Preceeding of PHYSOR 2012, Knoxville, Tennessee, USA, April 15-20, 2012, on CD-ROM
A new Monte Carlo (MC) eigenvalue calculation scheme that substantially reduces the number of
cycles is introduced with the aid of coarse mesh finite difference (CMFD) formulation. First, it is
confirmed in terms of pin power errors that using extremely many particles resulting in short
active cycles is beneficial even in the conventional MC scheme although wasted operations in
inactive cycles cannot be reduced with more particles. A CMFD-assisted MC scheme is introduced
as an effort to reduce the number of inactive cycles and the fast convergence behavior and reduced
inter-cycle effect of the CMFD assisted MC calculation is investigated in detail. As a practical
means of providing a good initial fission source distribution, an assembly based few-group
condensation and homogenization scheme is introduced and it is shown that efficient MC
eigenvalue calculations with fewer than 20 total cycles (including inactive cycles) are possible for
large power reactor problems.
