1、Designation: C 1592 04Standard Guide forNondestructive Assay Measurements1This standard is issued under the fixed designation C 1592; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthese
2、s indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide is a compendium of Good Practices forperforming measurements of radioactive material using non-destructive assay (NDA) instruments. The primary
3、 purpose ofthe guide is to assist its users in arriving at quality NDA results,that is, results that satisfy the end users needs. This isaccomplished by providing an acceptable and uniform basis forthe collection, analysis, comparison, and application of data.The recommendations are not compulsory o
4、r pre requisites toachieving quality NDA measurements, but are consideredcontributory in most areas.1.2 This guide applies to the use of NDA instrumentationfor the measurement of nuclear materials by the observation ofspontaneous or stimulated nuclear radiations, including pho-tons, neutrons, or the
5、 flow of heat. Recommended calibration,operating, and assurance methods represent guiding principlesbased on current NDA technology. The diversity of industry-wide nuclear materials measurement applications and instru-mentation precludes discussion of specific measurement situ-ations. As a result, c
6、ompliance with practices recommended inthis guide must be based on a thorough understanding ofcontributing variables and performance requirements of thespecific measurement application.1.3 Selection of the best instrument for a given measure-ment application and advice on the use of this instrument
7、mustbe provided by a qualified NDA professional following guid-ance provided in Guide C 1490. This guide is to be used as areference, and to supplement the critical thinking, professionalskill, expert judgement, and experimental test and verificationneeded to ensure that the instrumentation and meth
8、ods havebeen properly implemented.1.4 The intended audience for this guide includes but is notlimited to Management, Auditor Support, NDA QualifiedInstrument Operators, NDA Technical Specialists, and NDAProfessionals.2. Referenced Documents2.1 ASTM Standards:2C 859 Terminology Relating to Nuclear Ma
9、terialsC 1030 Test Method for Determination of Plutonium Isoto-pic Composition by Gamma-Ray SpectrometryC 1133 Test Method for Nondestructive Assay of SpecialNuclear Material in Low-Density Scrap and Waste bySegmented Passive Gamma-Ray ScanningC 1207 Test Method for Nondestructive Assay of Plutonium
10、in Scrap and Waste by Passive Neutron CoincidenceCountingC 1215 Guide for Preparing and Interpreting Precision andBias Statements in Test Method Standards used in theNuclear IndustryC 1221 Test Method for Nondestructive Analysis of SpecialNuclear Materials in homogeneous Solutions by Gamma-Ray Spect
11、rometryC 1254 Test Method for Determination of Uranium inMineral Acids by X-ray FluorescenceC 1268 Test Method for Quantitative Determination ofAmericium 241 in Plutonium by Gamma-Ray Spectrom-etryC 1316 Test Method for Nondestructive Assay of NuclearMaterial in Scrap and Waste by Passive-Active Neu
12、tronCounting Using a252Cf ShufflerC 1455 Guide for Nondestructive Assay of Special NuclearMaterial Holdup Using Gamma-Ray Spectroscopic Meth-odsC 1458 Test Method for Nondestructive Assay of Pluto-nium, Tritium and241Am by Calorimetric AssayC 1490 Guide for the Selection, Training and Qualificationo
13、f Nondestructive Assay (NDA) PersonnelC 1493 Test Method for Non Destructive Assay of NuclearMaterial in Waste by Passive and Active Neutron CountingUsing a Differential Die Away System1This guide is under the jurisdiction of ASTM Committee C26 on Nuclear FuelCycle and is the direct responsibility o
14、f Subcommittee C26.10 on Non DestructiveAssay.Current edition approved Feb. 1, 2004. Published March 2004.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standa
15、rds Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.C 1514 Test Method for Measurement of235U FractionUsing the Enrichment Meter Principle3. Terminology3.1 Definitions presented here are confi
16、ned to those termsnot defined in common nuclear materials glossaries/referencesor whose use is specific to this application. The use ofstatistical terms is consistent with the definitions in AmericanNational Standard Statistical Terminology and Notation forNuclear Materials Management, N15.5-1972. S
17、ome of thosedefinitions are repeated here for convenience to the reader.3.2 Definitions:3.2.1 (a n) reactions(a, n) reactions occur when energeticalpha particles collide with low atomic number nuclei, such asO, F, or Mg, producing single neutrons.3.2.2240Pu effective massmeffis the mass of240Pu that
18、would produce the same coincident, or total, neutron responsein the instrument as the assay item, all other factors remainingunchanged. It is correlated to the quantity of even massisotopes of plutonium in the assay item.3.2.3 absorber foilsthin metal foils that are used to reducethe contribution of
19、 low-energy gamma rays to the overall countrate.3.2.4 accidentalsthe accidental or random summing ofneutrons generate a signature like that from true or Realcoincidences. For shift register pulse train deconvolution thenumber of neutrons detected in the (A) gate period followingthe initial detection
20、 of each neutron during the selected counttime t. This is a measured quantity.3.2.5 accuracy(1) bias; (2) the closeness of a measuredvalue to the true value; and (3) the closeness of a measuredvalue to an accepted reference or standard value.3.2.6 assayto determine quantitatively the amount of oneor
21、 more nuclides of interest contained in an item, or the resultof such a determination.3.2.7 backgroundextraneous signal superimposed on thesignal of interest.3.2.8 benign matrixbulk material that has no effect on theresult of the measured parameter.3.2.9 biasa constant positive or negative deviation
22、 of themethod average from the correct value or accepted referencevalue.3.2.10 calibrationthe determination of the values of thesignificant parameters by comparison with values indicated bya reference instrument, by a set of reference standards ormodeled parameters. C 8593.2.11 certificationa writte
23、n declaration from a certifyingbody or its legitimate designee that a particular measurementprocess complies with stated criteria, or a measured item hasthe stated characteristics.3.2.12 coincident neutronstwo or more neutrons emittedsimultaneously from single event, such as from a nucleusduring fis
24、sion.3.2.13 collimatorusually constructed of lead or tungsten,a collimator serves to define a gamma-ray detectors horizontaland vertical viewing angles and to shield the detector fromambient radiation.3.2.14 confidence intervalthe range of values, calculatedfrom an estimate of the mean and standard
25、deviation, which isexpected to include the population mean with a stated level ofconfidence.3.2.15 control charta graphical plot of test results withrespect to time or sequence of measurement together withlimits in which they are expected to lie when the system is ina state of statistical control.3.
26、2.16 control limitsthe limits shown on a control chartbeyond which it is highly improbable that a point could liewhile the system remains in a state of statistical control.3.2.17 correctionstechniques that are part of the dataanalysis or method, which compensate for the effects ofvariables that inte
27、rfere with the measurement and degradeaccuracy. These corrections account for such things as matrixmaterial, lumps, heterogeneity, dead time, and background.3.2.18 dead timethe period following the detection of anevent during which the system cannot register a subsequentevent. Dead time is usually e
28、xpressed as a percentage ofelapsed time.3.2.19 differential die away technique (DDT)an NDAtechnique for characterizing the prompt neutrons from fission-able isotopes in scrap and waste using a neutron generatorinterrogation source.3.2.20 good measurement practicean acceptable way toperform some oper
29、ation associated with a specific measure-ment technique that is known or believed to influence thequality of a measurement (a way to perform some operationassociated with a specific NDA technique in a manner thatmeets the quality requirements of a measurement).3.2.21 holdupthe amount of nuclear mate
30、rial remaining inprocess equipment and facilities after the in process material,stored materials and product are removed.3.2.22 homogeneous matrixthe degree to which the ma-trix materials are spread uniformly throughout the item con-tainer. Non homogeneous matrices are referred to as heteroge-neous.
31、3.2.23 in process materialthe nuclear material in a pro-cess stream, excluding holdup.3.2.24 itemnuclear material in a container or other suit-able configuration for assay.3.2.25 lower limit of detectabilitya stated limiting valuewhich designates the lowest concentration, mass, or activitythat can b
32、e detected with confidence and which is specific to aparticular measurement. C 859, C 12153.2.26 low level wastewaste that is not defined as transu-ranic or high level waste. DOE order 435.13.2.27 matrixthe material, which comprises the bulk ofthe item, except for the special nuclear material and th
33、econtainer. This is the material in which the special nuclearmaterial is embedded.3.2.28 matrix-specific calibrationuses a calibration ma-trix similar to the matrix to be measured. No matrix correctionfactors are used. This calibration is generally not appropriatefor other matrices.3.2.29 modelingth
34、e use of mathematical techniques tosimulate a measurement process or alternatively the process ofcreating a physical mock up of a measurement.C15920423.2.30 neutron absorbersmaterials, which have relativelylarge thermal-neutron absorption cross sections. Absorberswith the largest cross sections are
35、commonly known as neutronpoisons. Some examples are lithium, boron, cadmium, andgadolinium.3.2.31 neutron moderatorsmaterials which slow downneutrons through elastic scattering or inelastic interactions.Materials containing large amounts of low atomic weightmaterials, for example, hydrogen are highl
36、y moderating.3.2.32 neutron multiplicationmultiplication takes placewhen a neutron interaction yields more than one neutron as aproduct. Induced fission is the primary mechanism for neutronmultiplication, however (n,2n) interactions are also multipli-cation events.3.2.33 nondestructive assay (NDA)th
37、e observation ofspontaneous or stimulated nuclear radiations, interpreted toestimate the content of one or more nuclides of interest in theitem assayed, without affecting the physical or chemical formof the material.3.2.33.1 active assayassay based on the observation ofradiation(s) induced by irradi
38、ation from an external source.3.2.33.2 passive assayassay based on the observation ofnaturally occurring or spontaneous nuclear radiation(s).3.2.34 nuclidean atomic species characterized by thecomposition of its nucleus, that is, by the number of protonsand neutrons it contains.3.2.35 passive neutro
39、n coincidence countinga techniqueused to measure the rate of coincident neutron emission in theassay item. The terminology used in this test method refersspecifically to shift-register electronics.3.2.36 Poisson assumptionfor counting measurements, itis assumed that the net counts in a fixed period
40、of time followa Poisson distribution. This assumption can be verified bycomparing the observed standard deviation of a series ofmeasurements on an item with the square root of the averagenumber of counts. If the Poisson assumption is correct, thesenumbers should be equal within random error.3.2.37 p
41、recisiona generic concept used to describe thedispersion of a set of measured values. Measures frequentlyused to describe precision are standard deviation, relativestandard deviation, variance, repeatability, reproducibility, con-fidence interval, and range. (See Guide C 1215 for a morecomplete disc
42、ussion of precision.)3.2.38 procedurea set of systematic instruction for usinga method of measurement or of the steps associated with themethod.3.2.39 qualitative analysisan analysis in which some orall of the components of an item are determined. A measure-ment in which the amount of one or more co
43、mponents of anitem are determined.3.2.40 radioactive emissionsalpha, beta, gamma-ray,x-ray, heat, and neutron emissions from spontaneous fission,induced fission, or delayed neutron emission following betadecay.3.2.41 radioactive scrapmaterials that contain sufficientquantities of source or special n
44、uclear material to be worthy ofrecovery. C 8593.2.42 radioactive wasteitems containing radioactive ma-terials not currently considered useful or economically recov-erable. C 8593.2.43 random errorthe chance variation encountered inall measurement work, characterized by the random occurrenceof deviat
45、ions from the mean value. C 12153.2.44 rate loss correctiona correction for count raterelated losses that are used for some gamma-ray NDA tech-niques. The correction may use radioactive sources withgamma-ray energies lower than the gamma-ray from thenuclide of interest or a pulser.3.2.45 realsthis q
46、uantity is the difference between the(R+A) and (A) quantities.3.2.46 reals plus accidentalsthe number of events de-tected in the (R+A) gate period following the initial detection ofeach neutron associated with neutron counting. This is ameasured quantity during the count time.3.2.47 repeatabilitythe
47、 within group dispersion of severalgroups of measurements. C 12153.2.48 replicatea counterpart of another measurement. Itis the general case for which duplicate, consisting of twomeasurements, is the special case.3.2.49 reproducibilitythe between group dispersion ofseveral groups of measurements. C
48、12153.2.50 samplea portion of a population or lot. In thecontext of NDA measurements, it may consist of measure-ments of items that are part of a larger group that could havebeen considered.3.2.51 secular equilibriumthe state of equilibrium thatexists when series of radioisotopes have equal and cons
49、tantactivity levels. Secular equilibrium is established when the halflife of the parent is much greater than that of the decayproducts.3.2.52 segmented gamma scannera nondestructive assaytechnique used to measure the gamma-ray emissions fromlow-density scrap and waste packaged in cylindrical contain-ers. The technique involves independent measurements of thevertical segments of the container and may incorporate correc-tions for count rate losses and matrix attenuation.3.2.53 self-attenuationthe attenuation of emitted radiationby t
