Cross section homogenization for transient calculations in a spatially heterogeneous geometry. (June 2018)

• Record Type: Journal Article
• Authors: Dugan, K.; Sanchez, R.; Zmijarevic, I.
• Is Part Of: Annals of nuclear energy. Volume 116(2018)
• Page Start: 439
• Page End: 447
• Publication Date: 2018-06
• Subjects: Homogenization -- Multiphysics -- Accident transient; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2018.02.041
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: Applies time-integrated flux in homogenization to spatially heterogeneous geometry. New cross section homogenization reduces errors significantly. Refinement of time intervals reduces errors in new method. Abstract: The current norm in reactor accident simulation is to use homogenized cross sections that are computed using a fundamental mode flux. It is shown however, that using such cross sections in super prompt critical kinetic calculations can introduce large errors in the time dependent power. This work uses a previously developed homogenization technique (Dugan et al., 2016a), but applied to a spatially heterogeneous domain. The new homogenization method is shown to reduce the error in maximum power from ∼40% when using fundamental mode homogenized cross sections to ∼6% when using the new homogenization technique in the case studied. Focus is given to the time discretization used in the new homogenization technique; refinement of the temporal discretization is used to show that error reduction is possible until the point at which other sources of error dominate. Additionally, a study of the computational cost involved in this method is examined and improvements are suggested to reduce the cost incurred from using this new homogenization method.