This work presents a methodology to coarsen subchannel models accelerate largescale Serpent2-SUBCHANFLOW calculations. The method is based on first building fully detailed model and then combining subchannels into larger channels with condensed hydraulic parameters. To quantify the accuracy performance of this scheme, full-core VVER-1000 problem simulated using two types coarsened models, as we...

This report has been prepared as a part of the Agreement on Research Participation and Technical Exchange under the International Code Application and Maintenance Program. KS-i Test 35-1 data on the behaviour of the heated rod temperatures in the partially uncovered VVER Core model were simulated with RELAP5/MOD3.2 to assess the code, especially its non equilibrium (unequal phase temperatures) ...

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Modeling of dynamic processes in nuclear reactors is carried out, mainly, on the basis of the multigroup diffusion approximation for the neutron flux. The basic model includes a multidimensional set of coupled parabolic equations and ordinary differential equations. Dynamic processes are modeled by a successive change of the reactor states, which are characterized by given coefficients of the e...

The safety performance of nuclear power plants (NPPs) is a very important factor in evaluating energy sustainability. Safety analysis passive and active systems have positive influence on reactor transient mitigation. One the common transients primary coolant leg rupture. This study focused guillotine large break loss (LB-LOCA) one vessels, which cold rupture occurred, after establishment stead...