Experimental Study On The Heat Pipe For The Long-term Passive Cooling System Of Spent Fuel Pool

To remove the decay heat released by the spent fuel stored in the spentfuel pool, the spent fuel pool must be effectively cooled. The heat pipecooling system is passive and no electricity driven component. Using the heatpipe to cool the spent fuel pool can significantly increase the passive coolingtime without the active intervention, which is prominent for achieving thelong-term passivly cooling the advanced pressurized water reactor in theacidential conditon. In this paper, experimental study on a simpliedlarge-scale separated type heat pipe for the spent fuel pool was carries out.The heat transfer performance of the large-scale heat pipe was tested and it isconcluded that it is feasible to passively cool the spent fuel pool using heatpipe. The main contents and results include:(1) To provide the basis for the designing large-scale separated type heatpipe experimental program, three-dimensional geometric model and highquality mesh structure for CAP1400spent fuel pool heat pipe coolingsolution was built, then the numerical model based on Fluent software wasestablished. The CFD results showed the spent fuel pool flow field andtemperature distribution characteristics at different heat sources and differentheat pipe layout.(2) A large-scale separated type heat pipe experimental platform wasdesigned and built. The heat pipe evaporator is7.6m high with inner diameter65mm and the condensation section is20m long. The variance of the waterstate inside the separated type heat pipe was revealed. It was found that the working fluid flowing through the heat pipe evaporator section generallyexperienced a subcooled zone, pool boiling zone and high gas qualitytwo-phase region. Under typical operating conditions(filling ratio height5.6m, heating water inlet temperature80℃, heating water flow rate0.011m/s,air velocity1.5m/s), the separated type heat pipe has the ability to cool thespent fuel pool and its heat transfer rate up to13kW.(3) The parametric sensitivity analysis for the heat transfer rate oflarge-scale separated type heat pipe was done. It is revealed that the hot watertemperature and its flow rate play an important role on the heat transfercapacity. The effect of the air velocity outside condenser and filling ratio areminor. Furthermore, the separated type heat pipe thermodynamic cycle andheat transfer characteristics is closely related to the working fluid physicalproperties.