FprEN ISO 12800
(Main)Nuclear fuel technology - Guidelines on the measurement of the specific surface area of uranium dioxide and plutonium dioxide powders by the BET method (ISO/FDIS 12800:2026)
- Abstract
ISO 12800:2017 gives guidelines on the determination of the specific surface area of as-fabricated uranium dioxide powder by volumetric or gravimetric determination of the amount of nitrogen adsorbed on the powder, and can be applied to other similar materials, e.g. U3O8, UO2-PuO2 powders, and other bodies with similar surface areas, e.g. powder granules or green pellets, provided that the conditions described are fulfilled. Modifications using other adsorbing gases are included.
The method is relevant as long as the expected value is in the range between 1 m2/g and 10 m2/g.
- Status
- Not Published
- Publication Date
- 10-Feb-2027
- Current Stage
- 5020 - Submission to Vote - Formal Approval
- Start Date
- 17-Sep-2026
- Completion Date
- 17-Sep-2026
FprEN ISO 12800 is the CEN draft for guidelines on measuring the specific surface area of uranium dioxide and plutonium dioxide powders by the Brunauer-Emmett-Teller (BET) method. It is aimed at fuel-fabrication and laboratory users who need a comparable way to determine powder surface area from gas adsorption behavior.
This standard focuses on as-fabricated nuclear fuel powders and on the sample preparation, measurement, calculation and reporting needed to obtain a BET surface-area result. It is written for users who work with uranium dioxide (UO2), plutonium dioxide (PuO2), and closely related materials under the conditions described.
What does FprEN ISO 12800 specify?
FprEN ISO 12800 specifies guidelines for determining the specific surface area of UO2 and PuO2 powders by measuring the amount of nitrogen adsorbed on the powder, using volumetric or gravimetric methods. It also allows modified methods using other adsorbing gases when the stated conditions are met.
The document is organized into the scope, normative references, terms and definitions, principle, procedure, expression of results, and test report. Clause 4 explains the BET principle, Clause 5 covers sample preparation and measurement methods, Clause 6 covers calculation and accuracy, and Clause 7 states what to include in the report.
What are the key requirements of FprEN ISO 12800?
FprEN ISO 12800 applies to fuel fabrication and is relevant when the expected specific surface area is in the stated range for UO2 powders and PuO2 powders. In practice, that means the method is intended for powders in the BET measurement range, not for materials outside the adsorption conditions described.
Sample preparation matters
Clause 5 requires removal of surface impurities, especially water vapor, before measurement. The sample may be evacuated and heated, or purged with purified inert gas, but the treatment has to avoid decomposition, sintering, or changes in crystal structure. This matters because the surface state directly affects the adsorption result.
The BET method has to fit the adsorption behavior
Clause 4 states that the method is based on a monomolecular layer of adsorbed gas and on isothermal adsorption curves. It applies only when nitrogen is not absorbed into the material, does not react chemically, all pores are reachable, and the adsorption curve is of type 2 or type 4. That means the user has to confirm that the material behaves like a BET-suitable surface, not just any powder.
Measurements can be volumetric, gravimetric, or dynamic
Clause 5 describes volumetric measurement in a calibrated bulb, gravimetric measurement with a microbalance, and a dynamic carrier-gas method. For routine use, the practical choice is the equipment that best matches the powder and the required accuracy.
Use enough points for the calculation
Clause 5.4 calls for at least three points in the relative-pressure region used for BET analysis, with equilibrium conditions. A single-point method is allowed when lower accuracy is acceptable. In practice, the more complete multipoint approach gives a better basis for the result.
Calculation and reporting are part of the method
Clause 6 gives the BET calculation for multipoint and single-point determinations and links the surface-area calculation to the adsorbed gas and the occupied area per molecule. Clause 7 requires the report to include the standard reference, sample identification, result with expanded uncertainty, test location and date, reference materials used, degassing and heating conditions, method and calculation approach, adsorbate purity, and measurement temperature.
Precision depends on the setup
Clause 6.2 states that precision depends on the equipment used, and the user is responsible for method qualification. Periodic calibration with a certified reference material is expected, so results can be defended in quality control, validation, or customer-facing documentation.
What terms does FprEN ISO 12800 define?
- BET method - The adsorption method used here to estimate surface area from the amount of gas needed to form a monolayer.
- Adsorbate - The gas being adsorbed on the powder surface, such as nitrogen.
- Adsorbent - The powder material whose surface area is being measured.
- Relative pressure (p/p0) - The pressure ratio used to compare adsorption data at a given temperature.
- S.T.P. - Standard temperature and pressure, used for reporting gas volumes in the calculations.
- MOX (UO2-PuO2) - Mixed uranium-plutonium oxide powder referenced in the scope.
- UO2 / PuO2 - Uranium dioxide and plutonium dioxide, the powder types covered by the standard.
Who uses FprEN ISO 12800?
FprEN ISO 12800 is used in nuclear fuel fabrication, analytical laboratories, and quality-control teams that measure powder surface area. It is relevant for staff who prepare samples, run adsorption measurements, calculate BET results, validate methods, and report test results for uranium dioxide, plutonium dioxide, and related powders.
What changed in FprEN ISO 12800 from the previous edition?
FprEN ISO 12800 is the second edition and cancels and replaces ISO 12800:2003. The document states that the edition has been technically revised.
Which standards are used with FprEN ISO 12800?
- ISO 9277:2022 - The normative reference for BET determination of the specific surface area of solids by gas adsorption; it also supports the calculation approach and reference-material practice.
- ISO/IEC Guide 98-3:2008 - Used for expressing the expanded uncertainty reported with the test result.
What does the FprEN ISO 12800 document contain?
FprEN ISO 12800 contains the BET principle, a description of adsorption isotherms, and the conditions under which the method can be applied. It also sets out sample preparation options, volumetric and gravimetric measurement approaches, a dynamic carrier-gas method, and alternative adsorbates and temperatures.
The document includes the BET calculation path for multipoint and single-point determinations, guidance on precision and accuracy, and the required contents of the test report. It also contains a figure classifying adsorption isotherms and a table giving standard occupied areas for different adsorbates.
Relations
- Effective Date
- 12-Feb-2026
- Effective Date
- 22-Jan-2025
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Frequently Asked Questions
FprEN ISO 12800 is a draft published by the European Committee for Standardization (CEN). Its full title is "Nuclear fuel technology - Guidelines on the measurement of the specific surface area of uranium dioxide and plutonium dioxide powders by the BET method (ISO/FDIS 12800:2026)". This standard covers: ISO 12800:2017 gives guidelines on the determination of the specific surface area of as-fabricated uranium dioxide powder by volumetric or gravimetric determination of the amount of nitrogen adsorbed on the powder, and can be applied to other similar materials, e.g. U3O8, UO2-PuO2 powders, and other bodies with similar surface areas, e.g. powder granules or green pellets, provided that the conditions described are fulfilled. Modifications using other adsorbing gases are included. The method is relevant as long as the expected value is in the range between 1 m2/g and 10 m2/g.
ISO 12800:2017 gives guidelines on the determination of the specific surface area of as-fabricated uranium dioxide powder by volumetric or gravimetric determination of the amount of nitrogen adsorbed on the powder, and can be applied to other similar materials, e.g. U3O8, UO2-PuO2 powders, and other bodies with similar surface areas, e.g. powder granules or green pellets, provided that the conditions described are fulfilled. Modifications using other adsorbing gases are included. The method is relevant as long as the expected value is in the range between 1 m2/g and 10 m2/g.
FprEN ISO 12800 is classified under the following ICS (International Classification for Standards) categories: 27.120.30 - Fissile materials and nuclear fuel technology. The ICS classification helps identify the subject area and facilitates finding related standards.
FprEN ISO 12800 has the following relationships with other standards: It is inter standard links to ISO/FDIS 12800, EN ISO 12800:2019. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
FprEN ISO 12800 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)
SLOVENSKI STANDARD
oSIST prEN ISO 12800:2026
01-marec-2026
Tehnologija jedrskih goriv - Smernice za merjenje specifične površine prahu
uranovega dioksida in plutonijevega dioksida po metodi BET (ISO/DIS 12800:2026)
Nuclear fuel technology - Guidelines on the measurement of the specific surface area of
uranium dioxide and plutonium dioxide powders by the BET method (ISO/DIS
12800:2026)
Kernbrennstofftechnologie - Leitlinien für die Messung der spezifischen Oberfläche von
Uranoxid-Pulvern mittels des BET-Verfahrens (ISO/DIS 12800:2026)
Technologie du combustible nucléaire - Lignes directrices pour le mesurage de l'aire
massique (surface spécifique) des poudres d'oxyde d'uranium et de plutonium par la
méthode BET (ISO/DIS 12800:2026)
Ta slovenski standard je istoveten z: prEN ISO 12800
ICS:
27.120.30 Cepljivi materiali in jedrska Fissile materials and nuclear
gorivna tehnologija fuel technology
oSIST prEN ISO 12800:2026 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN ISO 12800:2026
oSIST prEN ISO 12800:2026
DRAFT
International
Standard
ISO/DIS 12800
ISO/TC 85/SC 5
Nuclear fuel technology —
Secretariat: BSI
Guidelines on the measurement of
Voting begins on:
the specific surface area of uranium
2026-01-08
dioxide and plutonium dioxide
Voting terminates on:
powders by the BET method
2026-04-02
ICS: 27.120.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
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POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 12800:2026(en)
oSIST prEN ISO 12800:2026
DRAFT
ISO/DIS 12800:2026(en)
International
Standard
ISO/DIS 12800
ISO/TC 85/SC 5
Nuclear fuel technology —
Secretariat: BSI
Guidelines on the measurement of
Voting begins on:
the specific surface area of uranium
dioxide and plutonium dioxide
Voting terminates on:
powders by the BET method
ICS: 27.120.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
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POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
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TO SUBMIT, WITH THEIR COMMENTS,
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NOTIFICATION OF ANY RELEVANT PATENT
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RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 12800:2026(en)
ii
oSIST prEN ISO 12800:2026
ISO/DIS 12800:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
4.1 Summary of the BET method .1
4.2 Isothermal adsorption curves .2
4.3 Conditions and assumptions .3
5 Procedure . 3
5.1 Sample preparation .3
5.1.1 Uranium dioxide powders .3
5.1.2 Plutonium dioxide powders .3
5.1.3 Mass of sample .3
5.2 Volumetric measurement .4
5.3 Gravimetric measurement .4
5.4 Multipoint and single-point methods .4
5.5 Dynamic method (carrier gas method) .4
5.6 Alternative methods .4
6 Expression of results . 5
6.1 Methods of calculation .5
6.1.1 Multipoint determination .5
6.1.2 Single-point determination .7
6.2 Precision and accuracy .7
7 Test report . 7
Bibliography . 8
iii
oSIST prEN ISO 12800:2026
ISO/DIS 12800:2026(en)
Foreword
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This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies, and
radiological protection, Subcommittee SC 5, Nuclear installations, processes and technologies.
This second edition cancels and replaces the first edition (ISO 12800:2003), which has been technically
revised.
iv
oSIST prEN ISO 12800:2026
DRAFT International Standard ISO/DIS 12800:2026(en)
Nuclear fuel technology — Guidelines on the measurement of
the specific surface area of uranium dioxide and plutonium
dioxide powders by the BET method
1 Scope
This document is applicable to fuel fabrication. It gives guidelines on the determination of the specific
surface area of as-fabricated uranium dioxide and plutonium dioxide powders by volumetric or gravimetric
determination of the amount of nitrogen adsorbed on the powder. The measurement of other uranium oxide
powders refers to uranium dioxide, such as UO and U O . The measurement of MOX(UO -PuO ) powders
3 3 8 2 2
refers to plutonium dioxide. When conditions described are fulfilled, modifications using other adsorbing
gases are included.
2 2
The method is relevant as long as the expected value is in the range from 1 m /g to 10 m /g for uranium
2 2
dioxide powders, in the range from 0.1 m /g to 45 m /g for plutonium dioxide powders.
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 9277:2022, Determination of the specific surface area of solids by gas adsorption — BET method
3 Terms and definitions
No terms and definitions are listed in this document.
ISO
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