Thermal-Hydraulic Analysis of a NTD System during Irradiation

HANARO has a utility for the neutron transmutation doping(NTD) of silicon(Si), which can produce a high quality semiconductor by neutron absorption of a Si crystal ingot. The Si ingot generates heat during the irradiation process. A NTD system is designed to remove heat by a natural circulation of reactor pool water through a small gap between the silicon ingot and its cylindrical irradiation can. If the heat released from a Si ingot can not be removed sufficiently by natural convection, a boiling occurs on the silicon ingot surface. The boiling disturbs the uniformity of the neutron flux, which directly affects the silicon quality. A thermal-hydraulic analysis using a CFD code and a measurement were carried out to examine the temperature distribution of Si ingot during an irradiation. In a comparison these two results agreed well with each other