By John LaForge
Spring 2017 Quarterly
A plume of radioactive iodine-131 was detected “in the ground-level atmosphere” over large areas of Europe during the month of January 2017, France’s Institute for Radiation Protection and Nuclear Safety (Institute de Radioprotection et de Süreté Nucléaire, or IRSN) reported February 13. The source of the reactor-borne contamination remains unknown.
The agency noted that because iodine-131 has a relatively short hazard life (half of it decays away in eight days), its detection “is proof of a rather recent release.”
The IRSN was unable to identify the source of the radio-iodine, but its press release noted that it was certainly “of anthropogenic origin,” the result of a release from a nuclear reactor or a reactor fuel facility accident. The agency acknowledged that “iodine-131 in the air could come from an incident with a nuclear reactor.”
The Independent Barents Observer reported that a monitoring station in Svanhovd, Norway was the first to measure the airborne iodine-131 during the second week of January. IRSN noted that, “The preliminary report states it was first found during week 2 of January 2017 in northern Norway. Iodine-131 was also detected in Finland, Poland, Czech Republic, Germany, France and Spain, until the end of January.”
The highest documented amounts of the radio-iodine were reported in Poland and Spain (see chart). Both the IRSN and the Barents Observer accounts called the observed amounts of radio-iodine “tiny,” and IRSN also used the phrase “trace amounts”—the scientific term-of-art that refers to very small volumes of radioactive isotopes.
Airborne radioactive materials are ordinarily measured in terms of the number of atomic disintegrations (Becquerels) in a given cubic meter of air. France’s IRSN said, “At Svanhovd, [Norway] measurements in the period January 9-16 show levels of 0.5 micro Becquerel per cubic meter air.” A micro Becquerel is one-millionth of a Becquerel.
Neither of the accounts noted that airborne iodine-131 can be ingested by breathing or by swallowing contaminated food or water, nor that internal radioactive contamination is more dangerous than external exposures. Iodine-131 accumulates in the thyroid gland where it is associated with the development of thyroid cancer.