Disquisition on the third seal leakage flow of reactor coolant pump

The third seal leakage flow of reactor coolant pump (RCP) is an important factor to monitor the RCP's function. The flow rate is very small during normal operation of nuclear power plant. And the radioactive liquid contains boron. It is difficult to measure such leakage flow rate for normal equipment. This article describes a new method to deal with the difficulties. By taking the new method, the new flow meter adopts collecting-container theory, and successfully overcomes the shortages of normal flow meter such as instability, slow response, low precision, etc. The new flow meter was put into use for more than two years with satisfactory functions. It is a good reference for small flow rate measurements. (authors)