ISO 8298:2000 pdf download

ISO 8298:2000 pdf download.Nuclear fuel technology – Determination ofmilligram amounts of plutonium in nitricacid solutions -Potentiometric titrationwith potassium dichromate after oxidationby Ce(Iv) and reduction by Fe(II).
WARNING — Osmium tetroxide is a volatile toxic chemical and the vapour attacks the eyes. It should only be handled in a fume cupboard or glove box, wearing safety glasses and surgeon’s gloves.
Add progressively and while stirring 4 ml of concentrated sulfuric acid (p = 1,84 kg/I) to 36 ml of water in a glass beaker and allow to cool. Dissolve the content of a 0,1 g ampoule of osmic acid in this solution. Store the solution in a glass bottle with a glass stopper and do not use later than one month after preparation.
5.4 0,05% mol/l sodium arsenite solution.
Dissolve 6,5 g of sodium arsenite in 11 of water.
5.5 0,04 mol/l and 0,004 mol/l potassium permanganate solutions.
5.5.1 Dissolve 0,63 g of potassium permanganate in 100 ml of water to obtain a 0,04 mol/I solution. Boil the solution gently for 15 mm. Cool down to room temperature.
5.5.2 Before use, filter the necessary volume of 0,04 mol/I permanganate solution through a Whatman glass-fibre filter or through a plug of glass wool. Dilute 10 ml of the filtrate to 100 ml with water to obtain a 0,004 mol/I solution. Store the diluted solution in a glass bottle and do not use later than one month after preparation.
5.6 0,02 mol/l oxalic acid solution.
Dissolve 0,63 g of oxalic acid dihydrate in water and dilute to 250 ml with water.
5.7 3 mol/l sulfuric acid.
Cautiously, with stirring, add 167 ml of concentrated sulfuric acid (p = 1,84 kg/I) to 750 ml of water in a glass
beaker, cool to room temperature, mix and dilute to 11 with water.
5.8 6,69 x i0 mol/l iron(ll) sulfate solution (239Pu equivalent 0,8 g/kg of solution), in 3 mol/l sulfuric acid and
0,3 mol/l amidosulfonic acid.
Cautiously, with stirring, add 167 ml of concentrated sulfuric acid (p = 1,84 kg/I) to 750 ml of water in a glass beaker, cool to room temperature. Dissolve 29,1 g of amidosulfonic acid and 1,86 g of iron(ll) sulfate heptahydrate in this solution and dilute to 11 with water.
5.9 Potassium dichromate titrant solution (239Pu equivalent 0,5 g/kg of solution).
Introduce 1,03 g of potassium dichromate into a 5 I glass flask, dissolve and dilute to 5 I with water. Standardize the dichromate solution by titrating it with at least five aliquots of the plutonium reference solution (5.10) in accordance with the procedure specified in 5.11 or a more accurate one. Express the titre as the 239Pu equivalent in g/kg of solution.
5.10 Plutonium reference solution (see ISO 10980).
Dissolve an accurately known mass (in0) of a certified plutonium metal (e.g. NBL CRM 126, CETAMA MP2 or UK/Pul) in a 10:1 mixture of concentrated nitric acid (p = 1,40 kg/I) and 0,1 mol/l hydrofluoric acid. Heat gently to dissolve without losses of aerosols. After complete dissolution, continue to heat the open vessel for at least 1 h at about 90 °C to destroy and expel nitrous compounds, and then allow to cool to room temperature. Alternatively, the metal may be dissolved in 4 mol/I hydrochloric acid, which can be removed by fuming with nitric acid, if necessary, after the dissolution is completed. Dilute with the required volume of 2 mol/l nitric acid to obtain a solution containing about 2 mg Pu/mI in about 3 mol/I nitric acid. Homogenize, weigh to within 0,0001 g (in.1) and store tightly stoppered till needed.
The strength of the solution, expressed as the Pu equivalent in g/kg of solution, is calculated using the following equation:
Verify the titre of the plutonium reference solution against the potassium dichromate reference solution in accordance with ISO 10980, titrating at least five aliquots with the potassium dichromate reference solution using the procedure specified above or a more accurate one. Repeat this verification on at least one other day. The solution is acceptable if the calculated titre and the mean of the measured titres agree within 0,1 %. If not, repeat the preparation of the reference solutions.
6 Apparatus
Normal laboratory equipment for a laboratory analysing plutonium, plus the following:
6.1 High-impedance millivoltmeter, 100 M2 input resistance, with a digital read-out capable of discriminating tolmV.
6.2 Burettes, capacity 1 ml and 10 ml, capable of delivering increments down to 4 tl, with non-return valves controlling the addition of the reagent into the titration cell through polyethylene tubes, and fitted with a labyrinthtype anti-diffusion tip. The burettes used for the addition of iron(ll) sulfate solution and potassium dichromate titrant solution shall be calibrated gravimetrically.
6.3 Magnetic stirrer, with speed control and plastic-coated stirrer bar.
6.4 Temperature sensor, with digital read-out, to measure the temperature of the solutions of iron(lI) sulfate (5.8) and potassium dichromate (5.9).