ABSTRACT
A new reference material for the activity concentration of (137)Cs, (40)K and (90)Sr in a dried berry matrix was certified from a batch of bilberries collected in the vicinity of the Chernobyl nuclear power plant. Radionuclides in this material were metabolised by the plants, therefore no spiking had to be performed. The material was processed at IRMM and homogeneity and stability of the certified parameters were demonstrated. The certified property values for (137)Cs, (40)K and (90)Sr were determined in the course of a supplementary comparison, CCRI(II)-S8.
Subject(s)
Chernobyl Nuclear Accident , Radiation Monitoring/methods , Radioactive Pollutants/analysis , Vaccinium myrtillus/chemistry , Reference StandardsABSTRACT
Radioactivity found in wild food products has assumed greater importance when assessing the total exposure of the population. For this reason, IRMM has been developing a reference material for the activity concentration of three radionuclides in bilberry samples. In order to characterise this new material, a CCRI(II) supplementary comparison was organised. The difficulties encountered in this comparison are discussed, in particular the efficiency calibration for volume sources of gamma-ray emitters, and comparison reference values for (137)Cs and (40)K are calculated.
Subject(s)
Food Analysis/standards , Food Contamination, Radioactive/analysis , Fruit/chemistry , Radioisotopes/analysis , Radioisotopes/chemistry , Radiometry/standards , Vaccinium myrtillus/chemistry , Internationality , Radiation Dosage , Reference Standards , Reference ValuesABSTRACT
A comparison of different radiochemical separation procedures and measurement techniques used to determine the activity concentration of (226)Ra and (228)Ra in water is made with respect to accuracy, detection limits and turn-around time. Radium-226 activity concentration was determined by the radon emanation technique, alpha-particle and gamma-ray spectrometry. To determine the (228)Ra activity concentration, four different techniques were used: low-level liquid scintillation counting, low-level proportional counting, alpha-particle and low-level gamma-ray spectrometry.
Subject(s)
Mineral Waters/analysis , Radiation Monitoring/methods , Radium/analysis , Water Pollutants, Radioactive/analysis , Alpha Particles , Limit of Detection , Methods , Reproducibility of Results , Scintillation Counting , Spectrometry, Gamma , Spectrum AnalysisABSTRACT
In anticipation of new European requirements for monitoring radioactivity concentration in drinking water, IRMM organized an interlaboratory comparison on the determination of low levels of activity concentrations (about 10-100 mBq L(-1)) of the naturally occurring radionuclides (226)Ra, (228)Ra, (234)U and (238)U in three commercially available mineral waters. Using two or three different methods with traceability to the International System of Reference (SIR), the reference values of the water samples were determined prior to the proficiency test within combined standard uncertainties of the order of 3%-10%. An overview of radiochemical separation and measurement methods used by the 45 participating laboratories are given. The results of the participants are evaluated versus the reference values. Several of the participants' results deviate by more than a factor of two from the reference values, in particular for the radium isotopes. Such erroneous analysis results may lead to a crucial omission of remedial actions on drinking water supplies or to economic loss by an unjustified action.
Subject(s)
Environmental Monitoring/methods , Radium/analysis , Uranium/analysis , Water Pollutants, Radioactive/analysis , Water Supply/analysis , Clinical Laboratory Techniques , Europe , Mineral Waters , Reference ValuesABSTRACT
Procedures for the sequential determination of low level (210)Po and uranium radioisotopes in drinking water by alpha-particle spectrometry are presented. After addition of (208)Po and (232)U tracers, the radionuclides were preconcentrated from water samples by co-precipitation on Fe(OH)(3) or MnO(2) at pH 9 using ammonia solution. The (210)Po source was prepared by spontaneous deposition onto a copper disc either before or after uranium separation. The uranium source for alpha-particle counting was prepared by micro co-precipitation with CeF(3). The procedures were tested on mineral water and the results obtained are compared.
Subject(s)
Alpha Particles , Polonium/analysis , Uranium/analysis , Water Pollutants, Radioactive/analysis , Chemical Precipitation , Fresh Water/analysis , Spectrum AnalysisABSTRACT
For more than 15 years, European Union (EU) laboratories monitoring environmental radioactivity have been obliged to participate in measurement comparisons organised by the European Commission. After a short review of comparisons conducted during the 1990s, the approach of IRMM organising these comparisons since 2003 is presented. It relies on the provision of comparison samples with reference values traceable to the International Reference System for radionuclides (SIR). The results of the most recent comparison, the determination of (40)K, (90)Sr and (137)Cs in milk powder, are presented. The influence of repetitive participation in measurement comparisons on laboratory performance is studied on the basis of data from more than 20 laboratories having participated in several exercises during the last 15 years.
