Author(s)

YOUNG SEOK BANG

Abstract

A method is developed to determine the hydraulic resistance in Safety Injection Tanks (SIT) with Fluidic Device (FD), which is to be used in the system thermal-hydraulic calculation of Large Break Loss-Of-Coolant Accident (LBLOCA) of Advance Power Reactors 1400 (APR1400). From the overall loss factor estimated from the SIT blowdown test data, the loss factor through the standpipe flow path and the one through the connecting holes of FD are determined from the hydrodynamic consideration. Also, a range of uncertainty of the hydraulic resistances is obtained by confirming that the trend of the SIT test data is covered by the results from the calculations of the test sequence using the set of lower bound K-factors and the set of upper bound K-factors, respectively. Nitrogen release during the blow-down test is discussed in terms of its amount and timing. Implementing the K-factors and the related modelling scheme of SIT, a LBLOCA of APR1400 is calculated using a system thermal-hydraulic code, MARS-KS 1.4. Fuel cladding response and nitrogen gas intrusion to the core are investigated. Sensitivity study is conducted to support to address the effect of uncertainty of SIT/FD to fuel cladding thermal response.

Keywords

ECCS bypass, hydraulic resistances of standpipe and fluidic devices, MARS-KS code, nitrogen gas behavior, safety injection tank with fluidic device