Background radiation in the northern Russian city of Severodvinsk briefly rose up to 16 times normal levels following an explosion at a nuclear missile test site last week, Russian authorities said Tuesday.
The accident took place at an Arctic military facility on the coast of the White Sea on Thursday when a missile being tested on an offshore platform exploded, killing five.
Russian nuclear agency Rosatom said said its staff were providing engineering and technical support for the “isotope power source” of a missile engine.
“The Arkhangelsk territorial system of radiation control registered gamma radiation levels 4-16 times above the background rate of the ambient dose equivalent for the given territory,” Russian meteorological service Rosgidromet said in a statement carried by news agency TASS.
Rosgidromet said the levels were higher at six out of eight of its stations in Severodvinsk and that levels returned to normal after 2.5 hours.
One of the sensors registered a level of 1.78 microsieverts per hour, well above the local average but far below dangerous levels.
Russia’s nuclear agency chief also confirmed that the scientists who were killed were developing “new weapons” and vowed to continue testing despite the explosion.
Severodvinsk is located 30 kilometers (20 miles) from the Nyonoksa missile test site.
Earlier statements by local authorities regarding elevated radiation levels were denied by the Russian military.
Severodvinsk civil defense chief Valentin Magomedov pegged local radiation levels at three times acceptable levels for a period of a half hour following the explosion.
Leonid Bolshov of the Russian Academy of Sciences’ Nuclear Safety Institute told TASS that residents of the Arkhangelsk Region were not in any danger following in the explosion.
The explosion fueled speculation regarding Russia’s pursuit of a nuclear-powered cruise missile, a concept examined and abandoned by Washington during the height of the Cold War.
Unnamed intelligence sources told The New York Times that they believed the explosion involved a prototype missile known in NATO circles as the SSC-X-9 Skyfall, which could theoretically reach anywhere on the planet. Russian President Vladimir Putin showed off an animation of such a system last year.
If successfully deployed, such a weapon would pose a strategic threat to the United States because it would be capable of bypassing current American missile defenses. However, there is currently no indication that the Russians have managed to succeed where their geopolitical rivals have failed.
US President Donald Trump said Monday that the United States is learning “much” from the deadly blast but that “we have similar, though more advanced, technology.”
Experts challenged Trump’s assertion of a program to develop US nuclear-powered missiles