Radiation Survey in the Vicinity of the Shipyards Involved in Decommissioning and Dismantlement of Nuclear Ships

Abstract

Purpose: To study radiation and health physics situation in the vicinity of the shipyards “The 10th Shipyard, a Holder of Order of the Red Banner of Labor” (JSC “10 SRZ”) and “The Nerpa Shipyard” – a branch of the JSC “The Shipyard Center “Zvezdochka” (SRZ “Nerpa”) after the completion of the main stage of nuclear submarine dismantling and to assess potential effect of on-going activities to the environment and population.
 Material and methods: The following methods were used in radiation survey: pedestrian gamma survey of the site using portable gamma spectrometry complexes, gamma spectrometry and radiochemistry methods to determine the activity of manmade radionuclides in samples of environmental media. 
 Results: Radiation and health physics studies were carried out from 2013 till 2017. It was shown that gamma dose rate within the health protection zones and supervision areas (SA) of the shipyards including the territories of the nearest cities – Snezhnogorsk and Polyarnyi – was at the level of regional values and did not exceed 0.14 µSv/h. The activities of radionuclides in soil from the surveyed sites did not exceed 23 Bq/kg for 90Sr and 100 Bq/kg for 137Cs. Concentrations of 90Sr and 137Cs in plants (mosses) at the surveyed sites did not exceed 70 and 48 Bq/kg, respectively, this is a bit higher than the background levels of the reference village of Belokamenka (1 and 20 Bq/kg, respectively, for 90Sr and 137Cs). The activity of seawater (Barents Sea) in 2016–2018 reached 60 mBq/l for 90Sr and 4 mBq/l for 137Cs, at mean values from 2 to 4 mBq/l over the period between 1990 and 2000 for the studied radionuclides. Data for 137Cs and 90Sr measured in samples of local wild plants, in particular, mushrooms, did not exceed 100 Bq/kg, this is much lower than the established permissible specific activities.
 Conclusion: Considerable impact of the work on the dismantling of nuclear submarines, maintenance ships and ships with a nuclear energy installation on the radiation situation in the areas of shipyards and health effects in the population of Snezhnogorsk and Polyarnyi was not revealed. However, along the external border of the surveyed shipyards some local parts of the sites of 5500 m2 area were found, where the specific activities of 90Sr and 137Cs in soil exceeded background levels and bordered by the level of permissible specific activity for unlimited use of solid materials (137Cs – 100 Bq/kg).