An underground nuclear power reactor having a hollow blast tunnel which extends from one end of a containment member which houses a nuclear reactor, heat exchanger, generator, etc. A hollow blast tunnel extends from one end of the containment member with a normally closed door positioned therebetween. The blast tunnel defines a blast chamber having a plurality of spaced-apart debris deflectors positioned therein. The blast chamber has an upper wall with a roof opening formed therein which is selectively closed by a roof portion. If the reactor needs to be repaired or replaced, the door is opened so that the reactor will pass therethrough into the blast chamber and outwardly through the roof opening. If the reactor explodes, the blast therefrom drives the debris therefrom through the door and into the blast chamber where the deflectors reduce the blast force as the debris passes through the blast chamber.

The present disclosure relates to an online monitoring method of a nuclear power plant system based on an isolation forest method and a sliding window method. An isolation forest method used in the present disclosure is an abnormal detection model based on the idea of binary tree division, and has no requirements on the dimension and linear characteristics of monitoring data. In view of the characteristics of strong nonlinearity and high dimension of operation data of the nuclear power plant system, in the process of state monitoring, system abnormalities can be detected more quickly and accurately. In the present disclosure, a sliding window method is used to improve an isolation forest model, so that the improved isolation forest model has the functions of model online updating and real-time state monitoring, and the usability of an isolation forest state monitoring method is enhanced.

A nuclear-power-plant computer-based procedure display device is disposed in a main control room of a nuclear power plant, and includes a operating procedure storage unit that stores a computer-based procedure in which plant operation procedures of the nuclear power plant are divided into procedure steps and listed, a operating procedure display unit that displays the computer-based procedure, and a operating procedure display control unit that controls display of the computer-based procedure. In a case where the procedure step displayed on the operating procedure display unit is selected by an operator, the operating procedure display control unit displays an indication that the procedure step is selected, on the operating procedure display unit.

A nuclear-power-plant computer-based procedure display device is disposed in a main control room of a nuclear power plant, and includes a operating procedure storage unit that stores a computer-based procedure in which plant operation procedures of the nuclear power plant are divided into procedure steps and listed, a operating procedure display unit that displays the computer-based procedure, and a operating procedure display control unit that controls display of the computer-based procedure. In a case where the procedure step displayed on the operating procedure display unit is selected by an operator, the operating procedure display control unit displays an indication that the procedure step is selected, on the operating procedure display unit.

Chemical control system for a power plant including at least one coolant electrochemical indication sensor of a flow type electrically connected to the measurement data processing and transmission unit with its outlet connected to a central computer (CPC) controlling the actuator for injection of hydrogen and chemical reagents. The hydraulic inlet of the electrochemical sensor in use of the system is connected by a sampling tube to the power plant process circuit and its hydraulic outlet is hydraulically connected to the first heat exchanger and the first throttling device with a coolant supply circuit in series. The sampling tube is configured to pass a coolant sample to the coolant electromechanical sensor and the coolant supply circuit contains tubes and valves configured to reverse the flow of the coolant sample through the first throttling device.

Chemical control system for a power plant including at least one coolant electrochemical indication sensor of a flow type electrically connected to the measurement data processing and transmission unit with its outlet connected to a central computer (CPC) controlling the actuator for injection of hydrogen and chemical reagents. The hydraulic inlet of the electrochemical sensor in use of the system is connected by a sampling tube to the power plant process circuit and its hydraulic outlet is hydraulically connected to the first heat exchanger and the first throttling device with a coolant supply circuit in series. The sampling tube is configured to pass a coolant sample to the coolant electromechanical sensor and the coolant supply circuit contains tubes and valves configured to reverse the flow of the coolant sample through the first throttling device.

Surrogate materials are in the form of solid particles that include surrogate isotopes, namely, short-lived isotopes selected and formed to serve as surrogates for the radioactive materials of a nuclear fallout without including isotopes that are, or that decay to, biologically or environmentally deleterious and persistent isotopes. The surrogate material may be formed using high-purity reactant material and irradiation and separation techniques that enable tailoring of the isotopes and ratios thereof included in the surrogate material, and the surrogate material may be dispersed, e.g., in a training environment, in solid form.

Provided is a statistical overpower penalty calculation system for a generic thermal margin analysis model, the system including: a random number generating unit generating a plurality of random numbers; an power distribution generating unit generating power information of an axial direction and a radial direction for a core burnup; an operating condition generating unit extracting an arbitrary value for a plurality of operating conditions from the random number generated above; a POL calculating unit calculating a POL of a reload core thermal margin analysis model and a POL of a generic thermal margin analysis model and calculating a plurality of the overpower penalties through the POLs; and a statistics processing unit calculating tolerance limit values according to the core burnup by statistically analyzing a distribution formed of the plurality of the overpower penalties and selecting a smallest tolerance limit value as a representative value of the overpower penalties.

An anti-rotation device for preventing separation of a valve stem and valve disc(s) in a gate valve in a nuclear reactor power plant of the type where connection means, such as a wedge or disc hub, is threadedly engaged by the valve stem to actuate the valve and a method for maintenance or repair of the valve without disassembly of the valve or removal of the valve actuator.

A system for use in shutting down a nuclear reactor includes a housing that defines a region therein sealed from an ambient environment and a gate member disposed within the region in a manner such that the gate member segregates the region into a first compartment and a second compartment isolated from the first compartment. The gate member is formed from a material having a predetermined melting point. The system further includes a neutron absorbing material disposed within the first compartment and a dispersion mechanism disposed within the region. The dispersion mechanism structured to encourage the neutron absorbing material from the first compartment into the second compartment.