ISO 9463:2019 pdf download

ISO 9463:2019 pdf download

ISO 9463:2019 pdf download.Nuclear energy — Nuclear fuel technology — Determination of plutonium in nitric acid solutions by spectrophotometry
1 Scope
This document specifies an analytical method by spectrophotometry, for determining the plutonium concentration in nitric acid solutions, with spectrophotometer implemented in hot cell and glove box allowing the analysis of high activity solutions. Commonly, the method is applicable, without interference, even in the presence of numerous cations, for a plutonium concentration higher than 0,5 mg·l −1 in the original sample with a standard uncertainty, with coverage factor k = 1, less than 5 %. The method is intended for process controls at the different steps of the process in a nuclear fuel reprocessing plant or in other nuclear facilities.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1042, Laboratory glassware — One-mark volumetric flasks
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Principle
Plutonium is quantitatively oxidized to the hexavalent state either with cerium (IV) or with silver oxide. The excess of silver oxide is destroyed by the addition of sulfamic acid. The optical density of the plutonium (VI) (PuO 2 2+ ) absorption peak at the wavelength of 831 nm is then measured on a spectrophotometer. The result is obtained by comparison to a calibration performed under similar conditions (with the same nitrate content).
5.2 Rate of oxidation of Pu(IV) to Pu(VI)
The rate of oxidation by Ce(IV) decreases as the acidity increases. With the reagent quantities stated in the method, the oxidation is complete in 2 min or more in 2 mol·l −1 or 3 mol·l −1 nitric acid. As an example, the oxidation of Pu(IV) in 4 mol·l −1 nitric acid is complete in between 10 min and 15 min when the Ce/Pu initial ratio is higher than 20 [2] . With silver oxide, the oxidation is very fast, much faster than with Ce(IV). In addition, the Ag 2+ /Ag + redox potential is higher than that of Ce 4+ /Ce 3+ and is better adapted to cope with the presence of organic traces in solution. On the other hand, cerium presents the advantage to be stable in sulfuric acid so that it can be added as a precise quantity in solution.