Modeling the radiation environment in rooms contaminated with radioactive isotopes using three-dimensional geometry in the domestic Digital Decommissioning Platform for decommissioning support of nuclear facilities: Part 1 – “Forward problem” solution

Modeling the radiation environment in rooms contaminated with radioactive isotopes using three-dimensional geometry in the domestic Digital Decommissioning Platform for decommissioning support of nuclear facilities: Part 1 – “Forward problem” solution

facility, caused by radioactive contamination of equipment and process system components. This type of modeling is used to assess the radiation environment inside rooms of a nuclear facility, particularly when analyzing the results of a comprehensive engineering and radiological survey and when designing technological solutions for dismantling during decommissioning.
Process facilities and building structures are specified with geometric primitives (phantoms), including cylinders, parallelepipeds, and toroidal sectors, both solid and hollow with known wall thicknesses. All phantoms are a priori treated as sources of gamma radiation, the specific activity level is set for each one, and a three-dimensional coordinate mesh is made up for each phantom. Configurations involving phantoms embedded within hollow phantoms are permitted,
for example multilayer structures or liquid contained within a vessel. The spatial arrangement of phantoms in the computational model corresponds to the geometry and positioning of the modeled objects and is not constrained by the coordinate axes
of the model. The number of objects (and thus phantoms) included in the model and depends solely on the available computational resources. Calculation points may be located outside phantoms, inside them, or within the walls of hollow phantoms. For objects composed of multiple materials, solid phantoms with homogenized composition are used; the gamma-ray attenuation coefficients and dose buildup factors are calculated based on the material composition of the modeled object.
The methodology is implemented as a computational module within a computer-aided system for nuclear facility decommissioning design. The module is written in Golang with parallelized computation. Validation of the results has been performed using benchmark calculations with the developed module and established software packages TDMCC and MERCURAD.

► Keywords: radiation environment, comprehensive engineering and radiological survey, specific activity, nuclear decommissioning, nuclear facility, gamma radiation, three-dimensional mesh models, calculation points, Golang.

Article language: Russian. Pp. 28–40. [in Russian]. DOI: 10.26277/SECNRS.2026.120.2.003.