Homogeneity evaluation of liquid reference material developed for nuclear decommissioning.

Homogeneity assessment is explicitly required by ISO Guide 35. In connection with the INSIDER project, relevant reference material was chosen to be developed. For this purpose liquid material characterised for radionuclide content with accuracy better than 10% at the 95% confidence level and based on liquid effluent tank waste from JRC Ispra was produced by CMI and homogeneity of the selected radionuclides was evaluated.

Equipment for Testing Measuring Devices at a Low-Level Radon Activity Concentration.

The National Institute for Nuclear, Biological, and Chemical Protection, under the European project 16ENV10 MetroRADON (the European metrology program for innovation and research, EMPIR), has developed unique equipment for the testing of measuring devices at low-level radon activity concentrations. The equipment consists particularly of an airtight low-level radon chamber (LLRCH) with an inner volume of 324 liters; a Rn-222 type RF 5 flow-through source with a Ra-226 activity of 4.955 kBq developed by Czech Metrological Institute within the above-mentioned project; and a pressure vessel as a radon-free air source. The mass flow controller of the Bronkhorst EL-Flow type is a part of the apparatus and ensures the requested airflow through the radon source-partialized if necessary-through the chamber. The homogeneity of the atmosphere in the chamber is ensured by means of a continuously regulated fan (airflows in the range of 0.1-3.5 m·s-1 can be established). Another important chamber component is the measuring device of climatic conditions, since temperature, air pressure, and relative humidity must be determined. The construction of the equipment allows the time-stable radon activity concentration to be maintained at a precise level for several days. Radon concentration values can be arbitrarily and continuously set in the range from 100 Bq·m-3 to 300 Bq·m-3.

Emission probability measurement of γ- and X- rays in Ra-226 and Pb-210 decay.

The emission intensities of 186.21keV, 46.54keV, XL(Bi) and XK(Rn) photons were measured with calibrated HPGe detectors. The efficiency was computed with the MCNP Monte Carlo code and validated using experimental points. Sources of Ra-226 were prepared from two different radioactive materials. The X-ray emission intensities in Ra-226 decay were determined without X-rays from the daughter decay products using a radon emanation source. The standard CMI source with Pb-210 was used and compared with a source prepared from the NPL solution delivered under the EMRP project "Metrology for processing materials with high natural radioactivity - MetroNORM".

Advancements in NORM metrology - Results and impact of the European joint research project MetroNORM.

The results of the three years European Metrology Research Programme's (EMRP) joint research project 'Metrology for processing materials with high natural radioactivity' (MetroNORM) are presented. In this project, metrologically sound novel instruments and procedures for laboratory and in-situ NORM activity measurements have been developed. Additionally, standard reference materials and sources for traceable calibration and improved decay data of natural radionuclides have been established.

Comparison of properties of digital spectrometer systems.

We have tested two digital spectrometer systems, the DSP 9660 and Lynx(®) modules, connected to a HPGe detector. Lynx(®) is a fully integrated 32K channel signal analyzer based on digital signal processing techniques, which offers advanced digital stabilization. The model DSP 9660 digitalizes the signal directly at a very high sampling rate. The evaluated properties were integral nonlinearity, differential linearity, channel profiles, resolution and throughput. We found that the DSP system has slightly inferior resolution and throughput in comparison with the Lynx(®) system.