摘要:
A member adapted for use under a stress in an atmosphere of a temperature below the creep temperature and made from an Ni base alloy having a high resistance to stress corrosion cracking. The Ni alloy consists essentially of, by weight, 15 to 25% of Cr, 1 to 8% of Mo, 0.4 to 2% of Al, 0.7 to 3% of Ti, 0.7 to 4.5% of Nb and the balance Ni, and has an austenite matrix in which precipitated is at least one of .gamma.' phase and .gamma." phase. The member can suitably used as parts which are subjected to pure water in nuclear reactor.
摘要:
In-pile parts for a nuclear reactor made of alloy consisting essentially of by weight 0.01-0.2% C, 10-21% Cr, 1-4% Ti, 0.3-2% Nb, 0.1-2% Al and the balance Ni wherein Ti content being higher than Nb content, said alloy having the microstructure of chromium carbides precipitated in the grain boundaries and a .gamma.' phase precipitated in the grains with the matrix thereof being austenite in microstructure.
摘要:
A butt welded tubular structure composed of tubular members of austenite stainless steel including a restraining member providing a cover to the entire outer circumferential surfaces of a welded joint and heat affected zones of the tubular members, the restraining member being formed of a metal or alloy of lower stress corrosion cracking sensitivity than the material of the tubular members and joined at the entire surfaces of opposite end portions thereof to the tubular members by welding, although the restraining member is not joined to the tubular members at portions of the restraining member corresponding to the welded joint and heat affected zones of the tubular members. The butt welded tubular structure is produced by joining tubular members of austenite stainless steel by butt welding, covering the entire outer circumferential surfaces of the welded joint and heat affected zones of the tubular members with a restraining member formed of a metal or alloy of lower stress corrosion cracking sensitivity than the material of the tubular members, and joining by welding the entire surfaces of opposite end portions of the restraining member to the tubular members while avoiding the joining of the restraining member to the welded joint and heat affected zones of the tubular members at portions of the restraining member corresponding to the welded joint and heat affected zones.
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 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:
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 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.
摘要:
A plant operational status monitoring supervisory system comprising; means for extracting information directly relating to water quality of an objective portion consecutively for a period of time by means of an electrochemical water quality sensor installed in an objective portion to monitor in-situ in a plant; means for evaluating water quality based on thus extracted information; means for comparing an obtained water quality evaluation result with a reference value for a predetermined plant operation procedure; and means for displaying or storing necessary portion out of said comparison results; is disclosed.An electrochemical reference electrode used in this system being provided with an electrolyte layer containing ion of the electrode member; a porous ceramic layer surrounding the same without permeating liquid; and electrode member electrochemically contacting with said elec-trolyte layer; and a terminal electrically contacting with said electrode member; and further having a long life in high temperature water, various status of high temperature water in objective portions and that of nearby constituent members in a plant are possible to be monitored online by means of this reference electrode.Further, because monitored data are processed by means of a neural network, the higher precision level of monitoring has been achieved.
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.