ASTM C1807-15(2023)
(Guide)Standard Guide for Nondestructive Assay of Special Nuclear Material (SNM) Holdup Using Passive Neutron Measurement Methods
Standard Guide for Nondestructive Assay of Special Nuclear Material (SNM) Holdup Using Passive Neutron Measurement Methods
SIGNIFICANCE AND USE
5.1 This guide assists in satisfying requirements in such areas as safeguards, SNM inventory control, nuclear criticality safety, waste disposal, and decontamination and decommissioning (D&D). This guide can apply to the measurement of holdup in process equipment or discrete items whose neutron production properties may be measured or estimated. These methods may meet target accuracy for items with complex distributions of SNM in the presence of moderators, absorbers, and neutron poisons; however, the results are subject to larger measurement uncertainties than measurements of less complex items.
5.2 Quantitative Measurements—These measurements result in quantification of the mass of SNM in the holdup. They include all the corrections and descriptive information, such as isotopic composition, that are available.
5.2.1 High-quality results require detailed knowledge of radiation sources and detectors, radiation transport, calibration, facility operations, and error analysis. Consultation with qualified NDA personnel is recommended (Guide C1490).
5.2.2 Holdup estimates for a single piece of process equipment or piping often include some compilation of multiple measurements. The holdup estimate must appropriately combine the results of each individual measurement. In addition, uncertainty estimates for each individual measurement must be made and appropriately combined.
5.3 Scan—Radiation scanning, typically gamma, may be used to provide a qualitative description of the extent, location, and the relative quantity of holdup. It can be used to plan or supplement the quantitative neutron measurements. Other indicators (for example, visual) may also indicate a need for a holdup measurement.
5.4 Nuclide Mapping—To appropriately interpret the neutron data, the specific neutron yield is needed. Isotopic measurements to determine the relative isotopic composition of the holdup at specific locations may be required, depending on the facility.
5.5 Spot Check an...
SCOPE
1.1 This guide describes passive neutron measurement methods used to nondestructively estimate the amount of neutron-emitting special nuclear material compounds remaining as holdup in nuclear facilities. Holdup occurs in all facilities in which nuclear material is processed. Material may exist, for example, in process equipment, in exhaust ventilation systems, and in building walls and floors.
1.1.1 The most frequent uses of passive neutron holdup techniques are for the measurement of uranium or plutonium deposits in processing facilities.
1.2 This guide includes information useful for management, planning, selection of equipment, consideration of interferences, measurement program definition, and the utilization of resources.
1.3 Counting modes include both singles (totals) or gross counting and neutron coincidence techniques.
1.3.1 Neutron holdup measurements of uranium are typically performed on neutrons emitted during (α, n) reactions and spontaneous fission using singles (totals) or gross counting. While the method does not preclude measurement using coincidence or multiplicity counting for uranium, measurement efficiency is generally not sufficient to permit assays in reasonable counting times.
1.3.2 For measurement of plutonium in gloveboxes, installed measurement equipment may provide sufficient efficiency for performing counting using neutron coincidence techniques in reasonable counting times.
1.4 The measurement of nuclear material holdup in process equipment requires a scientific knowledge of radiation sources and detectors, radiation transport, modeling methods, calibration, facility operations, and uncertainty analysis. It is subject to the constraints of the facility, management, budget, and schedule, plus health and safety requirements, as well as the laws of physics. This guide does not purport to instruct the NDA practitioner on these principles.
1.5 The measurement process includes...
General Information
Relations
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: C1807 − 15 (Reapproved 2023)
Standard Guide for
Nondestructive Assay of Special Nuclear Material (SNM)
Holdup Using Passive Neutron Measurement Methods
This standard is issued under the fixed designation C1807; 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 the laws of physics. This guide does not purport to instruct the
NDA practitioner on these principles.
1.1 This guide describes passive neutron measurement
methods used to nondestructively estimate the amount of 1.5 The measurement process includes defining measure-
ment uncertainties and is sensitive to the chemical
neutron-emitting special nuclear material compounds remain-
ing as holdup in nuclear facilities. Holdup occurs in all composition, isotopic composition, distribution of the material,
various backgrounds, and interferences. The work includes
facilities in which nuclear material is processed. Material may
exist, for example, in process equipment, in exhaust ventilation investigation of material distributions within a facility, which
could include potentially large holdup surface areas. Nuclear
systems, and in building walls and floors.
material held up in pipes, ductwork, gloveboxes, and heavy
1.1.1 The most frequent uses of passive neutron holdup
equipment is usually distributed in a diffuse and irregular
techniques are for the measurement of uranium or plutonium
manner. It is difficult to define the measurement geometry,
deposits in processing facilities.
identify the form of the material, and measure it.
1.2 This guide includes information useful for management,
1.6 Units—The values stated in SI units are to be regarded
planning, selection of equipment, consideration of
as the standard. No other units of measurement are included in
interferences, measurement program definition, and the utili-
this standard.
zation of resources.
1.7 This standard does not purport to address all of the
1.3 Counting modes include both singles (totals) or gross
safety concerns, if any, associated with its use. It is the
counting and neutron coincidence techniques.
responsibility of the user of this standard to establish appro-
1.3.1 Neutron holdup measurements of uranium are typi-
priate safety, health, and environmental practices and deter-
cally performed on neutrons emitted during (α, n) reactions and
mine the applicability of regulatory limitations prior to use.
spontaneous fission using singles (totals) or gross counting.
1.8 This international standard was developed in accor-
While the method does not preclude measurement using
dance with internationally recognized principles on standard-
coincidence or multiplicity counting for uranium, measurement
ization established in the Decision on Principles for the
efficiency is generally not sufficient to permit assays in
Development of International Standards, Guides and Recom-
reasonable counting times.
mendations issued by the World Trade Organization Technical
1.3.2 For measurement of plutonium in gloveboxes, in-
Barriers to Trade (TBT) Committee.
stalled measurement equipment may provide sufficient effi-
ciency for performing counting using neutron coincidence
2. Referenced Documents
techniques in reasonable counting times.
2.1 ASTM Standards:
1.4 The measurement of nuclear material holdup in process
C1009 Guide for Establishing and Maintaining a Quality
equipment requires a scientific knowledge of radiation sources
Assurance Program for Analytical Laboratories Within the
and detectors, radiation transport, modeling methods,
Nuclear Industry
calibration, facility operations, and uncertainty analysis. It is
C1455 Test Method for Nondestructive Assay of Special
subject to the constraints of the facility, management, budget,
Nuclear Material Holdup Using Gamma-Ray Spectro-
and schedule, plus health and safety requirements, as well as
scopic Methods
C1490 Guide for the Selection, Training and Qualification of
Nondestructive Assay (NDA) Personnel
This guide is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel
Cycle and is the direct responsibility of Subcommittee C26.10 on Non Destructive
Assay. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2023. Published December 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2015. Last previous edition approved in 2015 as C1807 – 15. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1807-15R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1807 − 15 (2023)
C1592/C1592M Guide for Making Quality Nondestructive methods (for example, sampling and X-ray fluorescence to
Assay Measurements determine chemical composition and high-resolution gamma-
C1673 Terminology of C26.10 Nondestructive Assay Meth- ray spectroscopy to determine isotopic composition). Both the
ods chemical and isotopic distribution have significant effects on
specific neutron yield.
2.2 NRC Standard:
NRC Regulatory Guide 5.23 In-Situ Assay of Plutonium
4.4 Definition of Requirements—Definition of the holdup
Residual Holdup
measurement requirements should include, as a minimum, the
2.3 ANSI Standard:
measurement objectives (that is, nuclear criticality safety,
ANSI N15.20 Guide to Calibrating Nondestructive Assay
special nuclear material (SNM) accountability, radiological
Systems
safety, or combinations thereof); time and resource constraints;
the desired measurement sensitivity, accuracy, and uncertainty;
3. Terminology
and available resources (schedule, funds, and subject matter
3.1 Definitions—Refer to Terminology C1673 for defini-
experts). Specific data quality objectives should be provided
tions used in this guide.
when available.
4.5 Information Gathering and Initial Evaluation—
4. Summary of Guide
Information shall be gathered concerning the item or items to
4.1 Introduction—Holdup measurements using neutron
be assayed, and an initial evaluation should be made of the
methods typically measure the (α, n) or spontaneous fission
measurement techniques and level of effort needed to meet the
production of neutrons, or both. Neutrons generated in items
holdup measurement requirements. Preliminary radiation mea-
that do not include significant masses of neutron moderators,
surements may be needed to define the location and extent of
such as hydrogenous materials, typically have an escape
the holdup. Additional information should be collected prior to
fraction of nearly one. The isotopic distribution and, for (α, n)
commencement of measurements. This information includes,
production, the chemical composition of the measured material
but is not limited to, the geometric configuration of the item or
affect assay results and shall be determined by process knowl-
process equipment to be assayed, location of the equipment in
edge or an alternative measurement technique. Ref (1) pro-
the facility, the presence of neutron moderators and absorbers,
vides an example of a holdup campaign using neutron mea-
neutron leakage multiplication, factors affecting specific neu-
surements.
tron yield, sources of background or interferences, facility
4.2 Choice of Measurement Method—Passive neutron mea-
processing status, radiological and industrial safety
surement methods are typically used for holdup when other considerations, plus the personnel and equipment needed to
methods of measurement (for example, gamma-ray assay) are
complete the assay. Sources of information may include a
not practical or would produce large biases. In some cases, visual survey, engineering drawings, process knowledge, pro-
neutron measurements are performed in conjunction with
cess operators, results of sampling and wet chemical analysis,
gamma-ray measurements for defense in depth or to obtain and prior assay documentation.
isotopic information, or both. Neutron measurement instru-
4.6 Measurement Plan—A measurement plan shall be de-
mentation is typically heavier, more difficult to shield, and has
veloped. The initial evaluation provides a basis for choosing
more difficult data interpretation than other NDA measurement
the quantitative method and assay model and, subsequently,
methods. Neutrons, though, are very penetrating and less
leads to the determination of the detection system and calibra-
influenced by lumps than gamma rays, and the instrumentation
tion method to be used. Appropriate reference materials and
has a very stable response. Examples of when neutron mea-
support equipment are developed or assembled for the specific
surements are preferred include containers that severely attenu-
measurement technique. The plan will include measurement
ate gamma rays of interest for the nuclides measured or when
locations and geometries or guidance for their selection. In the
sufficient nuclear material is present that self-attenuation of
plan, required documentation; operating procedures; back-
gamma rays of interest is severe (see Test Method C1455 and
ground measurement methods and frequencies; plus training,
Guide C1592/C1592M).
quality, and measurement control requirements (Guide C1009)
4.3 Specific Neutron Yield—The number of neutrons gener-
are typically outlined. Necessary procedures, including those
ated per unit time per unit mass of the nuclide(s) of interest is
for measurement control, shall be developed, documented, and
an important parameter that is affected by conditions (for
approved.
example, chemical composition and isotopic distribution) not
4.7 Calibration—Calibration and initialization of measure-
detectable by passive neutron holdup measurement methods.
ment control is completed before measurements of unknowns.
Information used to estimate specific neutron yield shall be
Calibration requires reference materials traceable to a National
determined using process knowledge or alternate analysis
Measurement Institute to establish detection efficiency and
modeling detector response to neutron sources. If modeling is
used for calibration (for example, Monte Carlo n-Partical
Available from U. S. Nuclear Regulatory Commission (NRC), One White Flint
North, 11555 Rockville Pk., Rockville, MD 20852-2738, http://www.nrc.gov.
(MCNP) modeling), detailed specifications for the detector
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
package will be required. If modeling is used, validation of the
4th Floor, New York, NY 10036, http://www.ansi.org.
calibration shall include validation of each model developed.
The boldface numbers in parentheses refer to a list of references at the end of
this standard. Familiarity with the facility on which assays will be performed
C1807 − 15 (2023)
is required to ensure that calibration is sufficiently robust to of the measurement parameters against calibration and model-
encompass all reasonable measurement situations. ing assumptions. Depending on the calibration, models, and
252 252
4.7.1 Calibration Using Cf— Cf is commonly used for measurement methods used, corrections may be necessary for
calibrating neutron detectors. Cf is convenient in that it geometric effects (differences between holdup measurement
provides a point source of neutron emissions with a strong and calibration geometries); neutron moderators, absorbers, or
signal so that calibrations can be completed using relatively poisons; scattering from nearby process equipment; the influ-
short measurement times. Corrections for the difference in ence (scattering and shielding) of and holdup in nearby process
detection efficiency between neutrons from Cf and neutrons equipment that is in the detector field of view; background; and
from assayed items may be significant because of the differ- interferences. Measurement uncertainties (random and item-
ence in average energy from the two sources. For example, the specific bias) are estimated based on uncertainties in assay
average energy of neutrons from Cf is 2.14 MeV and the parameters. A comprehensive total measurement uncertainty
average energy of neutrons from holdup is 1.2 MeV for (α, n) analysis must accompany every measurement result.
with Fluorine as a target and an alpha energy of 5.2 MeV (2). 4.9.2 Results should be evaluated against previous results or
An additional issue is that Cf standards are typically clean-out data, if either are available. This evaluation provides
certified for total neutron activity, and isotopes present in the a cross-check between measurement techniques. The results of
this evaluation can be used to provide feedback to measure-
standards produce an increasing number of neutrons as the
mass of Cf decreases relative to the mass of longer-lived ment personnel, to refine the measurement and analysis
techniques, and to evaluate the measurement uncertainty
isotopes as time passes. As the time since separation of the
Cf increases, this may become a significant source of bias against estimates. If a discrepancy is evident, an evaluation
should be made. Modeling errors or other sources of bias can
unless appropriate corrections are made.
4.7.2 Calibration Using Surrogate Materials—Surrogate be identified using this technique. Additional measurements
with subsequent evaluation may be required. This can be used
materials, typically created using the same materials that will
be subsequently measured, may also be used for calibration, as a step in a phased approach.
4.9.3 If practical, measurements should be made of clean
provided sufficient characterization is performed to establish
traceability. These sources typically produce fewer neutrons process equipment or, ideally, a plant that has not yet had
nuclear material introduced. This provides a baseline for future
per unit time than Cf and require longer measurement times
for equivalent calibration uncertainty. In addition, surrogate measurement of holdup.
materials are typically significantly larger than point sources,
4.10 Documentation—Measurement documentation should
which may complicate the process of evaluating calibration
include the plans and procedures, a description of measurement
data. Calibration using surrogate materials reduces the number
parameters considered important to the calibration and for each
of corrections (for ex
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.