ASTM C1592-04
(Guide)Standard Guide for Nondestructive Assay Measurements
Standard Guide for Nondestructive Assay Measurements
SCOPE
1.1 This guide is a compendium of Good Practices for performing measurements of radioactive material using nondestructive assay (NDA) instruments. The primary purpose of the guide is to assist its users in arriving at quality NDA results, that is, results that satisfy the end users needs. This is accomplished by providing an acceptable and uniform basis for the collection, analysis, comparison, and application of data. The recommendations are not compulsory or pre requisites to achieving quality NDA measurements, but are considered contributory in most areas.
1.2 This guide applies to the use of NDA instrumentation for the measurement of nuclear materials by the observation of spontaneous or stimulated nuclear radiations, including photons, neutrons, or the flow of heat. Recommended calibration, operating, and assurance methods represent guiding principles based on current NDA technology. The diversity of industry-wide nuclear materials measurement applications and instrumentation precludes discussion of specific measurement situations. As a result, compliance with practices recommended in this guide must be based on a thorough understanding of contributing variables and performance requirements of the specific measurement application.
1.3 Selection of the best instrument for a given measurement application and advice on the use of this instrument must be provided by a qualified NDA professional following guidance provided in Guide C 1490. This guide is to be used as a reference, and to supplement the critical thinking, professional skill, expert judgement, and experimental test and verification needed to ensure that the instrumentation and methods have been properly implemented.
1.4 The intended audience for this guide includes but is not limited to Management, Auditor Support, NDA Qualified Instrument Operators, NDA Technical Specialists, and NDA Professionals.
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Designation:C1592–04
Standard Guide for
Nondestructive Assay Measurements
This standard is issued under the fixed designation C 1592; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This guide is a compendium of Good Practices for 2.1 ASTM Standards:
performing measurements of radioactive material using non- C 859 Terminology Relating to Nuclear Materials
destructive assay (NDA) instruments. The primary purpose of C 1030 Test Method for Determination of Plutonium Isoto-
theguideistoassistitsusersinarrivingatqualityNDAresults, pic Composition by Gamma-Ray Spectrometry
that is, results that satisfy the end user’s needs. This is C 1133 Test Method for Nondestructive Assay of Special
accomplishedbyprovidinganacceptableanduniformbasisfor Nuclear Material in Low-Density Scrap and Waste by
the collection, analysis, comparison, and application of data. Segmented Passive Gamma-Ray Scanning
The recommendations are not compulsory or pre requisites to C 1207 TestMethodforNondestructiveAssayofPlutonium
achieving quality NDA measurements, but are considered in Scrap and Waste by Passive Neutron Coincidence
contributory in most areas. Counting
1.2 This guide applies to the use of NDA instrumentation C 1215 Guide for Preparing and Interpreting Precision and
for the measurement of nuclear materials by the observation of Bias Statements in Test Method Standards used in the
spontaneous or stimulated nuclear radiations, including pho- Nuclear Industry
tons, neutrons, or the flow of heat. Recommended calibration, C 1221 Test Method for NondestructiveAnalysis of Special
operating, and assurance methods represent guiding principles Nuclear Materials in homogeneous Solutions by Gamma-
based on current NDA technology. The diversity of industry- Ray Spectrometry
wide nuclear materials measurement applications and instru- C 1254 Test Method for Determination of Uranium in
mentation precludes discussion of specific measurement situ- Mineral Acids by X-ray Fluorescence
ations.As a result, compliance with practices recommended in C 1268 Test Method for Quantitative Determination of
this guide must be based on a thorough understanding of Americium 241 in Plutonium by Gamma-Ray Spectrom-
contributing variables and performance requirements of the etry
specific measurement application. C 1316 Test Method for Nondestructive Assay of Nuclear
1.3 Selection of the best instrument for a given measure- Material in Scrap and Waste by Passive-Active Neutron
ment application and advice on the use of this instrument must Counting Using a Cf Shuffler
be provided by a qualified NDA professional following guid- C 1455 Guide for NondestructiveAssay of Special Nuclear
ance provided in Guide C 1490. This guide is to be used as a Material Holdup Using Gamma-Ray Spectroscopic Meth-
reference, and to supplement the critical thinking, professional ods
skill, expert judgement, and experimental test and verification C 1458 Test Method for Nondestructive Assay of Pluto-
needed to ensure that the instrumentation and methods have nium, Tritium and Am by Calorimetric Assay
been properly implemented. C 1490 Guide for the Selection, Training and Qualification
1.4 The intended audience for this guide includes but is not of Nondestructive Assay (NDA) Personnel
limited to Management, Auditor Support, NDA Qualified C 1493 Test Method for Non Destructive Assay of Nuclear
Instrument Operators, NDA Technical Specialists, and NDA MaterialinWastebyPassiveandActiveNeutronCounting
Professionals. Using a Differential Die Away System
1 2
This guide is under the jurisdiction ofASTM Committee C26 on Nuclear Fuel For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Cycle and is the direct responsibility of Subcommittee C26.10 on Non Destructive contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Assay. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Feb. 1, 2004. Published March 2004. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1592–04
C 1514 Test Method for Measurement of U Fraction 3.2.14 confidence interval—the range of values, calculated
Using the Enrichment Meter Principle from an estimate of the mean and standard deviation, which is
expected to include the population mean with a stated level of
3. Terminology confidence.
3.2.15 control chart—a graphical plot of test results with
3.1 Definitions presented here are confined to those terms
respect to time or sequence of measurement together with
not defined in common nuclear materials glossaries/references
limits in which they are expected to lie when the system is in
or whose use is specific to this application. The use of
a state of statistical control.
statistical terms is consistent with the definitions in American
3.2.16 control limits—the limits shown on a control chart
National Standard Statistical Terminology and Notation for
beyond which it is highly improbable that a point could lie
Nuclear Materials Management, N15.5-1972. Some of those
while the system remains in a state of statistical control.
definitions are repeated here for convenience to the reader.
3.2.17 corrections—techniques that are part of the data
3.2 Definitions:
analysis or method, which compensate for the effects of
3.2.1 (a n) reactions—(a, n)reactionsoccurwhenenergetic
variables that interfere with the measurement and degrade
alpha particles collide with low atomic number nuclei, such as
accuracy. These corrections account for such things as matrix
O, F, or Mg, producing single neutrons.
material, lumps, heterogeneity, dead time, and background.
240 240
3.2.2 Pu effective mass—m is the mass of Pu that
eff
3.2.18 dead time—the period following the detection of an
would produce the same coincident, or total, neutron response
event during which the system cannot register a subsequent
in the instrument as the assay item, all other factors remaining
event. Dead time is usually expressed as a percentage of
unchanged. It is correlated to the quantity of even mass
elapsed time.
isotopes of plutonium in the assay item.
3.2.19 differential die away technique (DDT)—an NDA
3.2.3 absorber foils—thinmetalfoilsthatareusedtoreduce
technique for characterizing the prompt neutrons from fission-
thecontributionoflow-energygammaraystotheoverallcount
able isotopes in scrap and waste using a neutron generator
rate.
interrogation source.
3.2.4 accidentals—the accidental or random summing of
3.2.20 good measurement practice—an acceptable way to
neutrons generate a signature like that from true or Real
perform some operation associated with a specific measure-
coincidences. For shift register pulse train deconvolution the
ment technique that is known or believed to influence the
number of neutrons detected in the (A) gate period following
quality of a measurement (a way to perform some operation
the initial detection of each neutron during the selected count
associated with a specific NDA technique in a manner that
time t. This is a measured quantity.
meets the quality requirements of a measurement).
3.2.5 accuracy—(1) bias; (2) the closeness of a measured
3.2.21 holdup—theamountofnuclearmaterialremainingin
value to the true value; and (3) the closeness of a measured
process equipment and facilities after the in-process material,
value to an accepted reference or standard value.
stored materials and product are removed.
3.2.6 assay—to determine quantitatively the amount of one
3.2.22 homogeneous matrix—the degree to which the ma-
or more nuclides of interest contained in an item, or the result
trix materials are spread uniformly throughout the item con-
of such a determination.
tainer. Non homogeneous matrices are referred to as heteroge-
3.2.7 background—extraneous signal superimposed on the
neous.
signal of interest.
3.2.23 in-process material—the nuclear material in a pro-
3.2.8 benign matrix—bulk material that has no effect on the
cess stream, excluding holdup.
result of the measured parameter.
3.2.24 item—nuclear material in a container or other suit-
3.2.9 bias—a constant positive or negative deviation of the
able configuration for assay.
method average from the correct value or accepted reference
3.2.25 lower limit of detectability—a stated limiting value
value.
which designates the lowest concentration, mass, or activity
3.2.10 calibration—the determination of the values of the
that can be detected with confidence and which is specific to a
significant parameters by comparison with values indicated by
particular measurement. C 859, C 1215
a reference instrument, by a set of reference standards or
3.2.26 low level waste—waste that is not defined as transu-
modeled parameters. C 859
ranic or high level waste. DOE order 435.1
3.2.11 certification—a written declaration from a certifying
3.2.27 matrix—the material, which comprises the bulk of
body or its legitimate designee that a particular measurement
the item, except for the special nuclear material and the
process complies with stated criteria, or a measured item has
container. This is the material in which the special nuclear
the stated characteristics.
material is embedded.
3.2.12 coincident neutrons—two or more neutrons emitted
3.2.28 matrix-specific calibration—uses a calibration ma-
simultaneously from a single event, such as from a nucleus
trix similar to the matrix to be measured. No matrix correction
during fission.
factors are used. This calibration is generally not appropriate
for other matrices.
3.2.13 collimator—usually constructed of lead or tungsten,
a collimator serves to define a gamma-ray detector’s horizontal 3.2.29 modeling—the use of mathematical techniques to
and vertical viewing angles and to shield the detector from simulate a measurement process or alternatively the process of
ambient radiation. creating a physical mock up of a measurement.
C1592–04
3.2.30 neutron absorbers—materials which have relatively erable. C 859
large thermal-neutron absorption cross sections. Absorbers 3.2.43 random error—the chance variation encountered in
with the largest cross sections are commonly known as neutron
allmeasurementwork,characterizedbytherandomoccurrence
poisons. Some examples are lithium, boron, cadmium, and of deviations from the mean value. C 1215
gadolinium.
3.2.44 rate loss correction—a correction for count rate
3.2.31 neutron moderators—materials which slow down
related losses that are used for some gamma-ray NDA tech-
neutrons through elastic scattering or inelastic interactions. niques. The correction may use radioactive sources with
Materials containing large amounts of low atomic weight
gamma-ray energies lower than the gamma ray from the
materials, for example, hydrogen are highly moderating. nuclide of interest or a pulser.
3.2.32 neutron multiplication—multiplication takes place 3.2.45 reals—this quantity is the difference between the
when a neutron interaction yields more than one neutron as a
(R+A) and (A) quantities.
product. Induced fission is the primary mechanism for neutron
3.2.46 reals plus accidentals—the number of events de-
multiplication, however (n,2n) interactions are also multipli-
tectedinthe(R+A)gateperiodfollowingtheinitialdetectionof
cation events. each neutron associated with neutron counting. This is a
3.2.33 nondestructive assay (NDA)—the observation of measured quantity during the count time.
spontaneous or stimulated nuclear radiations, interpreted to 3.2.47 repeatability—the within group dispersion of several
estimate the content of one or more nuclides of interest in the
groups of measurements. C 1215
item assayed, without affecting the physical or chemical form
3.2.48 replicate—a counterpart of another measurement. It
of the material.
is the general case for which duplicate, consisting of two
3.2.33.1 active assay—assay based on the observation of
measurements, is the special case.
radiation(s) induced by irradiation from an external source.
3.2.49 reproducibility—the between group- dispersion of
3.2.33.2 passive assay—assay based on the observation of several groups of measurements. C 1215
naturally occurring or spontaneous nuclear radiation(s).
3.2.50 sample—a portion of a population or lot. In the
3.2.34 nuclide—an atomic species characterized by the
context of NDA measurements, it may consist of measure-
composition of its nucleus, that is, by the number of protons ments of items that are part of a larger group that could have
and neutrons it contains.
been considered.
3.2.35 passive neutron coincidence counting—a technique 3.2.51 secular equilibrium—the state of equilibrium that
used to measure the rate of coincident neutron emission in the exists when series of radioisotopes have equal and constant
assay item. The terminology refers specifically to shift-register
activity levels. Secular equilibrium should be established when
electronics. the half life of the parent is much greater than that of the decay
3.2.36 Poisson assumption—for counting measurements, it products.
is assumed that the net counts in a fixed period of time follow 3.2.52 segmented gamma scanner—a nondestructive assay
a Poisson distribution. This assumption can be verified by technique used to measure the gamma-ray emissions from
comparing the observed standard deviation of a series of low-density scrap and waste packaged in cylindrical contain-
measurements on an item with the square root of the average ers. The technique involves independent measurements of the
number of counts. If the Poisson assumption is correct, these vertical segments of the container and may incorporate correc-
numbers should be equal within random error. tions for count rate losses and matrix attenuation.
3.2.37 precision—a generic concept used to describe the 3.2.53 self-attenuation—theattenuationofemittedradiation
dispersion of a set of measured values. Measures frequently by the emitting material itself.
used to describe precision are standard deviation, relative
3.2.54 sensitivity—the capability of methodology or instru-
standarddeviation,variance,repeatability,reproducibility,con- mentation to discriminate between items having differing
fidence interval, and range. (See Guide C 1215 for a more
concentrations or containing differing amounts of a radioactive
complete discussion of precision.) material.
3.2.38 procedure—a set of systematic instructions for using 3.2.55 shift-register-base
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