Development of Different Types of Shaft Seals for Nuclear Power Units

Because the main pump shaft seal is the consumption piece, a large number of spare parts are needed in the life period of the power plant. Considering the occupancy rate of the static pressure shaft seal in the power plant and the follow-up spare parts market, it is worthwhile for the domestic manufacturers to research and develop. The hydrodynamic seal itself has the characteristics of stable performance, simple structure and single key technology. Its long-term operation reliability is easier to guarantee. Although the French hot Mongolia has introduced the hydrostatic seal technology of the American Westinghouse, it has developed the fluid dynamic pressure shaft seal, which is due to the direction of the technology trend. New power plant users in the United States have also demanded that the EPR stack main pump, which France's areva bids for in the U.S. market, be equipped with a hydrodynamic shaft seal.

Considering the future trend of technology development, dynamic pressure type shaft seal is also the technology that domestic manufacturers need to master. Only in this way can China's self-designed nuclear power shaft seal be competitive in the world.

(1) Both the hydrostatic type shaft seal and the fluid dynamic type shaft seal have the mature application on the nuclear power unit, and have good experience feedback. The practice proves that these 2 seals are all reliable.

(2) The hydrostatic type shaft seal is mainly applied to the American style main pump. It still needs to be improved in performance stability and resistance to impurities. Considering the SBO accidents, the hydrostatic type shaft seal must be equipped with parking seal to ensure integrity.

(3) The fluid dynamic type shaft seal is mainly applied to the the European style main pump. Its performance is relatively stable and the pressure difference is relatively small. Through tests, the manufacturers have proved that it can not be equipped with a parking seal to ensure complete under the SBO condition. It is the future trend of technology development.

Whether it is the main pump static type shaft seal or the dynamic pressure type shaft seal, it is very important to realize the complete domestic independent design and manufacture. It is related to the strategic safety of China's nuclear power and the expansion of the overseas market. The static pressure shaft seal has a large market prospect for spare parts, while the dynamic pressure seal has a good market prospect in the future.