Participation of the LDPM, IFIN-HH, in the proficiency test on a radioactive solution, using the rapid sample evaporation method

摘要

Participation of the Dosimetry Laboratory for Personnel and EnvironmentLaboratory (LDPM) from IFIN-HH in the AQUACHECK-2011 proficiency test (PT),organized by the LGC Standards, UK, is presented, in terms of the following aspects:"Type of sample: radioactive solution, in the domain of low radioactivityconcentration, consisting from a mixture of unknown radionuclides."Type of required measurements and report was the gross alpha and betaequivalent radioactive concentration: Alpha "239Pu and 241Am; Beta "40K, 137Cs and90Sr."The method of processing of the solution, in order to perform activitymeasurements. The new scientific information consists in the fact that themeasurements implied two parallel independent methods. They are intended to checktheir validity, by the comparison of the results: i) A preliminary gamma-rayspectrometry measurement, to identify the gamma-ray emitters in the mixture and todetermine their content; ii) Measurement of the gross alpha and respectively grossbeta activity of the prepared samples, applied to thick samples, with the use ofselfabsorption corrections, using the equipment calibrated in response for allradionuclides from the list provided by LGC Standards; iii) The third step in PT wasthe processing of the measurement data, by applying the necessary corrections andreporting the results. The sample was slowly evaporated to dryness in order to obtaina constant mass, at a temperature under 90 oC, to avoid loss of radionuclides.After the transmission of the measurement results, from all the 11 participatinglaboratories, the organizer of the PT, LGC Standards, processed the received valuesand published the following data: the reported values of the laboratories and theaccomplishment of the z"score performance. Our laboratory, code AQ2757, obtainedsatisfactory results, passing the z"score test for all the reported values. On the other side,the comparison of the two methods: gamma-ray spectrometry and gross alpha, betameasurement confirms the agreement between the results obtained for 241Am and 40K.