A system for removing thermal energy generated by radioactive materials is provided. The system comprises an air-cooled shell-and-tube heat exchanger, comprising a shell and plurality of heat exchange tubes arranged in a substantially vertical orientation within the shell, the heat exchange tubes comprising interior cavities that collectively form a tube-side fluid path, the shell forming a shell-side fluid path that extends from an air inlet of the shell to an air outlet of the shell, the air inlet at a lower elevation than the air outlet; a heat rejection closed-loop fluid circuit comprising the tube-side fluid path, a coolant fluid flowing through the heat rejection closed-loop fluid circuit, the heat rejection closed-loop fluid circuit thermally coupled to the radioactive materials; and the air-cooled shell-and-tube heat exchanger transferring thermal energy from the coolant fluid flowing through the tube-side fluid path to air flowing through the shell-side fluid path.

A method and apparatus for maintaining or establishing a readiness state in a fuel cell backup system of a nuclear reactor system are disclosed. A method includes maintaining a readiness state of a fuel cell system within a set of readiness parameters, the readiness parameters a function of a characteristic of the nuclear reactor system. Another method includes monitoring a nuclear reactor system characteristic and, responsive to the monitored nuclear reactor system characteristic, establishing a readiness state of a fuel cell system. An apparatus includes a fuel cell system associated with a nuclear reactor system and a fuel cell control system configured to maintain a readiness state of the fuel cell system. Another apparatus includes a fuel cell system associated with a nuclear reactor system, a nuclear reactor characteristic monitoring system, and a fuel cell control system configured to establish a readiness state of the fuel cell system.

A method and apparatus for maintaining or establishing a readiness state in a fuel cell backup system of a nuclear reactor system are disclosed. A method includes maintaining a readiness state of a fuel cell system within a set of readiness parameters, the readiness parameters a function of a characteristic of the nuclear reactor system. Another method includes monitoring a nuclear reactor system characteristic and, responsive to the monitored nuclear reactor system characteristic, establishing a readiness state of a fuel cell system. An apparatus includes a fuel cell system associated with a nuclear reactor system and a fuel cell control system configured to maintain a readiness state of the fuel cell system. Another apparatus includes a fuel cell system associated with a nuclear reactor system, a nuclear reactor characteristic monitoring system, and a fuel cell control system configured to establish a readiness state of the fuel cell system.

A nuclear power plant control system (3) is provided with detection units (30a to 30d) which detect phenomena that occurs in a nuclear power plant for each of four systems, a trip control device (20) which starts, in the case where a signal that indicates an occurrence of the phenomenon is input from at least a predetermined number of signal lines out of signal lines of two systems, processing corresponding to the phenomenon, and majority circuits (50a and 50b) which are provided for each signal line of the two systems and each output, in the case where the phenomenon is detected by N or more detection units out of the detection units (30a to 30d), a signal that indicates an occurrence of the phenomenon to a corresponding signal line.

A nuclear power plant control system (3) is provided with detection units (30a to 30d) which detect phenomena that occurs in a nuclear power plant for each of four systems, a trip control device (20) which starts, in the case where a signal that indicates an occurrence of the phenomenon is input from at least a predetermined number of signal lines out of signal lines of two systems, processing corresponding to the phenomenon, and majority circuits (50a and 50b) which are provided for each signal line of the two systems and each output, in the case where the phenomenon is detected by N or more detection units out of the detection units (30a to 30d), a signal that indicates an occurrence of the phenomenon to a corresponding signal line.

The present invention relates to a method for monitoring a nuclear power plant in a transient state, the method comprising the steps of: classifying signals to be monitored of the nuclear power plant into a constant monitoring signal, a primary system monitoring signal, a secondary system monitoring signal, and a monitoring signal during normal operation; constantly monitoring the constant monitoring signal at the time of starting the nuclear power plant; sequentially initiating monitoring of the primary system monitoring signal and the secondary system monitoring signal while monitoring the constant monitoring signal; and initiating monitoring of the monitoring signal during normal operation when it is determined to be operating normally after initiating the monitoring of the secondary system monitoring signal.

The present invention relates to a method for monitoring a nuclear power plant in a transient state, the method comprising the steps of: classifying signals to be monitored of the nuclear power plant into a constant monitoring signal, a primary system monitoring signal, a secondary system monitoring signal, and a monitoring signal during normal operation; constantly monitoring the constant monitoring signal at the time of starting the nuclear power plant; sequentially initiating monitoring of the primary system monitoring signal and the secondary system monitoring signal while monitoring the constant monitoring signal; and initiating monitoring of the monitoring signal during normal operation when it is determined to be operating normally after initiating the monitoring of the secondary system monitoring signal.

An in-vessel cooling and power generation system according to the present disclosure may include a small scale reactor vessel, a heat exchange section provided inside the reactor vessel, and formed to supply supercritical fluid to receive heat from a reactor coolant system in the reactor vessel, an electric power production section comprising a supercritical turbine formed to produce electric energy using the energy of the supercritical fluid whose temperature has increased while receiving heat from the reactor coolant system, a cooling section configured to exchange heat with the supercritical fluid discharged after driving the supercritical turbine to shrink a volume of the supercritical fluid, wherein the supercritical fluid that has received heat from the reactor coolant system in the heat exchange section is formed to circulate through the electric power production section, and the cooling section.

An in-vessel cooling and power generation system according to the present disclosure may include a small scale reactor vessel, a heat exchange section provided inside the reactor vessel, and formed to supply supercritical fluid to receive heat from a reactor coolant system in the reactor vessel, an electric power production section comprising a supercritical turbine formed to produce electric energy using the energy of the supercritical fluid whose temperature has increased while receiving heat from the reactor coolant system, a cooling section configured to exchange heat with the supercritical fluid discharged after driving the supercritical turbine to shrink a volume of the supercritical fluid, wherein the supercritical fluid that has received heat from the reactor coolant system in the heat exchange section is formed to circulate through the electric power production section, and the cooling section.

Methods for nuclear power plant maintenance which reduces outage time while a polar crane is maintained. In some examples, the method includes the steps of placing an auxiliary crane on a set of rails of a polar crane, using the auxiliary crane to perform maintenance work while the polar crane is maintained, and removing the auxiliary crane after maintenance work on the polar crane is completed. In some further examples, the method includes placing a second auxiliary crane on the set of rails. Still in other example, bridge motors are used to turn the rails, allowing the auxiliary crane to reach every area of the plant floor.