ISO 12749-3:2015

INTERNATIONAL ISO
STANDARD 12749-3
First edition
2015-08-15
Nuclear energy, nuclear technologies,
and radiological protection —
Vocabulary —
Part 3:
Nuclear fuel cycle
Énergie nucléaire, technologies nucléaires et protection
radiologique — Vocabulaire —
Partie 3: Cycle de combustibles nucléaires
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
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ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Structure of the vocabulary . 1
3 Terms and definitions . 2
3.1 General terms related to nuclear fuel cycle . 2
3.2 Terms related to conversion and enrichment . 6
3.3 Terms related to fuel fabrication . 7
3.4 Terms related to fuel characteristics . 8
3.5 Terms related to transport of radioactive material .10
3.6 Terms related to reprocessing .12
3.7 Terms related to radioactive waste .12
3.8 Terms related to decommissioning .17
3.9 Terms related to nuclear criticality safety.19
Annex A (informative) Methodology used in the development of the vocabulary .21
Annex B (informative) Alphabetical index .33
Bibliography .36
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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different types of ISO documents should be noted. This document was drafted in accordance with the
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The committee responsible for this document is ISO/TC 85, Nuclear energy, nuclear technologies, and
radiological protection.
This first edition cancels and replaces ISO 921:1997, of which it forms the subject of a technical revision.
ISO 12749 consists of the following parts, under the general title Nuclear energy, nuclear technologies,
and radiological protection:
— Part 2: Radiological protection
— Part 3: Nuclear fuel cycle
— Part 4: Dosimetry for radiation processing
The following parts are under preparation:
— Part 5: Reactors
iv © ISO 2015 – All rights reserved

Introduction
This part of ISO 12749 will provide terms and definitions for nuclear fuel cycle concepts dealing with
specific subjects such as fuel fabrication, fuel characteristics, and nuclear criticality safety and with
transport and radioactive waste related topics, excluding reactors operations. Terminological data are
taken from ISO standards developed by TC 85/SC 5 and other technically validated documents issued
by international organizations.
Unambiguous communication of nuclear energy concepts is crucial taking into account the relevant
implications that may arise from misunderstandings with regard to equipment and materials involved
in the standards dealing with any subject regarding nuclear energy activities. Nuclear fuels for different
power reactors are produced according to different designs. However, several concepts are present in
all of them and need to be designated by common terms and described by harmonized definitions in
order to avoid misunderstandings. In another nuclear fuel technology subfield, difficulties arise due to
the wide variety of units employed to measure the fuel burnout level. Thus, to enhance comprehension,
it is advisable to adopt unified measure units.
Conceptual arrangement of terms and definitions is based on concepts systems that show corresponding
relationships among nuclear energy concepts. Such arrangement provides users with a structured view
of the nuclear energy sector and will facilitate common understanding of all related concepts. Besides,
concepts systems and conceptual arrangement of terminological data will be helpful to any kind of user
because it will promote clear, accurate, and useful communication.
INTERNATIONAL STANDARD ISO 12749-3:2015(E)
Nuclear energy, nuclear technologies, and radiological
protection — Vocabulary —
Part 3:
Nuclear fuel cycle
1 Scope
This part of ISO 12749 lists unambiguous terms and definitions related to nuclear fuel cycle concepts
in the subject field of nuclear energy, excluding reactor operations. It is intended to facilitate
communication and promote common understanding.
2 Structure of the vocabulary
The terminology entries are presented in the conceptual order of the English preferred terms. The
structure of each entry is in accordance with ISO 10241-1:2011.
All the terms included in this part of ISO 12749 deal exclusively with nuclear fuel cycle. When selecting
terms and definitions, special care has been taken to include the terms that need to be defined, that is
to say, either because the definitions are essential to the correct understanding of the corresponding
concepts or because some specific ambiguities need to be addressed.
The notes appended to certain definitions offer clarification or examples to facilitate understanding of
the concepts described. In certain cases, miscellaneous information is also included, for example, the
units in which a quantity is normally measured, recommended parameter values, references, etc.
According to the title, the vocabulary deals with concepts belonging to the general nuclear energy
subject field within which concepts in the nuclear fuel cycle sub-subject field are taken into account.
See Annex A for the methodology used to develop the vocabulary.
nuclear fuel cycle
3.1 General terms related to
nuclear fuel cycle
3.8
3.7
3.3 3.4 3.5 3.6
3.2
Terms
Terms
Terms Terms related Terms Terms related
Terms
related related to
related to to fuel related to to
related to
decommi-
to radio-
fuel characteristics transport of reprocessing
conversion
ssioning
active
fabrication radioactive
and
waste
material
enrichment
3.9
Terms related to nuclear
criticality safety
3 Terms and definitions
3.1 General terms related to nuclear fuel cycle
3.1.1
nuclear fuel
fissionable nuclear material used in a reactor core or intended for use in a reactor core
3.1.1.1
nuclear fuel cycle
operations associated with the production of nuclear energy
Note 1 to entry: The nuclear fuel cycle includes the following stages:
a)  mining and processing of uranium or thorium ores;
b)  conversion;
c)  enrichment of uranium;
d)  manufacture of nuclear fuel (3.1.1);
e)  uses of the nuclear fuel;
f)  reprocessing (3.1.1.1.2.2) and recycling (3.1.1.1.2.3) of spent fuel;
g)  temporary radioactive material storage (3.1.1.1.2.1)of spent fuel and radioactive waste (3.7.1) from fuel
fabrication (3.1.1.1.1.3) and reprocessing (3.1.1.1.2.2) and disposal of spent nuclear fuel (3.1.1.1.5) [open fuel cycle
(3.1.1.7)] or high-level waste (closed fuel cycle (3.1.1.8)];
h)  any related research and development activities;
i)  transport of radioactive material;
j)  all waste management (3.7.7) activities [including decommissioning (3.8.1]) relating to operations associated
with the production of nuclear energy.
Note 2 to entry: Reactor operation and other activities at a reactor site are not addressed in this part of ISO 12749,
but are to be addressed in ISO 12749-5.
[SOURCE: Adapted from IAEA Safety Glossary, 2007 Edition, modified — By splitting the definition into
a definition and a note.]
3.1.1.1.1
front end
steps of the nuclear fuel cycle (3.1.1.1) ending with fuel introduction into the reactor core
3.1.1.1.1.1
nuclear material conversion
modification of the chemical composition of nuclear material so as to facilitate its further use or
processing; in particular, to provide feed material for enrichment of isotopes of interest and/or reactor
fuel fabrication (3.1.1.1.1.3)
Note 1 to entry: To produce material for fuel fabrication (3.1.1.1.1.3), the following are examples of conversion
that can be carried out: U O or UF to uranium dioxide (UO ), U or Pu nitrate to oxide, or U or Pu oxides to metal.
3 8 6 2
[SOURCE: IAEA Safeguards Glossary, 2001 Edition, modified — By splitting the definition into a
definition and note 1 to entry.]
2 © ISO 2015 – All rights reserved

3.1.1.1.1.2
isotope enrichment
isotope separation process by which the fractional abundance of a specified isotope in an element is
increased such as increasing the abundance of U relative to natural uranium (3.1.1.2) or increasing
the abundance of the D O in water
Note 1 to entry: Usually, the term will be “enrichment”.
3.1.1.1.1.2.1
enriched fuel
fuel made with uranium that has been modified by increasing the abundance of the fissile isotope U
3.1.1.1.1.3
fuel fabrication
process for manufacturing fuel elements (3.3.6) or other reactor components containing nuclear material
Note 1 to entry: Manufacturing process includes nuclear material conversion (3.1.1.1.1.1), storage, and physic-
chemical analyses of materials.
[SOURCE: IAEA Safeguards Glossary, 2001 Edition]
3.1.1.1.2
back end
steps of the nuclear fuel cycle (3.1.1.1) beginning with the final removal of the fuel from the reactor core
Note 1 to entry: The processes can include radioactive material storage (3.1.1.1.2.1)at or away from reactor,
reprocessing (3.1.1.1.2.2), recycling (3.1.1.1.2.3), conditioning and disposal.
[SOURCE: IAEA-TECDOC-1613 “Nuclear fuel cycle information system”, 2009, modified — By splitting
the definition into a definition and note 1 to entry.]
3.1.1.1.2.1
radioactive material storage
holding of radioactive sources, spent nuclear fuel (3.1.1.1.5), or radioactive waste (3.7.1) in a facility that
provides for containment with the intention of retrieval
[SOURCE: IAEA Safety Glossary 2007]
3.1.1.1.2.2
reprocessing
process or operation of extracting fission products (3.1.5) from spent nuclear fuel (3.1.1.1.5) to enable
reuse of the nuclear fuel (3.1.1)in a reactor
3.1.1.1.2.3
recycling
use, for the fabrication of nuclear fuel (3.1.1), of fissionable materials (
...