Coal, Nuclear

Nickel plating prevents water stress cracking in heater nozzles

Issue 5 and Volume 99.

Nickel plating prevents water stress cracking in heater nozzles

B&W Nuclear Technologies (BWNT) has completed a program to extend the qualification of a steam generator nickel plating process to pressurizer heater nozzles at Baltimore Gas & Electric`s Calvert Cliffs Unit 1.

Nickel plating was developed by BWNT`s parent company, Framatome, and Belgatome as an effective means of preventing primary water stress corrosion cracking in Alloy 600 steam generator tubes. This repair process involves electrolytic deposition of a thin layer of nickel over a variable length of the inner tube surface. Nickel plating is intended to prevent contact between the tube and the primary coolant, arrest the growth of existing cracks, and prevent the occurrence of new ones.

Framatome has utilized this process to plate more than 1,500 steam generator tubes in nuclear power plants overseas. BWNT performed nickel plating on pressurizer heater nozzles at Calvert Cliffs Unit 1 to mitigate the potential occurrence of water stress cracking in the heating nozzles.

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