Abstract: A radiation source reducing system and method for nuclear power plants whereby radiation source can be reduced are provided. The radiation source reducing system for nuclear power plants includes a dispersant injecting unit, which injects a dispersant into a coolant of a nuclear power plant coolant system. The dispersant is polyacrylic acid, and has an average molecular weight in a range of 16000 to 26000, inclusive.

Abstract: To provide a practical infrared transmissive protective cover capable of detecting a heating abnormality of an internal heating element and the like by visual observation and by using infrared rays. The infrared transmissive protective cover includes a light transmission section, the light transmission section is made of a resin sheet containing a resin composition, and a total light transmittance of the light transmission section in a visible light region is 70% or more, and an average infrared transmittance in a wavelength range of 8 to 14 ?m is 5% or more.

Abstract: Provided are radiation source reducing system and method for nuclear power plants whereby radiation source can be reduced. This radiation source reducing system for nuclear power plants is characterized in being provided with a dispersant injecting unit, which injects a dispersant into a coolant of a nuclear power plant coolant system.

Abstract: According to an embodiment, a radioactivity evaluation method has: a first input step; a selection step in which the calculating section selects a representative neutron energy spectrum and a representative neutron fluence rate; a second input step; an radioactivity calculating step in which the calculating section calculates quantities of the radioactivity that correspond to the representative neutron energy spectra and the representative neutron fluence rates; a data storing step; a nuclide-by-nuclide radioactivation reaction rate calculating step in which the calculating section calculates a radioactivation reaction rate of each nuclide based on the neutron energy spectra at the position of each of the object sections; an object-by-object adding-up step; a nuclide determining step; and an object position determining step.

Abstract: An object is to provide a method and an apparatus for improving a residual stress in a tubular body, which are enabled to improve the residual stress reliably by clearly defining controlling rage for treatment conditions without depending on an installation state and configuration of the tubular body. When a cylindrical tubular body (2) is improved in its residual stress by locally irradiating an outer-circumferential surface of a welded portion (C) of the tubular body (2) with laser beams (5a) and by moving an irradiation area (s) in an circumferential direction, a plurality thermocouples (9) are installed on the tubular body (2) to be improved, a temperature history of the outer surface of the tubular body (2) by the irradiation of the laser beam (5a) is managed by measuring the temperature history itself.

Abstract: To provide a practical infrared transmissive protective cover capable of detecting a heating abnormality of an internal heating element and the like by visual observation and by using infrared rays. The infrared transmissive protective cover includes a light transmission section, the light transmission section is made of a resin sheet containing a resin composition, and a total light transmittance of the light transmission section in a visible light region is 70% or more, and an average infrared transmittance in a wavelength range of 8 to 14 ?m is 5% or more.

Abstract: An apparatus with which areas near surfaces in a water environment that are contaminated by radioisotopes are decontaminated by non-thermal laser peeling without suffering re-melting, re-diffusing and re-contaminating. The apparatus includes a piping structure with which a substance to be irradiated that has been deposited on outer and inner surfaces of a nuclear reactor pressure vessel, and a nuclear reactor container tank, and the internal nuclear reactor structures all having been contaminated with radioisotopes, can be removed in the water environment. The piping structure, to secure a region in a water environment that is gas pressurized to discharge the water and filled with the gas to not interfere with laser irradiation, has a semi-hermetically closed, incomplete water seal that is half-open with a siphon provided downward, a mechanical structure that withstands water pressure in a radial direction, and an extendable bellows-like tube to enable the piping structure to tilt.

Abstract: An apparatus with which areas near surfaces in a water environment that are contaminated by radioisotopes are decontaminated by non-thermal laser peeling without suffering re-melting, re-diffusing and re-contaminating. The apparatus includes a piping structure with which a substance to be irradiated that has been deposited on outer and inner surfaces of a nuclear reactor pressure vessel, and a nuclear reactor container tank, and the internal nuclear reactor structures all having been contaminated with radioisotopes, can be removed in the water environment. The piping structure, to secure a region in a water environment that is gas pressurized to discharge the water and filled with the gas to not interfere with laser irradiation, has a semi-hermetically closed, incomplete water seal that is half-open with a siphon provided downward, a mechanical structure that withstands water pressure in a radial direction, and an extendable bellows-like tube to enable the piping structure to tilt.

Abstract: Parts, structural components, etc. that have their surfaces contaminated by radioisotopes in the accelerators, nuclear reactors, RI product manufacturing factories, nuclear fuel factories, nuclear fuel reprocessing factories, etc. are decontaminated by non-thermal laser peeling without suffering re-melting, re-diffusing and re-contaminating such that upon non-thermal laser irradiation, areas near the irradiated surface are evaporated and removed faster than the heat generated in the irradiated surface is transmitted to nearby areas.

Abstract: An object is to provide a method and an apparatus for improving a residual stress in a tubular body, which are enabled to improve the residual stress reliably by clearly defining controlling rage for treatment conditions without depending on an installation state and configuration of the tubular body. When a cylindrical tubular body (2) is improved in its residual stress by locally irradiating an outer-circumferential surface of a welded portion (C) of the tubular body (2) with laser beams (5a) and by moving an irradiation area (s) in an circumferential direction, a plurality thermocouples (9) are installed on the tubular body (2) to be improved, a temperature history of the outer surface of the tubular body (2) by the irradiation of the laser beam (5a) is managed by measuring the temperature history itself.

Abstract: The current methods of removing the surface-deposited layer contaminated by radioisotopes has the disadvantage of rigorous applicability conditions in such terms as the substance to be treated, the area and the shape, so the scope of their applicability is quite limited; in addition, 100% decontamination is not guaranteed and in spite of more than 50% that can be decontaminated, a greater part of the deposited radioisotopes remain unremoved, limiting the decontamination performance of the methods. Parts, structural components, etc. that have their surfaces contaminated by radioisotopes in the accelerators, nuclear reactors, RI product manufacturing factories, nuclear fuel factories, nuclear fuel reprocessing factories, etc.

Abstract: A valve drive device which can prevent a locknut fixing a stem nut to a drive sleeve from getting loosened. The valve drive device comprises: the stem nut for screwing a valve stem thereinto; the drive sleeve engaging with a male spline formed on a peripheral outer surface of said stem nut, said drive sleeve including a worm gear on a peripheral outer surface thereof; a worm in meshing engagement with said worm gear; and a housing that supports said drive sleeve by bearings. The valve drive device further comprises: a stem nut fastening member having a first male screw that engages with a female screw provided on a peripheral inner surface of said drive sleeve; and a locknut that engages with a second male screw provided on a reduced diameter portion of said stem nut fastening member, said second male screw having a reverse screw thread relative to said first male screw, so that no slack may arise between said stem nut fastening member and said drive sleeve.

Abstract: A valve drive device which can prevent a locknut fixing a stem nut to a drive sleeve from getting loosened. The valve drive device comprises: the stem nut for screwing a valve stem thereinto; the drive sleeve engaging with a male spline formed on a peripheral outer surface of said stem nut, said drive sleeve including a worm gear on a peripheral outer surface thereof; a worm in meshing engagement with said worm gear; and a housing that supports said drive sleeve by bearings. The valve drive device further comprises: a stem nut fastening member having a first male screw that engages with a female screw provided on a peripheral inner surface of said drive sleeve; and a locknut that engages with a second male screw provided on a reduced diameter portion of said stem nut fastening member, said second male screw having a reverse screw thread relative to said first male screw, so that no slack may arise between said stem nut fastening member and said drive sleeve.

Abstract: The object of the present invention is to provide a material which takes on a color or which changes its colors when selectively sensitized by ionizing radiation (especially by low doses of radiation) and which is not sensitive to visible and ultraviolet light etc. This is achieved by microcapsules containing a radiation sensitive composition comprising leuco compounds (a) and organic halogen compounds (b) as indispensable components.

Abstract: A thermal fatigue prevention apparatus for a high temperature pump which includes an impeller in a high temperature pump casing, a pump shaft rotatably supported by a journal of a submerged bearing and projecting from a shaft through hole of a casing cover, and a shaft sealing device. The shaft sealing device is enclosed with a shaft sealing chamber which is supplied with a low temperature seal purging liquid, and a part of the seal purging liquid flows into the pump casing through the shaft through hole. A heater is provided within the high temperature pump, the heater raises the temperature of the low temperature seal purging liquid before the seal purging liquid flows into the pump casing by using the high temperature pumping liquid.

Abstract: A high temperature reactor has a downflow type nuclear reactor provided at the top portion thereof with a gas inlet and a plurality of steam generators provided around the nuclear reactor. The steam generator has a heat insulation tube provided vertically from the bottom portion of the nuclear reactor to a level higher than the top gas inlet of the reactor, a heat exchanger provided in a descending gas flow path formed around the heat insulation tube, and a gas circulator provided at the bottom portion thereof for feeding a gas coolant to the gas inlet of the nuclear reactor, whereby said gas coolant, after being used for cooling the reactor core, delivered from the bottom portion of the reactor, flows into the heat insulation tube, flows upward to the top portion of the tube, is reversed in direction at the top end of the tube, then flows downward through the descending gas flow where the heat exchanger is provided, and is then recycled to the gas inlet flow path of the reactor by the gas circulator.

Abstract: A suspension type transporter suspends a bolt drawing machine through a trolley and a hoist above a pressure container having many bolt attached thereto and transports the bolt drawing machine to a target position. A track settling portion having a guide is provided on an outer periphery of a lid of the pressure container. The suspension type transporter for the bolt drawing machine comprises a guide mechanism which restricts movement of the bolt drawing machine in the air by the guide. The guide mechanism of the transporter is provided with a position detector which can detect a position of the bolt drawing machine. A positioning controller of the suspension type transporter controls the transporter so that the transporter starts at slow speed, is then accelerated to a prescribed speed and is gradually decelerated near the target position.