摘要:
A water jet peening method in which a pressurized water jet flow containing cavities is jetted through a nozzle having a velocity increasing orifice portion and a horn-like jetting hole formed continuously with the velocity increasing orifice portion to impinge against a surface of a metallic material immersed in water and to cause the cavities to collapse at the surface of the metallic member, and a tensile plastic deformation is caused in a surface layer of the metallic material by a local high pressure generated by the impingement and the collapse so that a residual tensile stress in the surface of the metallic member is reduced. In this method, the nozzle is vibrated so that vibration-induced cavities are formed in the vicinity of a nozzle wall surface, and the vibration-induced cavities are caused to impinge against the surface of the metallic member by the pressurized water jet flow containing cavities. It is thereby possible to promote the generation of cavities even in a case where pure water existing in a nuclear reactor and scant of nuclei from which cavities will be generated is used in peening of an internal structual member of the reactor.
摘要:
On the basis of a finding that a magnetic hysteresis of a metal material, among magnetization characteristics changing with secular degradation of the metal material, shows a clear correspondence with the degree of degradation of the metal material, a change in such a magnetization characteristic is measured to estimate the degree of secular degradation of the metal material. In a typical embodiment, a superconducting quantum interference device is used to detect the magnetization characteristic of a measuring object. According to the present invention, the degree of embrittlement of a metal material used in an environment of high temperatures can be quickly detected in a non-destructive fashion so that the danger of brittle fracture of the metal material can be reliably prevented.
摘要:
An apparatus preventive maintenance having a driving mechanism capable of driving a jet nozzle 24 to cause it to travel upward-and-downward, to rotate and to swing is settled on the top of a housing in the bottom portion of a reactor pressure vessel and on a hole for a fuel support piece, water pumped by a high pressure pump is spouted from a jet nozzle, and cavitation bubbles generated during the spouting are supplied to the positions to be treated for preventive maintenance, such as housings in the bottom portion of the reactor pressure vessel. Therewith, the residual tensile stress in the position to be treated is improved in a releasing direction by the energy generated by the collapsing of the cavitation bubbles.
摘要:
Low temperature water in a low temperature water tank 12 installed outside a reactor pressure vessel 9 is pumped by a high pressure pump 15 and supplied through a conductor 17 under pressure. The supplied water is ejected, as a stream of cold water jet 8, from a nozzle 14 connected to the conductor 17 and introduced into the reactor pressure vessel 9 by a driving mechanism. The stream of cold water jet 8 ejected from the nozzle 14 is directed to impinge against a predetermined position of a core shroud 13 in reactor water 11 filled in the reactor pressure vessel 9 and being at temperature higher than the low temperature water. Then, while continuing to eject the cold water jet 8 from the nozzle 14, the nozzle 14 is moved away from the predetermined position, or the ejection of the cold water jet 8 from the nozzle 14 is stopped, allowing the predetermined position to be heated again with the temperature of the reactor water 11. A thermal shock is thereby applied to the predetermined position for improvement in residual stress of the core shroud 13.
摘要:
A non-destructive inspection apparatus includes a magnetic field applying device and a magnetic sensor. The magnetic field applying device is adapted to apply DC and AC magnetic fields to an object to be inspected. Degradation/damage of the object is detected by measuring a magnetic characteristic of the object in a state in which the DC and AC magnetic fields are applied. Also, a non-destructive inspection apparatus includes as a magnetic sensor a plurality of pickup coils and a SQUID(s) connected to the pickup coils and decides the form of a defect of an object to be inspected by producing a difference between outputs of the pickup coils or SQUIDs.
摘要:
A method of maintaining the housing of a reactor pressure vessel having: a reactor pressure vessel into which cooling water is introduced; a cylindrical housing which penetrates an end bracket of the reactor pressure vessel; and a circumferential weld for securing the intermediate portion of the housing to the reactor pressure vessel by welding, the method of maintaining a housing of a reactor pressure vessel comprising the steps of: remaining the cooling water in the reactor pressure vessel; preventing leakage of the cooling water in the reactor pressure vessel through the housing by sealing the housing; making the inside portion of the housing lower than the seal to be a hollow space of a gas atmosphere; heating a heat affected zone due to welding by using a heating device inserted into the hollow space from a lower portion so as to compressive-yield the inner surface of the housing in the heat affected portion upper than the circumferential weld and tensile-yield the outer surface; and cooling heated portion inside of the housing, which has been yielded, so as to tensile-yield the inner surface of the housing by using a cooling device inserted into the housing from a lower portion, whereby compressive stress is allowed to remain in the tensile-yielded portion.
摘要:
A laser tube including an anode and a hollow cathode and adapted to obtain laser oscillation by utilizing a negative glow generated in a space within the hollow cathode. The laser tube has an elongate cylindrical member in which the anode and the hollow cathode are disposed opposite to each other, and the hollow cathode has formed therein a plurality of holes for communication between its internal space and the space outside thereof. The laser tube may further include a conducting grid provided in proximity to the anode and a conducting grid provided in a cathode dark space.
摘要:
The invention scans potential measurement terminals on the surface of a structural member to measure a potential distribution on the surface, detects the direction of a crack from the potential distribution and determining a detailed potential distribution in the direction of the crack thus detected. This potential distribution is compared with master curves of the potential distributions of cracks of various shapes, that have been obtained by analysis in advance, in order to detect the shape of the crack. The present invention can detect accurately a crack shape.
摘要:
A fluid jet nozzle has a water chamber accommodating therein pressurized fluid, an orifice communicating with the water chamber and contracting the fluid from the water chamber, a throat communicating with the orifice and through which the fluid from the orifice passes, a multiplication chamber communicating with the throat and receiving the fluid from the throat for multiplying cavitation, and a diffusion chamber receiving the fluid from the multiplication chamber for diffusing the fluid.
摘要:
A fluxmeter includes an application unit for applying a magnetic field, a superconducting quantum interference element and a flux transmitting circuit. The flux transmitting circuit includes a pickup coil formed of a superconducting print coil and a core for the pickup coil. The core is formed of a soft magnetic material. The core serves to suppress the leakage of magnetic flux to magnetically couple the pickup coil and the superconducting quantum interference element efficiently to improve the sensitivity and resolution of the fluxmeter. The pickup coil may be manufactured by photolithography, sputtering, laser beam deposition, MBE deposition, MOCVD or spray pyrolysis.