ASTM C1316-2008(2017) Standard Test Method for Nondestructive Assay of Nuclear Material in Scrap and Waste by Passive-Active Neutron Counting Using&x2009 252Cf Shuffler《使用a252Cf的被动.pdf

1、Designation: C1316 08 (Reapproved 2017)Standard Test Method forNondestructive Assay of Nuclear Material in Scrap andWaste by Passive-Active Neutron Counting Using252CfShuffler1This standard is issued under the fixed designation C1316; the number immediately following the designation indicates the ye

2、ar oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the nondestructive assay ofscr

3、ap and waste items for U, Pu, or both, using a252Cf shuffler.Shuffler measurements have been applied to a variety of matrixmaterials in containers of up to several 100 L. Corrections aremade for the effects of matrix material.Applications of this testmethod include measurements for safeguards, accou

4、ntability,TRU, and U waste segregation, disposal, and process controlpurposes (1, 2, 3).21.1.1 This test method uses passive neutron coincidencecounting (4) to measure the240Pu-effective mass. It has beenused to assay items with total Pu contents between 0.03 g and1000 g. It could be used to measure

5、 other spontaneouslyfissioning isotopes such as Cm and Cf. It specifically describesthe approach used with shift register electronics; however, itcan be adapted to other electronics.1.1.2 This test method uses neutron irradiation with amoveable Cf source and counting of the delayed neutrons fromthe

6、induced fissions to measure the235U equivalent fissilemass. It has been used to assay items with235U contentsbetween 0.1 g and 1000 g. It could be used to assay other fissileand fissionable isotopes.1.2 This test method requires knowledge of the relativeisotopic composition (See Test Method C1030) o

7、f the specialnuclear material to determine the mass of the different elementsfrom the measurable quantities.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 The techniques described in this test method have beenapplied to

8、 materials other than scrap and waste. These otherapplications are not addressed in this test method.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and hea

9、lth practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:3C1009 Guide for Establishing and Maintaining a QualityAssurance Program forAnalytical Laboratories Within theNuc

10、lear IndustryC1030 Test Method for Determination of Plutonium IsotopicComposition by Gamma-Ray SpectrometryC1068 Guide for Qualification of Measurement Methods bya Laboratory Within the Nuclear IndustryC1128 Guide for Preparation of Working Reference Materi-als for Use in Analysis of Nuclear Fuel Cy

11、cle MaterialsC1133 Test Method for Nondestructive Assay of SpecialNuclear Material in Low-Density Scrap and Waste bySegmented Passive Gamma-Ray ScanningC1156 Guide for Establishing Calibration for a Measure-ment Method Used to Analyze Nuclear Fuel Cycle Mate-rialsC1207 Test Method for Nondestructive

12、 Assay of Plutoniumin Scrap and Waste by Passive Neutron CoincidenceCountingC1210 Guide for Establishing a Measurement System Qual-ity Control Program for Analytical Chemistry Laborato-ries Within the Nuclear IndustryC1215 Guide for Preparing and Interpreting Precision andBias Statements in Test Met

13、hod Standards Used in theNuclear IndustryC1490 Guide for the Selection, Training and Qualification ofNondestructive Assay (NDA) PersonnelC1592 Guide for Nondestructive Assay Measurements1This test method is under the jurisdiction ofASTM Committee C26 on NuclearFuel Cycle and is the direct responsibi

14、lity of Subcommittee C26.10 on NonDestructive Assay.Current edition approved Jan. 1, 2017. Published January 2017. Originallyapproved in 1995. Last previous edition approved in 2008 as C1316 08. DOI:10.1520/C1316-08R17.2The boldface numbers in parentheses refer to a list of references at the end oft

15、his test method.3For 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 standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor

16、 Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendation

17、s issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1C1673 Terminology of C26.10 Nondestructive Assay Meth-ods2.2 ANSI Documents:ANSI 15.20 Guide to Calibrating Nondestructive AssaySystems4ANSI N15.36 Nondestructive Assay Measurement Controland Assurance43. Terminolo

18、gy3.1 DefinitionsTerms shall be defined in accordance withTerminology C1673.3.2 Definitions of Terms Specific to This Standard:3.2.1 active mode, ndetermines total fissile mass in theassayed item through neutron interrogation and counting of thedelayed neutrons from induced fissions.4. Summary of Te

19、st Method4.1 This test method consists of two distinct modes ofoperation: passive and active. The instrument that performs theactive mode measurement is referred to as a shuffler due to thecyclic motion of the252Cf source. This test method usuallyrelies on passive neutron coincidence counting to det

20、ermine thePu content of the item, and active neutron irradiation followedby delayed neutron counting to determine the U content.4.1.1 Passive Neutron Coincidence Counting ModeTheeven mass isotopes of Pu fission spontaneously. On averageapproximately 2.2 prompt neutrons are emitted per fission. Thenu

21、mber of coincident fission neutrons detected by the instru-ment is correlated to the quantity of even mass isotopes of Pu.The total Pu mass is determined from the known isotopic ratiosand the measured quantity of even mass isotopes. This testmethod refers specifically to the shift register coinciden

22、cecounting electronics (see (4) and Test Method C1207).4.1.2 Active Neutron (Shuffler) ModeFissionsin235U,239Pu and other fissile nuclides can be induced bybombarding them with neutrons. Approximately 1 % of theneutrons emitted per fission are delayed in time, being emittedfrom the fission products

23、over the time range from s to severalminutes after the fission event. Roberts et. al (5) were the firstto observe delayed neutron emission. We now know that over270 delayed neutron precursors contribute to the yield althoughthe time behavior can be adequately described for mostpurposes using a few (

24、six to eight) effective groups each witha characteristic time constant. The idea of detecting delayedneutrons for the analysis of235U has been attributed to Echoand Turk (6). The active shuffler mode consists of severalirradiate-count cycles, or shuffles, of the252Cf neutron sourcebetween the positi

25、ons illustrated in Fig. 1.252Cf emits a fissionneutron spectrum. During each shuffle, the252Cf source ismoved close to the item for a short irradiation, then moved toa shielded position while the delayed neutrons are counted.Thenumber of delayed neutrons detected is correlated with thequantity of fi

26、ssile and fissionable material. The total U mass isdetermined from the known relative isotopic compostion andthe measured quantity of235U equivalent (7).4.2 Either corrections are made for the effects of neutronabsorbers and moderators in the matrix, or a matrix-specificcalibration is used. The effe

27、ct that needs correction is theincrease or decrease in the specific neutron signal caused by thematrix.4.3 Corrections are made for deadtime, neutron background,and the Cf source decay.4.4 The active mode also induces fissions in Pu if it ispresent in the assay item. The passive measurement of Pu ca

28、nbe used to correct the active measurement of235U effective forthe presence of Pu.4.5 Calibrations are generally based on measurements ofwell documented reference materials (8) and may be extendedby calculation (9-11). The method includes measurementcontrol tests to verify reliable and stable perfor

29、mance of theinstrument.5. Significance and Use5.1 This test method is used to determine the U and Pucontent of scrap and waste in containers. Active measurementtimes have typically been 100 to 1000 s. Passive measurementtimes have typically been 400 s to several hours. The followinglimits may be fur

30、ther restricted depending upon specificmatrix, calibration material, criticality safety, or countingequipment considerations.5.1.1 The passive measurement has been applied to benignmatrices in 208 L drums with Pu content ranging from 30 mgto 1 kg.5.1.2 The active measurement has been applied to wast

31、edrums with235U content ranging from about 100 mg to 1 kg.5.2 This test method can be used to demonstrate compliancewith the radioactivity levels specified in safeguards, waste,disposal, and environmental regulations (for example, see NRCregulatory guides 5.11, 5.53, DOE Order 5820.2a, and10CFR61 se

32、ctions 61.55 and sections 61.56, 40CFR191, andDOE/WIPP-069).5.3 This test method could be used to detect diversionattempts that use shielding to encapsulate nuclear material.5.4 The bias of the measurement results is related to theitem size and density, the homogeneity and composition of thematrix,

33、and the quantity and distribution of the nuclear mate-rial. The precision of the measurement results is related to thequantity of nuclear material and the count time of the mea-surement.5.4.1 For both the matrix-specific and the matrix-correctionapproaches, the method assumes the calibration materia

34、lsmatch the items to be measured with respect to the homoge-neity and composition of the matrix, the neutron moderator andabsorber content, and the quantity of nuclear material, to theextent they affect the measurement.5.4.2 It is recommended that measurements be made onsmall containers of scrap and

35、 waste before they are combinedin large containers. Special arrangement may be required toassay small containers to best effect in a large cavity generalpurpose shuffer.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.C131

36、6 08 (2017)2NOTE 1The shuffler measurement consists of several cycles. Each cycle includes the movement of the252Cf source from the storage (or home)position to the irradiation position close to the item, irradiation of the item for a period of about 10 s, return of the source to the shield followed

37、 by acounting period of about 10 s. In obvious notation this cycle structure may be succinctly described by the four time periods involved (tin,tirr,tout,tcnt).Typically the one-way transit times are less than 1 s.FIG. 1 Cf Shuffler Measurement PrincipleC1316 08 (2017)35.4.3 It is recommended that m

38、easurements be made oncontainers with homogeneous contents. In general, heteroge-neity in the distribution of nuclear material, neutronmoderators, and neutron absorbers has the potential to causebiased results.5.5 This test method requires that the relative isotopiccompositions of the contributing e

39、lements are known.5.6 This test method assumes that the distribution of thecontributing isotopes is uniform throughout the container whenthe matrix affects neutron transport.5.7 This test method assumes that lump affects areunimportantthat is to say that large quantities of specialnuclear material a

40、re not concentrated in a small portion of thecontainer.5.8 For best results from the application of this test method,appropriate packaging of the items is required. Suitable train-ing of the personnel who package the scrap and waste prior tomeasurement should be provided (for example, see ANSI15.20,

41、 Guide C1009, Guide C1490, and Guide C1068 fortraining guidance). Sometimes site specific conditions andrequirements may have greater bearing.6. Interferences6.1 Potential sources of measurement interference includeunexpected nuclear material contributing to the active orpassive neutron signal, self

42、-shielding by lumps of fissilematerial, neutron self-multiplication, excessive quantities ofabsorbers or moderators in the matrix, heterogeneity of thematrix, and the non-uniformity of the nuclear material spatialdistribution especially within a moderating matrix. In general,the greatest potential s

43、ource of bias for active neutron mea-surement is heterogeneity of the nuclear material within ahighly moderating matrix, while the greatest for passiveneutron measurement is neutron moderation and absorption(12).6.2 The techniques described in this test method cannotdistinguish which isotope is gene

44、rating the measured response.If more than one nuclide that produces a response is present,the relative abundances and relative specific responses of thosenuclides must be known.6.2.1 Active ModeThe unidentified presence of other fis-sionable nuclides will increase the delayed neutron count rate,caus

45、ing an overestimation of the235U content. For example, acalibration based on highly enriched U will cause biased resultsif the unknowns actually contain low-enriched U due to thepotential difference in the fractional contribution arising fromthe fast fission in238U (13, 14).6.2.2 Passive ModeThe uni

46、dentified presence of otherspontaneous fission nuclides, such as Cm and Cf, will increasethe coincident neutron rates, causing an overestimation of thePu content. The active mode measurement of Pu is generallynot sensitive to this source of bias (although counting precisionmay be affected) because t

47、he masses of concern are so smalland present a comparatively tiny induced fission signal.6.3 Lumps of nuclear material can exhibit self-shielding ormultiplication. This effect is often larger for moderating(hydrogenous) matrices.6.3.1 Active Mode (Self-Shielding)The nuclear materialon the surface of

48、 the lump shields the inside of the lump fromthe interrogating neutrons (15, 16).6.3.2 Passive Mode (Multiplication)Neutrons originatingin the lump induce fissions in the same lump which boosts thespecific coincident rate.6.4 Moderators in the matrix can cause a bias in themeasurement results, unles

49、s a correction is made or an appro-priate matrix specific calibration is used. The magnitude anddirection of this bias depend on the quantity of moderatorpresent, the distribution of the fissile material, and the size ofthe item (2, 17).6.4.1 Although moderation is the greatest potential sourceof bias for passive measurements, the passive method isgenerally less susceptible to the presence of moderator than theactive method.6.4.2 The presence of absorbers in the matrix can cause biasif there is sufficient moderator present. The moderator slowsfast neutrons which can th