Nuclear reactor systems and methods are described having many unique features tailored to address the special conditions and needs of emerging markets. The fast neutron spectrum nuclear reactor system may include a reactor having a reactor tank. A reactor core may be located within the reactor tank. The reactor core may include a fuel column of metal or cermet fuel using liquid sodium as a heat transfer medium. A pump may circulate the liquid sodium through a heat exchanger. The system may include a balance of plant with no nuclear safety function. The reactor may be modular, and may produce approximately 100 MW.sub.e.

Nuclear reactor systems and methods are described having many unique features tailored to address the special conditions and needs of emerging markets. The fast neutron spectrum nuclear reactor system may include a reactor having a reactor tank. A reactor core may be located within the reactor tank. The reactor core may include a fuel column of metal or cermet fuel using liquid sodium as a heat transfer medium. A pump may circulate the liquid sodium through a heat exchanger. The system may include a balance of plant with no nuclear safety function. The reactor may be modular, and may produce approximately 100 MW.sub.e.

Nuclear reactor systems and methods are described having many unique features tailored to address the special conditions and needs of emerging markets. The fast neutron spectrum nuclear reactor system may include a reactor having a reactor tank. A reactor core may be located within the reactor tank. The reactor core may include a fuel column of metal or cermet fuel using liquid sodium as a heat transfer medium. A pump may circulate the liquid sodium through a heat exchanger. The system may include a balance of plant with no nuclear safety function. The reactor may be modular, and may produce approximately 100 MW.sub.e.

Nuclear reactor systems and methods are described having many unique features tailored to address the special conditions and needs of emerging markets. The fast neutron spectrum nuclear reactor system may include a reactor having a reactor tank. A reactor core may be located within the reactor tank. The reactor core may include a fuel column of metal or cermet fuel using liquid sodium as a heat transfer medium. A pump may circulate the liquid sodium through a heat exchanger. The system may include a balance of plant with no nuclear safety function. The reactor may be modular, and may produce approximately 100 MW.sub.e.

A reactor shutdown system includes a reactor, a control-rod drive unit that can drive a control rod in pulling and inserting directions with respect to a fuel assembly, a power source that can supply power to the control-rod drive unit, and a power converter that is provided between the control-rod drive unit and the power source, in which when power supply is cut off, the control-rod drive unit inserts the control rod into the fuel assembly to stop nuclear reaction in the reactor, and the reactor shutdown system includes a reactor trip breaker provided between the power converter and the control-rod drive unit, a safety protection-system device that controls the reactor trip breaker to cut off power supply to the control-rod drive unit, and a CCF device that controls the power converter to cut off power supply to the control-rod drive unit.

A reactor shutdown system includes a reactor, a control-rod drive unit that can drive a control rod in pulling and inserting directions with respect to a fuel assembly, a power source that can supply power to the control-rod drive unit, and a power converter that is provided between the control-rod drive unit and the power source, in which when power supply is cut off, the control-rod drive unit inserts the control rod into the fuel assembly to stop nuclear reaction in the reactor, and the reactor shutdown system includes a reactor trip breaker provided between the power converter and the control-rod drive unit, a safety protection-system device that controls the reactor trip breaker to cut off power supply to the control-rod drive unit, and a CCF device that controls the power converter to cut off power supply to the control-rod drive unit.

A nuclear reactor shutdown system includes a shielded path that passes through a reactor core fuel housed in a nuclear reactor vessel in a hermetically sealed manner, one end of the shielded path having an opening and another end of the shielded path being closed; a neutron absorber that is allowed to enter from the opening of the shielded path; an elastic member that is configured to urge the neutron absorber in a direction entering inside from the opening of the shielded path by being released from a compressed state; and a braking part that is disposed so as to maintain the compressed state of the elastic member and is configured to release the elastic member from the compressed state when the braking part reaches or exceeds a threshold temperature.

A nuclear reactor shutdown system includes a shielded path that passes through a reactor core fuel housed in a nuclear reactor vessel in a hermetically sealed manner, one end of the shielded path having an opening and another end of the shielded path being closed; a neutron absorber that is allowed to enter from the opening of the shielded path; an elastic member that is configured to urge the neutron absorber in a direction entering inside from the opening of the shielded path by being released from a compressed state; and a braking part that is disposed so as to maintain the compressed state of the elastic member and is configured to release the elastic member from the compressed state when the braking part reaches or exceeds a threshold temperature.

A nuclear reactor shutdown system includes a housing vessel that is disposed above a reactor core fuel housed in a nuclear core vessel in a hermetically sealed manner, houses a plurality of neutron absorbers, and has an opening enabling the neutron absorbers to pass through at a bottom, a shielded path that passes through the reactor core fuel to extend in an up-and-down direction, an upper end of the shielded path communicating with the opening of the housing vessel and a lower end of the shielded path being closed, and a communicating part that is disposed so as to close the opening and causes the housing vessel and the shielded path to communicate with each other when the communicating part reaches or exceeds a threshold temperature.

A nuclear reactor shutdown system includes a housing vessel that is disposed above a reactor core fuel housed in a nuclear core vessel in a hermetically sealed manner, houses a plurality of neutron absorbers, and has an opening enabling the neutron absorbers to pass through at a bottom, a shielded path that passes through the reactor core fuel to extend in an up-and-down direction, an upper end of the shielded path communicating with the opening of the housing vessel and a lower end of the shielded path being closed, and a communicating part that is disposed so as to close the opening and causes the housing vessel and the shielded path to communicate with each other when the communicating part reaches or exceeds a threshold temperature.