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1 | 1 | # Task Introduction |
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3 | | -Currently OpenMC supports two types of variance reduction (survival biasing and weight windows). |
4 | | -A detailed description of each method can be found in the [documentation](https://docs.openmc.org/en/stable/methods/neutron_physics.html?highlight=survival#variance-reduction-techniques). |
| 3 | +Variance reduction techniques are essential for efficiently simulating deep-penetration shielding problems where analogue Monte Carlo would require prohibitively many particles. In this task you will use OpenMC to apply survival biasing, weight windows and FW-CADIS to shielding and sphere problems. |
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6 | | -OpenMC also supports methods of generating weight windows including the [Magic Method and FW-CADIS](https://docs.openmc.org/en/stable/methods/variance_reduction.html?highlight=magic) |
| 5 | +A detailed description of each method can be found in the [OpenMC documentation](https://docs.openmc.org/en/stable/methods/neutron_physics.html?highlight=survival#variance-reduction-techniques). OpenMC also supports methods of generating weight windows including the [Magic Method and FW-CADIS](https://docs.openmc.org/en/stable/methods/variance_reduction.html?highlight=magic). |
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8 | | -The notebooks contain all the methods for completeness, however ff you just have time to learn one method then I would recommend the FW-CADIS approach. |
| 7 | +The examples cover all methods for completeness, however if you only have time to learn one method then the FW-CADIS approach is recommended. |
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10 | | -The workshop contains the following variance reduction examples: |
| 9 | +**Learning Outcomes** |
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12 | | -| Filename | variance reduction technique | geometry | mesh type | |
13 | | -|---|---|---|---| |
14 | | -| 1_shielded_room_survival_biasing.py | survival_biasing | shielded bunker | RegularMesh | Flux map | air space and concrete | |
15 | | -| 2_shielded_room_single_ww.ipynb | weight windows | sphere | RegularMesh | air space and concrete | |
16 | | -| 3_sphere_iterative_per_run_ww.py | weight windows | cube | RegularMesh | Water | |
17 | | -| 4_sphere_iterative_per_batch_ww.py | weight windows | sphere | SphericalMesh | concrete | |
18 | | -| 5_shielded_room_single_fw_cadis.py | survival_biasing | shielded bunker | RegularMesh | Flux map | air space and concrete | |
| 11 | +- Survival biasing prevents particles from being killed by absorption, instead reducing their weight, which improves statistics in deep-penetration problems. |
| 12 | +- Weight windows control particle weights across the geometry, splitting particles in important regions and killing them in unimportant regions. |
| 13 | +- Weight windows can be generated iteratively (per-run or per-batch) using the Magic method. |
| 14 | +- FW-CADIS (Forward-Weighted Consistent Adjoint Driven Importance Sampling) automates weight window generation using an adjoint flux calculation to optimise for a specific tally. |
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