A nuclear reactor incorporates a fully passive decay heat removal system with a modular cold source. The decay heat removal system is configured to remove heat passively, via the outside of a primary vessel included in the nuclear reactor. The cold source has a plurality of modules grouped together in assemblies. Each module is filled with a phase change material. Each module is cooled by a monotube heat exchanger. The decay heat removal system includes a hot collector and a cold collector to ensure the distribution of a heat transfer fluid in the plurality of monotube heat exchangers.

Modifications to power plants for moderating climate warming and increasing safety combine a large compressed air energy storage (CAES) system with a thermal power plant such that free power plant waste heat replaces natural gas used at existing and planned CAES facilities. The system allows higher percentages of wind and solar energy on existing grids. The compressed air in a companion CAES can cool a nuclear reactor during an emergency. Also an inexpensive, add-on, external, Emergency Core Cooling System (ECCS) can cool a nuclear reactor after shutdown, even when all internal cooling water circulation has been disabled. All embodiments are installed outside the plant where they will not be damaged in the event of a plant accident. Both systems use environmentally friendly compressed air energy storage in new ways, and can be built and installed quickly around the world at existing plants using only proven infrastructure.

Modifications to power plants for moderating climate warming and increasing safety combine a large compressed air energy storage (CAES) system with a thermal power plant such that free power plant waste heat replaces natural gas used at existing and planned CAES facilities. The system allows higher percentages of wind and solar energy on existing grids. The compressed air in a companion CAES can cool a nuclear reactor during an emergency. Also an inexpensive, add-on, external, Emergency Core Cooling System (ECCS) can cool a nuclear reactor after shutdown, even when all internal cooling water circulation has been disabled. All embodiments are installed outside the plant where they will not be damaged in the event of a plant accident. Both systems use environmentally friendly compressed air energy storage in new ways, and can be built and installed quickly around the world at existing plants using only proven infrastructure.

A nuclear reactor is configured with a primary coolant loop for transferring heat away from the nuclear reactor core. In a shutdown event, the primary coolant pump may stop pumping primary coolant through the reactor core, resulting in decay heat buildup within the reactor core. An inertial energy coast down system can store kinetic energy while the nuclear reactor is operating and then release the stored kinetic energy to cause the primary coolant to continue to flow through the nuclear reactor core to remove decay heat. The inertial energy coast down system may include an impeller and a flywheel having a mass. During normal reactor operation, the flowing primary coolant spins up the impeller and flywheel, and upon a shutdown event where the primary coolant pump stops pumping, the flywheel and impeller can cause the primary coolant to continue to flow during a coast down of the flywheel and impeller.

An emergency spent nuclear fuel pool cooling system that requires no external electrical power source and relies on the expansion of a cryogenic fluid through an evaporator/heat exchanger submerged within the spent fuel pool, to power various components used to cool the spent fuel pool and adjacent areas and provide makeup water to the spent fuel pool. Other than the evaporator/heat exchanger to which the cryogenic fluid is connected, the remaining components employed to cool the pool and the surrounding area and provide makeup water can be contained in a relatively small, readily transportable skid.

A nuclear reactor is configured with a primary coolant loop for transferring heat away from the nuclear reactor core. In a shutdown event, the primary coolant pump may stop pumping primary coolant through the reactor core, resulting in decay heat buildup within the reactor core. An inertial energy coast down system can store kinetic energy while the nuclear reactor is operating and then release the stored kinetic energy to cause the primary coolant to continue to flow through the nuclear reactor core to remove decay heat. The inertial energy coast down system may include an impeller and a flywheel having a mass. During normal reactor operation, the flowing primary coolant spins up the impeller and flywheel, and upon a shutdown event where the primary coolant pump stops pumping, the flywheel and impeller can cause the primary coolant to continue to flow during a coast down of the flywheel and impeller.

A nuclear reactor is designed to couple the load path of the control elements with the reactor core, thus reducing the opportunity for differential movement between the control elements and the reactor core. A cartridge core barrel can be fabricated in a manufacturing facility to include the reactor core, control element supports, and control element drive system. The cartridge core barrel can be mounted to a reactor vessel head. Thus, any movement, such as through seismic forces, transmits an equal direction and magnitude to the control elements and the reactor core. This arrangement reduces the opportunity for differential movement between the control elements and the reactor core.