Verification measurements of the IRMM-1027 and the IAEA large-sized dried (LSD) spikes

In the frame of the accountancy measurements of the fissile materials, reliable determinations of the plutonium and uranium content in spent nuclear fuel are required to comply with international safeguards agreements. Large-sized dried (LSD) spikes of enriched ²³⁵U and ²³⁹Pu for isotope dilution mass spectrometry (IDMS) analysis are routinely applied in reprocessing plants for this purpose. A correct characterisation of these elements is a pre-requirement for achieving high accuracy in IDMS analyses. This paper will present the results of external verification measurements of such LSD spikes performed by the European Commission and the International Atomic Energy Agency.

     

Determination of the REE and Y in silicate materials with ICP-AES

Summary An ICP-AES method for the determination of 12 rare earth elements and Y is described. Following a Na₂O₂-sinter dissolution of silicate materials the REE and Y were separated and concentrated using ion-exchange chromatography. The dissolution and separation procedures are described in detail. Numerous tests show good recovery of the REE. Spectral interferences were quantified and discussed. The precision is better than 5% (r.s.d.) for all measured REE, except Pr. The accuracy was tested by analyzing more than 30 international reference samples, the results are in good agreement with published data. In this paper we present our latest data from 6 new reference samples.

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Bestimmung der Seltenen Erden und Yttrium in silikatischem Material mit ICP-AES

     

Combining magnetic resonance measurements with numerical simulations – Extracting blood flow physiology information relevant to the investigation of intracranial aneurysms in the circle of Willis

Cerebral aneurysms in the region of the circle of Willis have an incidence of 3–6% in western populations and involve the risk of rupture with subsequent subarachnoidal bleeding. The patient specific blood flow patterns are of substantial importance for understanding the pathogenesis of the lesions and may eventually contribute to deciding on the most efficient treatment procedure for a specific patient.A non-invasive method for performing in vivo measurements on blood velocity is 4D phase-contrast magnetic resonance angiography (PC-MRA), on the basis of which a flow field with all its parameters can be simulated. We are using this approach to investigate the hemodynamic parameters in the circle of Willis and, by analyzing the values at common locations of aneurysms, trying to find potential parameters to predict the development of aneurysms. Methodologically, we are acquiring the artery geometry with 3D-time-of-flight magnetic resonance (TOF) measurements and the blood velocity in the feeding arteries with 4D PC-MRA measurements in a healthy volunteer. These measurements are combined with computational fluid dynamics (CFD) to describe detailed hemodynamic patterns within the circle of Willis.