Neutronic library for ALLEGRO calculations by DYN3D - initial version

Darilek, Petr; VÚJE

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


Preparation of first files at interpolation cross section library of dynamic macrocode DYN3D,
suitable for calculation of gas cooled fast reactor, is described at this paper. Spectral code
HELIOS was used for very first library files preparation. DYN3D-MG was chosen as target
macrocode because of its excellent characteristics. Input of cross sections in the format of
interpolation tables was preferred for GFR calculations. First macrocode results with new
library were compared with results of spectral codes HELIOS and SERPENT. Good
functionality of first library version was concluded.
Dynamic macrocode DYN3D-MG was accepted for ALLEGRO reactor macro-calculations.
Suitable cross section library that enables burnup calculations is needed for core and reactor
analyses. Cross section interpolation tables were selected for this task performance.
Spectral code HELIOS is used regularly for preparation of LWR cross section libraries for
DYN3D-MG and other macrocodes. It was shown by comparison with general MC code
SERPENT, that HELIOS accuracy is acceptable also for ALLEGRO calculations.
Preparation of cross section data sets for VVER-440 and ALLEGRO reactors and its
transformation into cross section libraries by developed library code is described at this
Dynamic macrocode DYN3D-MG contains various possibilities for cross section input.
Choice ?IWQS = 22? was selected as alternative for VVER-440 burnup calculations 1.
This type of library is characterised by multi-dimensional tables of data records, in which all
possible combinations of parameter variation are considered. The accuracy of this method
increases with the density of ?data points?, calculated by the cell-code calculations. To avoid
huge tables and consequently immense computing times it make sense to choose the datapoint density in a way that matches the accuracy of both cell code and diffusion code
(DYN3D at this case).
Spectral code HELIOS was selected for generation of multi-dimensional-table library 2. It is
used at DYN3D-MG with linear multi-dimensional interpolation. In general, five
?dimensions? = operation parameters are used as follows:
? Burn-up
? Coolant density D
? Boron concentration Cb
? Fuel temperature Tf
? Coolant temperature Tm

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