AVOIDING A TWICE ACCOUNTING OF MACRO-COMPONENT IN THE UNCERTAINTY OF ESTIMATED ENGINEERING MARGIN FACTORS FOR PARAMETERS OF VVER POWER DENSITY
24th Symposium of AER on VVER Reactor Physics and Reactor Safety (2014, Sochi, Russia)
Advances in spectral and core calculation methods
Abstract
AVOIDING A TWICE ACCOUNTING OF MACRO-COMPONENT IN THE UNCERTAINTY OF ESTIMATED ENGINEERING MARGIN FACTORS FOR PARAMETERS OF VVER POWER DENSITY
Dementiev V.G., Gorodkov S.S., Mikailov E.F., Shishkov L.K., Sumarokova A.S., Sukhino-Homenko E.A.
NRC «Kurchatov Institute», Russia, Moscow
ABSTRACT
The analysis proves that traditional approaches to assessing engineering margin factors includes undue conservatism. In particular, some calculation uncertainties can be twice taken into account. For instance, MCU code evaluation of effect of changed gap between VVER- 1000 fuel assemblies to rod power also takes into account the changes in power macro-field induced by gap behaviour. Power macro-field contributes to calculated-and-measured deviation of calculated methodological uncertainty. Also, it is possible to point out that sometimes it happens that the contribution of technological deviations in the process of fuel fabrication to power macro-field is accounted in mechanical uncertainties though such contribution was already included in methodological uncertainties as these uncertainties are determined in the process of measurements at actual FAs.
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