Vitaly Mogulian

Monte Carlo Variance Reduction Research & Code Developing & Nuclear Engineering

CASTOR-V/21 multicase computations

For the given model of the isolated CASTOR-V/21 cask, those are considered additional 5 cases for each type of radiation defined using the cask side wall shield cutting by cylindrical surfaces. These 6 cases in total have been completed in a single computation of total running time 12.1 hours using the multi-thickness Monte Carlo technique [2].

In this calculation, the following techniques are used:

Expected value estimators;
Multi-thickness calculations;
Joint location-direction importance sampling from source (for primary gamma only);
Energy importance sampling from source (for primary gamma only);
Exponential transform;
Simplified adaptive splitting.

The primary computational gain is achieved here thanks to the simplified adaptive splitting, exponential transform (for both gamma), and multi-thickness calculation techniques.

Computed flux functional - ambient equivalent dose H*(10) [1] rates.

Below, the obtained results of neutron-gamma and gamma problems calculations are presented (see details in [2]).


Figure 1: Neutron axial dose rate distribution for the single cask


Figure 2: Neutron axial relative error distribution for the single cask


Figure 3: Secondary gamma axial dose rate distribution for the single cask


Figure 4: Secondary gamma axial relative error distribution for the single cask


Figure 5: Primary gamma axial dose rate distribution for the single cask


Figure 6: Primary gamma axial relative error distribution for the single cask

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References

International Commission on Radiological Protection., International Commission on Radiation Units, and Measurements. Conversion coefficients for use in radiological protection against external radiation. Annals of the ICRP ; v. 26, no. 3/4. Published for the Commission by Pergamon Press, Oxford ;, 1st ed. edition, 1996 - 1997.
V.G. Mogulian. An approach to radiation shielding evaluations using estimators by expected scoring. 2025. doi:10.5281/zenodo.16781416.