Abstract: The LSTF experiment simulating the SGTR accident at
the Mihama Unit-2 reactor is analyzed using the RELAP5/MOD3.3
code. In the accident, and thus in the experiment, the ECC water was
injected not only into the cold legs but into the upper plenum. Overall
transients during the experiment such as pressures and fluid
temperatures are simulated well by the code. The cold-leg fluid
temperatures are shown to decrease if the upper plenum injection
system is connected to the cold leg. It is found that the cold-leg fluid
temperatures also decrease if the upper-plenum injection is not used
and the cold-leg injection alone is actuated.
Abstract: Fuel rod analysis program transient (FRAPTRAN)
code was used to study the fuel rod performance during a postulated
large break loss of coolant accident (LBLOCA) in Maanshan nuclear
power plant (NPP). Previous transient results from thermal hydraulic
code, TRACE, with the same LBLOCA scenario, were used as input
boundary conditions for FRAPTRAN. The simulation results showed
that the peak cladding temperatures and the fuel centerline
temperatures were all below the 10CFR50.46 LOCA criteria. In
addition, the maximum hoop stress was 18 MPa and the oxide
thickness was 0.003mm for the present simulation cases, which are all
within the safety operation ranges. The present study confirms that this
analysis method, the FRAPTRAN code combined with TRACE, is an
appropriate approach to predict the fuel integrity under LBLOCA with
operational ECCS.