Abstract: A jet pump beam is made of improved heat-treated precipitation-hardened nickel base alloy excellent in anti-stress corrosion cracking properties and high-temperature strength, and having high ductility and a high elastic modulus. A jet pump beam 27 made of improved heat-treated nickel base alloy is produced by 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, 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 to age-hardening heat treatment at a temperature of 694° C. to 714° C.

Abstract: A control rod for nuclear reactors includes four wings including neutron absorbers containing hafnium, a front end structural member which has a cross shape in cross section and includes brackets bonded to the leading ends of the wings, and a terminal end structural member which has a cross shape in cross section and includes brackets bonded to the tailing ends of the wings. The four wings are bonded to a wing-bonding member including a cross-shaped center shaft so as to form a cross shape. The front end structural member and the wing-bonding member are made of a zirconium alloy. The wings include neutron-absorbing plates having neutron-absorbing portions and each have an outer surface which is opposed to a fuel assembly and at which a hafnium-zircaloy composite member covered with zircaloy is disposed. The neutron-absorbing plates are opposed to each other with trap spaces disposed therebetween.

Abstract: A control rod for nuclear reactors includes four wings including neutron absorbers containing hafnium, a front end structural member which has a cross shape in cross section and includes brackets bonded to the leading ends of the wings, and a terminal end structural member which has a cross shape in cross section and includes brackets bonded to the tailing ends of the wings. The four wings are bonded to a wing-bonding member including a cross-shaped center shaft so as to form a cross shape. The front end structural member and the wing-bonding member are made of a zirconium alloy. The wings include neutron-absorbing plates having neutron-absorbing portions and each have an outer surface which is opposed to a fuel assembly and at which a hafnium-zircaloy composite member covered with zircaloy is disposed. The neutron-absorbing plates are opposed to each other with trap spaces disposed therebetween.

Abstract: In one embodiment, a neutron shielding material is formed of boron-adding stainless steel of either austenite-ferrite two-phase stainless steel or ferritic stainless steel, the austenite-ferrite two-phase stainless steel containing, in mass %, B: 0.5% to 2.0%, Ni: 3.0 to 10.0%, and Cr: 21.00 to 32.00%, the ferritic stainless steel containing, in mass %, B: 0.5% to 2.0%, Ni: 4.0% or less, and Cr: 11.00 to 32.00%, and the boron-adding stainless steel being well in ductility and thermal conduction property.

Abstract: In one embodiment, a neutron shielding material is formed of boron-adding stainless steel of either austenite-ferrite two-phase stainless steel or ferritic stainless steel, the austenite-ferrite two-phase stainless steel containing, in mass %, B: 0.5% to 2.0%, Ni: 3.0 to 10.0%, and Cr: 21.00 to 32.00%, the ferritic stainless steel containing, in mass %, B: 0.5% to 2.0%, Ni: 4.0% or less, and Cr: 11.00 to 32.00%, and the boron-adding stainless steel being well in ductility and thermal conduction property.

Abstract: In one embodiment, a neutron shielding material is formed of boron-adding stainless steel of either austenite-ferrite two-phase stainless steel or ferritic stainless steel, the austenite-ferrite two-phase stainless steel containing, in mass %, B: 0.5% to 2.0%, Ni: 3.0 to 10.0%, and Cr: 21.00 to 32.00%, the ferritic stainless steel containing, in mass %, B: 0.5% to 2.0%, Ni: 4.0% or less, and Cr: 11.00 to 32.00%, and the boron-adding stainless steel being well in ductility and thermal conduction property.

Abstract: In one embodiment, a neutron shielding material is formed of boron-adding stainless steel of either austenite-ferrite two-phase stainless steel or ferritic stainless steel, the austenite-ferrite two-phase stainless steel containing, in mass %, B: 0.5% to 2.0%, Ni: 3.0 to 10.0%, and Cr: 21.00 to 32.00%, the ferritic stainless steel containing, in mass %, B: 0.5% to 2.0%, Ni: 4.0% or less, and Cr: 11.00 to 32.00%, and the boron-adding stainless steel being well in ductility and thermal conduction property.

Abstract: A jet pump beam is made of improved heat-treated precipitation-hardened nickel base alloy excellent in anti-stress corrosion cracking properties and high-temperature strength, and having high ductility and a high elastic modulus. A jet pump beam 27 made of improved heat-treated nickel base alloy is produced by 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, 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 to age-hardening heat treatment at a temperature of 694° C. to 714° C.

Abstract: A control rod for nuclear reactors includes four wings including neutron absorbers containing hafnium, a front end structural member which has a cross shape in cross section and includes brackets bonded to the leading ends of the wings, and a terminal end structural member which has a cross shape in cross section and includes brackets bonded to the tailing ends of the wings. The four wings are bonded to a wing-bonding member including a cross-shaped center shaft so as to form a cross shape. The front end structural member and the wing-bonding member are made of a zirconium alloy. The wings include neutron-absorbing plates having neutron-absorbing portions and each have an outer surface which is opposed to a fuel assembly and at which a hafnium-zircaloy composite member covered with zircaloy is disposed. The neutron-absorbing plates are opposed to each other with trap spaces disposed therebetween.