Radionuclide Metrology laboratories

The radionuclide metrology sector was the first to be established at JRC-Geel in 1959 (at that time called CBNM – Central Bureau for Nuclear Measurements). Its main objective was the accurate measurement of radioactivity and decay properties of radionuclides. Over the last 57 years, this group has built up a reputation as one of the world's leading laboratories in primary standardisation of radionuclides and SI-traceable radioactivity measurements. It has extended its work programme to characterisation of reference materials for radioactivity measurements, the organisation of intercomparisons among European monitoring laboratories, development of standards and development of source preparation techniques.

Measurements of radioactivity are becoming increasingly important in today’s society. Natural radioactivity is omnipresent and needs to be monitored to protect the health of the population and to understand processes in nature and industry. Anthropogenic (man-made) radioactivity is continuously produced in the nuclear industry and does not stop at borders if accidentally released. Nuclear medicine is developing rapidly and uses more radionuclides than ever before – an increase that will continue. Sustainability requires extensive recycling of materials which calls for robust measurements of radioactivity in scrap to minimise risks to society. All of this calls for harmonised measurement procedures and well-established calibrations in radioactivity monitoring laboratories.

JRC-Geel has developed and implemented instruments to measure radioactivity with the highest possible accuracy, which is important to maintain the SI-unit becquerel and establish international equivalence of radioactivity measurements.

Activities

Some of the key activities of the Radionuclide Metrology Sector are:

• Support of the Mutual Recognition Arrangement for national measurement standards and for calibration and measurement capabilities signed under the auspices of the Comité International des Poids et Mesures (CIPM) of the Metre Convention.
• Support to implementation of the Euratom Treaty Article 35 by performing regular controls of member states capacity to report accurate radioactivity monitoring results to the common database.
• Production of certified radioactive reference materials and support to certification of reference materials for radionuclides.
• Reference measurements in support of important policy domains like radioactive waste management, decommissioning of nuclear facilities, metal scrap industry, NORM industry and early warning monitoring networks.
• Precise decay data measurements that are essential for calibrations in routine laboratories, applications in nuclear medicine and many other scientific uses of radionuclides.
• Producing reference papers on metrology standards, including methodology and uncertainties.
• Development of procedures and standards for nuclear instruments and methods

List of instruments and methods

2.2 Radionuclide laboratories (above ground) at JRC-Geel

The Radionuclide laboratories located at the premises of JRC-Geel have a long tradition of more than 57 years. The laboratories are equipped with a variety of instruments, many of them unique in their kind, in order to perform measurements of a large number of radionuclides in samples as diversified as reference materials, solutions for standardisation, determination of nuclear decay data and environmental samples. Below in tables 1 and 2 are non-exhaustive lists of instruments available in the RN-laboratories:

DSA=Defined Solid Angle

PC=Proportional Counter

PPC=Pressurised PC

Table 2.2 List of instruments for primary standardization of radioactivity

Table 2.3 List of instruments for secondary standardization of radioactivity and radiological characterisation

2.2.1 Sample preparation

A dedicated controlled area for preparing radioactive sources of different types. This laboratory is equipped with state-of-the-art mass metrological equipment so that very precise sources can be made. Some of the available techniques are precision weighing, ampoulation, foil preparation, drop deposition, vacuum evaporation, electrodeposition.

2.2.2 Chemical Laboratory

This relatively small but fit for purpose laboratory is used for advanced chemical separation methods and to prepare samples from various matrices by isolating the necessary elements.

2.2.3 Methods for primary standardization

Primary methods are those methods where one in principle does not need to calibrate the detector. Here the activity follows from basic physical principles. An example of one technique is 4pß-g-coincidence counting, another is defined solid angle X-ray or alpha-particle counting. In specific applications, also liquid scintillation counting is considered a primary method. It is not always evident which method is most suitable for a specific radionuclide. Therefore it is important to have access to different methods to discover bias or problems with a certain method.

2.2.4. Methods for secondary standardization

Secondary methods are those methods where it is explicitly needed to calibrate a detector. Amongst these methods there are gamma-ray spectrometry, alpha-particle spectrometry and measurements using ionisation chambers. These methods are highly used as some of them (e.g. gamma-ray spectrometry) require little sample preparation and have the possibility of generating data for several radionuclides in one analysis. These methods are commonly used in industry so it is essential for us to use these techniques not only for fully characterising reference materials but also to be able to give training and advice on these techniques.

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