Radiation sensors in Stockholm have detected higher-than-usual but still harmless levels of isotopes produced by nuclear fission, probably from somewhere on or near the Baltic Sea, a body running a worldwide network of the sensors said on Friday.
The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) oversees a network of hundreds of monitoring stations that use seismic, hydroacoustic and other technology to check for a nuclear weapon test anywhere in the world. That technology can, however, be put to other uses as well.
One of its stations scanning the air for radionuclides - telltale radioactive particles that can be carried long distances by the wind - detected unusually high levels of three radionuclides earlier this week: caesium-134, caesium-137 and ruthenium-103.
The Stockholm monitoring station "detected 3isotopes; Cs-134, Cs-137 & Ru-103 associated w/Nuclear fission @ higher[ ] than usual levels (but not harmful for human health)", CTBTO chief Lassina Zerbo said on Twitter (here) on Friday evening.
The particles were detected on “22/23 June”, he added.“These are certainly nuclear fission products, most likely from a civil source,” a spokeswoman for the Vienna-based CTBTO said, referring to the atomic chain reaction that generates heat in a nuclear reactor.
“We are able to indicate the likely region of the source, but it’s outside the CTBTO’s mandate to identify the exact origin,” she added.