Progress state in uranium isotopic analysis in environmental particulate

In recent decades, the Nuclear Safeguards underwent quantitative changes, reaching the limits of control of the fissionable material at particle levels (pg/fg). This allows verification of the IAEA/ABACC by inspection, not only via swipes by the bulk method but also by identifying within each swipe, particles of different enrichment level by a technique referred to as "fission-track" (FT-TIMS) and individually determine the isotope of actinides. The new requirements determined by the IAEA make it necessary for improved self-control capabilities of its installation by the National Atomic Energy Commission, bringing forth the development and necessary investments, with the goal to implement this technology (FT-TIMS), is essential in a country with significant technological abilities in the nuclear area. For this reason, work has been completed on the renovation of the NUCLIDE mass spectrometer by thermal ionization mass spectrometry (TIMS) that the CNEA Headquarters has in its possession which provides a new vacuum system, modifies the ion source, updates electronic components, and improves an annex system, (degassing device) that allows for the removal of impurities and carburizing the filaments used for measurement of ultramicro amounts. Additionally, we are working on new software for NUCLIDE spectrometer regulation and the acquisition of data through Windows, This presentation outlines alternative methods of isotopic analysis, conventional analysis methods requiring microgram (10-6g) quantities thus allowing measurement of isotopes of ultramicro amounts and particles (10-9-10-12g) with acceptable uncertainty, One of these innovations was created for equipment that had a single detector SEM (IC), and consists of an accurate and continuous filament heating evaporation. This is achieved by a transition (2000 seconds) which allows to deduce the entire time signal of the major isotopes (²³⁸U) while sequentially measured by the process known as "peak stepping" all the isotopes including the minor isotopes (²³⁴U, ²³⁵U y ²³⁶U). The other method considered here, originally devised in IAI (Institute of Analytical Instrumentation) of the Russian Academy of Sciences for a similar equipment of NUCLIDE but provided with a multichannel detector "position sensitive ion detector" (PSID), it uses a heated tungsten evaporation filament so that the sample is consumed during rapid transient (100-200 seconds). The signal/noise ratio, achieve good LD, despite having relatively low ionization efficiency. The CNEA laboratory employs some filament configuration and acceleration lens changes which proved advantageous for this methodology. Finally, we are developing technical carburization, which can achieve an increase in the filament work function of rhenium on which the sample is deposited, improving the efficiency of the ionization in one order of magnitude and increasing both the stability and the strength of the signal. Thus, the sequential measurement is made possible on equipment that has a single counter being useful in detecting equally simultaneous measurements (MIC-TIMS). (author)