ISO/FDIS 24390

ISO/FDIS 24390:2023(E)
ISO/TC 85/SC 5/WG 5
Secretariat: BSI
Date: 2023-05-0708-10
Nuclear energy — Nuclear fuel technology — — Methodologies for
radioactivity characterization of very low-level waste (VLLW)
generated by nuclear facilities
FDIS stage
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ISO/FDIS 24390:2023(E)
© ISO 20222023
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ISO/FDIS 24390:2023(E)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Waste acceptance criteria (WAC) for VLLW . 3
5 Radioactivity characterization . 4
5.1 Principle of radioactivity characterization of VLLW . 4
5.1.1 Requirements and limits . 4
5.1.2 Measurement methodology . 4
5.2 Process for radioactivity characterization of VLLW . 5
5.2.1 General . 5
5.2.2 Step 1: Investigation of waste characteristics . 6
5.2.3 Step 2: Surface scanning . 8
5.2.4 Step 3: Gamma activity measurement . 9
5.2.5 Step 4: Destructive analysis . 10
5.3 Decision thresholds . 10
5.4 Correlation of measurement methods . 12
5.5 Scaling factor method . 12
5.6 Radionuclide vector method . 13
6 Sampling . 13
6.1 General . 13
6.2 Homogeneous waste . 14
6.3 Heterogeneous waste . 14
6.4 Sampling uncertainty . 15
7 Data quality objectives (DQO) . 15
8 Quality assurance . 15
8.1 General . 15
8.2 Laboratory . 16
8.3 Measuring instruments . 16
8.4 Personnel . 16
8.5 Documentation and procedures . 16
Annex A (informative) Typical application of characterization procedure to three different waste streams
. 17
Bibliography . 19

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ISO/FDIS 24390:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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The committee responsible for thisThis document iswas prepared by Technical Committee ISO/TC 85,
Nuclear energy, nuclear technologies, and radiological protection, Subcommittee SC 5, Nuclear
installations, processes and technologies.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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ISO/FDIS 24390:2023(E)
Introduction
The activity concentration of very low-level waste (VLLW) is generally below a few becquerels per gram
(Bq/g), which is still greater than the allowable limits for clearance waste (often 10 times to 100 times
greater). It is generally accepted that due to the low levels of activity associated with this type of waste,
VLLW does not require a high level of containment and isolation, as is the case for low and intermediate
level wasteswaste.
To take full advantage of opportunities for directing waste to alternative waste management routes that
are more advantageous, the waste should be appropriately characterized and classified. Accurate waste
characterization is also crucial for the protection of people and the environment, given the lower levels
of isolation or containment barriers at VLLW disposal sites (generally in ordinary landfills). Additionally,
proper characterization may allow waste classification for reuse or recycling.
Although the process for radioactively characterizing wasteswaste as low-level waste (LLW,), VLLW and
Clearance,clearance generally follows common principles, it is appropriate to establish a specific
document to assist in identifying low-level wasteswaste against waste acceptance criteria on VLLW.
This document describes the methodologies and procedures for the identification of wasteswaste that
can be categorized as VLLW.
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ISO/FDIS 24390:2023(E)
Nuclear energy — Nuclear fuel technology — Methodologies for
radioactivity characterization of very low-level waste (VLLW)
generated by nuclear facilities
1 Scope
This document describes methodologies for radioactivity characterization of very low-level waste
(VLLW) generated from the operation or decommissioning of nuclear facilities. The purpose is to
differentiate VLLW from low-level radioactive solid waste and waste below clearance levels. The aim is
to effectively characterize and to demonstrate that it satisfies the criteria for VLLW.
This document focuses specifically on characterization methods of radioactive solid waste. Clearance and
exemption monitoring are not covered within this document. Additionally, the characterization of liquid
and gaseous wastes is also excluded from this document.
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 12749--3, Nuclear energy, nuclear technologies, and radiological protection — Vocabulary — Part 3:
Nuclear fuel cycle
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 21238:2007, Nuclear energy — Nuclear fuel technology — Scaling factor method to determine the
radioactivity of low- and intermediate-level radioactive waste packages generated at nuclear power plants
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12749-3, and the following
apply.
ISO and IEC maintain terminologicalterminology databases for use in standardization at the following
addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
3.1
very low-level waste
VLLW
radioactive waste that does not necessarily meet the criteria of exempt waste, but that does not need a
high level of containment and isolation and, therefore, is suitable for disposal in landfill type near surface
repositories with limited regulatory control.
suchcontrolNote 1 to entry: Such landfill type near surface repositories may also contain other hazardous
waste. Typical waste in this class includes soil and rubble with low levels of activity concentration.
Concentrations of longer-lived radionuclides in VLLW are generally very limited.
[SOURCE: IAEA Safety Glossary: 2022 Editionedition]
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ISO/FDIS 24390:2023(E)
3.2
waste acceptance criteria
WAC
quantitative or qualitative criteria specified for the waste form and waste package to be accepted by the
operator of a waste management facility.
[SOURCE: IAEA Safety Glossary: 2022 Editionedition, modified: “by the regulatory body, or specified by
an operator and approved by the regulatory body” deleted] — Definition revised.]
3.3
data quality objective
DQO
process used to establish performance or acceptance criteria, which serve as the basis for designing a
plan for collecting data of sufficient quality and quantity to support the goals of a study
[SOURCE: ISO 18557:2017, 3.8]
3.4
difficult-to-measure radionuclide
DTM radionuclide
radionuclide whose radioactivity is difficult to measure directly from the outside of the waste packages
by non-destructive assay means
[SOURCE: ISO 21238:2007, 2.1], modified — Examples removed.]
3.5
key radionuclide
gamma-emitting radionuclidesradionuclide whose radioactivity is correlated with that of difficult-to-
measure radionuclides (3.4(3.3)) and can be readily measured directly by non-destructive assay means
Note 1 to entry: Also called “easy-to-measure radionuclide” or “marker radionuclide”.
[SOURCE: ISO 21238:2007, 2.2], modified — Example removed.]
3.6
scaling factor
factor or parameter derived from the mathematical relationship used in calculating the radioactivity of
DTMdifficult-to-measure radionuclides (3.4(3.3)) from that of key radionuclide (3.5(3.4)) determined from
sampling and analysis data
[SOURCE: ISO 21238:2007, 2.3]
3.7
nuclide vector
fingerprint
used to infer and quantify the presence of other key nuclides.
Note 1 to entry: Applying correlation factors enables estimations of difficult-to-measure radionuclides
(3.4nuclides.).
Note 2 to entry: It is a method which involves measurements of easy to measurekey radionuclides (3.5) (usually
gamma emitters, e.g. 137Cs, 60Co) to quantify difficult-to-measure nuclides.
[SOURCE: ISO 18557:2017, 3.12]
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ISO/FDIS 24390:2023(E)
3.8
heterogeneous waste
radioactive waste that does not meet the definition of homogeneous waste (3.9(3.7),), including solid
components and mixtures of solid components
EXAMPLE: such as cartridge Cartridge filters, contaminated tools or instruments, etc.
[SOURCE: ISO 21238:2007, 2.13], modified — Part of definition used to create EXAMPLES.]
3.9
homogeneous waste
radioactive waste that shows an essentially uniform distribution of activity and physical contents
EXAMPLE : Flowable wastes such as concentrates, solidified liquids and spent resins, etc.
[SOURCE: ISO 21238:2007, 2.12], modified — EXAMPLES revised.]
3.10
destructive analysis
analytical techniques of radioactive and chemical materials using methods which involve the destruction
of a sample, e.g.for example chemical and radiochemical analysis, ICP-MS, or alpha spectrometry
[SOURCE: ISO 18557:2017, 3.9], modified — Definition revised.]
3.11
non-destructive analysis
NDA
analytical techniques that allow measurement of specific properties without physical destruction of the
media/ or item
Note 1 to entry: Generally used for in situ measurements.
[SOURCE: ISO 18557:2017, 3.20]
4 Waste acceptance criteria (WAC) for VLLW
Waste acceptance criteria (WAC) are quantitative or qualitative criteria, which state the conditions by
which waste can be accepted by the operator of facilities that process, store or dispose of VLLW.
WAC specify the radiological, mechanical, physical, chemical and biological characteristics of the waste
packages or unpackaged waste which may be accepted into the facility.
WAC are important because they:
— — ensure compliance with safety and environmental requirements,;
— — are designed to assist with the selection of appropriate processing and packaging options,;
— — prevent technological problems during processing,;
— — standardize waste management operations, and;
— — assureensure waste tracking.
WAC are developed so as to be relevant, concise, measurable, and verifiable, provide some flexibility, and
be appropriate to each waste stream. WAC ensure that the interfaces between all parties and facilities
associated with the management and disposal of VLLW are clearly understood.
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ISO/FDIS 24390:2023(E)
Waste characterization requirements are typically developed from disposal safety and/or performance
assessment, and the waste acceptance criteria for disposal are derived at the same time.
The radioactivity characterization of VLLW should address the requirements of WAC and should ensure
that the requirements for each stage associated with waste management and disposal are considered. It
is good practice to develop and justify the requirements of WAC using a robust process, such as data
quality objectives (DQO).
The requirements for radioactivity characterization should be interpreted and confirmed, and sufficient
characterization should be accomplished to satisfy the requirements of the WAC.
5 Radioactivity characterization
5.1 Principle of radioactivity characterization of VLLW
5.1.1 Requirements and limits
The main purpose of VLLW characterization is to identify conveniently this waste stream from higher-
level radioactive waste (LLW) and lower-level radioactive waste (clearance waste). The general
measurement methods used for the characterization of LLW and clearance waste are also applicable to
VLLW. The selection of characterization methods for VLLW mainly depends on:
— — Regulatoryregulatory requirements, including activity limits or dose rate limits, ;
— — Monitoringmonitoring purpose, such as reused, recycling or landfill disposal, and;
— — Limitationlimitations on measurement possibilities.
Activity limits can be expressed in terms of surfacessurface activity or mass activity, and they can be fixed
for a single radionuclide or a group of radionuclides (such ase.g. alpha emitters, beta-gamma emitters,
pure beta emitters).
The limits of dose rate of gamma emitters can be derived from activity limits and are recommended to
identify and determine the classification of radioactive waste (as seen in 5.3Clause 5.3). ).
5.1.2 Measurement methodology
During the radioactivity measurement of VLLW, the following considerations should be taken into
account:
— — Surfacesurface activity measurements, that ismeasurement, i.e. in -situ direct measurement,
consistconsists mostly of beta and gamma measurement;
— — Resultsresults of in -situ direct measurement can be used to show the preliminary distribution of
the contamination and confirm “active spots”;
— — Surfacesurface activity measurements can guide targeted sampling and associated gamma
spectrometry/ or destructive analysis;
— — Alphaalpha particle, soft beta radiation as well as low energy gamma radiation are difficult to be
detecteddetect by in -situ direct measurement;
— — Measurementmeasurement of alpha particles and soft beta radiation typically requirerequires
radio-chemical analysis or spectroscopic analysis to define the composition of mixed radionuclides;
— — Radioradio-chemical analysis of low activity requires sufficient samples to facilitate easier
measurement and to improve the accuracy of specific activities;
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ISO/FDIS 24390:2023(E)
— — Alphaalpha contamination measurement of VLLW from reactors is usually unnecessary unless
cladding ruptures have occurred;
— — Forfor mixtures of radionuclides, easily detectable radionuclides (such ase.g. Co-60) can be used
as contamination indicators to determine quickly the activity level of radioactive waste;
— — Selectionselection of measurement apparatus should be based on the activity limits and the
characteristics of the apparatus;
— — Thethe apparatus should be calibrated following the standards of various energies. The; the
detection thresholds and background levels should be regularly checked to prevent any major error;
— — Thethe uncertainty should be carefully considered during the sampling and measurement.
5.2 Process for radioactivity characterization of VLLW
5.2.1 General
The following four steps are considered good practice for identification of waste that may be categorized
as VLLW:
— — investigation of waste properties;
— — surface scanning, dose ratesrate assessment;
— — theoretical calculation and measurement of waste activity;
— — activity measurement by means of destructive analysis.
The process is shown in Figure 1Figure 1.
The steps in the process are further described in 5.2.25.2.1 to 5.2.55.2.4.
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ISO/FDIS 24390:2023(E)

Key
L activity limit, in Bq
A
L dose rate limit, in Gy/h
D
Figure 1 — VLLW radioactivity characterization process
5.2.2 Step 1: Investigation of waste characteristics
The objective of the first step is to obtain as much information as possible about the properties of the
waste. This involves collecting, reviewing and analysis of all available data, guided by the Data Quality
Objectives (DQO) process. The aim is to define the waste characterization objectives and associated
sampling and analysis strategy against the appropriate waste acceptance criteria. Typically, the following
information, at a minimum, should be considered based on the specific waste stream:
— — basic information, including:
— — the process by which the waste was generated;
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ISO/FDIS 24390:2023(E)
— — the location of the waste;
— — the radiological history of the waste;
— — the processing technology and storage conditions.;
— — physical properties, including:
— — waste volume /or weight;
— — quantity of waste;
— — form of waste;
— — material composition;
— — geometry;

Figure 1 — VLLW radioactivity characterization process
— — moisture content;
— — containment, if any.;
— — chemical properties, including:
— — pH;
— — oxidation reducibility;
— — thermal stability;
— — presence of organic and inorganic compounds.;
— — radiation characteristics, including:
— — distribution of radioactivity (i.e.,. homogenous or heterogeneous);
— — surface activity;
— — radionuclides present;
— — radionuclidesradionuclide concentrations;
— — surface dose rates, and;
— — results from any previous measurements or characterization campaigns, including
surface scans.
VLLW can be generated from various processes at nuclear facilities, and the radiation characteristics of
waste from different sources can vary significantly. The characteristics of the waste are likely to be
different from those of other radioactive sources, depending on the source of contamination.
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ISO/FDIS 24390:2023(E)
The radiation properties of waste generated from uranium enrichment, conversion and fuel fabrication
are relatively well-defined, simple and stable. The radioactive contamination in such waste is mainly
uranium and its daughter nuclides. Waste generated from nuclear power plants (NPPs) has relatively
clear and stable radiation properties, but it is more complex. These wastesThis waste could be
contaminated with alpha, beta and gamma-emitting radionuclides. A large number of different
radionuclides are generated as a result of fission, activation and decay. The radiation properties of VLLW
generated from reprocessing of spent fuel are very complex. Radiation sources in such waste include
fission and activation products.
The application example for the characterization process of the three different waste streams is
presented in Annex AAnnex A.
During the investigation of waste properties, the integrity and reliability of the waste characterization
information should be assessed and updated regularly. This information will be used to establish the
scaling factors or ratios between different radionuclides. Depending on the specific radionuclides present
in the waste, verification can also be achieved through destructive sampling analysis.
5.2.3 Step 2: Surface scanning
5.2.3.1 General
Surface scanning is typically performed using portable instruments to detect surface dose rates and
measure surface contamination. Portable instruments are commonly used for this purpose. During the
operation of these instruments, several factors should be considered, including the environmental
background level, instrument resolution, detection limit and range and alarm threshold should be
considered during operation of these instruments.
5.2.3.15.2.3.2 5.2.2.1 Surface dose rate detection
The surface dose rate detection is used to:
— — prevent unnecessary radiation exposure during radioactivity measurement,;
— — identify hot spots inside the waste,;
— — measure the surface dose rate as specified in 5.35.3 and determine the radioactivity level of waste
following Formula (1)Formula (1) and Formula (2)Formula (2). As shown in Figure 1Figure 1,, if the
measured result exceeds L or L , the radioactive waste cannot be classified as VLLW.
D A
The uncertainty of surface scanning results from the uncertainty in instrument calibration and the
measurement process. For the dose rate detector, the uncertainty of calibration includes:
— — the choice of primary or secondary standard instrument,;
— — the distance of the instrument from radiation source,;
— — the uniformity of the radiation beam,;
— — the variation of background dose rate, and;
— — variation of environmental conditions.
The uncertainty of dose rate detection includes:
— — variations of environmental conditions during detection (background, temperature, humidity,),);
— — the characteristics of apparatus (background, efficiency, detection limit, stability,), and );
— — method of measurement, including speed of probe’sprobe movement, distance to the surface of
contamination, and position of counts reading, etc.
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ISO/FDIS 24390:2023(E)
5.2.3.25.2.3.3 5.2.2.2 Surface contamination measurement
Before conditioning and treatment of radioactive waste, surface contamination measurement is usually
used to initially estimate the characteristics of radioactive contaminants. The purpose of surface
contamination measurement is to prevent unnecessary contamination during radioactivity measurement
and to decrease the radioactive level through decontamination.
The principles, wipe test method, and apparatus calibration of surface contamination measurement are
given in ISO 7503-1, ISO 7503-2, ISO 7503-3, respectively.
5.2.4 Step 3: Gamma Activityactivity measurement
Given the potential waste stream generators identified in 5.2.2above,, gamma activity measurement can
usually be achieved through direct measurement. The objectives of gamma measurement include:
— — obtain the γ spectra;
— — identify possible γ radionuclides in the waste;
— — identify easily measurable key radionuclides;
— — provide input for
...