Investigation into the performance of dose rate measurement instruments used in non-governmental networks

Comparison of calibration factors for field-class dosimeters

“…There are sev eral rea sons for that: first, the spec tra of 137 Cs sources do not de pend strongly on lab o ra tory setup, sec ond, the en ergy de pend ence of con ver sion co ef ficient from air kerma to the op er a tional do sim e try quan tity is very small in this re gion [26], and third, the en ergy de pend ence of do sim e ter re sponse is usu ally small in the re gion around 662 keV, as can be seen from fig. 1 and the re cent re search [3,7,14,20,21]. The com mon prac tice of cal i brat ing or ver i fy ing field-class do sim e ters in only one ra di a tion qual ity (S-Cs) can there fore con ceal the prob lem that is discussed in this pa per.…”

“…Some de tec tors used by end-users as am bi ent do sim e ters are pur pose-built for contam i na tion mea sure ments or search for lost sources, and dose in di ca tion (if avail able) is only of sec ond ary im por tance [21]. Low-cost do sim e ters, which in most cases have in fe rior metrological prop er ties (e. g., overresponse at low en er gies of sev eral hun dred per -cent due to poor en ergy com pen sa tion) and are rarely cal i brated or tested, are of ten used by lay men or in non-gov ern men tal net works [7,22]. Such un re li able and un checked mea sure ment data are of ten avail able on line to the gen eral pub lic and can cause un sub stan tiated fear, which is es pe cially im por tant in case of radio log i cal or nu clear emer gen cies when con fi dence in of fi cial data and de ci sions can be crit i cal.…”

“…Even though sev eral In ter na tional Electrotechnical Com mis sion (IEC) stan dards give require ments for dif fer ent types of do sim e ters [4][5][6], which in prac tice limit the un cer tainty, there are many do sim eters in use that have in fe rior metrological prop er ties. In some cases, do sim e ter re sponse vari a tions can be much greater than the lim its of vari a tion de fined in the standards [7,8]. This is partly due to the fact that the type testing is a long and ex pen sive pro cess, and that com plete ex ten sive type test ing is avail able only in a very small num ber of spe cial ized fa cil i ties, e. g. Physikalisch-Technische Bundesanstalt, Ger many [9], as well as that type ap proval is not man da tory in all coun tries where radi a tion pro tec tion do sim e ters are reg u larly used (e. g. Ser bia or Bosnia and Herzegovina) or not man da tory for all end-us ers (e. g. non-gov ern men tal net works).…”