percent; chromium in a range of 0.2 to 0.3 wt. %, and typically 0.25 percent; niobium in a range of 0.3 to 0.5 wt. %, and typically 0.45 wt. %; nickel in a range of 0.012 to 0.03 wt. %, and typically 0.02 wt. %; silicon in a range of 50 to 200 ppm, and typically 100 ppm; and oxygen in a range 1,000 to 2,000 ppm, and typically 1,600 ppm, with the balance zirconium. The addition of iron and niobium improves mechanical properties of the alloy with its lower level of tin, while corrosion resistance is addressed by having an iron level of 0.45 wt. % and an iron/chromium ratio on the order of 1.5. The addition of niobium also counters the effect of higher iron on the hydrogen absorption characteristics of the alloy. The addition of nickel, silicon, carbon, and oxygen as alloying elements provide desired corrosion resistance and strength.

Zirconium alloy with improved post-irradiation properties

A burnable absorber controls axial power peaking or moderator temperature coefficient while additional elements are added to improve strength and/or corrosion resistance in a zirconium alloy containing erbium in a range of from about 0.05 to 2 wt. % selected from the group consisting of a naturally occurring distribution of isotopically enriched erbium-167 and a combination thereof; in a range of from a measurable amount up to 1.4% tin; from 0.2 to 0.5 wt. % iron; from 0.07 to 0.25 wt. % chromium; in a range of from a measurable amount up to 0.6 wt. % niobium; in a range of from a measurable amount up to 0.5 wt. % vanadium; 50-120 ppm silicon; 1000-2200 ppm oxygen and a balance of zirconium. Alternatively, the erbium can be replaced by gadolinium in a range of from about 0.05 to 6 wt. % selected from the group consisting of a naturally occurring distribution of gadolinium isotopes, isotopically enriched gadolinium-157 and a combination thereof.

Corrosion resistant zirconium alloy absorber material

A stabilized alpha metal matrix provides an improved ductility, creep strength, and corrosion resistance under neutron irradiation environment in a zirconium alloy containing tin in a range of 0.8 to 1.2 percent; iron in a range of 0.2 to 0.5 percent, and typically 0.35 percent; chromium in a range of 0.1 to 0.4 percent, and typically 0.25 percent; niobium in a range of from a measurable amount up to 0.6 percent, and typically 0.30 percent; silicon in a range of 50 to 200 ppm, and typically 100 ppm; and oxygen in a range 900 to 1800 ppm, typically 1600 ppm. The silicon is added as an alloying element to reduce hydrogen absorption by the alloy and to reduce variations in the corrosion resistance with variations in the processing history of the alloy.

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Simsbury, CT, United States of America

Satya R Pati