BS ISO 8425:2013 pdf free

BS ISO 8425:2013 pdf free.Nuclear fuel technology一Determination of plutonium in pure plutonium nitrate solutions一Gravimetric method
All non-volatile impurities interfere. If the mass fraction of the impurities is greater than 0,05 %,a correction shall be applied. If the mass fraction of the total non-volatile impurities is up to 0,1 %, the overall uncertainty of the measurement will depend on the precision of the impurities determination.
There is no interference from up to at least 1 000 μg:g-1 of phosphorus (present as phosphate) which is lost during the sulphuric acid treatment. The chloride and fluoride contents of the sample should not exceed 25 μg.g-1.
Heat a clean crucible (6.1)for 1 hat 1200 °C to 1 250°C. Cool in a desiccator for 20 min and then in the balance (6.4) for 5 min. Weigh to within ±0,1 mg, repeating the heating until the mass remains constant to within ±0,1 mg.
Weigh out1 g to 2 g of the sample solution containing 0,2 g to 0,4 g of plutonium from a polythene weighing burette (6.2) into the crucible. Record the masses (before the sample delivery, m2, and after the sample delivery, m3) to within ±0,1 mg.
In order to avoid errors due to thermal effects, the weighing burette shall be allowed to adjust to the balance temperature before each weighing.
Add 1,0 ml of the sulphuric acid solution (5.2) to the crucible and swirl gently to mix.
Evaporate the solution under a radiant heater (6.5), by heating gently until sulphuric acid fumes evolve and then more strongly until a dry residue has been obtained and the fuming has practically ceased.
NOTE Plutonium nitrate is converted to plutonium sulphate as the nitrate compound spatters during the evaporation to dryness.
Without delay, transfer the crucible and dried plutonium sulfate to the furnace (6.3) set at about 300 °C. Maintain this temperature for about 15 min. Then raise the temperature by 5 °C to 10 °C per minute to about 850 °C at which temperature the plutonium sulfate will have decomposed.
Increase the temperature to 1 200 °C to 1 250°C and ignite at this temperature for 1 h.
NOTE Alternatively, the operations in 7.4, 7.5, and 7.6 can be done in a temperature-programmed furnace with controlled air flow.
Cool the crucible and oxide in a desiccator (6.6) for 15 min and then in the balance for 5 min. Weigh to within ±0,1 mg.BS ISO 8425 pdf download.