ISO 9463:2019

ISO 9463:2019 pdf free.Nuclear energy – Nuclear fuel technology – Determination of
plutonium in nitric acid solutions by spectrophotometry.
7 Apparatus
Usual nuclear laboratory equipment.
7.1 Spectrophotometer, with spectral slit width of 2 nm or better, double-beam grating spectrophotometer, or equivalent, designed for measurements on fully contained high beta-gamma solutions and having, as far as possible, the following features.
a) Capable of performing absorbance measurements from 0,001 to 1,5.
b) Stable baseline.
c) A measurement spectral range of 800 nm to 860 nm shall be included. Usually, spectrometers with a minimum capability of 190 nm and a maximum capability of 1100 nm, or greater which allow the analysis of other element or the study of potential method interferences are convenient.
7.2 Measurement cell, a static or a flow cell. Main characteristic is the optical path in the cell. Common cell have an optical path of 1 cm but it can be greater to enhance sensitivity (e.g. 3 cm or 4 cm).
7.3 Volumetric flasks, volume 50 ml, complying with the requirements of ISO 1042.
7.4 Pipette, volume 5 ml or less, with a sampling uncertainty of ± 1 % or less.
8 Test procedure
The following test procedure is given as an example. The varying concentrations or/and volumes, in particular concentration and/or volume of reference solution, flask volume and other equipment or conditions, may be modified if needed.
The spectrophotometer shall be calibrated with a plutonium calibration solution to determine the relationship between plutonium concentration and absorbance.
The frequency of the calibration is chosen in accordance with the required accuracy of the analysis.
8.1 Preparation of the different solutions
8.1.1 Plutonium calibration solution Oxidation by silver oxide
The plutonium calibration solution can be prepared as follows. In a 50 ml volumetric flask (7.3),
— introduce with a pipette (7A) the desired volume, Vio, of the plutonium reference solution (6.2.3), commonly V10 is 5 ml,
— add a few ml of the 3 mol•l1 nitric acid solution (62.1) to clean the inner surface of the flask,
— add the minimum amount (a few grain) of silver oxide powder (6.3.2) to give a persistent dark colour,
— stir,
— keep reacting for 5 mm while stirring,
— check that the solution is still a dark colour,
— add, with a burette, 2 drops of sulfamic acid (6.3.1),
NOTE The addItion of an excess ofsulfamic acid will significantly reduce the molar extinction coefficient therefore the absorbance (as an example, the addition of 12 drops of sulfamic acid reduces the absorbance by approximately 0,8 %).
— homogenize until the solution becomes colourless, which shows that the excess of AgO has been consumed; if the excess of AgO is too high, the fading of the colour of the solution from dark to colourless will go through a brown colour. In this case, wait 2 mm or 3 mm more,
— adjust the volume of the flask with 3 mol•[1 nitric acid (6.2.1).
In order to keep the plutonium at the hexavalent state, it is mandatory to perform the analysis within a few hours following the addition of the silver oxide powder. Otherwise, repeat the valence adjustment by adding a few grains of silver oxide powder (6.3.2).
The analyst shall use available information to estimate the concentration of the sample and adjust the volume V1, of sample (solution to analyse) so that the final concentration is likely to be less than the calibration solution, If the result of the measurement shows that the sample concentration is higher than expected and is above the concentration of the calibration solution (prepared in &LL1). a new sample dilution shall be made to ensure that the concentration of the injected solution is less than the concentration of the calibration solution.ISO 9463 pdf download.

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