Explicit decay heat calculation in the nodal diffusion code DYN3D

Bilodid, Y.; Fridman, E.; Kotlyar, Dan; Shwageraus, E

doi:10.1016/j.anucene.2018.07.045

Cited by 6 publications

(1 citation statement)

References 16 publications

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“…burnup calculation and are important for reactor decay heat release calculations. Especially for Cs134m0, it is one of the main decay heat contributors of UOX fuels in long-term after reactor shutdown [32]. e updated relative uncertainty of Zr95m0 IFY is 16.1% while Cs134m0 and Mo95m0 have their relative uncertainties of 38.4% and 65.7%, respectively.…”

Section: Consider the Preservation Of Probability; The Relation Between Random Variables In Original Domain And Logarithmic Domain Is Formentioning

confidence: 99%

Lognormal-Based Sampling for Fission Product Yields Uncertainty Propagation in Pebble-Bed HTGR

Wang

Cui

Guo

et al. 2020

Science and Technology of Nuclear Installations

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Uncertainty analyses of fission product yields are indispensable in evaluating reactor burnup and decay heat calculation credibility. Compared with neutron cross section, there are fewer uncertainty analyses conducted and it has been a controversial topic by lack of properly estimated covariance matrix as well as adequate sampling method. Specifically, the conventional normal-based sampling method in sampling large uncertainty independent fission yields could inevitably generate nonphysical negative samples. Cutting off these samples would introduce bias into uncertainty results. Here, we evaluate thermal neutron-induced U-235 independent fission yields covariance matrix by the Bayesian updating method, and then we use lognormal-based sampling method to overcome the negative fission yields samples issue. Fission yields uncertainty contribution to effective multiplication factor and several fission products’ atomic densities at equilibrium core of pebble-bed HTGR are quantified and investigated. The results show that the lognormal-based sampling method could prevent generating negative yields samples and maintain the skewness of fission yields distribution. Compared with the zero cut-off normal-based sampling method, the lognormal-based sampling method evaluates the uncertainty of effective multiplication factor and atomic densities are larger. This implies that zero cut-off effect in the normal-based sampling method would underestimate the fission yields uncertainty contribution. Therefore, adopting the lognormal-based sampling method is crucial for providing reliable uncertainty analysis results in fission product yields uncertainty analysis.

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Section: Consider the Preservation Of Probability; The Relation Between Random Variables In Original Domain And Logarithmic Domain Is Formentioning

confidence: 99%