Criticality Research of ALLEGRO Fuel Configurations

Zajac, Radoslav; VÚJE

25th Symposium of AER on VVER Reactor Physics and Reactor Safety (2015, Balatongyörök, Hungary)
Nuclear fuel Cycle Perspectives and Sustainability


The most ambitious aim of experimental reactor operation in ALLEGRO project includes
qualification of carbide fuel. The first irradiation of carbide assemblies (UPuC) will be
provided with the MOX fuel combination. Using of both fuel types is associated with storage
of fresh as well as spent fuel assemblies. The research activities are therefore designed also to
ensure subcriticality of the storage and possibly for its handling.
The aim of the research is to design material and geometric configuration of storage space to
ensure subcriticality of fuel stored in accordance with national and international requirements
in all operational situations.
During the storage and transport of nuclear fuel is necessary to provide sub-criticality of
storage and transport equipment. The computer programs used to calculate must be
sufficiently precise. Accuracy programs are verified by comparing the calculated k coefficient
with measurements. Measurements of criticality in the world are provided by the critical
experiments in an experimental reactor. The results are published in the International
Handbook of Evaluated Criticality Safety Benchmark Experiments? 16.
SCALE 6.1.2 6 includes two modules for criticality calculation: elder and simple KENO V
module and newer KENO VI. Elder module doesn?t provide analyses of hexagonal geometry
such as ALLEGRO. New KENO VI are able to model hexagonal geometries.
Control module of criticality calculation is CSAS6 module which continuously calls
executive modules:
BONAMI ? self-shielding calculation based on Bondarenko method
CENTRM/PMC/WORKER ? library evaluation based on (?continuous energy? CE)
KENO VI ? 3D code for keff calculation by Monte Carlo method
Basic equation, which describes neutron balance, is Boltzman transport equation. Numerical
solution of this equation by Monte Carlo method is based on collision probability method
where is used P0 and P1 Legender polynomials. Weighted function is determined by Russian
roulette method.

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