Safety Analysis Code for Subcritical Pressure Condition

2 Safety Analysis Code for Subcritical Pressure Condition 

As described in Chap. 5, the sliding pressure startup is one of the candidate startup schemes. It is necessary to understand the reactor behavior in case of abnormal transients and accidents during the pressurization phase. To do that, SPRAT-DOWN is extended to the SPRAT-DOWN-SUB which can be applied to the transients and accidents during subcritical pressure operation [12]. 

In the calculation meshes with the two-phase condition, the homogeneous equilibrium model (HEM) is applied to the mass, momentum, and energy conservation equations. The following heat transfer correlations are used by referring to RELAP4 [13]. 

Furthermore, Groeneveld s 2002 look-up table is used for the stable film boiling heat transfer [17]. Groeneveld s 1995 look-up table is used for the critical heat flux [18]. The critical heat flux and stable film boiling heat transfer are the most important from the viewpoint of safety. When the pressure is below 20 MPa, 

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