Above: Map showing locations and dates of atmospheric I-131 detections in Europe in early 2017, in µBq/m3 (Source: IRSN)

A routine press release last week regarding the recent detection of radioactive iodine at trace levels in Europe has set off a flurry of alarm and speculation. On February 13, 2017, the French national radioprotection institute IRSN issued a brief online press release describing detections of particulate Iodine-131 beginning in January 2017 in Norway, Finland, Poland, Czech Republic, Germany, France and Spain. IRSN noted that origin of the release is still unknown, which led to speculation that it could be from an unannounced Russian nuclear weapons test at Novaya Zemlya. Informed observers quickly pointed out that I-131 can be produced in nuclear explosions, by nuclear reactors, or by industrial and medical isotope facilities, and that even a small nuclear test would have left a clear seismic signature as well as many other detectable nuclides, none of which were observed.

IRSN: Detection of radioactive iodine at trace levels in Europe in January 2017

Since then a few informative articles and commentaries have appeared, all of which stress that no evidence of a nuclear detonation has been detected. Most significantly in this regard, the Comprehensive Test Ban Treaty Organization (CTBTO), which operates a global network of sensitive radionuclide, seismic, and acoustic sensors designed specifically to detect weapons tests, issued a statement yesterday which says in part, “If a nuclear test were to take place that releases I-131 it would also be expected to release many other radioactive isotopes….No other nuclear fission isotopes have been measured at elevated levels in conjunction with I-131 in Europe so far.”

CTBTO Media Advisory

But what was the case of the I-131 release? On the one hand, experts debate whether the levels detected were actually above historical trace levels. But it had to come from somewhere. Cheryl Rofer, a retired Los Alamos scientist who maintains an active Twitter feed and writes the Nuclear Diner blog, consulted with colleagues actively for several days and concludes, “The fact that it was measured along with elevated levels of naturally occurring radioisotopes suggests that it is from medical uses, perhaps lofted in particles from spray processing of sewage.” We think this is a very plausible explanation, but someone somewhere knows the details and has not yet come forward with a more specific explanation.

Nuclear Diner: Iodine-131 Over Europe: Probably Medical

Barents Observer: Radioactive Iodine over Europe first measured in Finnmark

Meanwhile, our hunt for information about this issue led us to Russian and Norwegian realtime radiation monitoring websites we hadn’t seen before. It pays to be aware of sites like these, because you never know when they might become useful:

Rosatom radiation situation (in Russian)

Norwegian Radiation Protection Authority Radnett (in Norwegian)