Role of the Radionuclide Metrology Laboratory in organization of the interlaboratory comparisons for the measurement of activity (Becquerel) Maria Sahagia, Anamaria Cristina Razdolescu « Horia Hulubei » National Institute of R&D for Physics and Nuclear Enginnering, IFIN-HH IFIN-HH

1. Introduction 1. Introduction The Laboratory of Radionuclide Metrology (RML) from IFIN-HH is the laboratory which detains the primary Romanian standard of activity, designated by the Romanian Bureau of Legal Metrology (RBLM) for the participation at the activities of the International Committee of Measurements and Weights in the accomplishment of the Mutual Recognition Arrangement for the certifications and measurements (CIPM-MRA); it is authorized by RBLM for activities of legal metrology and by CNCAN for nuclear activities. In this quality, LMR has the responsibility to assure the equivalence of Romanian standards at international level by participation in comparisons and also the traceability of the standards and measurements at national level. These objectives are realized in three ways: delivery of radioactive standards (sources and solutions) to the laboratories which measure activity, standardization/calibration of the measurement equipments and organization of the inter-laboratory comparisons at national level in the frame of the accreditation of the laboratories in conformity with the ISO/EN/IEC requirements. The Laboratory of Radionuclide Metrology (RML) from IFIN-HH is the laboratory which detains the primary Romanian standard of activity, designated by the Romanian Bureau of Legal Metrology (RBLM) for the participation at the activities of the International Committee of Measurements and Weights in the accomplishment of the Mutual Recognition Arrangement for the certifications and measurements (CIPM-MRA); it is authorized by RBLM for activities of legal metrology and by CNCAN for nuclear activities. In this quality, LMR has the responsibility to assure the equivalence of Romanian standards at international level by participation in comparisons and also the traceability of the standards and measurements at national level. These objectives are realized in three ways: delivery of radioactive standards (sources and solutions) to the laboratories which measure activity, standardization/calibration of the measurement equipments and organization of the inter-laboratory comparisons at national level in the frame of the accreditation of the laboratories in conformity with the ISO/EN/IEC requirements. LMR has a long tradition for organization of the national comparisons, for the measurement of the radioactive sources and solutions, finalized with remarkable results for the laboratory and also for the participants. There were published four papers in international and national reviews [1-4] and were issued reports distributed to the participant laboratories and to the authorities (CNCAN, DSP). In present, LMR is in the course of RENAR accreditation, in conformity with SR EN/ ISO/ CEI [5]. Among the activities included in the accreditation program, the organization of national comparisons (inter-laboratory) for the measurement of sources and solutions activities and for the reference materials certified in LMR is included. LMR disposes of adequate facilities for safe operation of sealed and open radioactive sources, consisting from a radiochemistry laboratory, a balance room, two measurements laboratories. All the personnel are qualified for nuclear activities and posses license for work in nuclear field. In the followings, we present a proposal for work in organization of comparison focused manly on the choosing the type of comparison and their programs.

2. Types of inter-laboratory comparisons proposed to be organized Our laboratory organizes four types of national (inter-laboratory) comparisons, in the field of measuring the activity of the radioactive sources and solutions. Comparisons of low activity radioactive solutions for one radionuclide, or from mixtures of radionuclides, from alpha, beta and gamma emitters, for the units which measure the activity of environmental factors and for the units from food chain. Comparisons of high activity radioactive solutions from one radionuclide, from gamma emitters, and for beta emitters (but the application is conditioned of the existence, at the participants, of calibrators which were calibrated for beta radiations), for radiopharmaceuticals units, for nuclear medicine units from hospitals, and for the authorization and control bodies from radiopharmaceutical field. Comparisons of low activity radioactive sources, punctiform or extended, from alpha and beta emitters, for the units which measure “the alpha and beta global activity” from environment and food chain, and for the units which calibrate and/or verify metrologically the contaminometers. Comparisons of radioactive sources, punctiform or of volumic activity, or certified reference materials, from gamma emitters, from one radionuclide or from mixture of radionuclides, for units which measure the activity of the environmental samples, or from food chain, by the gamma spectrometry method.

3. Mode of organization of the inter-comparisons An intercomparison may be initialized in the following situations: At the solicitation of an organism which has in suborder a net of analyzing (measurement) laboratories, like Direction of Public Health (Radiation Hygiene) of Health Ministry, net for Security of the Food (certification of the radioactive content), net of Environment Radioactivity Survey. At the solicitation of an accreditation body, which wants to evaluate the capability of laboratories from the field, which are in the course of accreditation At the solicitation of an international body (IAEA) From self initiative of the RML

4.Stages of intercomparisons Establishing the type of inter-comparison, which define the types of sources or solutions which will be distributed and types of participant laboratories. Establishing the participant laboratories, if those were not specified in organization request and sending the participation invitation, along with the action schedule, especially with the deadline for receiving the results. Receiving the confirmation of participating at inter-comparison and of the details of transmitting of the samples, address, authorizations for possession of radioactive sources, etc. Preparation of the standard sources and solutions, which will be distributed, in conformity with the specific procedures of the laboratory.Their verification, before the distribution, packing, in conformity with the requirements of transportation of the radioactive materials. Drawing up the expedition documents, including the code of the distributed sample, in conformity with the annexed form. Drawing up the participation form at inter-comparison, in conformity with the annexed model. Carrying out the measurements in the participant laboratories, filling out the forms and their expedition at IFIN-HH, Radionuclide Metrology Laboratory. Receiving the results, their processing and issue of the project of report on inter-comparison. Transmitting the draft of the report to participants, only in electronic form, for analyze and decision the final form. Transmitting the final report, in electronic form, to participants and hard copies to reports to the organizations which asked the inter-comparison.

Conclusions Participation at exercises of inter-laboratory comparisons is the best way of verification of the mode of assurance of traceability at the national level, because it implies the measurement equipment, the standards and also the working methods and training of the personnel. LMR is prepared for organization of these types of exercises, and the accreditation for these activities will increase the quality of the actions.