Jet pump beam and method for producing the same

A method for producing a jet pump beam made of improved heat-treated nickel base alloy, comprising the steps of:

• preparing a precipitation-strengthened nickel base alloy material having a component composition containing by mass %, Ni:
• 50.0% to 55.0%, Cr:
• 17.0% to 21.0%, Nb+Ta:
• 4.75% to 5.50%, Mo:
• 2.8% to 3.3%, Ti:
• 0.65% to 1.15%, Al:
• 0.2% to 0.8%, C:
• 0.08% or less, Mn:
• 0.35% or less, Si:
• 0.35% or less, S:
• 0.015% or less, P:
• 0.03% or less, Cu:
• 0.30% or less, B:
• 0.006% or less, and Co:
• 1.0% or less, and Fe and inevitable impurities constituting a remaining part;
• forming the nickel base alloy material into a product shape by machining or cold working after subjecting the nickel base alloy material to solution heat treatment at a temperature of 1010° C. to 1090° C.;
• and
• subjecting the nickel base alloy material formed into the product shape to age-hardening heat treatment at a temperature of 694° C. to 714° C. for 5 to 7 hours.

A jet pump beam used in a jet pump for forcibly circulating high-temperature and high-pressure water within a reactor pressure vessel of a boiling water reactor, the jet pump beam comprising:

• a body made of an elastic material;
• a vertical threaded hole provided in a center portion of the body, into which a head bolt is screwed;
• and
• a body top portion support surface for supporting a head bolt fixing device,
• wherein the body is made of precipitation-strengthened nickel base alloy having a component composition containing by mass %, Ni:
• 50.0% to 55.0%, Cr:
• 17.0% to 21.0%, Nb+Ta:
• 4.75% to 5.50%, Mo:
• 2.8% to 3.3%, Ti:
• 0.65% to 1.15%, Al:
• 0.2% to 0.8%, C:
• 0.08% or less, Mn:
• 0.35% or less, Si:
• 0.35% or less, S:
• 0.015% or less, P:
• 0.03% or less, Cu:
• 0.30% or less, B:
• 0.006% or less, and Co:
• 1.0% or less, and Fe and inevitable impurities constituting a remaining part, and the nickel base alloy material is subjected to solution heat treatment at a temperature of 1010° C. to 1090° C., and subjected to age-hardening heat treatment at a temperature of 694° C. to 714° C. for 5 to 7 hours after the solution heat treatment, to thereby provide a jet pump beam made of an improved heat-treated nickel base alloy material.