BS ISO 24459:2021 pdf download – Determination of uranium content in samples coming from the nuclear fuel cycle by L-absorption edge spectrometry 6.1 X-ray tube. The maximum working voltage of X-ray tube is higher than 25 kV, voltage-controlled, current- controlled. It shall be stable over time and shall reach an intensity (adjustable, usually lower than 100 μA) high enough to ensure satisfactory total count rate for fast and accurate measurement (as described in Clause 4). 6.2 Shielding and collimator. The shielding body is made of brass or other shielding materials. X-ray tube, X-ray detector and sample cell are directly mounted in the shielding body. The thickness of the shielding is chosen to ensure no X-ray leakage, and to satisfy the radioprotection requirements. The collimator is made of tungsten, or other materials, whose fluorescence X-rays do not interfere with the region of interest. 6.3 Sample cell. The sample cell can be made of glass or polycarbonate (PC), which can withstand nitric acid and TBP- DILUANT or in quartz that is resistant to nitric acid. The optimum path length and the specifications of the cell depend on the characteristic of the apparatus and the analytical needs. Examples of cell specifications: — for process control purposes, disposable 4mm long PC cell; — for high accuracy purposes, fixed flow-through cell with a path length of 2 mm and a volume of 125 μl. 6.4 X-ray detector and multichannel analyser. The X-ray detector should have an energy resolution better than 135 eV (for the 55 Fe peak at 5,9 keV). For example, a Peltier-cooled, high-resolution 10 mm 2 × 0,5 mm silicon drift detector. 6.5 Software. 6.5.1 For data acquisition. Commercial or non-commercial spectroscopy software can be used to collect the X-ray spectrum. 6.5.2 For data processing. At the time of writing this document, no commercial solutions are available for the fitting of L-edge transmission spectrum. Examples of fitting algorithm are described in 7.5. 7 Method 7.1 Pre-checks Ensure that the temperature sensor is working properly and that the temperature is close to the temperature of reference. Setup the multi-channel analyser: — adjust the gain so that the peaks for energy calibration and the L III edge of uranium are evenly distributed across the spectrum; — perform the energy calibration by using induced X-rays in the spectrum, such as the characteristic lines of the X-ray tube target (silver or molybdenum) or the target positioned in...

Download Address

  • Download