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UO-2 vs MOX: Propagated nuclear data uncertainty with burnup using Fast Total Monte Carlo
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
2013 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Precise assessment of propagated nuclear data uncertainties in integral reactor

quantities is necessary for the development of new reactors as well as for modified

use, e.g. when replacing UO-2 fuel by MOX fuel in conventional thermal reactors.

The Fast Total Monte Carlo method (Fast TMC) is a further development of Total

Monte Carlo - a reliable, general and flexible way to study how uncertainties

propagate from differential nuclear data to integral results. The main idea is not new

or unique for the field: integral quantities of interest are computed multiple times

using differential data which is randomly sampled from distributions that quantify the

uncertainty of the differential data; the spread in the results is then used in the

quantification of the propagated uncertainties.

This text compares UO-2 fuel to two types of MOX fuel with respect to propagated

nuclear data uncertainty, primarily in the neutron multiplication factor k-eff, by

applying Fast TMC to a typical PWR pin cell model in the Monte Carlo transport code

SERPENT, including burnup. An extensive amount of nuclear data uncertainties is

taken into account, including transport and activation data for 105 isotopes, fission

yields for 13 actinides and thermal scattering data for hydrogen in water.

There is indeed a significant difference in propagated nuclear data uncertainty in k-eff;

at 0 burnup the uncertainty is 0.6 % for UO-2 and about 1 % for the MOX fuels. The

difference decreases with burnup. Uncertainties in fissile fuel isotopes and thermal

scattering are the most important for the difference and the reasons for this are

understood and explained.

This work thus suggests that there can be an important difference between UO-2 and

MOX for the determination of uncertainty margins. However, the effects of the

simplified model are difficult to overview; uncertainties should be propagated in more

complicated models of any considered system. Fast TMC however allows for this.

Place, publisher, year, edition, pages
UPTEC F, ISSN 1401-5757 ; 13025
National Category
Engineering and Technology
URN: urn:nbn:se:uu:diva-202725OAI: oai:DiVA.org:uu-202725DiVA: diva2:632976
External cooperation
NRG, Petten, The Netherlands
Educational program
Master Programme in Engineering Physics
Available from: 2013-08-02 Created: 2013-06-25 Last updated: 2013-08-02Bibliographically approved

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