Comparative analysis of the results of simulation of the consequences of a serious accident at a Belarusian NPP with the use of J-RODOS and RECASSEXPRESS software complexes

Using the J-RODOS and RECASS-EXPRESS software packages, modeling of the radiological and radiation-ecological consequences of a severe beyond design basis accident at the power unit of the Belarusian NPP with a VVER-1200 reactor was carried out. The simulation results showed that if radionuclides were released from the reactor containment at the level of 2.15·10¹⁵ Bq, the maximum values of the fallout from the atmosphere to the surface 1 day after the accident will be 2.98∙10⁵ Bq/m² for I-131 (J-RODOS) and 7∙10⁵ Bq/m² (RECASS-EXPRESS), and for Cs-137 − 1.11∙10⁴ Bq/m² and 1.3∙10⁵ Bq/m², respectively. The difference in the values of the radionuclide fallout, modeled by these software packages, increases with the distance from the release source and at a distance of more than 10 km reaches 1 order of magnitude. The predicted values of the equivalent thyroid dose for adults and children for the first 7 days after the accident, obtained using J-RODOS calculations, are 3–4 times higher than using RECASS-EXPRESS software product. At a distance of 3–5 km from the NPP site, doses ranged from 3.7 to 14.8 mSv for adults and 16.2 to 32.5 mSv for children. The values of the total effective dose with the J-RODOS simulation are 2 times higher than those with RECASS-EXPRESS at a distance of 3 km from the site (0.60 and 0.32 mSv, respectively) and 1.5 times higher at a distance of 5 km from the site (0.30 and 0.21 mSv respectively). As the distance from the NPP increases, the convergence in the obtained evaluation results of total effective dose increases. None of the obtained prediction results exceeds the established emergency response criteria and do not indicate the need for protective measures for the public.

1. Turner B. D. Workbook on Atmospheric Dispersion Estimates. North Carolina, U.S. EPA, 1970. 84 p.

2. NTERRAS 1.2: tutorial. Vienna, IAEA, 2000. 105 p.

3. Izrael’ Yu., A., Bogdevich I. M. et al., eds. Atlas of Modern and Predictive Aspects of the Consequences of the Accident at the Chernobyl Nuclear Power Plant in the Affected Territories of Russia and Belarus (AMPA Russia–Belarus). Moscow, Minsk, 2009. 140 p. (in Russian).

4. Izrael’ Yu. A., Vakulovskiy S. M., Vetrov V. A., Petrov V. N., Rovinskiy F. Ya., Stukin E. D.; Izrael’ Yu. A., ed. Chernobyl: Radioactive Contamination of Natural Environments. Leningrad, Gidrometeoizdat Publ., 1990. 296 p. (in Russian).