UNCERTAINTIES IN KINETICS PARAMETERS OF NATURAL-URANIUM-FUELLED CANDU CORES INTRODUCED BY LATTICE HOMOGENIZATION AND GROUP CONDENSATION
CNS 24th Nuclear Simulation Symposium - 2012 October 15-16


Presented at:
CNS 24th Nuclear Simulation Symposium
2012 October 15-16
Location:
Ottawa,Canada
Session Title:
Technical 8: Benchmarks & Uncertainties

Authors:
Eleodor Nichita (University of Ontario Institute of Technology)
Dumitru Serghiuta (Canadian Nuclear Safety Commission)
Serguei Podobed (Canadian Nuclear Safety Commission)
  

Abstract

In the Canadian Nuclear Industry, safety analysis-related reactor kinetics calculations are performed almost exclusively using the Improved Quasistatic (IQS) flux factorization method [1, 2].  The IQS method relies on calculating effective point kinetics parameters using adjoint-weighted integrals.  The accuracy of the adjoint representation influences the accuracy of the effective kinetics parameters.  The work presented here evaluates the effect of homogenization and group condensation on the calculated effective kinetics parameters of a Natural-Uranium-fuelled CANDU lattice as a function of burnup.  Results show that, by using a two-group lattice-homogenized adjoint, the effective delayed neutron fraction is consistently overestimated by approximately 5% over a burnup range between 0 kWd/kg and 8000 kWd/kg.  The effective neutron generation time is underestimated by 0.4% at 0 kWd/kg and overestimated by 1.3% at 8000 kWd/kg. 

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