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Krajcar Bronić, Ines; Kožar Logar, Jasmina; Krištof, Romana; Nikolov, Jovana; Todorović, Nataša; Stojković, Ivana; Barešić, Jadranka; Sironić, Andreja; Borković, Damir (2019) Results of participation in the international intercomparison study for biogenic component in liquid fuels. In: Popić, Jelena; Coha, Ivana; Krajcar Bronić, Ines; Knežević Medija, Željka, (eds.) Zbornik radova Dvanaestog simpozija Hrvatskog društva za zaštitu od zračenja. Zagreb, Hrvatsko društvo za zaštitu od zračenja, pp. 355-362 . Abstract Direct method by measurement 14C activity of liquid fuel samples in liquid scintillation counter (the „direct LSC method“) has been recognized as a powerful and reliable method of determination of biogenic component in liquid fuels (fbio). Laboratories of the Ruđer Bošković Institute (RBI) in Zagreb, Croatia, the Jožef Stefan Institute (JSI) in Ljubljana, Slovenia, and at the Faculty of Science of the University of Novi Sad (UNS), in Novi Sad, Serbia, have been implemented and optimized slightly different methods. The 3 laboratories participated in the international intercomparison study ILC/2018 „Content of biocomponent in liquid fuel samples“, which was organized in 2018 by the Institute of Ceramics and Building Materials (Opole, Poland). Here we present the fbio results obtained by these 3 laboratories and compare the results with the expected fbio-exp values since at the moment of preparing this work the official results of the study have not been available. Laboratories obtained 7 samples of different colours and only the basic composition (diesel type of fuel) was known. The results for samples with the SQP(E) values well above the limits of applicability of the direct LSC method were satisfying in all three laboratories. Qualitatively acceptable, but quantitatively unacceptable results, were obtained for a sample in the SQP(E) region of limited applicability. For one of the samples the quenching was high, and the quenching parameter SQP(E) was below the limits of applicability of the direct LSC method in all 3 laboratories. The obtained results will be used for further validation and optimization of the developed direct LSC methods, especially for reconsidering the uncertainty budget and the background level. Although there are some differences in details of the applied direct LSC methods in the laboratories of RBI, JSI and UNS, the presented intercomparison results show that all the methods are suitable for determination of the fbio in liquid fuels, providing the correctly defined limits of applicability for highly quenched samples. Laboratories that have possibility of applying a different 14C measurement technique can satisfactorily determine fbio also in highly quenched samples, but these techniques are more complicated and more expensive.
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Krajcar Bronić, Ines; Barešić, Jadranka; Horvatinčić, Nada; Krištof, Romana; Kožar-Logar, Jasmina (2015) New technique of determination of biogenic fraction in liquid fuels by the 14C method. In: Petrinec, Branko; Bituh, Tomislav; Milić, Mirta; Kopjar, Nevenka, (eds.) Zbornik radova Desetog simpozija Hrvatskog društva za zaštitu od zračenja. Zagreb, Hrvatsko društvo za zaštitu od zračenja, pp. 360-365 . Abstract Povišenje koncentracije CO2 u atmosferi tijekom 20. stoljeća posljedica je intenzivnog korištenja fosilnih goriva. Smanjenje emisije CO2 nastalog izgaranjem fosilnih goriva proizvodnjom energije iz biogenih materijala (biogoriva) danas se stimulira i poreznom politikom pa se javlja potreba kontrole proizvođača i distributera goriva primjenom pouzdane metode određivanja udjela biogene komponente u gorivima. Jedna od metoda za određivanje udjela biogene komponente u smjesi fosilnog i biogoriva je 14C metoda, koja se zasniva na različitoj koncentraciji izotopa 14C u pojedinim komponentama smjese: biogoriva odražavaju 14C aktivnost suvremene atmosfere, dok fosilna goriva ne sadrže 14C. Za tekuća goriva moguće je primijeniti tehniku direktnog mjerenja u tekućinskom scintilacijskom brojaču (LSC) uz dodatak odgovarajućeg scintilatora. U ovom radu ćemo prikazati novu tehniku direktnog mjerenja koja koristi karakteristike gašenja zbog boje za kalibraciju brojača. Određivanje udjela biogene komponente u tekućim gorivima moguće je direktnim mjerenjem sadržaja 14C tekućinskim scintilacijskim brojačem. Tehnika obrade rezultata razvijena na IRB daje rezultate usporedive s drugačijom tehnikom korištenom na IJS. Donja granica detekcije je oko 0, 5 % biogene komponente, a tehnika se može primijeniti na sve vrste goriva bez obzira na fosilnu matricu i vrstu biogenog aditiva.