The present invention is applied to a power system of a power plant including a three-winding transformer, and relates to a double incoming breaker system, including: a plurality of main circuit breakers respectively connected one by one to the plurality of first non-safety class high voltage buses and the plurality of second non-safety class high voltage buses; a plurality of auxiliary circuit breakers, one of which is connected in series to one of the plurality of main circuit breakers; a first power source measurer installed to correspond to the main circuit breaker and measuring a power source level of a non-safety class high voltage bus applied to the main circuit breaker; a second power source measurer installed to correspond to the auxiliary circuit breaker and measuring a power source level at an installed first point thereof; and a controller that outputs a first open signal to the main circuit breaker when an abnormal situation of the non-safety class high voltage bus is checked through the power source level measured by the first power source measurer, and outputs a second open signal to the auxiliary circuit breaker when it is determined that the main circuit breaker fails through the power source level at the first point measured by the second power source measurer after outputting the first open signal.

The present invention is applied to a power system of a power plant including a three-winding transformer, and relates to a double incoming breaker system, including: a plurality of main circuit breakers respectively connected one by one to the plurality of first non-safety class high voltage buses and the plurality of second non-safety class high voltage buses; a plurality of auxiliary circuit breakers, one of which is connected in series to one of the plurality of main circuit breakers; a first power source measurer installed to correspond to the main circuit breaker and measuring a power source level of a non-safety class high voltage bus applied to the main circuit breaker; a second power source measurer installed to correspond to the auxiliary circuit breaker and measuring a power source level at an installed first point thereof; and a controller that outputs a first open signal to the main circuit breaker when an abnormal situation of the non-safety class high voltage bus is checked through the power source level measured by the first power source measurer, and outputs a second open signal to the auxiliary circuit breaker when it is determined that the main circuit breaker fails through the power source level at the first point measured by the second power source measurer after outputting the first open signal.

An inadvertent actuation block valve includes inlet and outlet orifices being in selective fluid communication via a chamber. A disc is disposed within the chamber and a bellows is configured to contract at a predetermined pressure differential between reactor fluid entering a reference pressure orifice and control fluid entering the inlet orifice. When the bellows contracts, the disc engages the outlet orifice and isolates fluid communication between the inlet and outlet orifices. The inadvertent actuation block valve prevents inadvertent opening of an emergency core cooling valve when a reactor is at operating pressure that is above the predetermined set pressure range. The inadvertent actuation block valve permits the emergency cooling valves to open and to remain open when reactor pressure is below the predetermined set pressure range. The inadvertent actuation block valve does not impede long term emergency cooling that occurs when the reactor is at low pressure.

An inadvertent actuation block valve includes inlet and outlet orifices being in selective fluid communication via a chamber. A disc is disposed within the chamber and a bellows is configured to contract at a predetermined pressure differential between reactor fluid entering a reference pressure orifice and control fluid entering the inlet orifice. When the bellows contracts, the disc engages the outlet orifice and isolates fluid communication between the inlet and outlet orifices. The inadvertent actuation block valve prevents inadvertent opening of an emergency core cooling valve when a reactor is at operating pressure that is above the predetermined set pressure range. The inadvertent actuation block valve permits the emergency cooling valves to open and to remain open when reactor pressure is below the predetermined set pressure range. The inadvertent actuation block valve does not impede long term emergency cooling that occurs when the reactor is at low pressure.

The present relates to the integration of the primary functional elements of graphite moderator and reactor vessel and/or primary heat exchangers and/or control rods into an integral molten salt nuclear reactor (IMSR). Once the design life of the IMSR is reached, for example, in the range of 3 to 10 years, it is disconnected, removed and replaced as a unit. The spent IMSR functions as the medium or long term storage of the radioactive graphite and/or heat exchangers and/or control rods and/or fuel salt contained in the vessel of the IMSR. The present also relates to a nuclear reactor that has a buffer salt surrounding the nuclear vessel. During normal operation of the nuclear reactor, the nuclear reactor operates at a temperature that is lower than the melting point of the buffer salt and the buffer salt acts as a thermal insulator. Upon loss of external cooling, the temperature of the nuclear reactor increases and melts the buffer salt, which can then transfer heat from the nuclear core to a cooled containment vessel.

According to an embodiment, a nuclear plant has: an outer well; an in-Containment Atmosphere Dilution System to inject a gas that has a low concentration of oxygen in the outer well into a containment vessel; an accumulator containing pressurized oxygen therein; and a passive containment cooling system including: a scrubbing pool arranged in the outer well; a cooling water pool installed above a dry well and the outer well; a heat exchanger partly submerged in a cooling water; a wet well gas supply pipe that is connected to an inlet plenum of the heat exchanger at one end and connected to a wet well gas phase at the other end; and a gas vent pipe that is connected to an outlet plenum of the heat exchanger at one end and is submerged in the scrubbing pool at the other end.

Disclosed herein is a nuclear power plant main steam system that reduces the atmospheric discharge of radioactive materials generated in an accident. The system includes: a decontamination water tank containing decontamination water; and a connection pipe for connecting the decontamination water tank to a main steam pipe which connects a steam generator and a turbine. A main steam safety valve or a connection valve is provided as a three-way valve configured to discharge the generated steam to the atmosphere when an accident occurs within a design basis and to transfer the generated steam to the decontamination water tank when an accident involving damage to nuclear fuel occurs. The main steam system reduces discharge of radioactive materials to the atmosphere when a containment bypass accident (e.g., a steam generator tube rupture caused by high-temperature steam) occurs.

Disclosed herein is a nuclear power plant main steam system that reduces the atmospheric discharge of radioactive materials generated in an accident. The system includes: a decontamination water tank containing decontamination water; and a connection pipe for connecting the decontamination water tank to a main steam pipe which connects a steam generator and a turbine. A main steam safety valve or a connection valve is provided as a three-way valve configured to discharge the generated steam to the atmosphere when an accident occurs within a design basis and to transfer the generated steam to the decontamination water tank when an accident involving damage to nuclear fuel occurs. The main steam system reduces discharge of radioactive materials to the atmosphere when a containment bypass accident (e.g., a steam generator tube rupture caused by high-temperature steam) occurs.

A passive waste heat removal system on the secondary side of a marine environmental reactor. The system includes a containment, an airtight water tank, and a steam generator. The containment is partially or fully immersed in seawater. The airtight water tank is disposed on the inner wall surface of the containment, the airtight water tank being provided with a water tank inlet and a water tank outlet. The steam generator is placed in the containment, the steam generator having a steam outlet and a feedwater inlet. The water tank inlet of the airtight water tank communicates with the steam outlet of the steam generator by means of a first pipe, and the water tank outlet of the airtight water tank communicates with the feedwater inlet of the steam generator by means of a second pipe.

A ventilation system for an operating space accessible to operators in a nuclear installation is intended to allow a supply of decontaminated fresh air for a period of a few hours in the event of serious accidents involving the release of radioactive activity. In particular, the component of radioactive inert gases in the fresh air supplied to the operating space should be as small as possible. For this purpose, the ventilation system has a supply air line that is guided from an external inlet to the operating space, and into which a first fan and a first inert gas adsorber column are connected. An exhaust air line is guided from the operating space to an external outlet, and into which a second fan and a second inert gas adsorber column are connected. A switching device is provided for interchanging the roles of the first and second inert gas adsorber columns.