Abstract: When a power source is lost after an operation stop of a nuclear power plant, a first open/close valve is opened via a first battery at an early stage and steam in a reactor pressure vessel (RPV) is condensed in a suppression pool. The heat of the water in the suppression pool is transmitted to a cooling water pool located below inner space between first and second reactor containment vessels surrounding the RPV. A second open/close valve is opened via a second battery at the early stage and cooling water in a tank is injected into the RPV. After the early stage, a third open/close valve is opened via a third battery, and a cooling medium becomes steam by an evaporator in the RPV, the steam being condensed by a condenser disposed in the inner space to become a liquid of the cooling medium and is returned to the evaporator.

Abstract: An operator of a nuclear plant is provided with an action margin time up to the execution of a next action to be performed in response to a detected accident based on sensor signals received from sensors for the plant. The operator is provided with a displayed graph showing the received sensor signals, estimated sensor signals for the future, the action margin time and an action threshold value corresponding to the next action. Accordingly, the operator can readily grasp how much time is available to perform the next action before the received sensor signals are predicted to exceed the action threshold value.

Abstract: In a fuel assembly, a plurality of fuel rods are arranged in an array of 10 rows and 10 columns in the cross section of the fuel assembly. A flow resistance member is disposed in a central portion in the cross section at upper end portions of partial length fuel rods which are a part of the fuel rods. In the flow resistance member, resistance members are each disposed between ferrules arranged in an array of 6 rows and 6 columns in the diagonal direction of the flow resistance member. Resistance members are each disposed between the ferrules in a peripheral portion of the flow resistance member. By disposing the resistance members, the pressure loss in an inner region in the cross section of the fuel assembly is increased, and the flow rate of a gas-liquid two-phase flow in an outer region surrounding the inner region is increased.

Abstract: An operator of a nuclear plan is provided with a margin time up to the execution of the action at the time of an accident. The system includes: a sensor signal input device; an accident event estimation device; a procedure manual database; a procedure manual selection device; a procedure automatic check device that checks items in the procedure manual and determines a next action using the sensor signal; a plant state analysis device that analyzes a state of the plant in a case where the actions are executed at a plurality of action timings based on the accident event and the next action, and calculates predicted values of the sensor signals; an action threshold value database in which an action threshold values of the sensor signals corresponding to the action procedure at the time of the accident are stored; and an action margin time calculation device.

Abstract: When a power source is lost after an operation stop of a nuclear power plant, a first open/close valve is opened via a first battery at an early stage and steam in a reactor pressure vessel (RPV) is condensed in a suppression pool. The heat of the water in the suppression pool is transmitted to a cooling water pool located below inner space between first and second reactor containment vessels surrounding the RPV. A second open/close valve is opened via a second battery at the early stage and cooling water in a tank is injected into the RPV. After the early stage, a third open/close valve is opened via a third battery, and a cooling medium becomes steam by an evaporator in the RPV, the steam being condensed by a condenser disposed in the inner space to become a liquid of the cooling medium and is returned to the evaporator.

Abstract: An object of the invention is to provide a system for assisting operation at the time of a plant accident, which, even if a device malfunctions at the time of the plant accident, can determine normality of a sensor without being influenced by the malfunction. A system for assisting operation at the time of a plant accident, includes: a phenomenon identification apparatus for identifying a state of a plant; a plant behavior analysis apparatus for predicting progress of a process state after a phenomenon occurs by using at least a phenomenon identification result as an initial condition of plant behavior analysis; and a sensor normality determination apparatus for determining normality of a sensor by comparing a result of prediction of the progress of the process state which is output from the plant behavior analysis apparatus with a sensor signal.

Abstract: To eliminate or reduce stress for an operator who operates an operation panel. A touch panel-type operation panel includes a display with touch panel including an image display surface for displaying an operation part and a control device. The display with touch panel detects approach of an operation finger to the operation part and the position of the operation part and outputs signals of the detected approach of the operation finger and the detected position. The control device predicts and analyzes, in response to an input of the signals of the approach of the operation finger and the position, a state of a control target by operation corresponding to the operation part with reference to state data of the control target, determines appropriateness of the predicted and analyzed operation, and outputs a result of the determination.

Abstract: An object of the invention is to provide an operation support system for plant accidents that estimates events reflecting plant states changing momentarily at plant accidents. The invention includes an event narrow-down device that narrows down occurring event candidates based on at least one of a sensor signal, a device state signal, and an alarm signal and a discriminant rule, an event analysis device that analyzes a plant behavior based on a plurality of event narrow-down results as output of the event narrow-down device, the sensor signal, the device state signal, and the alarm signal, and an event estimation device that estimates an occurring event by comparing an analysis result from an analysis of a process state as output of the event analysis device and the sensor signal, wherein the event estimation device outputs the analysis result of the process state and the sensor signal corresponding to the occurring event as an event estimation result.

Abstract: In a fuel assembly, a plurality of fuel rods are arranged in an array of 10 rows and 10 columns in the cross section of the fuel assembly. A flow resistance member is disposed in a central portion in the cross section at upper end portions of partial length fuel rods which are a part of the fuel rods. In the flow resistance member, resistance members are each disposed between ferrules arranged in an array of 6 rows and 6 columns in the diagonal direction of the flow resistance member. Resistance members are each disposed between the ferrules in a peripheral portion of the flow resistance member. By disposing the resistance members, the pressure loss in an inner region in the cross section of the fuel assembly is increased, and the flow rate of a gas-liquid two-phase flow in an outer region surrounding the inner region is increased.

Abstract: A fuel assembly with a plurality of fuel rods, extending along a uniform direction, disposed inside a channel box assuming a quadrangular duct shape, wherein: the plurality of fuel rods that are disposed on sides of a plurality of hypothetical concentric quadrangles of various sizes with shapes similar to a cross-sectional shape of the channel box viewed from an end along which the fuel rods extend, and include at least outermost fuel rods disposed on the sides of a largest hypothetical concentric quadrangle among the hypothetical concentric quadrangles and second layer fuel rods disposed on the sides of a second largest hypothetical concentric quadrangle among the hypothetical concentric quadrangles; and the outermost fuel rods are disposed so that consecutive outermost fuel rods are set apart from each other over equal intervals which are greater than intervals setting apart consecutive fuel rods among the second layer fuel rods.