Assessment of radiation effect of 137Cs, 134Cs, and 90Sr on biota of the Barents Sea in the vicinity of hypothetical accident with the sunken nuclear submarine K-159

Abstract

Radiation effect of 137Cs, 134Cs, and 90Sr on marine biota was modelled for early period of a hypothetical accident with the sunken nuclear submarine K-159 during its surfacing and transportation in the Barents Sea. Dynamics of radioactivity in seawater was described, using analytical 2-dimensional model of radionuclide dispersion from an instantaneous point release in seawater. Radioactive contamination of seawater and bottom sediments with 137Cs, 134Cs, and 90Sr was calculated for distances from 200 m to 30 km from the source. Estimated dose of acute exposure accumulated within the first 10 days was close to 100 mGy for bottom fish at a 200-m distance from the accidental source of contamination. The probability of lethal effects for fish at this dose was estimated to be below 1%. Chronic exposures from 137Cs, 134Cs, and 90Sr at a distance of 200 m from the accidental source of contamination during the first year after the accident were as follows: for bottom fish, 9.7 mGy·day−1; molluscs, 11 mGy·day−1; and aquatic plants, 6.3 mGy·day−1. These dose rates exceed the reference level ensuring safety of marine biota. Therefore, in the vicinity of the accident site, the radiation situation cannot be considered safe for bottom fish, molluscs, and aquatic plants. At distances of more than 500 m from the accidental source of contamination, expected dose rates of chronic exposure to marine biota were below reference level. Dose rates for biota resulting from a hypothetical accident in the Barents Sea were caused mainly by external exposure from contaminated sediments and also by accumulation of long-lived radionuclides from sediments by bottom biota.

Keywords

• Arctic
• Barents Sea
• radiation accident
• modelling
• marine biota
• dose