No abstract available

[en] An highly enriched ²⁴⁴Pu isotopic reference material (CBNM IRM-042a) has been prepared and certified for ²⁴⁴Pu isotope concentration. The certified value of (2.257 7 ± 0.004 4).10¹⁸ atoms ²⁴²Pu.kg^-1 of solution has been established by isotope dilution mass spectrometry. The plutonium isotopic composition has been determined by thermal ionization mass spectrometry and calibration of these measurements by means of synthetic ²⁴²Pu/²³⁹Pu mixtures. The isotopic reference material is supplied in a sealed glass ampoule containing approximately 10 g of a 5M nitric acid solution at an approximate concentration of 1 μg Pu per g solution. This isotopic reference material is part of a systematic CBNM programme to supply spike isotopic reference materials of various isotopes at different concentrations

[en] A procedure is described whereby rapid and accurate isotopic measurements can be performed on boron in boric acid and boron carbide after fusion of these compounds with calcium carbonate. It allows the determination of the isotopic composition of boron in boric acid and boron carbide and the direct assay of boron or the ¹⁰B isotope in boron carbide by isotope-dilution mass spectrometry. (author)

[en] Water resource is of prime importance for a producer of electricity like Electricite de France. As a matter of fact, EDF manages about 75 % of the French surface waters through hydro electricity which represents about 13 % of its production. EDF also needs access to water for the cooling of its thermal power plants, especially nuclear power plants which represent between 75 and 80 % of its electric production. Climate change is then studied with much care in order to be able to predict its effects on the future water repartition in time and place. The paper presents the results of studies carried out on the French Loire and Rhone rivers, using different climate models, with the assumption of doubling CO₂ in the atmosphere (which could happen during the second half of the century). Future river temperatures and flows have been quantified, showing in particular an increase of river flows in winter, and a rather large decrease in summer. These results will have to be taken into account for the future management of the power plants (some experience has already been drawn after the very hot 2003 summer), especially during dry periods when scarce waters will have to be shared between the various users (drinking water, irrigation, tourism, industries and hydroelectricity). (authors)

[en] Any mass spectrometric measurement system has inherent inaccuracies caused by isotope fractionation in the ion source and non-linearity of the detector and or measurement system. A set of well known triple isotope mixtures is an excellent means to verify and correct non-linearity of the mass spectrometer detector and measurement system after the isotope fractionation has been corrected for. CBNM IRM 072/1-15 is a set of such mixtures. Its preparation and characterization is described. It is available for interested users. (orig.)

[en] In view of the characterisation of reference materials for isotopic measurements of Plutonium, a series of 20 synthetic isotope mixtures have been made. Highly enriched ²³⁹Pu and ²⁴²Pu materials were mixed gravimetrically as Pu oxides in ratios ranging from 10^-1 to 10⁺¹. Taking into account the different uncertainty sources: chemical impurities in the starting materials, isotopic composition of the starting materials, hygroscopicity, stoichiometry and weighing, the total uncertainty for any of the mixtures is ≤0.02%. This means that the correction factor for isotope fractionation of two neighbouring masses (e.g. ²³⁹Pu/²⁴⁰Pu) can be determined to ±0.01% for all practical purposes. These mixtures are stored at CBNM in units of 1mg and will form the basis of absolute Pu isotopic measurements at CBNM for the next 20 years

No abstract available

No abstract available

[en] Preparation of two Isotopic Reference Materials of thorium has been performed, starting from highly enriched ²³²Th (99.99%) and ²³⁰Th (99.8%). After full characterization (chemical and isotopic) of these purified base materials the thorium nitrate was transformed to thorium dioxide. Accurately weighed amounts of the two isotopes in the dioxide form were subsequently dissolved in nitric acid and resulted in solutions with amount ratios n(²³⁰Th)/n(²³²Th) close to 10^-5 (IRMM-035) and 3 . 10^-6 (IRMM-036). These gravimetrically prepared ratios were finally verified by means of Thermal Ionization Mass Spectrometry (TIMS). The purpose of the Reference Materials is to calibrate thorium isotope amount ratio measurements. (orig.)

[en] Low level radioactive liquid discharges have been carried out in the Loire river since 1963. Since then, the number of power plants located on the Loire river and its tributaries has been steadily increasing to reach, in the year 2000, 14 reactors operating on 5 different sites. The question arose to evaluate to what extent the addition of several nuclear power plants on the same river system could increase the concentrations in radionuclides in the environment and affect the dose to the public. To address this issue, EDF initiated in 1998 the 'Loire river and estuary radioecology' program with the focus on assessing possible accumulation of radionuclide in river bottom sediments or on river shores. The following radionuclides were considered because of their importance in power plant liquid discharges: tritium, ¹⁴C, ⁵⁸Co, ⁶⁰Co, ^110mAg, ¹³⁴Cs, ¹³⁷Cs, ⁵⁴Mn, ¹²⁴Sb, and ¹³¹I. Radionuclide concentrations in the dissolved, particulate and sedimentary forms were evaluated using the CRESCENDO model. The development and validation of this model required a multi-step process. The first step was to design a 350-km long 1-D hydraulic and water transport based on currently available tools and data. Next, daily tritium concentrations measured in Angers, at the downstream limit of the river, were compared with computed values. The following step was to calibrate the sediment transport model. Areas where fine particles settled (dams and river shores) were monitored to improve our understanding of sediment dynamics. Then equations representing radionuclide exchange between water and particles were derived from laboratory experiments and included in the model. After each step the computed values were compared to measure data sets to ensure the model adequately described the processes involved. In the final step, CALVADOS model was used to calculate dose to the public at different locations along the Loire river. (author)