1、Designation: C1458 091C1458 16Standard Test Method forNondestructive Assay of Plutonium, Tritium and 241Am byCalorimetric Assay1This standard is issued under the fixed designation C1458; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, 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 NOTESection 6.2 was corrected editorially in March 2009.1. Scope1.1 This test method describes the nondestructiv
3、e assay (NDA) of plutonium, tritium, and 241Am using heat flow calorimetry.For plutonium the typical range of applicability applicability, depending on the isotopic composition, corresponds to 10.1 g to20005 g quantities while for tritium the typical range extends from 0.001 g to 10400 g. This test
4、method can be applied tomaterials in a wide range of container sizes up to 50380 L. It has been used routinely to assay items whose thermal power rangesfrom 0.001 W to 135 W.1.2 This test method requires knowledge of the relative abundances of the plutonium isotopes and the 241Am/Pu mass ratio todet
5、ermine the total plutonium mass.1.3 This test method provides a direct measure of tritium content.1.4 This test method provides a measure of 241Am either as a single isotope or mixed with plutonium.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are in
6、cluded in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior
7、to use.2. Referenced Documents2.1 ASTM Standards:2C697 Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Plutonium DioxidePowders and PelletsC1009 Guide for Establishing and Maintaining a Quality Assurance Program for Analytical Laboratories Within the Nucl
8、earIndustryC1030 Test Method for Determination of Plutonium Isotopic Composition by Gamma-Ray SpectrometryC1592 Guide for Nondestructive Assay MeasurementsC1673 Terminology of C26.10 Nondestructive Assay Methods2.2 ANSI Standards:Standard:3ANSI N15.22 N15.36 PlutoniumBearing SolidsCalibration Techni
9、ques for Calorimetric AssayMeasurement ControlProgram Nondestructive Assay Measurement Control and AssuranceANSI N15.54 Radiometric CalorimetersMeasurement Control Program3. Terminology3.1 Definitions:3.1.1 Terms shall be defined in accordance with C26.10 Terminology C1673 except for the following:1
10、 This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.10 on Non DestructiveAssay.Current edition approved Feb. 1, 2009March 1, 2016. Published March 2009April 2016. Originally approved in 2000. Last previous editi
11、on approved in 20002009 asC1458 00.C1458 091. DOI: 10.1520/C1458-09E01.10.1520/C1458-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summar
12、y page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made
13、to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyri
14、ght ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.2 active modea mode of calorimeter operation where an external power, applied by means of a series of band heaters forinstance, is used to maintain the calorimeter at constant temperature.
15、3.1.3 baseline, nthe calorimeter output signal with no heat-generating item in the calorimeter item chamber.3.1.4 basepower, base power, na constant thermal power applied in a calorimeter through an electrical resistance heater withno heat-generating item in the item chamber.3.1.5 equilibrium, nthe
16、point at which the temperature of the calorimeter measurement cell and the item being measured stopschanging.stabilizes.3.1.6 heat distribution error, nthe bias arising from the location of the heat source within the calorimeter chamber.3.1.7 passive mode, na mode of calorimeter operation where temp
17、erature change (caused by the heat to be quantified) ismeasured by means of temperature sensors with no external power is applied to the calorimeter applied except in the case ofWheatstone bridge temperature sensors where electrical current is needed to excite the bridge circuit.3.1.7 sensitivity, n
18、the change in calorimeter response per Watt of thermal power (usually in units of micro Volts per Watt) fora heat flow calorimeter.3.1.8 servo controlpower compensation mode, na mode of calorimeter operation where a constant applied thermal power ismaintained in a calorimeter measurement chamber thr
19、ough the use of an electric resistance heater in a closed loop control system.Historically, Mound Laboratory used to call this “Servo Control.”3.1.9 sensitivity, nthe change in calorimeter response per Watt of thermal power (usually in units of V/W) for a heat flowcalorimeter.3.1.10 specific power,
20、nthe rate of energy emission by ionizing radiation per unit mass of a radionuclide, such as 241Am ortritium.3.1.11 thermal diffusivity, nthe ratio of thermal conductivity to the heat capacity. It measures the ability of a material toconduct thermal energy relative to its ability to store thermal ene
21、rgy.3.1.12 thermal power, nthe rate at which heat is generated in a radioactively decaying item.3.1.13 thermal resistance, nratio of the temperature difference at two different surfaces to the heat flux through the surfacesat equilibrium.3.1.14 thermal time constant, nan exponential decay constant d
22、escribing the rate at which a temperature approaches a constantvalue. An item container combination The combination of the item and its container will have numerous thermal time constants.3.1.14 thermel, nthe THERMal ELement of the calorimeter, including the item chamber, and temperature sensor.4. S
23、ummary of Test Method4.1 The item is placed in the calorimeter measurement chamber and the heat flow at equilibrium, that is, the thermal power, fromthe item is determined by temperature sensors and associated electronic equipment.4.2 The thermal power emitted by a test item is directly related to t
24、he quantity of the radioactive material in it. The powergenerated by ionizing radiation absorbed in the item is measured by the calorimeter.4.3 The total power Witem from a mixture of isotopes in the test item is the sum of the power from each heat-producing isotope:Witem 5imiPi (1)where mi is the m
25、ass of the ith isotope and Pi is the specific power (W/g isotope) with the sum taken over all heat-producingisotopes, most usually 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, and 241Am for Pu-bearing items4.4 The mass (m) of Pu, tritium, or 241Am is calculated from the measured thermal power of an item (item
26、, referWi) using to11.3the following relationship:.m5 WiPeff(1)where:Peff = the effective specific power calculated from the isotopic composition of the item (see 11.3.2 for details of the calculationof Peff for plutonium).4.4.1 When tritium is the only heat source the measured thermal power can be
27、directly converted into the tritium mass usingthe specific power of tritium, Peff = (0.3240 6 0.00045) (SD) W/g (1).44.4.2 ForWhen 241Am is the only heat source, as a single isotope, the measured thermal power can be directly converted intomass using the specific power of 241Am, Peff = (0.1142 6 0.0
28、0042) (SD) W/g (see Table 1).Table 1).4 The boldface numbers in parentheses refer to the list of references at the end of this standard.C1458 1624.4.3 ForThe 241Am mixed with plutonium, the 241Am mass, MmAm, in a plutonium-bearing item is determined byMAm 5RAmMPu (2)multiplying the Pu mass by the Am
29、/Pu mass ratio. The Am/Pu mass ratio is typically determined by gamma-ray spectroscopy.where:R Am = the mass ratio of 241Am to Pu, andMPu = the mass of Pu.5. Significance and Use5.1 This test method is considered to be the most accurate NDAtechnique for the assay of many physical forms of Pu. Isotop
30、icmeasurements by gamma-ray spectroscopy or destructive analysis techniques are part of thethis test method when it is applied tothe assay of Pu.5.1.1 Calorimetry has been applied to a wide variety of Pu-bearing solids including metals, alloys, oxides, fluorides, mixed Pu-Uoxides, mixed oxide fuel p
31、ins, waste, and scrap, for example, ash, ash heels, salts, crucibles, and graphite scarfings) (192, 203).This test method has been routinely used at U.S. and European facilities for Pu process measurements and nuclear materialaccountability for the last 40 years since the mid 1960s (19-2-269).5.1.2
32、Pu-bearing materials have been measured in calorimeter containers ranging in size from about 0.025 m to about 0.600.63m in diameter and from about 0.076 m to about 0.91.38 m in height.5.1.3 Gamma-ray spectroscopy typically is used to determine the Pu-relativePu isotopic composition and 241Am to Pu r
33、atio (seeTest Method C1030). Isotopic However, isotopic information from mass spectrometry and alpha counting measurements may beused instead (see Test Method C697).5.2 This test method is considered to be the most accurate NDA method for the measurement of tritium. For many physicalforms of tritium
34、 compounds calorimetry is currently the only practical measurement technique available.5.3 Physical standards representative of the materials being assayed are not required for the test method.5.3.1 This test method is largely independent of the elemental distribution of the nuclear materials in the
35、 matrix.5.3.2 The accuracy of the method can be degraded for materials with inhomogeneous isotopic composition.5.4 The thermal power measurement is traceable to national measurement systems through electrical standards used to directlycalibrate the calorimeters or to calibrate secondary 238Pu heat s
36、tandards.5.5 Heat-flow calorimetry has been used to prepare secondary standards for neutron and gamma-ray assay systems (24-7-2912).TABLE 1 Nuclear Decay Parameters for Pu Calorimetric AssayAIsotope Half-Life,YearsStandardDeviation,YearsSpecificPower, W/gStandardDeviation,W/gReferences238Pu 87.74 0.
37、04 (0.05 %) 0.56757 0.00026 (0.05 %) (2,3)239Pu 24 119 16 (0.11 %) 1.9288 1030.0003 103 (0.02 %) (3-5)240Pu 6564 11 (0.17 %) 7.0824 1030.0020 103 (0.03 %) (6-11)241Pu 14.348 0.022 (0.15 %) 3.412 1030.002 103 (0.06 %) (12-16)242Pu 376 300 900 (0.24 %) 0.1159 1030.00026 103 (0.22 %) (17)241Am 433.6 1.
38、4 (0.32 %) 0.1142 0.00042 (0.37 %) (15,18)TABLE 1 Nuclear Decay Parameters for Pu Calorimetric AssayAIsotope Half-Life,Years RSD (%)SpecificPower(W/g)RSD (%) References238Pu 87.74 0.05 0.56757 0.05 (25, 26)239Pu 24 119 0.11 1.9288 103 0.02 (26-28)240Pu 6564 0.17 7.0824 103 0.03 (29-34)241Pu 14.348 0
39、.15 3.412 103 0.06 (35-39)242Pu 376 300 0.24 0.1159 103 0.22 (40)241Am 433.6 0.32 0.1142 0.37 (38, 41)A Numbers in parentheses are % relative standard deviation (RSD).ANSI N15.22, the original compiled source for these parameters, is no longer an activeANSI standard.The References are those from ANS
40、I N15.22 and are the appropriate references for the values in Table 1.C1458 1635.6 Calorimetry measurement times are typically longer than other NDA techniques. Four parameters of the item and the itempackaging affect measurement time. These four parameters are density, mass, thermal conductivity, a
41、nd change in temperature. Themeasurement well of passive calorimeters will also affect measurement time because it too will need to come to the newequilibrium temperature. Calorimeters operated in servo power compensation mode maintain a constant measurement welltemperature and have no additional ef
42、fect on measurement time.5.6.1 Calorimeter measurement times range from 20 minutes (3013) for smaller, temperature-conditioned,temperature-conditioned containers up to 2472 h (14) for larger containers and items with long thermal-time constants.5.6.2 Measurement times may be reduced by using equilib
43、rium prediction techniques, by temperature preconditioning of theitem to be measured, orby operating the calorimeter using the servo-control technique.power compensation technique, or byoptimization of the item container (low thermal mass and high thermal conductivity) and packaging.6. Interferences
44、6.1 For plutonium-bearing items alpha decay heating is usually the dominant heat source and any interferences are typicallynegligible. These minor effects included the points 6.2 and 6.3.6.2 Interferences for calorimetry are those processes that would add or subtract thermal power from the power of
45、theradionuclides being assayed. Some examples include phase changes, endothermic or exothermic chemical reactions, such asoxidation, radiolisisradiolysis of liquids, and bacterial action.6.3 Heat-generating radionuclidesFor the thatPeff are not included in the Pcalculation, charged particles are ass
46、umed to be totallyabsorbed in the matrix.eff determination willThe contribution of high energy gamma-rays (for example, 1.173 MeVand 1.333 MeVof the 60Co) needs to be calculated to not underestimate their contribution which could bias the measurement results high. results.These assessments requiring
47、 subject matter expertise are usually based on high-resolution gamma spectroscopy (HRGS) and needto be considered in a case by case basis. These effects are usually considered negligible (15, 16).6.4 The loss of energy by escaping neutrons following spontaneous and induced fissions is about 1 %. The
48、 loss of energy byescaping neutrons following (, ) reactions is around 0.007 % per alpha particle. These effects are also usually considerednegligible (15, 16).7. Apparatus7.1 Calorimeters are designed to measure different sizes and quantities of nuclear material. Different types of heat-flowcalorim
49、eter systems share the common attributes listed below.7.1.1 Measurement ChamberHeat flow calorimeters typically have a cylindrical cylindrical, cuboid, or hexagonal measure-ment chamber from which all of the heat flow generated by radioactive decay is directed through temperature sensors. It may alsohave a reference chamber in which a dummy can is placed (so-called twin cell calorimeter) (15, 17, 18).7.1.1.1 An electrical heater may be built into the walls or the base of the chamber to provide measured amounts of t
