A dynamic characteristic analysis method of DET and RELAP5 coupling based on a universal instrumental variable method includes steps of: constructing a DET simulation model of a discrete dynamic event tree and modifying TRIP cards of an input file by adding universal instrumental TRIP variables according to state transition types of DET simulation objects, the universal instrumental TRIP variable being variable type or logical type; setting a simulation time of the RELAP5, controlling a simulation step, and analyzing an output result file of each simulation step of the RELAP5; backtracking the RELAP5 according to state transition types of DET simulation objects. The dynamic characteristic analysis method has advantages of simplifying TRIP setting process and method of DET state transition objects in an input file of the RELAP5 required for the coupling of DET and RELAP5, reducing a modeling complexity and improving a modeling efficiency.

A dynamic characteristic analysis method of DET and RELAP5 coupling based on a universal instrumental variable method includes steps of: constructing a DET simulation model of a discrete dynamic event tree and modifying TRIP cards of an input file by adding universal instrumental TRIP variables according to state transition types of DET simulation objects, the universal instrumental TRIP variable being variable type or logical type; setting a simulation time of the RELAP5, controlling a simulation step, and analyzing an output result file of each simulation step of the RELAP5; backtracking the RELAP5 according to state transition types of DET simulation objects. The dynamic characteristic analysis method has advantages of simplifying TRIP setting process and method of DET state transition objects in an input file of the RELAP5 required for the coupling of DET and RELAP5, reducing a modeling complexity and improving a modeling efficiency.

The invention relates to a device for controlling a plurality of nuclear reactors, comprising, for each nuclear reactor, a plurality of sensors for measuring operating parameters as well a system for controlling the nuclear reactor.

An emergency decision-making assistance system includes an information management unit operable to generate display data on the basis of emergency information and to share the emergency information via a network; a display unit operable to display a plurality of pieces of the display data generated by the information management unit; a console unit operable to switch between the plurality of pieces of display data displayed on the display unit; and a database configured to store the plurality of pieces of display data generated by the information management unit. Decision-making is thereby effectively assisted by obtaining only necessary information in a plurality of sites.

A plant operation assistance system includes: a data obtaining unit-configured to obtain monitoring data indicating state quantity of a plant, the state quantity being detected by a sensor; an identifying unit configured to identify, based on the state quantity, a probability distribution of the monitoring data; a model generation unit configured to generate, based on a plant parameter composed from a database including design information of the plant, a stochastic model of the plant; a data processing unit configured to assign the probability distribution to the monitoring data obtained by the data obtaining unit; and a prediction unit configured to input the monitoring data assigned with the probability distribution, into the stochastic model, and predicts a state of the plant.

The present invention is related to a Thorium Molten Salt Reactor (Th-MSR) using 100% non-radioactive Thorium fuel, composed of LiF+BeF.sub.2+ThF.sub.4 without containing any U-235. The Th-MSR is consisted of a reactor chamber, a fuel injector, a fuel reservoir, an in-line chemical extraction unit, a heat exchanger, a few KW electricity turbine generator and a condenser. A few KW nuclear power generation system is adopting the controlling devices comprised of a neutron flux sensor, a fuel injecting sensor, a thermal sensor and a power output sensor. A neutron generator with a high neutron flux of 10.sup.13 n/s is used. The high flux fast neutrons are slowing down into the thermal neutrons by the graphite moderators in the reactor for initiating the fission.

The present invention provides a method of operating a nuclear power plant, considering a fatigue state of a small modular nuclear reactor, the nuclear power plant including a plurality of small modular nuclear reactors, the method comprising: a monitoring step of monitoring a fatigue state of each of the small modular nuclear reactors; an analyzing step of, when a problematic small modular nuclear reactor, the fatigue state of which has been determined to be a predetermined level or more, is identified, analyzing whether the problematic small modular nuclear reactor is operable by considering the driving state of the problematic small modular nuclear reactor; a diagnosing step of diagnosing cumulative fatigue states of the remaining small modular nuclear reactors when the problematic small modular nuclear reactor has been determined to be inoperable.

In a control system for a plant controlling a plant such as a nuclear power plant 1 with use of a plurality of digital control devices 41, the plurality of digital control devices 41 include a plurality of control functions 46 to 56, and the plurality of control functions 46 to 56 are provided in the plurality of digital control devices 41 in a distributed manner so that the digital control devices 41 may not fall below safety standards preset by safety analyses. This provides a control system for a plant using the plurality of digital control devices 41 and configured to control a plant safely even when a digital control device is failed.

A control method and system for controlling a nuclear power plant includes, in the absence of detection of an imbalance between a primary power signal (S1) and a secondary power signal (S2), the implementation of a setpoint-following mode. The nuclear power plant is controlled as a function of an operational power setpoint (COP), and in the event of detection of an imbalance, automatically implementing a power-limiting mode, including the calculation of a target equilibrium power (PEC) less than or equal to the primary power (P1) and less than or equal to the secondary power (P2), and controlling the nuclear power plant (2) as a function of the target equilibrium power (PEC).