title: Systematic influences of gamma-ray spectrometry data near the decision threshold for radioactivity measurements in the environment.
abstract: Several methods for reporting outcomes of gamma-ray spectrometric measurements of environmental samples for dose calculations are presented and discussed. The measurement outcomes can be reported as primary measurement results, primary measurement results modified according to the quantification limit, best estimates obtained by the Bayesian posterior (ISO 11929), best estimates obtained by the probability density distribution resembling shifting, and the procedure recommended by the European Commission (EC). The annual dose is calculated from the arithmetic average using any of these five procedures. It was shown that the primary measurement results modified according to the quantification limit could lead to an underestimation of the annual dose. On the other hand the best estimates lead to an overestimation of the annual dose. The annual doses calculated from the measurement outcomes obtained according to the EC's recommended procedure, which does not cope with the uncertainties, fluctuate between an under- and overestimation, depending on the frequency of the measurement results that are larger than the limit of detection. In the extreme case, when no measurement results above the detection limit occur, the average over primary measurement results modified according to the quantification limit underestimates the average over primary measurement results for about 80%. The average over best estimates calculated according the procedure resembling shifting overestimates the average over primary measurement results for 35%, the average obtained by the Bayesian posterior for 85% and the treatment according to the EC recommendation for 89%.
authors.affiliation: Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia. Electronic address: benjamin.zorko@ijs.si.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Zorko
authors.affiliation: Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia.
authors.forename: Matjaž
authors.initials: M
authors.lastname: Korun
authors.affiliation: CIEMAT, Avenida Complutense 40, 28040 Madrid, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Mora Canadas
authors.affiliation: IRS[N]/PRP-ENV/SERIS/LM2E, CE Cadarache Bât 159, 13115 Saint Paul lez Durance, France.
authors.forename: Valerie
authors.initials: V
authors.lastname: Nicoulaud-Gouin
authors.affiliation: Slovenské elektrárne, Mlynské nivy 47, 821 09 Bratislava, Slovak Republic.
authors.forename: Pavol
authors.initials: P
authors.lastname: Chyly
authors.affiliation: Vattenfall AB, Sweden.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Blixt Buhr
authors.affiliation: Swedish Radiation Safety Authority, Solna Strandväg 96, SE-171 16 Stockholm, Sweden.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Lager
authors.affiliation: Swedish Radiation Safety Authority, Solna Strandväg 96, SE-171 16 Stockholm, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Aquilonius
authors.affiliation: Central Laboratory for Radiological Protection, Konwaliowa 7, 03-194 Warsaw, Poland.
authors.forename: Pawel
authors.initials: P
authors.lastname: Krajewski
mesh_terms: D006801:Humans; D011829:Radiation Dosage; D011834:Radiation Monitoring; D011851:Radioactivity; D013051:Spectrometry, Gamma; D035501:Uncertainty
keywords: Best estimate; Decision threshold; Dose assessment; Limit of detection; Primary measurement result; Uncertainty analysis