Quasi-Heterogeneous 3-D Discrete Ordinates CANDU Calculations Using Attila

Abstract of the technical paper presented at:
International Conference on Future of Heavy Water Reactors
Oshawa ON, Canada
October 2–5, 2011

Prepared by:
T. Preeti and R.P. Rulko   
Canadian Nuclear Safety Commission
Ottawa, Ontario, Canada

Abstract

The Canadian Nuclear Safety Commission (CNSC) is preparing to license diverse reactor technologies (CANDU, LWR, small/research reactors). To this end, the CNSC has acquired the Attila SN transport code to serve as an independent tool in licensing reactor design evaluation. In this paper, we are presenting 3-D quasi-heterogeneous large scale parallel Attila calculations of a generic CANDU test problem. The test problem consists of 42 complete fuel channels and a reactivity device – we are using an adjuster rod. The solution method is that of the discrete ordinates SN and the computational model is quasi-heterogeneous, i.e., fuel bundle is partially homogenized into five homogeneous rings consistently with the DRAGON code model used by the industry for the incremental cross-section generation. In calculations, we are therefore using the Helios-generated 45 macroscopic cross-sections library. This approach to CANDU calculations has the following advantages: 1) it allows detailed bundle (and eventually channel) power calculations for each fuel ring in a bundle, 2) it allows the exact reactivity device representation for its precise reactivity worth calculation, and 3) it eliminates the need for incremental cross-sections. We compare our results to the reference Monte Carlo MCNP solution. The results show good agreement. In addition, we discuss performance of the Attila SN method in CANDU calculations characterized by significant upscattering.

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KEYWORDS: Attila, CANDU,  MCNP, SN