Abstract
The Transient Multi-Level (TML) method is applied to a time-dependent Monte Carlo transport solver to offload some of the computational burden of the expensive Monte Carlo solve to lower-order Coarse Mesh Finite Difference (CMFD) and Exact Point Kinetics Equations (EPKE) solvers via factorization of the neutron flux at the transport and CMFD levels using the Predictor Corrector Quasi-Static Method (PCQM). The Monte Carlo transient is solved by a modified fission source iteration scheme that introduces a single transient source bank. The method is implemented in the production-level Monte Carlo code, Shift, and verified with prescribed reactivity ramps from the two-dimensional version of the C5G7-TD reactor benchmark. The results show that, as compared to other quasi-static methods, the TML reduces the stochastic noise inherent to the transient Monte Carlo solver by factors of ∼2 to 6 for various norm comparisons of the reactor power amplitude. The TML additionally reduces the number of Monte Carlo evaluations needed to simulate the transient, leading to roughly an order of magnitude improvement in CPU time relative to the standard PCQM for the problems tested.
| Original language | English |
|---|---|
| Article number | 111021 |
| Journal | Annals of Nuclear Energy |
| Volume | 212 |
| DOIs | |
| State | Published - Mar 2025 |
Funding
This work was funded by the Spent Fuel and Waste Disposition program from the Department of Energy \u2013 Office of Nuclear Energy (DOE-NE). This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
| Funders | Funder number |
|---|---|
| Office of Nuclear Energy | |
| U.S. Department of Energy | |
| Lawrence Livermore National Laboratory | DE-AC52-07NA27344 |
| Lawrence Livermore National Laboratory |
Keywords
- Monte Carlo
- Quasi-static
- Transient