Study on thermal-hydraulic characteristic of OTSG at the case of loss-of-flow accident in the core

Once-Through Steam Generator (OTSG) is the key equipment of nuclear power plant. Thermal hydraulic characteristic of OTSG is very important for the safety of nuclear reactor. Based on right thermal hydraulic model, an analysis program is established to compute delay time response of reactor coolant system parameters after control rods inserting at the case of loss-of flow accident. The results show that the more time delays the more intensively thermal parameters of OTSG change. When the delay time of the control rods inserting core exceed 2s, impermanency boil will appear in the core outlet region. For the safety of nuclear reactor, the delay time of the control rods inserting core should not exceed 2s after appearance of half flow in the core. (authors)