ISO 8299:2019 pdf free

ISO 8299:2019 pdf free.Nuclear fuel technology – Determination of the isotopic and elemental uranium and plutonium concentrations of nuclear materials in nitric acid solutions by thermal-ionization mass spectrometry
The described method is based on isotope ratio measurements by thermal ionization mass spectrometry (TIMS). TIMS analysis requires isotope separation of different elements that have the same or similar masses as an isotope of the element being measured, such as 238U and 241Am influences 238Pu and 241Pu. Separation method for Pu and U using columns purifications are described in Clause 8. Other separation methods may be used provided that they lead to a separation of similar quality. Column extraction chromatography described in ISO 15366 (all parts) is an example of a suitable alternative.
The described method consists of two separate TIMS measurements:
a) Isotopic measurement
One measurement is made to determine the isotopic composition of the element in the sample. The 238Pu isotope abundance is determined by combining mass spectrometry following the present method and alpha spectrometry as described in ISO 11483, if the interference of the isobar 238U is not eliminated by chemical separation.
b) Element concentration measurement
A second measurement is made on a sample and a spike mixture consisting of an artificially enriched isotope of the element to be analysed. The sample element concentration is determined by calculating the difference of isotopic composition before and after the sample spike mixture.This method of measuring an element’s concentration is called isotope dilution mass spectrometry (IDMS). The spiking can be made using a spike isotope that either is present, only minimally present, or absent in the non-spiked sample. The use of 233U or 244Pu spikes can eliminate the need for an isotope measurement in the non-spiked sample to determine uranium and plutonium concentration. Although it is normally of interest to measure both the isotopic composition and the element concentration. It is also more common to use a less expensive spike made from 239Pu,240Pu, 242Pu or 235U. Accurate measurements made on the masses of the sample and spike in the mixture are required for the IDMS method. It is necessary that the isotopic composition and the concentration of the spike be known or measured accurately and has small uncertainties. The IDMS calculations are described in 12.6.ISO 8299 pdf free download.