Radioactive Contamination at the Epicenter of a Nuclear Accident and on the Territory of a Ship Repair Yard in Bukhta Chazhma

The radiation conditions at a ship repair yard in Bukhta Chazhma after a nuclear accident on a submarine on August 10, 1985 were reconstructed by means of hindcasting taking into account a 3D model of the enterprise and dose rate measurements during the first few days after the accident. The submarine presented the greatest danger during the first few days. The dose rate was equal to 1500–2500 mSv/h at height 3–5 m above the reactor compartment, 1–130 mSv/h on the hull, and 5–20 mSv/h at 100–130 m from the boat; the β-contamination was equal to 10⁵–10⁶ particles/(cm²·min). The radioactive substances were conservatively estimated to have propagated from the accident site to 0.9–1 km. Levels above 0.6 μSv/h, which are inadmissible for the population, did not go beyond 0.7–0.8 km and remained within the sanitary-protection zone. A radioactive track with dose rate 0.5–1.2 mSv/h and β-contamination to 2·10⁵ particles/(cm²·min) formed in the northern part of the yard, exceeded its borders, and crossed the uninhabited Dunai peninsula. The adjoining settlements of Dunai and Razboinik did not suffer; the radiation conditions on their territories were characterized as background.