Framatome Gmbh

Areva Np Gmbh

Areva Gmbh

Huntington Alloys Corporation

David E Waskey

Charles Allen Graves

Brian A Baker

Samuel D Kiser

Kenneth B Stuckey

Andrew Carl Smith

The invention is an innovative design/repair methodology for PWR piping nozzles and vessel nozzles that are attached to the piping/vessel base material with a full penetration weld joint geometry. The development of a robust repair methodology for nozzles of this configuration is necessary due to plant aging, potential material degradation in the original materials of construction, potential increased nondestructive examination requirements, and PWSCC phenomena in the susceptible original materials of construction. The purpose/objective of the repair methodology is to provide a means of partially replacing the existing pressure boundary susceptible materials with PWSCC-resistant materials to facilitate the long-term repair life of the plant. The invention may be applied to a plurality of nozzle, piping, and vessel sizes with a full penetration weld joint.

Excavation and weld repair methodology for pressurized water reactor piping and vessel nozzles

This invention provides an improved replacement nozzle configuration. The nozzle is provided in two pieces. A first nozzle piece is a relatively thin-walled cylinder that is inserted into the counterbored opening of a pressure vessel after the protruding portion of the original nozzle has been removed. A weld pad is attached to the pressure vessel, to which the first replacement nozzle piece is welded. Due to the reduced dimensions of the thin-walled first nozzle portion, a much smaller weld pad and pad-to-nozzle weld can be used. A second nozzle piece is positioned within the first nozzle piece and welded thereto. The existing instrumentation piping is connected to the free end of the second nozzle piece. This two-piece replacement nozzle can be implemented in approximately half the time required for the one-piece design.

Two-piece replacement nozzle

A nickel, chromium, iron alloy and method for use in producing weld deposits and weldments formed therefrom. The alloy comprises, in weight percent, about 28.5 to 31.0% chromium; about 0 to 16% iron; less than about 1.0% manganese; about 2.1 to 4.0% niobium plus tantalum; 1.0 to 6.5% molybdenum; less than 0.50% silicon; 0.01 to 0.35% titanium; 0 to 0.25% aluminum; less than 1.0% copper; less than 1.0% tungsten; less than 0.5% cobalt; less than about 0.10% zirconium; less than about 0.01% sulfur; less than 0.01% boron; less than 0.03% carbon; less than about 0.02% phosphorous; 0.002 to 0.015% magnesium plus calcium; and balance nickel and incidental impurities. The method includes the steps of forming a welding electrode from the above alloy composition and melting the electrode to form a weld deposit. A preferred weldment may be in the form of a tubesheet of a nuclear reactor.

Welding alloy and articles for use in welding, weldments and method for producing weldments

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Bedford, VA, United States of America

David E Waskey