MODELING AND SENSITIVITY/UNCERTAINTY ANALYSES OF ZED-2 BENCHMARK EXPERIMENTS USING DRAGON, DONJON & SUSD3D
Bibliographic record
Abstract
Due to the strong interest in thorium fuels in CANDU reactors rooting back to 1970’s and 1980’s, four experiments were done in the ZED-2 critical facility at Chalk River Laboratories to test the properties of (Th,Pu)O2 fuel. The fuel was placed in five bundles with a typical CANDU design, stacked vertically in the center of the core (K0 site) and surrounded by natural uranium fuel. The simulation of these experiments using the transport code DRAGON coupled with the diffusion code DONJON is presented. DRAGON is initially used to model two lattices and the full cores in 2D. These models are designed to calculate direct/adjoint flux, k∞ and keff values using the collision probability method. Furthermore, the models determine a set of homogenized and condensed cross sections in two energy groups. Subsequently, DONJON is used to model the full core facility in three dimensions. Using the homogenized and condensed macroscopic cross section libraries obtained from the DRAGON models, DONJON is able to calculate the flux alongside with the keff values for the specific cases in two energy groups. The results are then compared to those from the experiments and will further validate the accuracy of the simulations. Sensitivity and uncertainty results for the infinite lattices and the 2D full core model using DRAGON and SUSD3D code are discussed. The direct and adjoint flux values determined by DRAGON for the lattices and the full core model are used by SUSD3D to calculate the sensitivity profiles for specific reactions of the isotopes present. The sensitivity profiles are then used alongside with the covariance matrices to calculate the uncertainty contribution of nuclear data to criticality. The sensitivity and uncertainty (S/U) results of the 2D model for full core, using the DRAGON/SUSD3D code coupling are then compared with the S/U results of a 3D model of the full core using the code TSUNAMI within the SCALE6 package in reference. The comparisons will show an excellent degree of consistency between the two methods, while reasons for possible differences in the results are also presented.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".