The burst of gamma radiation detected in the city of Severodvinsk after a supposed rocket explosion on August 8 could be related to a cloud of radioactive noble gases that passed through the area, according to Russia’s Federal Weather Service.
“The meteorological situation in the Arkhangelsk region contributed to the rapid dispersal of the cloud,” Roshydromet announced on August 16. The agency previously said it recorded gamma radiation in Severodvinsk on August 8 that exceeded background levels by four to 16 times. The radiation background in the city later normalized.
According to the Rosatom State Nuclear Energy Corporation, a missile using an engine with a radioactive-isotope power source exploded in the White Sea on August 8, killing five researchers. Russia’s Defense Ministry also reported that two of its soldiers died in the incident. The total death toll remains unknown.
In a tweet on August 12, U.S. President Donald Trump claimed in a tweet that the weapon in question was Russia’s experimental “Skyfall” nuclear-powered missile (known as the “Burevestnik,” or “Thunderbird,” in Russia).