K-152 Nerpa Submarine Disaster

The K-152 Nerpa accident occurred aboard the Russian submarine K-152 Nerpa on 8 November 2008, which resulted in the deaths of 20 people and injuries to 41 more. The accident was blamed on a crew member who was allegedly playing with a fire suppressant system that he thought was not operative. Halon gas was released inside two compartments of the submerged submarine during the vessel's sea trials in the Sea of Japan, asphyxiating the victims or causing frostbite in their lungs. The high casualty count was attributed in part to the large number of civilians on board who were assisting with the testing before commissioning. Three of the dead were Russian naval personnel and the rest were civilian employees of the Vostok, Zvezda, Era, and Amur shipbuilding yards. The incident was the worst Russian submarine disaster since the sinking of Kursk in 2000.

At the time of the accident, Nerpa was undergoing sea trials at the Russian Pacific Fleet's test range in Peter the Great Gulf, an inlet of the Sea of Japan adjoining the coast of Russia's Primorski Krai province. The vessel had not yet been commissioned by the Russian Navy and was undergoing plant tests under the supervision of a team from the Amur shipyard. For this reason, it had a much larger than usual complement aboard, totaling 208 people, 81 military personnel and 127 civilian engineers from the shipyards responsible for building and outfitting the submarine.

The accident occurred at 8:30 pm local time on 8 November 2008, during the submarine's first underwater test run. The submarine's fire extinguishing system was triggered, sealing two forward compartments and filling them with R-114B2 gas (dibromotetrafluoroethane, known as khladon in Russian). The gas, a haloalkane refrigerant, is used in the Russian Navy's LOKh (lodochnaya obyemnaya khimischeskaya – "submarine volumetric chemical") fire-suppressant system. Each compartment of a Russian submarine contains a LOKh station from which the gas can be delivered into that or adjacent compartments. The gas displaces oxygen and chemically interferes with combustion, enabling it to extinguish fires rapidly in enclosed spaces. In high concentrations, it can cause narcosis, which progresses by stages into excitation, mental confusion, lethargy, and ultimately asphyxiation.

Twenty people died of asphyxiation in the accident. The number of injured was initially put at 21 but was later revised to 41 by the Amurskiy Shipbuilding Company, some of whose employees were among the injured. Many of the injured were reported to have suffered from frostbite caused by the chilling effect of the gas.

Following the incident, the Udaloy-class destroyer Admiral Tributs and the rescue vessel Sayany were dispatched from Vladivostok to provide assistance to the stricken submarine. The injured survivors were transferred to the destroyer and sent to military hospitals for treatment, while the submarine returned under its own power to Primorsky Krai. According to naval spokesman Igor Digaylo, the vessel was not damaged in the incident and radiation levels remained normal. More details