Evaluation of EC interlaboratory comparison on radionuclides in soil

A comparison was organised by the Institute for Reference Materials and Measurements among 73 environmental radioactivity monitoring laboratories for the determination of 15 radionuclides in soil. The reference material IAEA-375 Soil was reprocessed to provide the comparison material and reference values traceable to SI units and SIR were established at IRMM. The analytical procedures used by participating laboratories are described. A robust evaluation of the performance of laboratories is performed using three different approaches: relative deviations, En numbers and PomPlots. The performance of the participating laboratories varied depending on the radionuclide determined and method used. Gamma-ray spectrometry with respect to 137Cs and 40K is well controlled. The determination of 90Sr proved difficult for about two-thirds of the participants, which submitted results outside the acceptable range. Several laboratories need to improve their analytical procedures for the uranium isotopes and 226Ra. Moreover, the results for thorium isotopes are far from satisfactory mainly for the 230Th. The use of the En criterion revealed that the uncertainty estimation of many participants is poor.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Qualification of a precision pattern dispenser

The European Commission Joint Research Centre in Geel (JRC-Geel) is on a regular basis preparing radioactive sources. These sources can be used as calibration standards or reference sources in different applications, e.g. proficiency testing of laboratories monitoring radioactivity in the environment organized by JRC-Geel. In order to automate the sample preparation process a precision pattern dispenser was designed to reproducibly dispense radioactive solutions. The set-up should be able to dispense pre-set amounts of stock solution in an automated and reproducible way in predefined positions or patterns. Correct dispensing should be ensured by defining the positions of ampoules or special source holders precisely. The set-up must also be able to dispense pre-set amount of liquid according to designed patterns on air filters having a maximum size of 60x60 cm. During all manipulations no evaporation of stock solution can be afforded in order not to compromise its concentration. The liquids to be handled are mainly acidic solutions so all parts must be resistant to the acidic environment. The number of instrument parts that come in contact with the radioactive solution must be kept to a minimum to limit the amount of radioactive waste and should be easily replaceable. The precision pattern dispenser is composed of a commercially available sample handling unit that makes use of syringes to handle the liquid. This unit is coupled to an XYZ-table where e.g. air filters can be fixed on. A custom-made interface (protocol generator software) is used to design dispensing patterns on filters of different sizes and shapes. The combination of the filter and the pattern, called protocol, is sent to the software steering the sampling unit and the XYZ-table. The mass or volume to be dispensed and the position where it has to be dispensed is easily introducible and made visible in the protocol generator. Qualification tests were conducted to evaluate the performance of the instrument and to assess the compliance with the requirements. The two most important parameters to be tested were trueness and precision. The maximum values according to the specifications were 2 % for trueness and 1 % for precision. Tests were performed by dispensing water into glass ampoules. All other parameters described above were examined and found to be compliant with the specifications. The results of the tests demonstrate that the precision pattern dispenser can dispense liquid within the required specifications. The instrument can be used to spike air filters with an almost homogenous distribution of activity within a predefined area. The precision pattern dispenser makes it possible to prepare sources for different applications in a fast and accurate way.JRC.G.2-Standards for Nuclear Safety, Security and Safeguar

Evaluation of EC Measurement Comparison for 137Cs, 40K and 90Sr in Milk Powder

This report describes the full life cycle of the measurement comparison of 137Cs, 40K and 90Sr in milk powder among 60 European laboratories monitoring radioactivity in food and the environment. An available IAEA reference material was re-processed at IRMM into suitable intercomparison samples and the homogeneity of the distributed samples together with other quality parameters was determined. Reference values of the three radionuclides under study in this intercomparison were determined at IRMM using tracer techniques and standardised radionuclide solutions and are thus traceable to the SI units. The sample preparation and measurement processes applied in the participating laboratories are described and the results of the intercomparison are presented and discussed in detail. Whereas, in general, the measurement results for 137Cs and 40K show good agreement with the reference value, the results of this comparison point at problems of 90Sr determination in about one third of the laboratories. The corresponding participants should investigate and revise their analytical methods, next to many laboratories needing to improve their estimation of measurement uncertainty.JRC.D.4-Isotope measurement

Evaluation of EC Comparison on the Determination of 226Ra, 228Ra, 234U and 238U in Mineral Waters

This report describes all details of the comparison for the determination of 226Ra, 228Ra, 234U and 238U in mineral waters among 45 European laboratories monitoring radioactivity in food and the environment. Three commercially available mineral waters were provided as comparison samples. Reference values of the four radionuclides under study in this comparison were determined in collaborative work of IRMM and the Bundesamt für Strahlenschutz (BfS), using tracer techniques and standardised radionuclide solutions. The reference values are thus traceable to the SI units. The sample preparation and measurement processes applied in the participating laboratories are described and the results of the comparison are presented and discussed in detail. Whereas, in general, the measurement results for the uranium isotopes show a relatively favourable agreement with the reference value, the results of this comparison point at severe problems of 226Ra and 228Ra determination in about one fourth and more than one third of the laboratories, respectively. For radium, 19 results corresponding to 14 % of all are even off by a factor of two or more. By comparison, for uranium, this number amounts to 6 % (9 results out of 150). Nevertheless, also for the determination of uranium, 14 % to 23 % of the laboratories report results not compliant with the En evaluation criterion. The corresponding participants are urgently requested to investigate and revise their analytical methods.JRC.D.4-Nuclear physic

Status of Underground Radioactivity Measurements in HADES

The IRMM (Institute for Reference materials and Measurements) performs ultra low-level gamma-ray spectrometry at a depth of 225 m in the underground laboratory HADES. The facility currently houses 7 HPGe-detectors that are built and shielded using specially selected radiopure materials. The sandclay overburden of about 500 m water equivalent assures a muon flux reduction factor of about 5000, with subsequent reduction of the background of the detectors, which makes it possible to obtain detection limits close to 100 µBq for certain radionuclides. This paper describes the aim of the IRMM activities in the HADES laboratory, the equipment and the measurement program and gives examples of radiopurity measurements carried out in order to develop better low-level measurements.JRC.DG.D.5-Nuclear physic

Results of a European interlaboratory comparison on gross alpha/beta activity determination in drinking water

An interlaboratory comparison was organised by the Institute for Reference Materials and Measurements (JRC-IRMM) among environmental radioactivity monitoring laboratories for the determination of gross alpha/beta activity concentration in drinking water. Four independent standard methods were used for the determination of the reference values of three different water samples. The performance of participating laboratories was evaluated with respect to the reference values using relative deviations. Sample preparation and measurement methods used by the participating laboratories are described in detail, in particular in the view of method-dependency of the results. Many of the participants’ results deviate by more than two orders of magnitude from the reference values regardless of the techniques used. This suggests that gross methods need revision.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Evaluation of EC Measurement Comparison on Simulated Airborne Particulates - 137Cs in Air Filters

This report describes the full life cycle of the measurement comparison of 137Cs in air filters among 43 European laboratories monitoring radioactivity in the environment. Gravimetrically pipetting droplets of a gravimetrically diluted standardised 137Cs solution onto real air filters, SI-traceable reference values were established for intercomparison filters carrying a large range of activity close to the routine measurement conditions of the corresponding laboratory. The sample preparation and measurement processes applied in the participating laboratories are described and the results of the intercomparison are presented and discussed in detail. The results point at some problems of radioactivity measurement in air filters which need to be improved by several laboratories. Overall, with 41 out of 48 reported measurement results lying within +/- 33 % of the IRMM reference value, this comparison renders a rather fair result.JRC.D.4-Isotope measurement

Ionising radiation metrology for the metallurgical industry

Every year millions tons of steel are produced worldwide from recycled scrap loads. Although the detection systems in the steelworks prevent most orphan radioactive sources from entering the furnace, there is still the possibility of accidentally melting a radioactive source. The MetroMetal project, carried out in the frame of the European Metrology Research Programme (EMRP), addresses this problem by studying the existing measurement systems, developing sets of reference sources in various matrices (cast steel, slag, fume dust) and proposing new detection instruments. This paper presents the key lines of the project and describes the preparation of radioactive sources as well as the intercomparison exercises used to test the calibration and correction methods proposed within the project.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

The certification of the activity concentration of the radionuclides 137Cs, 90Sr and 40K in wild berries: IRMM-426

This report describes the production of CRM IRMM-426, a dried bilberry material certified for the radionuclide activity concentrations of 137Cs, 90Sr and 40K. The material was produced following ISO Guide 34:2009. Bilberry samples were collected in a woodland region of so-called “strontium hot spots” close to the Chernobyl reactor site. The samples were air-dried at the sampling site before transport to IRMM, where the raw material was oven-dried, cryo-milled, sieved, homogenised and bottled. The bottled material was sterilised by gamma-irradiation. Between-unit homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. The material was characterised by an intercomparison among laboratories of demonstrated competence and adhering to ISO/IEC 17025. Technically invalid results were removed but no outlier was eliminated on statistical grounds only. Uncertainties of the certified values were calculated in compliance with the Guide to the Expression of Uncertainty in Measurement (GUM) and include uncertainties related to possible inhomogeneity and instability and to characterisation. The material is intended for the assessment of method performance and quality control. As any reference material, it can also be used for control charts or validation studies. The CRM is available in amber glass jars containing about 100 g of dried bilberry powder. The minimum amount of sample to be used for analysis is 50 g for 90Sr and 18 g for 137Cs and 40K.JRC.D.2-Standards for Innovation and sustainable Developmen

Developments on the PIXE Technique for an Efficient and Accurate Analysis.

Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel