Westinghouse Electric Corporation

Samuel A Worcester

John P Foster

Charles R Woods

George P Sabol

Robert J Comstock

Thomas S Snyder

William R Gass

Laura J Ayers

James P Dougherty

Richard L Propst

Glenn S Galer

Gregory F Boris

Patti L Case

This is an improved method of fabricating Zircaloy-4 strip. The method is of the type wherein Zircaloy-4 material is vacuum melted, forged, hot reduced, beta-annealed, quenched, hot rolled, subjected to a post-hot-roll anneal and then reduced by at least two cold rolling steps, including a final cold rolling to final size, with intermediate annealing between the cold rolling steps and with a final anneal after the last cold rolling step. The improvement comprises: (a) utilizing a maximum processing temperature of 620.degree. C. between the quenching and the final cold rolling to final size; (b) utilizing a maximum intermediate annealing temperature of 520.degree. C.; and (c) utilizing hot rolling, post-hot-roll annealing, intermediate annealing and final annealing time-temperature combinations to give an A parameter of between 4.times.10.sup.-19 and 7.times.10.sup.-18 hour, where segment parameters are calculated for the hot rolling step and each annealing step, the segment parameters are calculated by taking the time, in hours, for which that step is performed, to the (-40,000/T) power, in which T is the temperature, in degrees K, at which the step is performed, and where the A parameter is the sum of the segment parameters. Preferably, the hot rolling and the post-hot-roll anneal are at 560.degree.-620.degree. C. and are for 1.5-3 hours and the intermediate annealing is at 400.degree.-520.degree. C. and is for 1.5-15 hours and the final anneal after the last cold rolling step is at 560.degree.-710.degree. C. for 1-5 hours, and the beta-anneal is at 1015.degree.-1130.degree. C. for 2-30 minutes.

Zircaloy-4 alloy having uniform and nodular corrosion resistance

This is an alloy comprising, by weight percent, 0.5-2.0 niobium, 0.7-1.5 tin, 0.07-0.14 iron, and 0.03-0.14 of at least one of nickel and chromium, and at least 0.12 total of iron, nickel and chromium, and up to 220 ppm C, and the balance essentially zirconium. Preferably, the alloy contains 0.03-0.08 chromium, and 0.03-0.08 nickel. The alloy is also preferably subjected intermediate recrystallization anneals at a temperature of about 1200.degree.-1300.degree. F., and to a beta quench two steps prior to final size.

Method of producing zirlo material for light water reactor applications

Zircaloy-4 processing for uniform and nodular corrosion resistance

Technetium is separated from nickel by electro-refining contaminated nickel. Electrorefining controls the electrolyte solution oxidation potential to selectively reduce the technetium from the metallic feedstock solution from Tc(VII) to Tc(IV) forcing it to report to the anodic slimes and thereby preventing it from reporting to the cathodic metal product. This method eliminates the need for peripheral decontamination processes such as solvent extraction to remove the technetium prior to nickel electrorefining. These methods are particularly useful for remediating nickel contaminated by radio-contaminants such as technetium and actinides.

Decontamination of radioactive metals

Two alternate, mutually exclusive, methods of removing radio contaminants from metal are taught based respectively on electrowinning or electrorefining of the base metal. The alternative using electrorefining controls the anolyte oxidation potential to selectively reduce the technetium in the metallic feedstock solution from Tc(VII) to Tc(IV) forcing it to report to the anodic slimes preventing it from reporting to the cathodic metal product. This method eliminates the need for peripheral decontamination processes such as solvent extraction and/or ion exchange to remove the technetium prior to nickel electrorefining. The other alternative method combines solvent extraction with electrowinning. By oxidizing technetium to the heptavalent state and by using mixtures of tri-n-octyalphosphine oxide and di-2-ethyl phosphoric acid in aliphatic hydrocarbon carriers to extract the radio contaminants prior to electrowinning, the background metal may be recovered for beneficial reuse. Electrowinning may further polish the decontamination extraction process to remove residual actinides in solution while winning a radio- chemical free metal product. These methods are particularly useful for the decontamination of nickel by radio contaminants such as technetium and actinides.

This invention is for the processing of a somewhat broader range of compositions, including ZIRLO material. It controls creep rate in an alloy having, by weight percent, 0.5-2.0 niobium, 0.7-1.5 tin, 0.07-0.28 of at least one of iron, nickel and chromium and up to 220 ppm carbon, and the balance essentially zirconium. The method is of a type which utilizes subjecting the material to a post extrusion anneal, a series of intermediate area reductions and intermediate recrystallization anneals, with one of the intermediate recrystallization anneals possibly being a late stage beta-quench, a final pass area reduction, and a final stress relief anneal. The creep rate is controlled to about the desired amount per hour by the use of an average intermediate recrystallization annealing temperature and a final pass area reduction combination selected from the designated area of a designated figure, with the figure being selected based on whether the post extrusion anneal was an alpha or a beta anneal; on whether the final anneal was a stress relief anneal or a recrystallization anneal, and whether or not a late stage beta-quench was utilized, and the desired creep rate range. The method may also comprise subjecting the material to an alpha post extrusion anneal and a final stress relief anneal, and controlling the creep rate by the use of certain intermediate recrystallization annealing temperatures and final pass true area reductions.

Processing zirconium alloy used in light water reactors for specified

Zirlo material for light water reactor applications

A superconductive alloy of titanium and niobium is formed during reduction of niobium pentoxide by adding an effective quantity of titanium metal and/or titanium oxide to a reduction mixture of aluminum and niobium pentoxide. The resulting mixture is reacted to form the desired niobium titanium alloy below an aluminum oxide or aluminum oxide-titanium oxide slag. The slag is easily separated from the alloy.

Direct production of niobium titanium alloy during niobium reduction

This is a process for making a very pure and very homogeneous material for use in lining the interior of zirconium alloy fuel element cladding. The improvement utilizes the forming of a consumable electrode from generally virgin sponge material, melting the consumable electrode in a multiple swept beam electron beam furnace with a feed rate between 1 and 20 inches per hour and then vacuum arc melting the EB melted material.

Combined electron beam and vacuum arc melting for barrier tube shell

This is a process for making a very pure and very homogeneous zirconium material for use in lining the interior of zirconium alloy fuel element cladding. The improvement utilizes the forming of consumable feed material from generally virgin sponge material, melting the consumable feed material in a multiple swept beam electron beam furnace with a feed rate generally between 0.1 and less than about 1.0 inch per hour and then vacuum arc melting the EB melted material.

Combined ultra slow electron beam and vacuum arc melting for barrier

This is a process for producing material for lining reactor fuel element claddings. Rather than using unalloyed zirconium, this invention provides for an alloy liner for the cladding. The process uses ultra-slow electron beam melting of zirconium, to give very low metallic impurities to reduce solid solution strengthening and second phase formation and property variability from lot to lot, while using alloying to reduce the susceptibility to steam corrosion. Oxygen is controlled to a very low level as well, and preferably only 0.1-0.4 tin is added to provide a low, but fabricable, hardness in the alloyed liner material.

Ultra slow EB melting to reduce reactor cladding

This is a material for lining reactor fuel element cladding. Rather than using unalloyed zirconium, this invention utilized for a 0.1-4% tin alloy liner for the cladding. The very low metallic impurities to reduce solid solution strengthening and second phase formation and property variability from lot to lot, while using alloying to reduce the susceptibility to steam corrosion. Preferably, oxygen is controlled to a very low level as well, to provide a low, but fabricable, hardness in the alloyed liner material.

Ultrapure zirconium-tin liner material

This is a process for producing material for lining reactor fuel element claddings. Rather than using unalloyed zirconium, this invention provides for an alloy liner for the cladding. The process uses electron beam melting of zirconium, to give very low metallic impurities to reduce solid solution strengthening and second phase formation and property variability from lot to lot, while using alloying to reduce the susceptibility to steam corrosion. Preferably, oxygen is controlled to a low level as well, to provide a low, but fabricable, hardness in the alloyed liner material.

Process for the control of liner impurities and light water reactor

Transition metal, notably zirconium alloy, is melted (e.g., by a plasma) to form droplets within the size range of minus 20, plus 60 mesh. The droplets are exposed to a hydrogen atmosphere for a short period while cooling through the hydriding temperature range (e.g., 600.degree. C. to 400.degree. C.). A friable particulate of uniform size and hydrogen content, suitable for sintering or forming components, is recovered.

Growing community of inventors

Butte, MT, United States of America

Samuel A Worcester