Qualification of the APOLLO2 lattice physics code of the NURISP platform for VVER hexagonal lattices
21st Symposium of AER on VVER Reactor Physics and Reactor Safety (2011, Dresden, Germany)
Reactor physics experiments and code validation
Abstract
The experiments performed at the ZR-6 zero critical reactor by the Temporary International
Collective (TIC) and a numerical assembly burnup benchmark specified for depletion
calculation of a VVER-440 assembly containing Gd burnable poison were used to qualify the
APOLLO2 (APOLLO2.8-E3) code as a part of its ongoing validation activity. The work is
part of the NURISP project, where KFKI AEKI undertook to develop and qualify some
calculation schemes for hexagonal problems. Concerning the ZR-6 measurements, single cell,
macro cell and 2D calculations of selected regular and perturbed experiments are being used
for the validation. In the 2D cases the radial leakage is also taken into account in the
calculations together with the axial leakage represented by the measured axial buckling.
Criticality parameter and reaction rate comparisons are presented. Although various sets of
the experiments have been selected for the validation, good agreement of the measured and
calculated parameters could be found by using the different options offered by APOLLO2. An
additional mathematical benchmark – presented in the paper – also attests for the reliability of
APOLLO2. All the test results prove the reliability of APOLLO2 for VVER core calculations.
1. INTRODUCTION
The main goal of the NUclear Reactor Integrated Simulation Project (NURISP) launched by
the European Union is to make new and significant steps towards a European Reference
Simulation Platform for applications relevant to present power plants including VVERs and
also to future reactors. The individual programs integrated into the platform are to be verified,
validated and demonstrated through several benchmarks corresponding to present and future
PWRs, VVERs and BWRs.
In the frame of this cooperation, MTA KFKI AEKI is performing calculations by using the
APOLLO2 code [1-2]. As a first step, calculations for ZR-6 experiments have been performed
on the basis of the NURISP benchmark specifications and the results have been compared to
the measured values and to the results from the lattice transport module of the code complex
KARATE-440 14. The experimental data used in this paper are compiled in the NEA data
bases 3. Calculations on single pin-cells, macro cells and 2D calculations of full