Global network's nuclear sensors in Russia went offline after mystery blast

The operator of a global network of radioactive-particle sensors said on Monday its two Russian sites closest to a mysterious explosion went offline days after the blast, soon followed by two more, fuelling suspicions that Russia tampered with them.

The Russian Defence Ministry, which operates the two stations, did not immediately reply to a request for comment.

Russia’s state nuclear agency, Rosatom, has acknowledged that nuclear workers were killed in the explosion on Aug. 8, which occurred during a rocket engine test near the White Sea in far northern Russia.

The explosion also caused a spike in radiation in a nearby city and prompted a local run on iodine, which is used to reduce the effects of radiation exposure.

Russian authorities have given no official explanation for why the blast triggered the rise in radiation. U.S.-based nuclear experts have said they suspect Russia was testing a nuclear-powered cruise missile vaunted by President Vladimir Putin last year.

“We’re ... addressing w/ station operators technical problems experienced at two neighbouring stations,” Lassina Zerbo, head of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), said on Twitter overnight.

The CTBTO’s International Monitoring System includes atmospheric sensors that pick up so-called radionuclide particles wafting through the air. Zerbo said data from stations on or near the path of a potential plume of gas from the explosion were still being analyzed.