Intercomparison of methods for coincidence summing corrections in gamma-ray spectrometry.

A comparison of the coincidence summing correction methods is presented. Since there are several ways for computing these corrections, each method has advantages and drawbacks that could be compared. This part of the comparison was restricted to point sources. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing correction factors for several energies of (152)Eu and (134)Cs, and three source-to-detector distances. They are presented and discussed.

Determination of thorium isotopes in mineral and environmental water and soil samples by alpha-spectrometry and the fate of thorium in water.

A method has been developed for determination of thorium isotopes in water and soil samples by alpha-spectrometry. After fusion with Na(2)CO(3) and Na(2)O(2) at 600 degrees C, soil samples were leached with HNO(3) and HCl. Thorium in water sample or in soil leaching solution was coprecipitated together with iron (III) as hydroxides and/or carbonates at pH 9 with ammonia solution, separated from uranium and other alpha-emitters by a Microthene-TOPO (tri-octyl-phosphine oxide) chromatographic column, electrodeposited on a stainless steel disk, and measured by alpha-spectrometry. The method was checked with two certified reference materials supplied by the IAEA, and reliable results were obtained. The detection limits of the method for water (soil) samples are 0.44 microBq l(-1) (0.070 Bq kg(-1)) for (232)Th, 0.80 microBq l(-1) (0.13 Bq kg(-1)) for (230)Th and 1.0 microBq l(-1) (0.16 Bq kg(-1)) for (228)Th, respectively, if 100 l of water (0.50 g) for each sample are analysed. A variety of water or soil samples were analysed using this procedure and giving average thorium yields of 75.5+/-14.2% for water and 93.4+/-4.5% for soil. The obtained concentrations of thorium isotopes in water samples are in the range of 0.0007-0.0326 mBq l(-1) for (232)Th,

Radiometric characterisation of more representative natural building materials in the province of Rome.

Natural building materials, characterised by middle-low-activity concentrations of primordial radionuclides ((40)K, (232)Th and (238)U series) are widely used in Italy. Since natural materials reflect the geological variability of their sites of origin, a systematic study was carried out in the province of Rome and the results are reported in this paper. In the present work, in order to evaluate average, minimum and maximum contents of primordial radionuclides, more representative lithologies outcropping on the territory of the province of Rome were identified and around 150 samples were collected. Also, these lithologies were characterised from a radioprotection point of view, by means of the evaluation of the index, I, when they are used as building materials. The results confirm the high-primordial radionuclide content within some materials used in Latium (central Italy). Although the study was carried out in a limited area, the results confirm considerable variation in the primordial radionuclide content depending on the sites of origin.

Substrate characterization for underwater gamma spectrometry: tank measurement results utilizing efficiencies calculated via Monte-Carlo code.

In order to study the sediment contamination, underwater gamma-ray spectrometry measurements performed by the sub-marine detector Canberra HpGe with a relative efficiency of 80% were carried out in an equipped tank at the Ukrainian Hydrometeorological Institute of Kiev. Different substrates, certified sources and experiment geometrical set-up were arranged. Efficiencies were calculated by in situ object counting system (ISOCS) software. ISOCS performance tests using certified sources were carried out by comparing laboratory measurements, and measurement results for mineralogy and density performances are reported.

Radioecological survey at selected sites hit by depleted uranium ammunitions during the 1999 Kosovo conflict.

A field study, organised, coordinated and conducted under the responsibility of the United Nations Environment Programme (UNEP), took place in Kosovo in November 2000 to evaluate the level of depleted uranium (DU) released into the environment by the use of DU ammunition during the 1999 conflict. Representatives of six different scientific organisations took part in the mission and a total of approximately 350 samples were collected. During this field mission, the Italian National Environmental Protection Agency (ANPA) collected water, soil, lichen and tree bark samples from different sites. The samples were analysed by alpha-spectroscopy and in some cases by inductively coupled plasma-source mass spectrometry (ICP-MS). The 234U/238U and 235U/238U activity concentration ratios were used to distinguish natural from anthropogenic uranium. This paper reports the results obtained on these samples. All water samples had very low concentrations of uranium (much below the average concentration of drinking water in Europe). The surface soil samples showed a very large variability in uranium activity concentration, namely from approximately 20 Bq kg(-1) (environmental natural uranium) to approximately 2.3 x 10(5) Bq kg(-1) (approximately 18000 mg kg(-1) of depleted uranium), with concentrations above environmental levels always due to DU. The uranium isotope measurements refer to soil samples collected at places where DU ammunition had been fired; this variability indicates that the impact of DU ammunitions is very site-specific, reflecting both the physical conditions at the time of the impact of the DU ammunition and any physical and chemical alteration which occurred since then. The results on tree barks and lichens indicated the presence of DU in all cases, showing their usefulness as sensitive qualitative bio-indicators for the presence of DU dusts or aerosols formed at the time the DU ammunition had hit a hard target. This result is particularly interesting considering that at some sites, which had been hit by DU ammunition, no DU ground contamination could be detected.