Abstract: A reactor building includes a spent fuel pool, spent fuel racks, and traveling rails. The spent fuel racks are located in the spent fuel pool and are configured to store nuclear spent fuel. A protection slab is located above the spent fuel racks. The traveling rails are fixed to a lower surface of the protection slab. The rails are parallel to each other. The spent fuel racks are located between the rails. A fuel transfer machine is suspended from the rails.

Abstract: To provide a fluid contact member whose corrosion resistance is particularly further improved than that in the related art. In order to solve this problem, a fluid contact member 10 includes a fluid contact portion 1 configured to be in contact with a fluid, the fluid contact portion 1 has a cobalt-based alloy phase 2 having a dendrite, and a compound phase 3 formed in an arm space of the dendrite and containing chromium carbide, and among a plurality of secondary arms 5 extending from one primary arm 4 constituting the dendrite, an average interval between adjacent secondary arms 5 is 5 ?m or less. At this time, the average interval is preferably 3 ?m or less. Further, the compound phase 3 is preferably formed discontinuously in the dendrite arm space.

Abstract: More accurate prediction of reactor water quality of a nuclear reactor is implemented. A device for prediction of reactor water quality of a nuclear reactor in a nuclear power plant is disclosed. The device stores a reactor water quality prediction model which is learned using learning data, and with which future reactor water quality is predicted. An explanatory variable of the reactor water quality prediction model includes a value in a predetermined period unit that is generated from data acquired in an operating nuclear power plant. The device generates the value in a predetermined period unit from data acquired in a target operating nuclear power plant, and acquires a predicted value of the reactor water quality in the target nuclear power plant based on the reactor water quality prediction model and the value in a predetermined period unit.

Abstract: A core of a fast reactor having arranged therein at least one gas expansion module each of which being a hollow tubular structure with one end closed and the other end opened, the core including at least one neutron absorber that absorbs neutron, or, at least one neutron moderator that slows down neutron, arranged so as to adjoin the outer face, in the radial direction of the core, of the gas expansion module.

Abstract: A fast reactor core includes a sodium plenum installed above the fuel. The sodium plenum is capable of reducing a void reactivity. During operation, a tip of a primary control rod is inserted in a core fuel region, and a tip of a backup control rod is arranged near an upper end of the sodium plenum.

Abstract: A fuel assembly includes full length fuel rods which contain a plutonium fissile (Puf) but do not contain a burnable poison, full length fuel rods which contain the fissile uranium and the burnable poison, and partial length fuel rods which contain Puf but do not contain the burnable poison in a channel box. The plutonium enrichment is decreased in an order of the full length fuel rods. The concentration of the burnable poison of the full length fuel rod is higher than the concentration of the full length fuel rod. In each side of a rectangular outermost periphery adjacent to the inner surface of the channel box in a horizontal cross-sectional view of the fuel assembly, two partial length fuel rods are adjacently disposed, and the full length fuel rod containing the burnable poison is disposed to be adjacent to each partial length fuel rod.

Abstract: The invention provides a method of manufacturing a transition piece that has a high degree of freedom in adjustment of a length, a shape, or the like, can carry out a dissimilar metal welding easily, and is easy to perform, and a transition piece. The transition piece includes one end having the same composition as one material to be welded, another end having the same composition as another material to be welded, and an intermediate layer formed between the one end and the other end. The composition of the one end and the composition of the other end become the same as approaching a center. In the method of manufacturing the transition piece according to the invention, at least the intermediate layer among the one end, the other end, and the intermediate layer is formed by a additive manufacturing method.

Abstract: An ultrasonic inspection method in which a pulse signal is output to an ultrasonic sensor to generate and transmit ultrasonic waves, the ultrasonic waves reflected or scattered by an object are received and converted into a waveform signal by the ultrasonic sensor, and the waveform signal is digitized to acquire waveform data, includes: executing modulation processing for modulating a plurality of waveform data acquired in multiple inspections and under the same inspection conditions by a phase modulation method to generate composite waveform data; and executing demodulation processing for demodulating the composite waveform data to generate compressed waveform data.

Abstract: To provide is a fuel assembly capable of easily adjusting average MA enrichment in an inner blanket region. An inner core fuel assembly 7 loaded in an inner core region 2 of a core of a fast reactor includes a plurality of fuel rods 10 and a plurality of fuel rods 19. Each of the fuel rods 10 includes a lower core fuel region 12, an inner blanket region 11, and an upper core fuel region 13. A U—Pu—Zr metal fuel is disposed in the lower core fuel region 12 and the upper core fuel region 13, and a U—Zr metal fuel is disposed in the inner blanket region 11. Each of the fuel rods 19 includes a lower core fuel region 12, an inner blanket region 20, and an upper core fuel region 13. A U—Pu—Zr metal fuel is disposed in the lower core fuel region 12 and the upper core fuel region 13 of the fuel rod 19, and a MA-Zr metal fuel is disposed in the inner blanket region 20.

Abstract: An organic iodine remover is a remover for removing organic iodine and is a substance composed of a cation and an anion, and the cation (for example, a phosphonium cation, an ammonium cation, or a sulfonium cation) has a molecular structure in which an electron donating group (for example, a phosphino group, an amino group, a sulfanyl group, a hydroxy group, or an alkoxy group) is bonded to a phosphorus atom, a nitrogen atom or a sulfur atom. An organic iodine removing apparatus includes: a vessel into which the organic iodine remover for removing the organic iodine is charged; and introduction pipes through which a fluid containing organic iodine is introduced into the organic iodine remover.

Abstract: In view of above problems, an object of the invention is to provide a primary containment vessel venting system having a structure capable of continuously discharging vapor in a primary containment vessel out of the system and continuously reducing pressure of the primary containment vessel without discharging radioactive noble gases to the outside of the containment vessel and without using an enclosing vessel or a power source. In order to achieve the above object, an nuclear power plant of the invention includes a primary containment vessel which includes a reactor pressure vessel, a radioactive substance separation apparatus which is disposed inside the primary containment vessel and through which the radioactive noble gases do not permeate but vapor permeates, a vent pipe which is connected to the radioactive substance separation apparatus, and an exhaust tower which is connected to the vent pipe and discharges a gas, from which a radioactive substance is removed, to the outside.

Abstract: An ultrasonic inspection system includes: an ultrasonic sensor including a piezoelectric element and a calibration piece interposed between the piezoelectric element and a subject; and a control device that computes a thickness of the subject, on the basis of a difference between an ultrasonic propagation time of one round trip in the calibration piece and the subject and an ultrasonic propagation time of one round trip in the calibration piece.

Abstract: An ultrasonic inspection system includes an ultrasonic sensor which includes a piezoelectric element to transmit and receive an ultrasonic wave and a calibration piece, and a control device. The calibration piece includes a propagation portion extending along an upper surface of the piezoelectric element, and a propagation redirecting portion which is formed on one side in an extending direction of the propagation portion, and is connected to the piezoelectric element through a heat resistant adhesive. The propagation redirecting portion includes a slope inclined in a vertical direction to the upper surface of the piezoelectric element.

Abstract: The invention provides a reactor containment vessel vent system capable of continuously releasing steam generated in a reactor containment vessel to the atmosphere even when a power supply is lost. In the reactor containment vessel vent system (15), the noble gas filter (23) that allows steam to pass through but does not allow radioactive noble gases to pass through among vent gas discharged from the reactor containment vessel (1) is provided at a most downstream portion of the vent line. An immediate upstream portion of the noble gas filter (23) and the reactor containment vessel (1) are connected to each other by the return pipe (24a, 24b) via the intermediate vessel (100). Further, when the radioactive noble gases having pressure equal to or higher than predetermined pressure stays in the immediate upstream portion of the noble gas filter (23), the staying radioactive noble gases flows into the intermediate vessel (100) by the relief valve (25).

Abstract: The fuel element of the present invention includes a cladding tube and a metal fuel contained in the cladding tube, in which a gas plenum region is formed above the metal fuel and inside the cladding tube and has a small-diameter portion in the gas plenum region. Further, the fuel assembly of the present invention includes the fuel element of the present invention and a wrapper tube surrounding the fuel element, in which a coolant material passage is formed between the fuel element and the fuel element. Further, the core of the present invention includes an inner core fuel region loaded with the fuel assembly according to the present invention, and an outer core fuel region loaded with the fuel assembly of the present invention.

Abstract: Provided is a control rod motion monitoring method and a control rod motion monitoring system, in which a control rod insertion in an entire core is monitored at all time during operation of a reactor and, when an abnormality occurs, a signal is issued to a countermeasure device that automatically starts operation and an alarm is issued to prompt operation of an operator. An LPRM detector in an LPRM assembly of the entire core is divided into four channels for each height; indicated values are averaged at all time; the average indicated value is compared with a set point; and a signal is issued to a countermeasure device when an abnormality occurs.

Abstract: A plant facility apparatus recognition system is provided, which appropriately recognizes a plant facility apparatus even in a plant facility in which a wireless facility and a marker are not able to be installed even when the shape of the plant facility apparatus is different from or has been changed from design data. The plant facility apparatus recognition system that uses a mobile device having a camera to recognize the plant facility apparatus to be subjected to work in the plant facility includes a characteristic length acquirer that acquires information on the pipe as a first characteristic length from an image obtained by causing the camera to image the plant facility apparatus and the pipe existing near the plant facility apparatus, and a characteristic length comparator that compares the first characteristic length with a second characteristic length acquired from the design data and related to the pipe.

Abstract: A reactor water radioactivity concentration of a nuclear power plant can be predicted with high accuracy. First, a plant state quantity prediction value is calculated by using a physical model that describes plant state quantities of the power plant including a flow rate of feedwater and a metal corrosion product concentration in feedwater of the reactor water is calculated. Next, data for supervised learning is created, and the data for supervised learning includes the previously calculated plant state quantity prediction value and a plant state quantity such as the flow rate of feedwater, the metal corrosion product concentration in feedwater, a metal corrosion product concentration in reactor water, and a radioactive metal corrosion concentration of the reactor water in the reactor as input data and includes a radioactive metal corrosion concentration in the reactor water which is an actual measured value as output data, and a predictive model is trained.

Abstract: A chemical decontamination method capable of improving the decontamination efficiency of chemical decontamination of a steam dryer in the RPV is provided. In particular, the decontamination method includes feeding a chemical decontamination aqueous solution into a reactor pressure vessel in which a steam dryer is arranged, and after chemical decontamination of the steam dryer, the water level of the chemical decontamination aqueous solution existing in the reactor pressure vessel is lowered to a first water level below the lower end of the steam dryer.

Abstract: A chemical decontamination method includes a dissolution step in which a radioactive insoluble substance containing a metal oxide, the radioactive insoluble substance being adhered to a decontamination object including carbon steel, is dissolved in a decontamination solution and a metal-ion removal step in which the decontamination solution containing the metal ion, the decontamination solution being produced in the dissolution step, is brought into contact with a cation-exchange resin in order to remove the metal ion, the dissolution step including a reductive dissolution step conducted using a decontamination solution containing formic acid, ascorbic acid and/or erythorbic acid, and a corrosion inhibitor.