Original scientific paper
Full Core Criticality Modeling of Gas-Cooled Fast Reactor using the SCALE6.0 and MCNP5 Code Packages
Mario Matijević
orcid.org/0000-0001-9775-5773
; University of Zagreb, Faculty of Electrical Engineering and Computing Unska 3, 10000 Zagreb, Croatia
Dubravko Pevec
orcid.org/0000-0002-1991-5193
; University of Zagreb, Faculty of Electrical Engineering and Computing Unska 3, 10000 Zagreb, Croatia
Krešimir Trontl
; University of Zagreb, Faculty of Electrical Engineering and Computing Unska 3, 10000 Zagreb, Croatia
Radomir Ječmenica
; University of Zagreb, Faculty of Electrical Engineering and Computing Unska 3, 10000 Zagreb, Croatia
Abstract
The Gas-Cooled Fast Reactor (GFR) is one of the reactor concepts selected by the Generation
IV International Forum (GIF) for the next generation of innovative nuclear energy systems. It was
selected among a group of more than 100 prototypes and his commercial availability is expected by
2030. GFR has common goals as the rest GIF advanced reactor types: economy, safety,
proliferation resistance, availability and sustainability. Several GFR fuel design concepts such as
plates, rod pins and pebbles are currently being investigated in order to meet the high temperature
constraints characteristic for a GFR working environment. In the previous study we have compared
the fuel depletion results for heterogeneous GFR fuel assembly (FA), obtained with TRITON6
sequence of SCALE6.0 with the results of the MCNPX-CINDER90 and TRIPOLI-4-D codes.
Present work is a continuation of neutronic criticality analysis of heterogeneous FA and full core
configurations of a GFR concept using 3-D Monte Carlo codes KENO-VI/SCALE6.0 and MCNP5.
The FA is based on a hexagonal mesh of fuel rods (uranium and plutonium carbide fuel, silicon
carbide clad, helium gas coolant) with axial reflector thickness being varied for the purpose of
optimization. Three reflector materials were analyzed: zirconium carbide (ZrC), silicon carbide
(SiC) and natural uranium. ZrC has been selected as a reflector material, having the best
contribution to the neutron economy and to the reactivity of the core. The core safety parameters
were also analysed: a negative temperature coefficient of reactivity was verified for the heavy metal
fuel and coolant density loss. Criticality calculations of different FA active heights were performed
and the reflector thickness was also adjusted. Finally, GFR full core criticality calculations using
different active fuel rod heights and fixed ZrC reflector height were done to find the optimal height
of the core. The Shannon entropy of the GFR core fission distribution was proved to be useful
technique to monitor both fission source convergence (stationarity) and core eigenvalue
convergence (keff) to fundamental eigenmode with MCNP5. All calculations were done with
ENDF/B-VII.0 library. The obtained results showed high similarity with reference results.
Keywords
Hrčak ID:
199057
URI
Publication date:
31.7.2017.
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