A nuclear power plant with a pressurized water reactor as a heat source. It is mainly composed of a nuclear island and a conventional island. The four major components of the nuclear island of a pressurized water reactor nuclear power plant are the steam generator. , voltage regulator, main pump and core. In the nuclear island system equipment mainly includes the pressurized water reactor body, the primary loop system and the auxiliary systems established to support the normal operation of the primary loop system and ensure the safety of the reactor. The conventional island mainly includes steam turbine units and secondary loop systems, and its shape is the same as that of conventional thermal power plants.
Pressurized water reactor nuclear power plants are designed and built in the 1980s, learned from experiences and lessonsons of the Chernobyl accident in the former Soviet Union and the Three Mile Island accident in the United States. Four barriers are installed.
The first barrier:
Fuel pellets. Placed in uranium oxide ceramic pellets, most of the fission products and gaseous products are retained in the core.
The second barrier:
Fuel cladding . The fuel pellets are sealed in a zirconium alloy cladding to form a nuclear fuel core rod. Zirconium alloy has sufficient strength and does not react with water at normal operating temperatures. third barrier:
The pressure vessel and pipes constitute the reactor's cooling system. The nuclear fuel core rod is sealed with a thickness of more than 20cm. High pressure resistant steel system prevents radioactive material from seeping into the reactor. building.
The fourth barrier:
Reactor containment. It is built of prestressed reinforced concrete, with walls. It is almost 100 cm thick and has a steel coating on the interior surface to resist theft. objects from inside or outside and prevent radioactive materials from entering the environment.
At the same time, the nuclear power plant is also equipped with peripheral safety systems, including: System d 'insulation.
It is used to isolate the reactor building, mainly by automatically closing the valves of the various operating pipelines passing through the factory building, collecting materials leaking into the reactor building. factory, by filtering them then evacuating them outside the factory.
Water injection system.
When the reactor risks losing power water, water is injected into the core to cool the fuel assemblytible and avoid rupture of the sheath. The injected water contains boron to prevent nuclear chain reactions. pressurized nitrogen and can automatically inject water when there is no power supply or unmanned operation.
Containment ventilation and spray system.
Containment ventilation and spray system.
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Used to cool the factory building to reduce the pressure in the factory building When the pressure in the factory building increases, the air cooling emergency chiller (heat exchanger heat by fan) is first started, the factory spray system can be started to spray cold water or boron-containing water into the factory building to reduce. heat and pressure.
All the above safety protection systems adopt independent equipment and redundant arrangements, and are equipped with emergency power supplies. The systems ofsafety can withstand earthquakes and operate in harsh environments with steam and radioactive materials.