ASTM C1455-14(2023)
(Test Method)Standard Test Method for Nondestructive Assay of Special Nuclear Material Holdup Using Gamma-Ray Spectroscopic Methods
Standard Test Method for Nondestructive Assay of Special Nuclear Material Holdup Using Gamma-Ray Spectroscopic Methods
SIGNIFICANCE AND USE
5.1 Measurement results from this test method assists in demonstrating regulatory compliance in such areas as safeguards SNM inventory control, criticality control, waste disposal, and decontamination and decommissioning (D&D). This test method can apply to the measurement of holdup in process equipment or discrete items whose gamma-ray absorption properties may be measured or estimated. This method may be adequate to accurately measure items with complex distributions of radioactive and attenuating material, however, the results are subject to larger measurement uncertainties than measurements of less complex distributions of radioactive material.
5.2 Scan—A scan is used to provide a qualitative indication of the extent, location, and the relative quantity of holdup. It can be used to plan or supplement the quantitative measurements.
5.3 Nuclide Mapping—Nuclide mapping measures the relative isotopic composition of the holdup at specific locations. It can also be used to detect the presence of radionuclides that emit radiation which could interfere with the assay. Nuclide mapping is best performed using a high resolution detector (such as HPGe) for best nuclide and interference detection. If the holdup is not isotopically homogeneous at the measurement location, that measured isotopic composition will not be a reliable estimate of the bulk isotopic composition.
5.4 Quantitative Measurements—These measurements result in quantification of the mass of the measured nuclides in the holdup. They include all the corrections, such as attenuation, and descriptive information, such as isotopic composition, that are available
5.4.1 High quality results require detailed knowledge of radiation sources and detectors, transmission of radiation, calibration, facility operations and error analysis. Judicious use of subject matter experts is required (Guide C1490).
5.5 Holdup Monitoring—Periodic re-measurement of holdup at a defined point using the same technique and a...
SCOPE
1.1 This test method describes gamma-ray methods used to nondestructively measure the quantity of 235U or 239Pu present as holdup in nuclear facilities. Holdup may occur in any facility where nuclear material is processed, in process equipment, in exhaust ventilation systems and in building walls and floors.
1.2 This test method includes information useful for management, planning, selection of equipment, consideration of interferences, measurement program definition, and the utilization of resources (1, 2, 3, 4) .2
1.3 The measurement of nuclear material hold up in process equipment requires a scientific knowledge of radiation sources and detectors, transmission of radiation, calibration, facility operations and uncertainty analysis. It is subject to the constraints of the facility, management, budget, and schedule; plus health and safety requirements. The measurement process includes defining measurement uncertainties and is sensitive to the form and distribution of the material, various backgrounds, and interferences. The work includes investigation of material distributions within a facility, which could include potentially large holdup surface areas. Nuclear material held up in pipes, ductwork, gloveboxes, and heavy equipment, is usually distributed in a diffuse and irregular manner. It is difficult to define the measurement geometry, to identify the form of the material, and to measure it without interference from adjacent sources of radiation.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles...
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1455 − 14 (Reapproved 2023)
Standard Test Method for
Nondestructive Assay of Special Nuclear Material Holdup
Using Gamma-Ray Spectroscopic Methods
This standard is issued under the fixed designation C1455; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This test method describes gamma-ray methods used to
235 239 mendations issued by the World Trade Organization Technical
nondestructively measure the quantity of Uor Pu present
Barriers to Trade (TBT) Committee.
as holdup in nuclear facilities. Holdup may occur in any
facility where nuclear material is processed, in process
2. Referenced Documents
equipment,inexhaustventilationsystemsandinbuildingwalls
2.1 ASTM Standards:
and floors.
C1490 GuidefortheSelection,TrainingandQualificationof
1.2 This test method includes information useful for
Nondestructive Assay (NDA) Personnel
management, planning, selection of equipment, consideration
C1592 Guide for Making Quality Nondestructive Assay
of interferences, measurement program definition, and the
Measurements
utilization of resources (1, 2, 3, 4).
C1673 Terminology of C26.10 NondestructiveAssay Meth-
1.3 The measurement of nuclear material hold up in process
ods
equipment requires a scientific knowledge of radiation sources
2.2 ANSI Standards:
and detectors, transmission of radiation, calibration, facility
ANSI N15.36 Measurement Control Program—
operations and uncertainty analysis. It is subject to the con-
Nondestructive Assay Measurement Control and Assur-
straints of the facility, management, budget, and schedule; plus
ance Systems
health and safety requirements. The measurement process
ANSI N15.56 Nondestructive Assay Measurements of
includes defining measurement uncertainties and is sensitive to
Nuclear Material Holdup: General Provisions
the form and distribution of the material, various backgrounds,
2.3 U.S. Nuclear Regulatory Commission Regulatory
and interferences. The work includes investigation of material
Guides:
distributions within a facility, which could include potentially
Regulatory Guide 5.23, In SituAssay of Plutonium Residual
large holdup surface areas. Nuclear material held up in pipes,
Holdup
ductwork, gloveboxes, and heavy equipment, is usually dis-
tributedinadiffuseandirregularmanner.Itisdifficulttodefine
3. Terminology
themeasurementgeometry,toidentifytheformofthematerial,
andtomeasureitwithoutinterferencefromadjacentsourcesof 3.1 Refer to Terminology C1673 for definitions used in this
radiation. test method.
1.4 This standard does not purport to address all of the
4. Summary of Test Method
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.1 Introduction—Holdup measurements range from the
priate safety, health, and environmental practices and deter-
solitary assay of a single item or routine measurement of a
mine the applicability of regulatory limitations prior to use. piece of equipment, to an extensive campaign of determining
1.5 This international standard was developed in accor-
the total SNM in-process inventory for a processing plant.
dance with internationally recognized principles on standard-
1 3
This test method is under the jurisdiction ofASTM Committee C26 on Nuclear For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Fuel Cycle and is the direct responsibility of Subcommittee C26.10 on Non contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Destructive Assay. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Jan. 1, 2023. Published January 2023. Originally the ASTM website.
ɛ1
approved in 2000. Last previous edition approved in 2014 as C1455 – 14 . DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/C1455-14R23. 4th Floor, New York, NY 10036, http://www.ansi.org.
The boldface numbers in parentheses refer to the list of references at the end of Available from the U.S. Nuclear Regulatory Commission, Washington, DC,
this standard. 20555.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1455 − 14 (2023)
Holdup measurements differ from other nondestructive mea- 4.5 Calibration—Calibration and initialization of measure-
surement methods in that the assays are performed in situ on ment control should be completed before measurements of
unknowns. Calibration requires traceable standards.
equipment or items instead of on multiple items with similar
characteristics measured in a specialized, isolated room. Often
4.6 Measurements—Perform measurements and measure-
the chemical form and geometric distribution of the SNM are
ment control as detailed in the measurement plan or procedure.
not well known. These challenges require unique preparation
4.7 Evaluation of Measurement Data—As appropriate, cor-
for every measurement to obtain a quality result. Unknown
rections to measured count rates are made for Compton
measurement parameters can lead to large measurement uncer-
background, gamma-ray attenuation effects by equipment
tainties.
walls, and measured area background. As appropriate, correc-
tions are made for finite geometry effects in the assay model
4.2 Definition of Requirements—Definition of the holdup
and for self-attenuation. These corrections are applied in the
measurement requirements should include, as a minimum, the
calculation of the assay value. Measurement uncertainties are
measurement objectives (that is, criticality control, SNM
established based on factors affecting the assay.
accountability, safety, or combinations thereof); the desired
4.7.1 Converting measurement data to estimates of the
measurement sensitivity, measurement uncertainty, and avail-
quantity of nuclear material holdup requires careful evaluation
able resources (schedule, funds, and subject matter experts).
of the measurement parameters against calibration assump-
The customer, the measurement organization, and appropriate
tions. Depending on the calibration and measurement methods
regulatoryauthoritiesshouldagreeontheholdupmeasurement
used, corrections may be necessary for geometric effects
requirements before holdup measurements commence.
(differences between holdup measurement and calibration
geometries), gamma-ray attenuation effects, background, and
4.3 Information Gathering and Initial Evaluation—
interferences. Measurement uncertainties (random and system-
Information must be gathered concerning the item or items to
atic) are estimated based on uncertainties in assay parameters,
beassayedandaninitialevaluationshouldbemadeofthelevel
for example, holdup distribution, attenuation effects, measured
ofeffortneededtomeettheholdupmeasurementrequirements.
count rates and finite source corrections.
Preliminary measurements may be needed to assess the
4.7.2 Resultsshouldbeevaluatedagainstpreviousresults,if
problem, to define the location and extent of the holdup, to
available. If a discrepancy is evident, an evaluation should be
determinetheSNMisotopiccompositionorenrichment,andto
made. Additional measurements with subsequent evaluation
identify potential interfering radionuclides. Factors to be con-
may be required.
sidered include the geometric configuration of the item or
process equipment to be assayed, location of the equipment in 4.8 Documentation—Measurement documentation should
the facility, attenuating materials, sources of background or includetheplansandprocedures,adescriptionofmeasurement
interferences,facilityprocessingstatus,radiologicalandindus- parameters considered important to the calibration and mea-
surement location, the measurement techniques used, the raw
trial safety considerations, plus the personnel and equipment
data, the assumptions and correction factors used in the
needed to complete the assay. Sources of information may
analysis, the results with estimated uncertainty, and compari-
include a visual survey, engineering drawings, process
son to other measurement techniques (when available).
knowledge, process operators, and prior assay documentation.
4.3.1 Subsequent measurement campaigns may well pro-
5. Significance and Use
ceed more rapidly when the objective is to quantify changes
5.1 Measurement results from this test method assists in
from the previous measurement campaigns and no changes
demonstrating regulatory compliance in such areas as safe-
have been made to the process.
guards SNM inventory control, criticality control, waste
4.3.2 Shutdown facilities are frequently measured once-
disposal, and decontamination and decommissioning (D&D).
through carefully and completely. Any subsequent measure-
This test method can apply to the measurement of holdup in
ment campaigns may only verify a subset of the data set.
process equipment or discrete items whose gamma-ray absorp-
tion properties may be measured or estimated. This method
4.4 Task Design and Preparation—The initial evaluation
may be adequate to accurately measure items with complex
provides a basis for choosing the quantitative method, assay
distributions of radioactive and attenuating material, however,
model, and subsequently leads to determination of the detec-
the results are subject to larger measurement uncertainties than
tion system and calibration method to be used. Appropriate
measurements of less complex distributions of radioactive
standards and support equipment are developed or assembled
material.
for the specific measurement technique. A measurement plan
5.2 Scan—Ascan is used to provide a qualitative indication
should be developed. The plan will include measurement
of the extent, location, and the relative quantity of holdup. It
locations and geometries or guidance for their selection. The
can be used to plan or supplement the quantitative measure-
measurementplanwillreferenceoverallmeasurementprogram
ments.
documents governing required documentation, operating
procedures, background measurement methods and
5.3 Nuclide Mapping—Nuclide mapping measures the rela-
frequencies, plus training, quality and measurement control
tive isotopic composition of the holdup at specific locations. It
requirements. Any needed additional procedures should be
can also be used to detect the presence of radionuclides that
developed, documented, and approved. emit radiation which could interfere with the assay. Nuclide
C1455 − 14 (2023)
mapping is best performed using a high resolution detector surements using the 330-414 keV region also have age-
(such as HPGe) for best nuclide and interference detection. If dependent interferences from Am in that region which are
theholdupisnotisotopicallyhomogeneousatthemeasurement considerable for low resolution detectors.
location, that measured isotopic composition will not be a
reliable estimate of the bulk isotopic composition.
7. Apparatus
5.4 Quantitative Measurements—These measurements re- 7.1 General guidelines for selection of detectors and
sult in quantification of the mass of the measured nuclides in
signal-processing electronics are discussed below (see Guide
the holdup. They include all the corrections, such as C1592).
attenuation, and descriptive information, such as isotopic
7.2 The apparatus chosen for measurements must have
composition, that are available
capabilities appropriate to the requirements of the measure-
5.4.1 High quality results require detailed knowledge of
ment being performed. For example, in order to locate holdup
radiation sources and detectors, transmission of radiation,
by scanning, a simple system based on a gross gamma-ray
calibration,facilityoperationsanderroranalysis.Judicioususe
detector, for example, a Geiger-Mueller tube, is adequate for
of subject matter experts is required (Guide C1490).
some applications. Other applications, where severe interfer-
5.5 Holdup Monitoring—Periodic re-measurement of
encesorabsorptionareexpected,mayrequireahigh-resolution
holdup at a defined point using the same technique and
Ge-detector-based system. The quality of assay results may be
assumptions can be used to detect or track relative changes in
dependent upon the capabilities of equipment. The user will
the holdup quantity at that point over time. Either a qualitative
choose a suitable trade-off between detector energy resolution,
or a quantitative method can be used.
detection efficiency, equipment complexity and equipment
portability (weight, size and number of pieces).
5.6 Indirect Measurements—Quantity of a radionuclide can
7.2.1 Scan Measurement Systems—The minimum gross
bedeterminedbymeasurementofadaughterradionuclideorof
gamma-ray detection system may be a survey meter. If limited
a second radionuclide if the ratio of the abundances of the two
energy discrimination is satisfactory, a low resolution scintil-
radionuclides is known and secular equilibrium (Terminology
lation detector may be used, such as a bismuth germanate
C1673) is present. This can be used when there are interfering
(BGO) or NaI detector. The detection system may be as
gamma rays or when the parent radionuclide does not have a
complex as a Ge-detector with a complete MCA system.
sufficiently strong gamma-ray signal to be readily measured. If
7.2.2 Low Resolution Measurement Systems—Quantitative
thismethodisemployed,itisimportantthattheratioofthetwo
holdup measurement may be performed using instrumentation
radionuclides be known with sufficient accuracy to meet assay
that offers portability and simplicity of operation. The instru-
uncertainty goals.
mentation typically includes a low resolution scintillation
5.7 Mathematical Modeling—Modeling is an aid in the
detector with spectroscopy electronics in a portable package.
evaluation of complex measurement situations. Measurement
Stabilization may be necessary to compensate for electronic
data are used with a mathematical model describing the
drift. At least two energy windows are recommended: one for
physical location of equipment and materials. (3, 5, 6, 7, 8).
the peak or multiplet of interest, and another to determine the
Compton continuum (background) under the peak.
6. Interferences
7.2.3 Medium Resolution Measurement Systems—CdZnTe
or
...
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