1、Designation: C1671 15Standard Practice forQualification and Acceptance of Boron Based MetallicNeutron Absorbers for Nuclear Criticality Control for DryCask Storage Systems and Transportation Packaging1This standard is issued under the fixed designation C1671; the number immediately following the des
2、ignation indicates the year 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 practice provides proced
3、ures for qualification andacceptance of neutron absorber materials used to providecriticality control by absorbing thermal neutrons in systemsdesigned for nuclear fuel storage, transportation, or both.1.2 This practice is limited to neutron absorber materialsconsisting of metal alloys, metal matrix
4、composites (MMCs),and cermets, clad or unclad, containing the neutron absorberboron-10 (10B).1.3 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 prac
5、tices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B557 Test Methods for Tension Testing Wrought and CastAluminum- and Magnesium-Alloy ProductsB557M Test Methods for Tension Testing Wrought and CastAluminum- and Magnesium-Alloy Pr
6、oducts (Metric)C791 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade Boron Car-bideE8 Test Methods for Tension Testing of Metallic MaterialsE21 Test Methods for Elevated Temperature Tension Tests ofMetallic MaterialsE456 Terminology Relating to Quality and
7、StatisticsE1225 Test Method for Thermal Conductivity of SolidsUsing the Guarded-Comparative-Longitudinal Heat FlowTechniqueE1461 Test Method for Thermal Diffusivity by the FlashMethod3. Terminology3.1 Definitions:3.1.1 acceptance test, nfor a neutron absorber material,quality control, tests, and ins
8、pections conducted to determinewhether a specific production lot meets selected specifiedmaterial properties, characteristics, or both, so that the lot canbe accepted.3.1.2 areal density, nfor neutron absorber materials withflat parallel surfaces, the density of the neutron absorber timesthe thickne
9、ss of the material (g/cm2).3.1.3 durability, nthe ability of neutron absorber materialsto withstand service conditions without physical changes thatwould render them unable to perform their design functions.3.1.4 lot, na quantity of a product or material accumulatedunder conditions that are consider
10、ed uniform for samplingpurposes. E4563.1.5 moderator, na material used to reduce neutronenergy by scattering without appreciable capture.3.1.6 neutron absorber, na nuclide that has a large thermalneutron absorption cross section (also known as a neutronpoison).3.1.7 neutron-absorber material, na com
11、pound, alloy,composite or other material that contains a neutron absorber.3.1.8 neutron attenuation test, nfor neutron absorbermaterials, a process in which a material is placed in a thermalneutron beam, and the number of neutrons transmitted throughthe material in a specified period of time is coun
12、ted. Theneutron count can be converted to areal density by performingthe same test on a series of appropriate calibration standardsand comparing the results.3.1.9 neutron cross section, barn, na measure of theprobability that a neutron will interact with a nucleus in theabsorbing medium and is a fun
13、ction of the neutron energy.3.1.10 open porosity, nthe volume fraction of all pores,voids, and channels within a solid mass that are interconnected1This practice is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.03 on NeutronAbs
14、orber Materials Specifications.Current edition approved Jan. 1, 2015. Published January 2015. Originallyapproved in 2007. Last previous edition approved in 2007 as C1671-07. DOI:10.1520/C1671-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、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 Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1with each other and communicate with the external su
16、rface,and thus are measurable by gas or liquid penetration. C242,C213.1.11 packaging, nin transport of radioactive material,the assembly of components necessary to enclose the radioac-tive contents completely.33.1.12 probability sampling, na sample selection proce-dure in which the sampling units ar
17、e selected by a chanceprocess such that, at each step of the selection, a specifiedprobability of selection can be attached to each sampling unitavailable for selection. E4563.1.13 qualification, nfor neutron absorber materials, theprocess of evaluating, testing, or both, a material produced bya spe
18、cific manufacturing process to demonstrate uniformityand durability for a specific application.3.1.14 systematic sampling, na sample selection proce-dure in which every kth element is selected from the universeor population, for example, u, u + k, u +2k, u +3k, etc., whereu is in the interval 1 to k
19、. E4563.2 Definitions of Terms Specific to This Standard:3.2.1 Designer, nthe organization responsible for the de-sign or the license holder for the dry cask storage system ortransport packaging. The designer is usually the purchaser ofthe neutron absorber material, either directly or indirectly(thr
20、ough a fabrication subcontractor).4. Significance and Use4.1 For criticality control of nuclear fuel in dry storage andtransportation, the most commonly used neutron absorbermaterials are borated stainless steel alloys, borated aluminumalloys, and boron carbide aluminum alloy composites. Theboron us
21、ed in these neutron absorber materials may be naturalor enriched in the nuclide10B. The boron is usually incorpo-rated either as an intermetallic phase (for example, AlB2,TiB2,CrB2, etc.) in an aluminum alloy or stainless steel, or as a stablechemical compound particulate such as boron carbide (B4C)
22、,typically in an aluminum MMC or cermet.4.2 While other neutron absorbers continue to be investi-gated,10B has been most widely used in these applications, andit is the only thermal neutron absorber addressed in thisstandard.4.3 In service, many neutron absorber materials are inac-cessible and not a
23、menable to a surveillance program. Theseneutron absorber materials are often expected to perform overan extended period.4.4 Qualification and acceptance procedures demonstratethat the neutron absorber material has the necessary character-istics to perform its design functions during the servicelifet
24、ime.4.5 The criticality control function of neutron absorbermaterials in dry cask storage systems and transportationpackagings is only significant in the presence of a moderator,such as during loading of fuel under water, or water ingressresulting from hypothetical accident conditions.4.6 The expect
25、ed users of this standard include designers,neutron absorber material suppliers and purchasers, govern-ment agencies, consultants and utility owners. Typical use ofthe practice is to summarize practices which provide input fordesign specification, material qualification, and productionacceptance. Ad
26、herence to this standard does not guaranteeregulatory approval; a government regulatory authority mayrequire different tests or additional tests, and may impose limitsor restrictions on the use of a neutron absorber material.5. Procedure5.1 Determination of Service Conditions and Design Re-quirement
27、s for the Neutron Absorber MaterialThe designershall specify the service conditions and design requirements,including environmental conditions, mechanical properties,and areal density or equivalent measure of neutron absorbercontent. Selection of environmental and service conditions thatare importan
28、t for neutron absorber material performance andqualification should take into consideration known failuremodes and industry experience.5.1.1 Environmental conditions to be considered include butare not limited to water chemistry, water temperature, paireddissimilar materials, hydrostatic pressure, d
29、uration ofimmersion, gamma and fast neutron flux, heat-up rate afterdraining, and maximum temperature.5.1.2 For structural applications, specify the mechanicalproperties required by the structural analysis. For non-structural uses of the neutron absorber material, specify me-chanical properties suff
30、icient to assure material durabilityunder the service conditions for which it is designed.5.1.3 Specify other design properties, for example, thermalconductivity, surface finish, etc., as required for the applica-tion.5.1.4 Product or feed material chemistry shall be specified.5.2 Neutron Absorber M
31、aterial QualificationQualificationshall consist of three components: (1) verify durability for theintended service as defined in 5.2.5, (2) verify that the physicalcharacteristics of components meet their design requirementsdefined in 5.2.6, and (3) verify that the uniformity of the10Bdistribution i
32、n the neutron absorber material is within accept-able bounds as specified by the designer as described in 5.2.6.5.2.1 Qualification is needed:5.2.1.1 When the neutron absorber material has not beenpreviously qualified,5.2.1.2 When a new supplier is producing a qualifiedneutron absorber material, or5
33、.2.1.3 When any key process or process control, as definedin 5.2.7, is altered for production of a qualified neutronabsorber material.5.2.2 The key processes and process controls for producingneutron absorber material for qualification should be the sameas those to be used for commercial production.
34、 Differencesshall be justified per 5.2.7.5.2.3 If a previously qualified material is manufactured by anew supplier, the designer should do a review of key processand controls and perform qualification testing demonstrating3“Regulations for the Safe Transport of Radioactive Material,” Safety SeriesSt
35、andards No. TS-R-1, International Atomic Energy Agency, Vienna, Austria.C1671 152that the neutron absorbing material has the required properties.If the supplier has shown that process changes do not causechanges in the density, open porosity, composition, surfacefinish, or cladding (if applicable) o
36、f the neutron absorbermaterial, the supplier should not be required to re-qualify thematerial with regard to thermal properties or resistance todegradation by corrosion and elevated temperatures.5.2.4 If a neutron absorber material can not be qualifiedcompletely by reference to prior testing with si
37、milar neutronabsorber materials for similar design functions and serviceconditions, complete the qualification by performing testing orportions thereof as described in 5.2.5 and 5.2.6.5.2.5 Environmental Qualification TestsFor these tests,verify by visual and dimensional inspection, mechanicaltestin
38、g, neutron attenuation testing, etc., as appropriate, that theneutron absorber material does not undergo physical changesthat would render it unable to perform its design functions.5.2.5.1 For radiation and thermal testing, expose the neutronabsorber material to the service conditions or equivalenta
39、ccelerated conditions.5.2.5.2 Corrosion testing shall consist of exposing testspecimens of the neutron absorber material to simulate in-service immersion conditions.5.2.5.3 If the neutron absorber material has open porosity,test it under simulated loading and service conditions usingbounding pressur
40、e, temperature, time, and vacuum.5.2.6 Mechanical, Absorber Uniformity, and Other Qualifi-cation Testing:5.2.6.1 Perform tensile tests according to Test MethodB557, B557M, E8,orE21. Perform any other mechanicaltesting, for example, fracture toughness testing, bend testing,etc., in accordance with th
41、e appropriate ASTM test method.For neutron absorber materials where standardized testing isnot appropriate, such as for laminates, develop the mechanicaltest appropriate for the materials.NOTE 1Most neutron absorbers are non-structural and are held inplace during service by structural components. If
42、 the absorber material isintended as a structural member, other tests may be necessary to conformto a structural code (for example, ASME Boiler and Pressure VesselCodes). It may also be necessary to consider the long term servicetemperature and the effect of aging on the tensile strength of aluminum
43、alloy-based absorber materials.5.2.6.2 Assess the uniformity of B10in the neutron absorbermaterial by measuring either the neutron absorber density(g/cm3) and thickness, or the areal density (g/cm2). Twomethods to assess uniformity include probability sampling orsystematic sampling throughout the te
44、st material, provided thatthe systematic sampling method is conservative. Determine thelower tolerance limit of the measurements as described in item#1 example below.Acceptance of Neutron absorbers shall meeta minimum 95 % confidence and 95 % probability criteria. Ifuniformity testing for areal dens
45、ity will be by means other thanneutron attenuation, the user of the proposed method shallconfirm that the proposed method is acceptable to the designer.(1) Neutron attenuation is a convenient method of deter-mining the10B content of the neutron absorber material andmay be used to analyze the10B unif
46、ormity. For neutronattenuation testing, compare thermal neutron attenuationthrough the product with attenuation through calibration stan-dards. The attenuation tests on the calibration standards and onthe product shall use the same test equipment and configura-tion. Homogenous neutron absorbing mate
47、rials with uniformabsorption properties such as zirconium diboride (ZrB2)orhot-pressed boron carbide (B4C), (typically paired with alumi-num shims) or heterogeneous calibration standards with trace-able pedigrees are acceptable as neutron attenuation calibrationstandards.(2) Neutron attenuation meas
48、urements shall be performedin accordance with written procedures that address, as aminimum, the following:(a) The calibration standards used and their validation,(b) The frequency of calibration as required to account forneutron beam intensity variation, or source decay,(c) Neutron source and beam c
49、ollimation, if any. Thecollimated beam size shall not exceed the active area ofthe detector.(d) Method of interpolation between calibration points, and(e) Neutron detection instrumentation.(f) If the material used for calibration standards containsneutron absorbing or scattering nuclides not present in theneutron absorber material to be examined, the procedureshall address the effect of these nuclides on the accuracyof the measurements.(3) Using a goodness of fit test, determine if the set ofmeasurement data is normally distributed. For a normaldistribution, calcu
