Health Effects of Onboard Radiation Accidents in the Soviet Nuclear Submarines

Purpose: To analyze the health effects of onboard radiation accidents in the Soviet nuclear submarines. Results: Over the entire operation period of Soviet nuclear submarines, eight severe accidents occurred related to nuclear power installations. These accidents occurred in a confined space and the associated radiation situation is more complex than in other conditions; therefore, health effects of such accidents are more significant. There were two types of onboard accidents: thermal accidents (five cases) associated with a failure during heat removal from the reactor core; and accidents (three cases) caused by a partial chain reaction. The first type of accidents occurred during the route operation of nuclear submarine, and the second one – during repair work. Thermal accidents were associated with varying degrees of depressurization of the primary circuit of the reactor, which increased the gamma and beta background due to the entry into the compartment of a large amount of radioactive noble gases (hereinafter – RBGs) and radioactive aerosols. It has been shown that in the confined space of nuclear submarines, RBG isotopes (mainly 85Кr, 133Хе, 135Хе) make a significant contribution to the individual dose and the skin is a critical organ. Conclusion: An analysis of the health effects of thermal onboard accidents showed that radiation injuries were caused by external gamma- and beta-exposure, as well as the ingestion of radioactive aerosols. If accidents are accompanied by prolonged minor leaks leading to entry of RBG into the compartment, the main contribution is made by beta-exposure and the skin is a critical organ. If there is a simultaneous inflow of coolant into the compartment, combined radiation injuries are formed and, in this case, skin lesions aggravate the acute radiation sickness. In accidents induced by a partial chain reaction, the main radiation factor is external γ-n-exposure during an outbreak of a partial chain reaction, and in the case of a thermal explosion, a traumatic factor also affects a person, leading to injuries of varying severity in the victims.