Quantification and mechanism analysis of the kinf uncertainty propagated from nuclear data for the TRISO particle fuel pebble. (May 2019)

• Record Type: Journal Article
• Authors: Hao, Chen; Cheng, Youying; Teng, Qichen
• Is Part Of: Annals of nuclear energy. Volume 127(2019)
• Page Start: 248
• Page End: 256
• Publication Date: 2019-05
• Subjects: Pebble bed HTR -- TRISO particle fuel pebble -- Eigenvalue -- Uncertainty -- Nuclear data; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2018.12.011
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: An explicit fuel pebble model with regular lattice of TRISO particles was built. A "step-by-step comparison scheme" was designed to understand the mechanism. Contribution difference on k inf uncertainty from different sources were quantified. A more clear picture of uncertainty propagation for pebble bed HTR was obtained. Abstract: To give a more clear picture of uncertainty propagation and quantification in the pebble bed high temperature reactor (HTR), an explicit fuel pebble model with regular lattice model of TRISO particles was built in the SCALE 6.2.1 code system to quantify the uncertainty of the infinite multiplication factor propagated from nuclear data. Based on this lattice model, a "step-by-step comparison scheme" was designed to fully understand the mechanism of the contributions of nuclear data to the total uncertainty of the infinite multiplication factor. Then the contribution difference arose from uranium loading, enrichment, temperature, material composition, position in a realistic reactor and covariance library was quantified. Some valuable observations were further drawn from the mechanism analysis. Numerical results show that the average number of neutrons emitted per fission event of 235 U is the most significant contributors to the total uncertainty. Same as the light water reactor, increasing temperature leads to a decreasing multiplication factor but an increasing uncertainty. Especially that 239 Pu will play a more and more important role to total uncertainty, and also the contribution of 135 Xe is also not negligible, when the depletion is considered. For the realistic reactor core, the position of fuel pebble in the core not only has a significant effect on the multiplication factor and spectrum, but also on the uncertainty propagation. Finally, the difference derives from libraries is also not to be ignored.