1、Designation: E910 07 (Reapproved 2013)Standard Test Method forApplication and Analysis of Helium Accumulation FluenceMonitors for Reactor Vessel Surveillance, E706 (IIIC)1This standard is issued under the fixed designation E910; the number immediately following the designation indicates the year ofo
2、riginal 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 describes the concept and use ofhelium accu
3、mulation for neutron fluence dosimetry for reactorvessel surveillance. Although this test method is directedtoward applications in vessel surveillance, the concepts andtechniques are equally applicable to the general field of neutrondosimetry. The various applications of this test method forreactor
4、vessel surveillance are as follows:1.1.1 Helium accumulation fluence monitor (HAFM)capsules,1.1.2 Unencapsulated, or cadmium or gadolinium covered,radiometric monitors (RM) and HAFM wires for heliumanalysis,1.1.3 Charpy test block samples for helium accumulation,and1.1.4 Reactor vessel (RV) wall sam
5、ples for helium accumu-lation.1.2 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 health practices and determine the applica-bility of regulatory limitation
6、s prior to use.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsE170 Terminology Relating to Radiation Measurements andDosimetryE244 Test Method forAtom Percent Fission in Uranium andPlutonium Fuel (Mass Spectrometric Method) (With-drawn 2001)3E261 Practice fo
7、r Determining Neutron Fluence, FluenceRate, and Spectra by Radioactivation TechniquesE482 Guide for Application of Neutron Transport Methodsfor Reactor Vessel Surveillance, E706 (IID)E706 Master Matrix for Light-Water Reactor PressureVesselSurveillance Standards, E 706(0) (Withdrawn 2011)3E844 Guide
8、 for Sensor Set Design and Irradiation forReactor Surveillance, E 706 (IIC)E853 Practice forAnalysis and Interpretation of Light-WaterReactor Surveillance Results, E706(IA)E854 Test Method for Application and Analysis of SolidState Track Recorder (SSTR) Monitors for ReactorSurveillance, E706(IIIB)E9
9、00 Guide for Predicting Radiation-Induced TransitionTemperature Shift in Reactor Vessel Materials, E706 (IIF)E944 Guide for Application of Neutron Spectrum Adjust-ment Methods in Reactor Surveillance, E 706 (IIA)E1005 Test Method for Application and Analysis of Radio-metric Monitors for Reactor Vess
10、el Surveillance, E 706(IIIA)E1018 Guide for Application of ASTM Evaluated CrossSection Data File, Matrix E706 (IIB)3. Terminology3.1 DefinitionsFor definition of terms used in this testmethod, refer to Terminology C859 and E170. For terms notdefined therein, reference may be made to other publishedg
11、lossaries.44. Summary of the HAFM Test Method4.1 Helium accumulation fluence monitors (HAFMs) arepassive neutron dosimeters that have a measured reactionproduct that is helium. The monitors are placed in the reactorlocations of interest, and the helium generated through (n,)reactions accumulates and
12、 is retained in the HAFM (or HAFMcapsule) until the time of removal, perhaps many years later.1This test method is under the jurisdiction ofASTM Committee E10 on NuclearTechnology and Applicationsand is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition ap
13、proved Jan. 1, 2013. Published January 2013. Originallyapproved in 1982. Last previous edition approved in 2007 as E910 07. DOI:10.1520/E0910-07R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar
14、ds volume information, refer to the standards Document Summary page ontheASTM website. The roman numeral-alphabetical designation at the end of someof the titles indicates that a brief description of this standard may be found in MatrixE706.3The last approved version of this historical standard is r
15、eferenced onwww.astm.org.4See Dictionary of Scientific Terms, 3rd Edition, Sybil P. Parker, Ed., McGrawHill, Inc.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1The helium is then measured very precisely by high-sensitivitygas mass sp
16、ectrometry (1, 2).5The neutron fluence is thendirectly obtained by dividing the measured helium concentra-tion by the spectrum-averaged cross section. Competing he-lium producing reactions, such as (,) do not, except for9Be(,), affect the HAFM results. The range of heliumconcentrations that can be a
17、ccurately measured in irradiatedHAFMs extends from 1014to 101atom fraction. This rangepermits the HAFMs to be tested in low fluence environmentsyet to work equally well for high fluence situations.4.2 Typically, HAFMs are either individual small solidsamples, such as wire segments (3) or miniature e
18、ncapsulatedsamples of small crystals of powder (4), as shown in Fig. 1.Aswith radiometric dosimetry, different materials are used toprovide different energy sensitivity ranges. Encapsulation isnecessary for those HAFM materials and reactor environmentcombinations where sample melting, sample contami
19、nation, orloss of generated helium could possibly occur. Additionally,encapsulation generally facilitates the handling and identifica-tion of the HAFM both prior to and following irradiation. Thecontents of HAFM capsules typically range from 0.1 to 10 mg.4.3 Following irradiation, encapsulated HAFMs
20、 are cleanedand identified in preparation for helium analysis. Heliumanalysis is then accomplished by vaporizing both the capsuleand its contents and analyzing the helium in the resulting gasesin a high sensitivity mass spectrometer system (5). The amountof4He is determined by measuring the4He-to-3H
21、e isotopicratio in the sample gases subsequent to the addition of anaccurately calibrated amount of3He “spike.” UnencapsulatedHAFMs, for example, pure element wires, are usually etched toremove a predetermined layer of outer material before heliumanalysis (3). This eliminates corrections for both cr
22、oss con-tamination between samples and -recoil into or out of thesample during the irradiation.4.4 The4He concentration in the HAFM, in general terms,is proportional to the incident neutron fluence. Considerationmust, however, be made for such factors as HAFM materialburnup, neutron self-shielding a
23、nd flux depression, -recoil,and neutron gradients. Corrections for these effects are dis-cussed more fully in Section 13. Generally, they total less than5 % of the measured helium concentration. Since the individualcorrections are usually known to within 50 %, the total errorfrom these corrections a
24、mounts to 2 %. Sources of uncer-tainty also lie in the HAFM material mass, isotopiccomposition, and mass spectrometric helium analysis. Asindicated in Section 13, however, these uncertainties generallycontribute less than 1 % of the total uncertainty for routineanalyses.4.5 Applying the above correc
25、tions to the measured HAFMhelium concentration, the total incident neutron fluence (overthe energy range of sensitivity of the HAFM) can be obtaineddirectly from a knowledge of the spectrum-integrated totalhelium production cross section for the particular irradiationenvironment.At the present time,
26、 the uncertainty in the derivedneutron fluence is mainly due to uncertainty in the spectrum-integrated cross section of the HAFM sensor material ratherthan the combined uncertainties in the helium determinationprocess. This situation is expected to improve as the crosssections are more accurately me
27、asured, integrally tested inbenchmark facilities (6), and reevaluated.5. Significance and Use5.1 The HAFM test method is one of several availablepassive neutron dosimetry techniques (see, for example, Meth-ods E854 and E1005). This test method can be used incombination with other dosimetry methods,
28、or, if sufficient dataare available from different HAFM sensor materials, as analternative dosimetry test method. The HAFM method yields adirect measurement of total helium production in an irradiatedsample. Absolute neutron fluence can then be inferred fromthis, assuming the appropriate spectrum in
29、tegrated total heliumproduction cross section. Alternatively, a calibration of thecomposite neutron detection efficiency for the HAFM methodmay be obtained by exposure in a benchmark neutron fieldwhere the fluence and spectrum averaged cross section are bothknown (see Matrix E706 IIE).5.2 HAFMs have
30、 the advantage of producing an endproduct, helium, which is stable, making the HAFM methodvery attractive for both short-term and long-term fluencemeasurements without requiring time-dependent correctionsfor decay. HAFMs are therefore ideal passive, time-integrating5The boldface numbers in parenthes
31、es refer to the list of references appended tothis test method.FIG. 1 Helium Accumulation Fluence Monitor CapsuleE910 07 (2013)2fluence monitors. Additionally, the burnout of the daughterproduct, helium, is negligible.5.2.1 Many of the HAFM materials can be irradiated in theform of unencapsulated wi
32、re segments (see 1.1.2). Thesesegments can easily be fabricated by cutting from a standardinventoried material lot. The advantage is that encapsulation,with its associated costs, is not necessary. In several cases,unencapsulated wires such as Fe, Ni,Al/Co, and Cu, which arealready included in the st
33、andard radiometric (RM) dosimetrysets (Table 1) can be used for both radiometric and heliumaccumulation dosimetry. After radiometric counting, thesamples are later vaporized for helium measurement.5.3 The HAFM method is complementary to RM and solidstate track recorder (SSTR) foils, and has been use
34、d as anintegral part of the multiple foil method. The HAFM methodfollows essentially the same principle as the RM foil technique,which has been used successfully for accurate neutron dosim-etry for the past 20 to 25 years. Various HAFM sensormaterials exist which have significantly different neutron
35、energy sensitivities from each other. HAFMs containing10Band6Li have been used routinely in LMFBR applications inconjunction with RM foils. The resulting data are entirelycompatible with existing adjustment methods for radiometricfoil neutron dosimetry (refer to Method E944).5.4 An application for t
36、he HAFM method lies in the directanalysis of pressure vessel wall scrapings or Charpy blocksurveillance samples. Measurements of the helium productionin these materials can provide in situ integral information onthe neutron fluence spectrum. This application can providedosimetry information at criti
37、cal positions where conventionaldosimeter placement is difficult if not impossible. Analysesmust first be conducted to determine the boron, lithium, andother component concentrations, and their homogeneities, sothat their possible contributions to the total helium productioncan be determined. Boron
38、(and lithium) can be determined byconverting a fraction of the boron to helium with a knownthermal neutron exposure. Measurements of the helium in thematerial before and after the exposure will enable a determi-nation of the boron content (7). Boron level down to less than1 wt. ppm can be obtained i
39、n this manner.5.5 By careful selection of the appropriate HAFM sensormaterial and its mass, helium concentrations ranging from;1014to 101atom fraction can be generated and measured. Interms of fluence, this represents a range of roughly 1012to 1027n/cm2. Fluence (1 MeV) values that may be encountere
40、dduring routine surveillance testing are expected to range from;31014to21020n/cm2, which is well within the range ofthe HAFM technique.5.6 The analysis of HAFMs requires an absolute determi-nation of the helium content. The analysis system specified inthis test method incorporates a specialized mass
41、 spectrometerin conjunction with an accurately calibrated helium spikingsystem. Helium determination is by isotope dilution withsubsequent isotope ratio measurement. The fact that the heliumis stable makes the monitors permanent with the heliumanalysis able to be conducted at a later time, often wit
42、hout theinconvenience in handling caused by induced radioactivity.Such systems for analysis exist, and additional analysis facili-ties could be reproduced, should that be required. In thisrespect, therefore, the analytical requirements are similar toother ASTM test methods (compare with Test Method
43、E244).6. Apparatus6.1 High-Sensitivity Gas Mass Spectrometer System, ca-pable of vaporizing both unencapsulated and encapsulatedHAFM materials and analyzing the resulting total heliumcontent is required. A description of a suitable system iscontained in Ref (5).6.2 Analytical Microbalance for Accura
44、te Weighing ofHAFM Samples, minimum specifications: 200-mg capacitywith an absolute accuracy of 60.5 g. Working standardmasses must be traceable to appropriate national or interna-tional mass standards. Additionally, a general purpose balancewith a capacity of at least 200 g and an accuracy of 0.1 m
45、g isrequired for weighing larger specimens.TABLE 1 Neutron Characteristics of Candidate HAFM Materials for Reactor Vessel SurveillanceHAFM Sensor MaterialPrincipal Helium ProducingReactionThermal Neutron CrossSection, (b)Fission Neutron SpectrumCross Section, (mb)A90 % ResponseRange, (MeV)ALi6Li(n,)
46、T 942 457 0.1675.66Be9Be(n,)6He ;ra6Li . 284 2.57.3B10B(n,)7Li 3838 494 0.0665.25N14N(n,)11B . 86.2 1.75.7F19F(n,)16N . 27.6 3.79.7AlB 27Al(n,)24Na . 0.903 6.4711.9S32S(n,)29Si . . .Cl35Cl(n,)32P . ;13 (Cl) 2.68.3TiB 47Ti(n,)44Ca . 0.634 (Ti) 6.512.8FeB 56Fe(n,)53Cr . 0.395 (Fe) 5.211.9NiB 58Ni(n,)5
47、5Fe . 5.58 (Ni) 3.910.1CuB 63Cu(n,)60Co . 0.330 4.7411.1316-SSPV SteelCharpy BlockJHelium Production Largelyfrom56Fe and58NiAEvaluated235U fission neutron spectrum averaged helium production cross section and energy range in which 90 % of the reactions occur. All values are obtained fromENDF/B-V Gas
48、 Production Dosimetry File data. Bracketed terms indicate cross section is for naturally occurring element.BOften included in dosimetry sets as a radiometric monitor, either as a pure element foil or wire or, in the case of aluminum, as an allaying material for other elements.E910 07 (2013)36.3 Lami
49、nar flow (optional) clean benches, for use in thepreparation of HAFM samples and capsules.6.4 Stereo microscope, with 7 to 30 magnification, a;0.1-mm graticule, and an optical illuminator.6.5 Electron beam welder, with moveable platform stage,for sealing HAFM capsules, minimum specifications: variablebeam power to 0 to 1 kW, variable beam size capable offocusing down to a diameter of 0.5 mm. Controls must also beavailable to permit automatic control of beam duration andonset and offset beam power slopes.6.6 High temperature vacuum furnace for
