Session: 05-07: System Performance and Safety Enhancements

Paper Number: 135031

135031 - Experimental Study in Cooling Rate by Containment Spray 

Abstract: 

In case of loss of coolant accident, temperature and pressure in the containment would rise due to evaporation of coolant. Besides, radioactive aerosol and gas could possibly release to the containment in case of severe accident. Containment spray system is designed to cool it down, reduce its pressure and remove airborne radioactive material.

Spray cooling are analyzed both theoretically and experimentally in several countries. C. Kaltenbach simulated spray cooling in the model containment THAI using commercial CFD code ANSYS CFX 16.1, and results indicated a good agreement with experimental data for the poly disperse spray configuration. TOSQAN facility was built in IRSN, which was used to perform thermal hydraulic containment studies including mass and heat transfers between spray droplets and the gas mixture.

According to NUREG 1465, 95% of released fission product exists in form of aerosol. Therefore, one experimental apparatus for typical China three loop PWR was built to investigate the above phenomenon. Temperature is one of the key factors that influence the behavior of aerosol, so spray cooling rate was studied in the beginning. Experiments were conducted to obtain cooling rate by containment spay. It consists of 3 systems: 1) spray vessel, which simulates reactor containment; 2) Spray system; 3) measurement system including temperature, pressure and flow rate; 4) Water tank, which stores and provides spray water. The spray vessel is a closed stainless steel cylinder. It is 2m high, 1m internal diameter, and volume is 1.57m³. Design pressure is 0.8MPa and design temperature is 180℃. There is a electric heater in the bottom of the vessel to heat atmosphere of the vessel. When steam is needed the heater can produce steam since it can be flooded by water. Air compressor is used to inject air into the vessel. There is a safety valve above the vessel. If pressure exceeds 0.66MPa, the valve would open. The spray tank is 1.0m high with an internal diameter of 1.0m. The spray system consists of a spray nozzle, a pump, a flowmeter and a electric control valve. The pump is used to pump spray water from the tank to the vessel. The spray nozzle locates in the dome of the spray vessel on the vertical axis. The flowmeter and the electric control valve are used to control spray flow rate ,which ranges from 0 to 20L/min.

Experiments were conducted to obtain cooling rate by containment spay, which was the basis for aerosol removal coefficient experiment. Temperature distribution of spray vessel during the spray was obtained and cooling down rate was measured. Results show that spray flow rate and spray water temperature are the main parameters that determines cooling down rate. In future, aerosol spray removal coefficient will be obtained.

Presenting Author: Ning Wang China Institute For Radiation Protection

Presenting Author Biography: Wang Ning, an assistant researcher, graduated from the Radiation Protection and Environmental Protection major of the China Institute for Radiation Protection in July 2018 with a Master's degree in Engineering. From July 2018 to present, I have been employed at the China Institute for Radiation Protection, engaged in nuclear and radiation emergency research, including reactor emergency condition prediction, internal containment behavior experiments, etc.

Authors:

Ning Wang China Institute For Radiation Protection
Yapeng Yang China Institute for radiation protection
Zhe Liu China Institute for radiation protection