The Research Of Heat Pipe Technology Applied In The Field Of Nuclear Reactor

With the rapid development of China’s economy, increasing demand for energy, nuclear energy will become an important part of China’s energy development. In order to make sure the security of nuclear reactor, especially nuclear reactor malfunction when the core temperature rises rapidly, to transfer the heat out of the nuclear reactor must be quick. As is known to all, heat pipe is a kind of efficient heat transfer component. With the development of heat pipe technology and its application in nuclear power engineering is more and more widely. The working temperature range of heat pipe is determined by its working fluid, so we’re going to make some research about the characteristic of the working fluid.According to the working temperature of nuclear reactor on its first loop outlet about300℃, selecting the working fluid temperature range of200℃～500℃. In contrast with the working fluid on the temperature range of200℃～500℃, the thermal characteristic of sodium and potassium alloy surpass other working fluid. The relevant research on sodium and potassium alloy (whose mass fraction of potassium is55percentages) is rare. Therefore, the thermal characteristics of the sodium-potassium alloy were studied.The sodium-potassium alloy thermal characteristics system established consists of three parts:the container with sodium-potassium alloy, electric furnace and temperature measurement system. Electric furnace has been completed in the early work. This paper completed the design of the vessel, the research of temperature measurement methods, the accuracy of the thermometer and sodium-potassium alloy thermal characteristics.Through the current domestic and abroad thermal characteristics research of the sodium-potassium alloy, design principles of wick material, working fluid and shell materials and the size requirements of container. Base on the above finished container selection, welding, leak detection, cleaning, vacuum degassing, sodium-potassium alloy filling process. Two different accuracy resistance bridge Microk400and Guildline6622A used in temperature measurement devices. Basis of previous work done in electric furnace design, the container equipped with sodium-potassium alloy and the two temperature measuring devices consist of two different experimental system.Temperature measuring device includes a standard platinum resistance thermometer and high-precision temperature measurement bridge. The true thermal characteristics sodium-potassium alloy can be get when the test results of standard platinum resistance thermometer are accurate and the high-precision resistance bridge is working properly. The accuracy research of temperature measurement devices is based on the triple point of water, which the most important, most accurate and easy-to-use temperature standard.Electric furnace temperature control is achieved by the temperature control device, a large number of applied research results show that the PID control algorithm developed and widely used in temperature control instrument. Temperature control device realized the control of electric furnace temperature by programming, and then self-tuning PID parameters to obtain stable temperature field. When self-tuning PID parameters obtained inappropriate, obtain the appropriate parameters manually adjusted. The improper PID parameters can’t control the temperature well. Therefore, the controller need to adjust the PID parameters to stabilize the setting temperature.The two sets of experiments systems tested the thermal properties of sodium potassium alloy of200℃～500℃.The results showed that:at200℃～500℃temperature region, the stability of sodium and potassium alloy within3hours superior to8mK,the vertical temperature uniformity of0～5cm better than40mK;at200℃and400℃,the1st experimental system can maintain longer period temperature stability, the2nd experimental system stabilize the temperature in a short time, and then main a stable temperature field; at300℃and500℃, more experiments need to be continued.In view of the above-mentioned research, conclusions can be drawn:at200℃-500℃temperature region, sodium potassium alloy has good stability and uniformity, and the results provide basic data for the usage in nuclear reactor.