摘要:
A method of producing cladding tube comprises a step of temperature-gradient annealing in which the inner surface of the tube is heated to a temperature higher than the recrystallization temperature thereof, while the outer surface of the tube is cooled, after the tube has been hot-extruded. The temperature-gradient annealing is effected while a temperature gradient is maintained between the inner surface and the outer surface of the cladding tube. While keeping the inner surface at a temperature higher than the recrystallization temperature, and the outer surface at a temperature lower than the recrystallization temperature. The cladding tube is obtained with the outer surface which has an excellent resistance to nodular corrosion and a soft inner surface which has an excellent resistance to stress corrosion cracking.
摘要:
A zirconium-based alloy with a high corrosion resistance, consisting essentially of 1 to 2 wt % Sn, 0.20 to 0.35 wt % Fe, 0.03 to 0.16 wt % Ni and the balance substantially Zr. The Fe/Ni content ratio of the alloy ranges between 1.4 and 8. The structure of the alloy has fine intermetallic compound of Sn and Ni is precipitated within the zirconium crystal grain of .alpha.-phase. The alloy may further contain 0.05 to 0.15 wt % Cr. This alloy exhibits reduced hydrogen absorption rate and suffers from no nodular corrosion, so that it can suitably be used as a material of nuclear fuel cladding tubes. The nuclear fuel cladding tube made of this alloys exhibits extended service life when used in a nuclear reactor of high degree of burn-up.
摘要:
In a process for producing a zirconium-based alloy in which after the zirconium-based alloy is subjected to hot plastic working, it is subjected to cold plastic working and then to annealing and these steps are repeated at least twice, the present invention provides a process for producing a zirconium-based alloy characterized in that after the alloy is subjected to solid solution treatment in which it is heated to a temperature within the range including the .alpha. phase and the .beta. phase of the alloy, or within the range of the .beta. phase and is then quenched, cold plastic working is effected at least twice.
摘要:
A channel box and/or a spacer of a fuel assembly is a welded construction and made of a Zr-Nb-Sn alloy comprising 0.5-2.2 wt % Nb, 0.5-1.5 wt % Sn contained so as to satisfy the relation of Sn(wt %) 22.times.Nb(wt %)--3.0, and balance Zr or a Zr-Nb-Sn-Mo alloy comprising 0.5-2.2 wt % Nb, 0.5-1.5 wt % Sn contained so as to satisfy the relation of Sn(wt %).gtoreq.2.times.Nb(wt %)--0.3, 0.1-0.8 wt % Mo, and balance Zr. The welded portion, its heat affected zone and the unwelded portion of the channel box and/or the spacer have substantially the whole equilibrium phase structure.
摘要:
In a process for producing a zirconium-based alloy in which after the zirconium-based alloy is subjected to hot plastic working, it is subjected to cold plastic working and then to annealing and these steps are repeated at least twice, the present invention provides a process for producing a zirconium-based alloy characterized in that after the alloy is subjected to solid solution treatment in which it is heated to a temperature within the range including the .alpha. phase and the .beta. phase of the alloy, or within the range of the .beta. phase and is then quenched, cold plastic working is effected at least twice.
摘要:
A nuclear reactor having structural members made of austenitic stainless steel which is corrosion-resistant in an environment of neutron irradiation, and can suppress stress corrosion cracking and embrittlement. At least one additive selected from the group consisting of Ti more than 0.2% by weight but not more than 0.6%, Zr more than 0.2% but not more than 1.14%, Hf more than 0.2% but not more than 2.24%, V more than 0.2% but not more than 0.64%, Nb more than 0.5% but not more than 1.17% and Ta more than 0.5% but not more than 2.27% is added to austenitic stainless steel containing Cr, Ni and so on, and said at least one exists in a solid-solution state. In addition, the steel has a wholly austenitic structure substantially free of carbide. In order to maintain the irradiation-induced segregation prevention effected by the addition element, the C content is limited to 0.01 to 0.008%, and the N content is limited to 0.001 to 0.0%. The irradiation-induced segregation, of the constituent elements, such as Cr and Ni, occurring in a grain boundary under irradiation, can be prevented, and the deterioration of the corrosion resistance of the material, as well as the embrittlement, can be prevented.
摘要:
An alloy for use in an environment exposed to neutron rays consists principally of Cr-Ni austenite stainless steel containing nitrogen in an amount exceeding the amount of an impurity and having principally an austenite structure. The alloy is used for reactor core members such as a core shroud, core supporters, control rods, etc. which are exposed to the neutron radiation but prevented from being embrittled by the radiation.
摘要:
A method for cooling a weld in steel piping during butt welding with cooling of the inside comprises, after joining of pipe ends by a root pass on the inside, cooling the junction being welded by subsequent passes with injection of a liquid medium at room temperature from the center of the pipe against the surrounding wall, in a direction between radial and tangential directions relative to the inner pipe surface. An apparatus for practicing the cooling method comprises a rotatable multi-nozzle assembly having a radius of rotation corresponding to the inside diameter of the pipe and is capable of injecting the cooling medium against the inner surface of the pipe, a duct for conducting the cooling medium to the nozzles, and a pumping device for forcing the cooling medium under pressure into the nozzles.
摘要:
A zirconium alloy having superior corrosion resistance, containing Sn of a small amount not less than the amount of Sn existing in the solid-solution of the zirconium alloy at a room temperature, and at least one kind of Fe and Cr each of a small amount not less than the amount of each of Fe and Cr existing in the solid-solution of the zirconium alloy at a room temperature,the zirconium alloy being annealed after the solution heat treatment at a temperature at which both the .alpha. phase and .beta. phase thereof are included in the zirconium alloy,the total amount of said at least one kind of Fe and Cr existing in the solid-solution of the zirconium alloy being not less than 0.26%.
摘要:
A groove is provided on the side of a metallic structure opposite to the side thereof which is exposed to a corrosive atmosphere, and the groove is subjected to build-up welding while cooling with a liquid coolant, whereby any stress corrosion cracking which otherwise occurs on the side of the structure to be exposed to the corrosive atmosphere can be prevented. Especially, this method of manufacture is appropriate for the repair welding of a butt-welded pipe of austenite type stainless steel, and it is effective to perfectly prevent the stress corrosion cracking of the pipe prone to be caused by reactor water during use in a nuclear reactor.