ISO 21484:2017
(Main)Nuclear Energy - Fuel technology - Determination of the O/M ratio in MOX pellets by the gravimetric method
Nuclear Energy - Fuel technology - Determination of the O/M ratio in MOX pellets by the gravimetric method
ISO 21484:2017 describes a method for determining the Oxygen-to-Metal (O/M) ratio in mixed uranium-plutonium oxide (U,Pu)O2 ± X pellets. The parameters given in the following paragraphs are relevant for pellets within a range of O/M ratio corresponding to 1,98 to 2,01. The method described in the document is adapted, with regard to the parameters, if the expected values of O/M ratio are outside the range.
Énergie nucléaire — Technologie du combustible — Détermination du rapport O/M dans les pastilles MOX par la méthode gravimétrique
L'ISO 21484:2017 décrit une méthode de détermination du rapport oxygène/métal (O/M) dans les pastilles de mélange d'oxydes d'uranium et de plutonium (U,Pu)O2 ± X. Les paramètres indiqués dans les paragraphes suivants sont applicables aux pastilles dont le rapport O/M est compris entre 1,98 et 2,01. La méthode décrite dans le présent document doit être adaptée, en ce qui concerne les paramètres, si les valeurs attendues du rapport O/M ne sont pas situées dans cette plage.
General Information
- Status
- Published
- Publication Date
- 29-Jan-2017
- Technical Committee
- ISO/TC 85/SC 5 - Nuclear installations, processes and technologies
- Drafting Committee
- ISO/TC 85/SC 5 - Nuclear installations, processes and technologies
- Current Stage
- 9060 - Close of review
- Completion Date
- 02-Sep-2027
Relations
- Effective Date
- 18-May-2013
Overview
ISO 21484:2017 is an international standard developed by the International Organization for Standardization (ISO) that specifies a precise method for determining the Oxygen-to-Metal (O/M) ratio in mixed uranium-plutonium oxide (MOX) pellets, expressed as (U,Pu)O₂ ± X. This gravimetric method is essential in nuclear fuel technology to ensure the optimal stoichiometry and performance of MOX fuel pellets used in nuclear reactors.
The standard is applicable primarily for samples with O/M ratios between 1.98 and 2.01, with adjustments recommended for values outside this range. Accurate measurement of the O/M ratio is critical for reactor safety, efficiency, and fuel longevity in the nuclear energy sector.
Key Topics
Principle of Method
The gravimetric technique involves subjecting the MOX pellets to controlled oxidation-reduction heat treatments under specific thermodynamic conditions to adjust their O/M ratio exactly to 2.000. The change in mass before and after treatment allows for calculation of the initial O/M ratio.Reagents and Materials
Use of high-purity reagents like 50% nitric acid solution and high-purity gases (argon, nitrogen, hydrogen mixtures) is mandatory to maintain analytical accuracy and prevent contamination.Apparatus and Equipment
Key equipment includes a controlled muffle or infrared furnace capable of reaching 950 °C, platinum or quartz crucibles, and an analytical balance with accuracy of ±0.1 mg or better, ensuring precise weighing of samples.Sample Preparation and Handling
Representative sampling from pellet batches is essential, with protocols to minimize sample oxidation during preparation. Handling under inert atmosphere (e.g., argon) maintains sample integrity.Heat Treatment Procedure
The standard outlines detailed oxidation-reduction cycles, including temperature ramps and gas compositions-for example, argon sweeps followed by air at 900 °C, then hydrogen-argon mixtures for several hours-to adjust pellet oxygen content accurately.Calculation of O/M Ratio
A formula based on sample mass changes and atomic masses of constituent elements allows determination of the O/M ratio, with emphasis on precise atomic mass values of plutonium, uranium, americium, and oxygen.Precision and Sensitivity
The method demonstrates high accuracy, with a standard deviation better than 0.001 in O/M ratio determinations, and sensitivity such that a 0.5 mg weight change in a 15 g sample results in a 0.001 O/M ratio change.Test Reporting
Reports must include sample identification, method references, individual results, mean O/M ratio, any procedural deviations, anomalies observed, and test dates to ensure traceability and reproducibility.
Applications
Nuclear Fuel Quality Control
ISO 21484:2017 provides nuclear fuel fabricators and laboratories with a reliable measurement protocol to ensure MOX pellet stoichiometry meets design specifications for reactor fuel behavior.Reactor Safety and Performance
Accurate O/M ratio assessment enables optimization of fuel oxidation states, impacting thermal conductivity, fission gas release, and structural stability of fuel pellets under operating conditions.Research and Development
The standard supports R&D activities focused on advanced fuel materials by providing a consistent method for characterizing oxygen content and stoichiometry changes during experimental treatments.Regulatory Compliance
Compliance with ISO 21484:2017 helps nuclear facilities meet international quality assurance standards required by regulators and international nuclear agencies.
Related Standards
ISO 3696 – Water for Analytical Laboratory Use: Specifies quality and test methods for water used in analytical procedures, which is referenced for reagent purity in ISO 21484:2017.
Other Nuclear Fuel Standards from ISO/TC 85
ISO Technical Committee 85 develops various standards related to nuclear fuel technology, safety, and testing, complementing ISO 21484 and contributing to harmonized global practices.
Keywords: ISO 21484:2017, O/M ratio, MOX pellets, gravimetric method, nuclear fuel technology, mixed uranium-plutonium oxide, nuclear energy standards, fuel stoichiometry, oxidation-reduction, sample analysis, nuclear safety, analytical balance, heat treatment, fuel quality control.
ISO 21484:2017 - Nuclear Energy -- Fuel technology -- Determination of the O/M ratio in MOX pellets by the gravimetric method
ISO 21484:2017 - Énergie nucléaire -- Technologie du combustible -- Détermination du rapport O/M dans les pastilles MOX par la méthode gravimétrique
Frequently Asked Questions
ISO 21484:2017 is a standard published by the International Organization for Standardization (ISO). Its full title is "Nuclear Energy - Fuel technology - Determination of the O/M ratio in MOX pellets by the gravimetric method". This standard covers: ISO 21484:2017 describes a method for determining the Oxygen-to-Metal (O/M) ratio in mixed uranium-plutonium oxide (U,Pu)O2 ± X pellets. The parameters given in the following paragraphs are relevant for pellets within a range of O/M ratio corresponding to 1,98 to 2,01. The method described in the document is adapted, with regard to the parameters, if the expected values of O/M ratio are outside the range.
ISO 21484:2017 describes a method for determining the Oxygen-to-Metal (O/M) ratio in mixed uranium-plutonium oxide (U,Pu)O2 ± X pellets. The parameters given in the following paragraphs are relevant for pellets within a range of O/M ratio corresponding to 1,98 to 2,01. The method described in the document is adapted, with regard to the parameters, if the expected values of O/M ratio are outside the range.
ISO 21484:2017 is classified under the following ICS (International Classification for Standards) categories: 17.240 - Radiation measurements; 27.120.30 - Fissile materials and nuclear fuel technology. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO 21484:2017 has the following relationships with other standards: It is inter standard links to ISO 21484:2008. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ISO 21484:2017 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 21484
Second edition
2017-01
Nuclear Energy — Fuel technology —
Determination of the O/M ratio in MOX
pellets by the gravimetric method
Énergie nucléaire — Technologie du combustible — Détermination
du rapport O/M dans les pastilles MOX par la méthode gravimétrique
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO 2017 – All rights reserved
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reactions . 1
6 Reagents and materials . 1
7 Apparatus . 2
8 Sampling . 2
9 Procedure. 2
9.1 Preliminary test . 2
9.2 Preparing the crucibles . . 2
9.3 Weighing the sample . 2
9.4 Heat treatment cycles . 3
9.4.1 General. 3
9.4.2 Example 1 . 3
9.4.3 Example 2 . 3
9.5 Final weighing . 3
10 Calculation . 4
10.1 Mean atomic mass of oxide after heat treatment . 4
10.2 Calculation of O/M ratio. 4
11 Precision . 4
11.1 Accuracy . 4
11.2 Precision . 5
11.3 Sensitivity . 5
12 Test report . 5
Bibliography . 6
Foreword
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This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, n
...
NORME ISO
INTERNATIONALE 21484
Deuxième édition
2017-01
Énergie nucléaire — Technologie du
combustible — Détermination du
rapport O/M dans les pastilles MOX
par la méthode gravimétrique
Nuclear Energy — Fuel technology — Determination of the O/M ratio
in MOX pellets by the gravimetric method
Numéro de référence
©
ISO 2017
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2017, Publié en Suisse
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copyright@iso.org
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ii © ISO 2017 – Tous droits réservés
Sommaire Page
Avant-propos .iv
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 1
4 Principe . 1
5 Réactions . 1
6 Réactifs et matériaux . 1
7 Appareillage . 2
8 Échantillonnage . 2
9 Mode opératoire. 2
9.1 Essai préliminaire . 2
9.2 Préparation des creusets . 2
9.3 Pesée de l’échantillon . 3
9.4 Cycles de traitement thermique . 3
9.4.1 Généralités . 3
9.4.2 Exemple 1 . 3
9.4.3 Exemple 2 . 3
9.5 Pesée finale . 3
10 Calcul . 4
10.1 Masse atomique moyenne d’oxyde après traitement thermique . 4
10.2 Calcul du rapport O/M. 4
11 Fidélité . 4
11.1 Exactitude . 4
11.2 Fidélité . 5
11.3 Sensibilité . 5
12 Rapport d’essai . 5
Bibliographie . 6
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iv © ISO 2017 – Tous droits réservés
NORME INTERNATIONALE
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