CALCULATION OF THE SECOND KINETIC AER BENCHAMRK BY USING NEW NODAL METHODS
22nd Symposium of AER on VVER Reactor Physics and Reactor Safety (2012, Průhonice, Czech Republic)
NEUTRON KINETICS AND REACTOR DYNAMICS METHODS
Abstract
A new, multigroup version of the KIKO3D code allowing arbitrary number of energy
groups ? called KIKO3DMG ? was developed for calculation of the fast spectrum
reactors. From among the advanced new features, the possibility of using triangular
geometry and the automated cutting the triangles into further ones at many levels was
utilized for an attempt to reach a converged solution of the Second AER Kinetic
Benchmark Problem.
1. INTRODUCTION
From the 1990?s, several kinetic and dynamic benchmark problems have been defined
in the frame of the AER (Atomic Energy Research) cooperation. Most of them can be
classified into the group of the ?numerical exercise benchmarks? as far as
measurements are not supporting them and – at the same time – some modeling details
are entrusted to the participants. Although the most important ?integral? modeling
features are ?normalized? in the definitions (shut down margin, recriticality
temperature, advised thermal hydraulic correlations, etc.), in the strict sense the
abovementioned feature prevails starting from the third AER kinetic benchamark
concerning the not fully exact prescription of the cross sections or all the details of the
thermal hydraulic modeling. (An advantage of these characteristics must also
mentioned, namely this approach is representing the real situation concerning the
modeling uncertainties as far as the variance of the different solutions is regarded.)
The first and second kinetic benchmarks 1 are exceptions from this point of view
because their definition makes it theoretically possible to have the converged
reference solution. In this sense, the two latter mentioned benchmarks can be regarded
as ?mathematical benchmarks? in close relation with their relative simplicity.
Nevertheless, the efforts for determining their converged reference solutions seem not
fully satisfactory, especially regarding the AER Benchmark Book
(?http://aerbench.kfki.hu/aerbench/ ?). A very important, large step in this direction
was made by N. Kolev, R. Lenain, and C. Magnaud calculating the second kinetic
benchmark by using the CRONOS fine-mesh method 2. An extrapolated to zero
mesh size reference solution was recommended for the steady states and it revealed
significant deviations from the solutions obtained from the nodal codes. The
significant deviation raised certain doubts in some participants concerning the advised
reference solution. The goal of the present work is to contribute to the existence of the
reference solution of the second kinetic rod ejection benchmark in the AER
Benchmark Book.