Numerical simulation of the early startup period of heat pipe cooled reactor system from the room temperature state

Heat pipe cooled reactor has unique characteristics during reactor startup and power operation due to the design of solid reactor and heat pipes heat transportation. In this paper, numerical simulation of the early startup period of typical heat pipe cooled reactor is carried out. Based on the calculation, it can be found that it takes about 6000s to complete startup from the room temperature, and fuel temperature reaches about 730 K. Important phenomenon of power pulse is also discovered. For power pulse, reactor power can rapidly increase from 80 wt to 40kWt with about 220 s, leading to rapid increase in fuel temperature from 300 K to 420 K. It is also found that heat pipes may cool down again if reactor power is low enough. Studies carried out in this paper show the dynamic characteristics and point out the key issues that need to be focused on during the reactor early startup period.