1、Designation: C1673 10a1Standard Terminology ofC26.10 Nondestructive Assay Methods1This standard is issued under the fixed designation C1673; 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 par
2、entheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEText was added editorially to the definition of “working standard” in August 2011.1. Scope1.1 The terminology defined in this document is associatedwith no
3、ndestructive assay of nuclear material.1.2 All of the definitions are associated with measurementtechniques that measure nuclear emissions (that is, neutrons,gamma-rays, or heat) directly or indirectly.1.3 definitions are relevant to any standards and guideswritten by subcommittee C26.10.2. Referenc
4、ed Documents2.1 ASTM Standards:2E456 Terminology Relating to Quality and Statistics2.2 DOE Orders:3DOE Order 435.1 Low-level Waste RequirementsDOE Order 5820.2 Radioactive Waste Management3. Terminology(alpha, n) reaction, na reaction that occurs when energeticalpha particles collide with low atomic
5、 number nucleiresulting in the emission of a neutron240Pu-effective mass,240Pueff, nthe mass of240Pu thatwould produce the same coincident neutron response in theinstrument as the assay item.DISCUSSIONIt is a function of the quantity of even mass isotopes ofplutonium in the assay item and fundamenta
6、l nuclear constants,sometimes referred to as effective240Pu mass.absorber foils, nfoils, usually of copper, tin, cadmium, orlead, used to attenuate the gamma flux reaching a detector.DISCUSSIONAbsorber foils are used to reduce the count rate,typically from intense low-energy X or gamma rays.accident
7、als, nthe detection of multiple neutron eventswithin the gate width that are not produced from the samefission.DISCUSSIONAccidental events take their name from the fact that itis the accidental or random summing of neutrons, which are not timecorrelated with a common origin (fission or cosmic-ray bu
8、rst), that giverise to the appearance of a signature like that from genuine correlatedevents.active assay, nassay based on the observation of radiation(s)induced by irradiation from an external source.alpha, a, nthe ratio of the uncorrelated neutron emissionrate from (a, n) reactions to the spontane
9、ous neutronemission rate from a non-multiplying item.aperture, nthe size of the opening in the collimator throughwhich the radiation of interest is intended to pass.assay, vto determine quantitatively the amount of one ormore nuclides of interest contained in an item.attenuation correction, ncorrect
10、ion to the measured countrate for attenuation of radiation that provides an estimate ofthe unattenuated radiation emission rate of the radionuclidesbeing assayed.attenuation, nreduction of radiation flux due to the interac-tion of radiation with material between the source of theradiation and the de
11、tector.background, nextraneous signal superimposed on the signalof interest.Beers Law, nthe fraction of uncollided gamma rays trans-mitted through layers of equal thickness of an absorber is aconstant.benign matrix, nbulk material that has a negligible effect onthe result of the measured parameter.b
12、lank, na prepared item containing a matrix as similar aspractical to the items being measured that is free, to theextent possible, of the radionuclides of interest.1This terminology is under the jurisdiction ofASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C
13、26.10 on NonDestructive Assay.Current edition approved Nov. 1, 2010. Published December 2010. Originallyapproved in 2007. Last previous edition approved in 2010 as C1673 - 10. DOI:10.1520/C1673-10AE01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servi
14、ce at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from the U.S. Department of Energy (DOE), 1000 IndependenceAve., SW Washington, DC 20585.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box
15、 C700, West Conshohocken, PA 19428-2959, United States.DISCUSSIONThe most important matrix parameters are those thataffect the result of the measurement technique being used.calibration standard, nan item similar to the items to beassayed, for which the parameters of interest and all prop-erties to
16、which the measurement technique is sensitive areknown.calorimeter, na device to measure heat or rate-of-heatgeneration.calorimetric assay, ndetermination of the mass of radioac-tive material through the measurement of its thermal powerby calorimetry and the use of nuclear decay constants and, ifnece
17、ssary, additional isotopic measurements.certification, na written declaration from a certifying bodyor its legitimate designee that a particular measurementprocess or measurement personnel comply with stated crite-ria or that a measured item has the stated characteristics.code validation, nprocess t
18、o determine that the softwareperforms its intended functions correctly, ensure that itperforms no unintended functions, and provides informationabout its quality and reliability.coincidence gate length, nthe time interval following thedetection of a neutron during which additional neutrons areconsid
19、ered to be in coincidence with the original neutron.coincident neutrons, ntwo or more neutrons emitted simul-taneously from a single event, such as from a nucleus duringfission.collimated detector, na detector surrounded by a shield thatimposes a directional response on the collimated detector.colli
20、mator, na shield that imposes a directional response onthe detector. Generally, for gamma ray detection the colli-mator is a hollow cylinder or rectangular prism of highatomic number (Z) and high density material, mountedcoaxially to the detector and extending over the detector andbeyond the detecto
21、r face.Compton scattering, nscattering of gamma rays that may ormay not be from the radionuclide of interest.DISCUSSIONThe scattering reduces the energy of the gamma ray andresults in a continuum of gamma ray puted tomography, nsee tomography.confidence interval, nThe range of values, calculated fro
22、mthe probability distribution (often sufficiently well character-ized by the estimate of the mean and standard deviation),which is expected to include the population mean with astated level of confidence or likelihood.DISCUSSIONFor more details see Test Method E456.contact measurement, na special ca
23、se of a near-fieldmeasurement in which measurements are made with thedetector assembly in contact with the item, for example,tank, pipe, ductwork, being assayed.control chart, na graphical plot of test results with respectto time or sequence of measurement together with limits inwhich they are expec
24、ted to lie when the system is in a stateof statistical control.control limits, nthe limits beyond which it is statisticallyhighly improbable that one or several point(s) could lie whilethe system remains in a state of statistical control.data quality objective, nmeasurement uncertainty and con-fiden
25、ce levels specified by the scope of work.dead time, nthe period following the detection of an eventduring which the detection electronics cannot register asubsequent event.DISCUSSIONDead time is usually expressed as a percentage ofelapsed time.delayed neutrons, nneutrons emitted by the item that are
26、produced from decay of the fission products.DISCUSSIONThese neutrons are produced at a time after the initialfission event.depleted uranium, nuranium containing less than the natu-rally occurring fraction of235U isotopes (0.7 weightpercent).die-away time, nthe average life time of the neutronpopulat
27、ion as measured from the time of emission todetection, escape, or absorption. The average lifetime is thetime required for the neutron population to decrease by afactor of 1/e.doubles, nthe detection of neutron pairs produced from thesame fission event.DISCUSSIONThe doubles terminology is often used
28、 in reference tomultiplicity counting, but it is the same as the reals from coincidencecounting.effective specific power, peff, nthe rate of energy emissionper unit mass of radionuclide at the time of measurement.far-field measurement, na measurement geometry wherethe analyst can assume that all gam
29、ma rays emitted from theitem enter the detector along paths parallel to each other.field of view, nthe entire solid angle subtended by thecollimated detector.fissile isotopes, nisotopes that can be induced to fission bythermal neutrons.DISCUSSION233U,235U,239Pu, and241Pu are the most commonfissile i
30、sotopes.flux monitors, ndetectors in the measurement chamber thatmeasure the neutron flux of interrogating neutrons (cavityflux monitor) or item neutrons (drum flux monitor).heat-flow calorimeter, na calorimeter so constructed thatthe heat generated in the calorimeter flows past a tempera-ture sensi
31、ng element, through a thermal resistance, to aconstant temperature heat sink.holdup, nthe residual nuclear material remaining in processequipment and facilities.homogeneous matrix, na matrix whose characteristics im-portant to the measurement result is uniform throughout theitem.infinite thickness,
32、nthe thickness of material through which99.9 % of the gamma rays of the designated energy cannotpenetrate.DISCUSSIONThis is nominally equal to 7 mean-free paths in purematerial.item, nmaterial potentially containing radioisotope to bemeasured.C1673 10a12low level waste, nis radioactive containing ma
33、terial that isnot classified as high-level waste, transuranic waste, spentnuclear fuel, or by-product material.lower limit of detectability, na stated limiting value whichdesignates the lowest concentration, mass, or activity thatcan be detected with confidence and which is specific to aparticular m
34、easurement.lump, nthat contiguous mass of nuclear material that issufficiently large to affect the measured signal.matrix, nthe material that comprises the bulk of the item,except for the radionuclide(s) of interest and the container.matrix-specific calibration, na calibration that uses a ma-trix si
35、milar to the matrix to be measured.DISCUSSIONNo matrix correction factors are used. This calibrationis normally not appropriate for other matrices.model validation, nprocess to determine the suitability ofthe model for a given application.multiplicity distribution, nthis is the distribution of thenu
36、mber of neutrons emitted in fission events.near-field measurement, nmeasurement made at interme-diate or close distances from the item where the measuredradiation enters the detector from a variety of distances andangles.neutron absorbers, nmaterials which have relatively largethermal-neutron captur
37、e cross-sections.DISCUSSIONAbsorbers with the largest capture cross-sections arecommonly known as neutron poisons. Some examples are boron,cadmium, gadolinium and lithium.neutron moderators, nmaterials which efficiently slowdown neutrons. Materials containing large amounts of lowatomic weight materi
38、als, such as hydrogen are highly mod-erating.neutron multiplication, nmultiplication takes place when aneutron interaction yields more than one neutron as aproduct.DISCUSSIONInduced fission is the primary mechanism for neutronmultiplication, however (n, 2n) interactions are also multiplicationevents
39、.nondestructive assay, NDA, nan analysis of an item inwhich the chemical and physical properties of that item andcontainer remain essentially unaltered.one pass assay, na gamma ray measurement in which thetransmission and emission data are collected simultaneously.passive assay, nassay based on the
40、observation of naturallyoccurring or spontaneous nuclear radiation(s).passive mode, na technique used to determine thespontaneously-fissioning mass in the measured item throughthe detection of spontaneously emitted neutrons rather thanneutrons induced by external interrogation sources.peaked backgro
41、und, ngamma rays of the assay energy,which originate in sources other than the item material beingassayed.point model, nthe mathematical model used to analyzemeasurements of radioactive items where the item is repre-sented as a point source.point source, nsource material confined to a volume whosedi
42、mensions are small compared with the distance betweenthe source and detector.pre-delay, nthe coincidence circuit has a time period imme-diately after a neutron has been detected during whichsignals are not accepted.prompt neutrons, nneutrons released within approximately1014s of the fission.rate-los
43、s correction, na correction for count rate relatedlosses that are used for some gamma-ray NDA techniques.reals, R, ndetection of neutron pairs produced from the samefission event.DISCUSSIONThe reals terminology is often used in reference tocoincidence counting, but it is the same as the doubles from
44、 multiplicitycounting.sample, na portion of a population or lot. In the context ofNDA measurements, it may consist of measurements ofitems that are part of a larger group that could have beenconsidered.scrap, nmaterials that contain sufficient quantities of radio-active material to be worthy of reco
45、very.screening, nrapid, that is, short-count time, measurements atspecific locations or with a moving gamma-ray detector(sometimes with a neutron probe) along an item to qualita-tively identify the presence and rough distribution of radio-active material.DISCUSSIONThe information from the screening
46、can be used tooptimize the assay procedure for the item(s).secular equilibrium, nthe state of equilibrium that existswhen a series of daughter radioisotopes have constantactivity levels determined by the parent activity rate.self-attenuation, nthe attenuation of emitted radiation bythe emitting mate
47、rial itself.sensitivity, nthe capability of methodology or instrumenta-tion to discriminate between items having differing concen-trations or containing differing amounts of a radioactivematerial or no radioactive material.singles, S, nin multiplicity counting, the sum of all detectedneutrons.DISCUS
48、SIONEquivalent to the totals from coincidence counting.special nuclear material, nplutonium,233U, uranium en-riched in235U and any other materials defined as SNMunder the Atomic Energy Act of 1954 as amended and DOEorders.spontaneously-fissioning nuclei, nthose nuclei which donot require an external
49、 neutron source to undergo significantfission.DISCUSSIONThe most common isotopes are238,240,242Pu,242,244Cm, and252Cf.C1673 10a13total measurement uncertainty (TMU), nan estimatedparameter, either mass, activity, concentration, or fractional,used to quantify the overall confidence in the assay result ata prescribed level including all sources of precision and bias.totals, T, nin coincidence counting, the sum of all detectedneutrons.DISCUSSIONEquivalent to the singles fr
