1、Designation: E910 18Standard Test Method forApplication and Analysis of Helium Accumulation FluenceMonitors for Reactor Vessel Surveillance1This standard is issued under the fixed designation E910; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e 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 accumulation for neutron fluence do
3、simetry 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 vessel surveillance are as foll
4、ows: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 samples for helium accumu-lation.1
5、.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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.
6、1.3 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to
7、 Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsE170 Terminology Relating to Radiation Measurements andDosimetryE261 Practice for Determining Neutron Fluence, FluenceRate, and Spectra by Radioactivation TechniquesE482 Guide for Applicat
8、ion of Neutron Transport Methodsfor Reactor Vessel SurveillanceE706 Master Matrix for Light-Water Reactor PressureVesselSurveillance StandardsE844 Guide for Sensor Set Design and Irradiation forReactor SurveillanceE853 Practice forAnalysis and Interpretation of Light-WaterReactor Surveillance Result
9、sE854 Test Method for Application and Analysis of SolidState Track Recorder (SSTR) Monitors for Reactor Sur-veillanceE900 Guide for Predicting Radiation-Induced TransitionTemperature Shift in Reactor Vessel MaterialsE944 Guide for Application of Neutron Spectrum Adjust-ment Methods in Reactor Survei
10、llanceE1005 Test Method for Application and Analysis of Radio-metric Monitors for Reactor Vessel SurveillanceE1018 Guide for Application of ASTM Evaluated CrossSection Data FileE2005 Guide for Benchmark Testing of Reactor Dosimetryin Standard and Reference Neutron Fields3. Terminology3.1 Definitions
11、For definition of terms used in this testmethod, refer to Terminologies C859 and E170. For terms notdefined therein, reference may be made to other publishedglossaries.34. Summary of the HAFM Test Method4.1 Helium accumulation fluence monitors (HAFMs) arepassive neutron dosimeters that have a measur
12、ed reactionproduct that is helium. The monitors are placed in the reactorlocations of interest, and the helium generated through (n,)reactions accumulates and is retained in the HAFM (or HAFMcapsule) until the time of removal, perhaps many years later.1This test method is under the jurisdiction ofAS
13、TM Committee E10 on NuclearTechnology and Applicationsand is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition approved Feb. 1, 2018. Published March 2018. Originallyapproved in 1982. Last previous edition approved in 2013 as E910 07 (2013).DOI: 10.1520/E
14、0910-18.2For 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 standards Document Summary page onthe ASTM website.3See Dictionary of Scientific Terms, 3rd Edition, Syb
15、il P. Parker, Ed., McGrawHill, Inc.Copyright ASTM International, 100 Barr Harbor 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 Pri
16、nciples for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1The helium is then measured very precisely by high-sensitivitygas mass spectrometry (1, 2).4The neutron fluence is thendirectly obtain
17、ed 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 accurately measured in irradiatedHAFMs extends from 1014to 101
18、atom 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 encapsulatedsamples of small crystals of powder (4), as shown
19、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 contamination, orloss of generated helium could possibly occur. Addi
20、tionally,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 are cleanedand identified in preparation for helium analysis
21、. 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-3He isotopicratio in the sample gases subsequent to the additio
22、n 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 cross con-tamination between samples and -recoil into or out of
23、 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 and flux depression, -recoil,and neutron gradients. Correction
24、s 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 amounts to 2 %. Sources of uncer-tainty also lie in the HAFM m
25、aterial 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 corrections to the measured HAFMhelium concentration, the total inc
26、ident 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, the uncertainty in the derivedneutron fluence is mainly due
27、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 measured, integrally tested inbenchmark facilities (6), and ree
28、valuated.5. Significance and Use5.1 The HAFM test method is one of several availablepassive neutron dosimetry techniques (see, for example, TestMethods E854 and E1005). This test method can be used incombination with other dosimetry methods, or, if sufficient dataare available from different HAFM se
29、nsor 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 integrated total heliumproduction cross section. Alternative
30、ly, 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 Guide E2005).5.2 HAFMs have the advantage of producing an endproduct, helium, which is st
31、able, 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-integrating4The boldface numbers in parentheses refer to the list of references appended tothis test method
32、.FIG. 1 Helium Accumulation Fluence Monitor CapsuleE910 182fluence 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 wire segments (see 1.1.2). Thesesegments can easily be fabricated by cu
33、tting 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 standard radiometric (RM) dosimetrysets (Table 1) can be used for both
34、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 used as anintegral part of the multiple foil method. The HAFM methodfoll
35、ows essentially the same principle as the RM foil technique,which has been used successfully for accurate neutron dosim-etry. Various HAFM sensor materials exist which have signifi-cantly different neutron energy sensitivities from each other.HAFMs containing10B and6Li have been used routinely inLMF
36、BR applications in conjunction with RM foils. Theresulting data are entirely compatible with existing adjustmentmethods for radiometric foil neutron dosimetry (refer to GuideE944 ).5.4 An application for the HAFM method lies in the directanalysis of pressure vessel wall scrapings or Charpy blocksurv
37、eillance samples. Measurements of the helium productionin these materials can provide in situ integral information onthe neutron fluence spectrum. This application can providedosimetry information at critical positions where conventionaldosimeter placement is difficult if not impossible. Analysesmus
38、t 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 (and lithium) can be determined byconverting a fraction of the boron to helium with a knownther
39、mal 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 in this manner.5.5 By careful selection of the appropriate HAFM sensormaterial and its mass, hel
40、ium 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 encounteredduring routine surveillance testing are expected to range from;31014to21020n/cm2, which is wel
41、l 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 spectrometerin conjunction with an accurately calibrated helium spikingsystem. Helium determin
42、ation 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 without theinconvenience in handling caused by induced radioactivity.Such systems for analysis exi
43、st, and additional analysis facili-ties could be reproduced, should that be required. In thisrespect, therefore, the analytical requirements are similar toother ASTM test methods.6. Apparatus6.1 High-Sensitivity Gas Mass Spectrometer System, ca-pable of vaporizing both unencapsulated and encapsulate
44、dHAFM materials and analyzing the resulting total heliumcontent is required. A description of a suitable system iscontained in Ref (5).6.2 Analytical Microbalance for Accurate Weighing ofHAFM Samples, minimum specifications: 200-mg capacitywith an absolute accuracy of 60.5 g. Working standardmasses
45、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 mg isrequired for weighing larger specimens.TABLE 1 Neutron Characteristics of Candidate HAFM Materials for Reactor Vessel Surve
46、illanceHAFM Sensor MaterialPrincipal Helium ProducingReactionThermal Neutron CrossSection, (b)Fission Neutron SpectrumCross Section, (mb)A90 % ResponseRange, (MeV)ALi6Li(n,)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.
47、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,)55Fe . 5.58 (Ni) 3.910.1CuB 63Cu(n,)60Co . 0.330 4.7411.1316-SSPV SteelCharpy BlockJHelium Production Largelyfrom56Fe and58NiAEv
48、aluated235U 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 Production Dosimetry File data. Bracketed terms indicate cross section is for naturally occurring element.BOften included in d
49、osimetry 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 1836.3 Laminar 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 diamete
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