Proceeding of PHYSOR 2006, Sept 10-14, 2006
An efficient multigroup nodal calculation method based on the two-group
CMFD formulation and a multigroup one-node semi-analytic nodal method
(SANM) kernel is presented. The SANM solution here is based on a quartic
expansion of all the source terms. The three transverse integrated
one-dimensional equations for a three-dimensional one-node problem
specified with the incoming current boundary conditions are solved
simultaneously for the outgoing currents and the node average flux. With the
use of the two-group CMFD structure for the global calculation, the
multigroup calculation needs to be performed only at the local one-node
level and thus the implementation of this method into an existing code is
facilitated. The effectiveness of this method is examined by solving a set of
multigroup problems. The results of a set of sensitivity studies to determine
the number of one nodes sweeps per nodal update, order of the energy and
space sweeps and group split pattern are also presented.
