Abstract
The Very High Temperature Critical Assembly (VHTRC) experiment represents one of the few data sets available for the validation of HTGR lattice physics. Within the framework of the IAEA Coordinated Research Project on HTGR Uncertainty Analysis in Modeling, uncertainty and sensitivity analyses of this graphite-moderated facility are performed as the validation reference to the prismatic MHTGR-350 fuel block calculations. Nominal multi-group and continuous-energy criticality calculations with the KENO-VI Monte Carlo code of the SCALE code package are compared with the continuous-energy Monte Carlo Code Serpent. Good agreement with a maximum difference of 250 pcm is obtained. The experimental data set, however, differs by several hundred pcm with the results of both codes when using the ENDF-VII.0 library. When using ENDF/B-VII.1 data, this difference is reduced to a few hundred pcm and the calculations lie within the experimental error bars. Uncertainties of the VHTRC multiplication factors due to uncertainties in nuclear data are determined with SAMPLER/KENO-VI of SCALE 6.2 and with continuous-energy TSUNAMI of SCALE 6.2. For all experimental configurations, the obtained uncertainty is found to be 0.58% when using ENDF/B-VII.0 data. The top contributor to this uncertainty is the average number of neutrons per fission event of U-235. With ENDF/B-VII.1 data, uncertainties of about 0.66% are obtained in particular due to an increased uncertainty of U-235 nu-bar in the latest ENDF release. When considering these nuclear data uncertainties, the obtained 1σ uncertainty intervals are overlapping with the experimental error bars.
| Original language | English |
|---|---|
| Pages (from-to) | 317-329 |
| Number of pages | 13 |
| Journal | Annals of Nuclear Energy |
| Volume | 110 |
| DOIs | |
| State | Published - Dec 2017 |
| Externally published | Yes |
Funding
This work was supported by the German Federal Ministry for Economic Affairs and Energy, and the U.S. Department of Energy, Assistant Secretary for the Office of Nuclear Energy, under DOE Idaho Operations Office Contract DE-AC07-05ID14517. The assistance of Christopher M. Perfetti (ORNL) for the generation of the CE TSUNAMI models, and the generation of the initial Serpent full core models by Hans R. Hammer (Texas A&M University) is greatly appreciated.
| Funders | Funder number |
|---|---|
| German Federal Ministry for Economic Affairs and Energy | |
| U.S. Department of Energy | DE-AC07-05ID14517 |
| Office of Nuclear Energy | |
| Oak Ridge National Laboratory |
Keywords
- HTGR
- SCALE
- Sensitivity analysis
- Uncertainty analysis
- VHTRC