COMPARISON OF SENSITIVITY AND UNCERTAINTY IN GD AND ER CONTAINING FUELS FOR VVER-1000 USING TSUNAMI-2D
22nd Symposium of AER on VVER Reactor Physics and Reactor Safety (2012, Průhonice, Czech Republic)
Advances in spectral and core calculation methods
Abstract
Computer calculations are an important part of operation of any nuclear reactor. They are used
to predict properties of fuel assemblies during depletion in the core and they prove meeting of
all criteria for a safe operation. All calculations and their results are inevitably connected with
uncertainties. They can originate in numerical method applied, the calculated system model
developed by the user, and finally there are fundamental uncertainties in nuclear data. The
latter source of uncertainties is difficult to quantify and usually it is accounted for by some
conservative estimated increase of safety margins (by 5 % or more).
A new tool for quantitative determination of nuclear data uncertainties is being developed in
Oak Ridge National Laboratory. It is called TSUNAMI and it is distributed as a part of
SCALE package. This tool works with 1D and 2D deterministic calculations and 3D MonteCarlo calculations and processes the results. Output of the calculation is a complete
characterization of the solved system with an overall uncertainty of multiplication factor
determination caused by nuclear data for the included nuclides. Contribution of each of the
nuclides is also calculated. Furthermore, different system responses can be defined (e.g. pin
power peaking) and their sensitivity to nuclear data in dependence on neutron energy is
determined.
This analysis is aimed at comparison of uncertainties in nuclear data affecting model of
VVER-1000 fuel assembly containing either gadolinium or erbium as a burnable absorber
using TSUNAMI-2D. Both fuel types have different conditions, e.g. burnable absorber
concentration and number of pins with burnable absorber, which influences uncertainties.
Also number of benchmark experiments for either of the elements will be compared and
resulting effect on calculation uncertainties will be stated.