Analysis of reactor coolant pump transient performance in primary coolant system during start-up period

The reactor coolant pump is “the heart” of a nuclear reactor and the only high-speed revolving equipment in a pressurized water reactor primary cooling loop system. The accurate prediction of flow and pump transient performance, during start-up transients, is a very important factor in the reactor coolant pumps design and the nuclear reactor design. Based on the momentum conservation equation of the primary coolant and the moment balance relation of the reactor coolant pump, the transient pump total head, the acceleration head and the overcoming friction head during a pump start up are derived. The relationship between the above heads and the parameters of the system fluid and pump is established too. Furthermore, the transient torques during a pump start-up are also derived. They include the torques required to accelerate the coolant fluid, to accelerate the pump rotating parts and to overcome friction of coolant fluid in the pipes system. The relation between the above three transient torques and the parameters of the coolant fluid and the pump is respectively established. In addition, the above variables are all non-dimensionlized in order to design a new system. The transient flow rate and pump speed are solved analytically. The detailed information of the centrifugal pump characteristics is not required. The analytical non-dimensional flow rate, the pump speed, heads and torques are all affected by an energy ratio β. The effects of β on the three transient heads and the three transient torques are discussed respectively. A comparison with Tsukamoto’s experimental results, during the pump start-up, shows an excellent agreement.

► Relationships between pump heads and the parameters of a system are established.
► Relationships between pump torques and the parameters of a system are established.
► The variables are non-dimensionlized in order to design a new system and pump.
► All variables are solved analytically. Pump characteristics are not required.
► Mechanism of reactor coolant pump start-up is mathematically solved and clarified.