title: The influence on the radioxenon background during the temporary suspension of operations of three major medical isotope production facilities in the Northern Hemisphere and during the start-up of another facility in the Southern Hemisphere.
abstract: Medical isotope production facilities (MIPF) have recently been identified to emit the major part of the environmental radioxenon measured at many globally distributed monitoring sites deployed to strengthen the radionuclide component of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification regime. Efforts to raise a global radioxenon emission inventory revealed that the yearly global total emission from MIPF's is around 15 times higher than the total radioxenon emission from nuclear power plants (NPP's). Given that situation, from mid 2008 until early 2009 two out of the ordinary hemisphere-specific events occured: 1) In the Northern hemisphere, a joint temporary suspension of operations of the three largest MIPF's made it possible to quantify the effects of the emissions related to NPP's. The average activity concentrations of (133)Xe measured at a monitoring station close to Freiburg, Germany, went down significantly from 4.5 +/- 0.5 mBq/m(3) to 1.1 +/- 0.1 mBq/m(3) and in Stockholm, Sweden, from 2.0 +/- 0.4 mBq/m(3) to 1.05 +/- 0.15 mBq/m(3). 2) In the Southern hemisphere the only radioxenon-emitting MIPF in Australia started up test production in late November 2008. During eight test runs, up to 6.2 +/- 0.2 mBq/m(3) of (133)Xe was measured at the station in Melbourne, 700 km south-west from the facility, where no radioxenon had been observed before, originating from the isotopic production process. This paper clearly confirms the hypothesis that medical isotope production facility are at present the major emitters of radioxenon to the atmosphere. Suspension of operations of these facilities indicates the scale of their normal contribution to the European radioxenon background, which decreased two to four fold. This also gives a unique opportunity to detect and investigate the influence of other local and long distance sources on the radioxenon background. Finally the opposing effect was studied: the contribution of the start-up of a renewed radiopharmaceutical facility to the build up of a radioxenon background across Australia and the Southern hemisphere.
authors.affiliation: Vienna University of Technology, Atomic Institute of the Austrian Universities, Stadionallee 2, 1020 Vienna, Austria. paul.saey@ati.ac.at
authors.forename: Paul R J
authors.initials: PR
authors.lastname: Saey
authors.forename: Matthias
authors.initials: M
authors.lastname: Auer
authors.forename: Andreas
authors.initials: A
authors.lastname: Becker
authors.forename: Emmy
authors.initials: E
authors.lastname: Hoffmann
authors.forename: Mika
authors.initials: M
authors.lastname: Nikkinen
authors.forename: Anders
authors.initials: A
authors.lastname: Ringbom
authors.forename: Rick
authors.initials: R
authors.lastname: Tinker
authors.forename: Clemens
authors.initials: C
authors.lastname: Schlosser
authors.forename: Michel
authors.initials: M
authors.lastname: Sonck
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis*; D001417:Background Radiation; D002617:Chemical Industry; D011834:Radiation Monitoring; D011847:Radioactive Fallout / Q000032:analysis; D014980:Xenon Radioisotopes / Q000032:analysis / Q000737:chemistry*
chemical_list: D000396:Air Pollutants, Radioactive; D011847:Radioactive Fallout; D014980:Xenon Radioisotopes