1、ANSI/ANS-6.4.2-2006specification for radiationshielding materialsANSI/ANS-6.4.2-2006REAFFIRMED September 27, 2016 ANSI/ANS-6.4.2-2006; R2016 This standard has been reviewed and reaffirmed with the recognition that it may reference other standards and documents that may have been superseded or withdr
2、awn. The requirements of this document will be met by using the version of the standards and documents referenced herein. It is the responsibility of the user to review each of the references and to determine whether the use of the original references or more recent versions is appropriate for the f
3、acility. Variations from the standards and documents referenced in this standard should be evaluated and documented. This standard does not necessarily reflect recent industry initiatives for risk informed decision-making or a graded approach to quality assurance. Users should consider the use of th
4、ese industry initiatives in the application of this standard. ANSI/ANS-6.4.2-2006American National StandardSpecification for RadiationShielding MaterialsSecretariatAmerican Nuclear SocietyPrepared by theAmerican Nuclear SocietyStandards CommitteeWorking Group ANS-6.4.2Published by theAmerican Nuclea
5、r Society555 North Kensington AvenueLa Grange Park, Illinois 60526 USAApproved September 28, 2006by theAmerican National Standards Institute, Inc.AmericanNationalStandardDesignation of this document as an American National Standard attests thatthe principles of openness and due process have been fol
6、lowed in the approvalprocedure and that a consensus of those directly and materially affected bythe standard has been achieved.This standard was developed under procedures of the Standards Committee ofthe American Nuclear Society; these procedures are accredited by the Amer-ican National Standards I
7、nstitute, Inc., as meeting the criteria for AmericanNational Standards. The consensus committee that approved the standardwas balanced to ensure that competent, concerned, and varied interests havehad an opportunity to participate.An American National Standard is intended to aid industry, consumers,
8、 gov-ernmental agencies, and general interest groups. Its use is entirely voluntary.The existence of an American National Standard, in and of itself, does notpreclude anyone from manufacturing, marketing, purchasing, or using prod-ucts, processes, or procedures not conforming to the standard.By publ
9、ication of this standard, the American Nuclear Society does not insureanyone utilizing the standard against liability allegedly arising from or afterits use. The content of this standard reflects acceptable practice at the time ofits approval and publication. Changes, if any, occurring through devel
10、opmentsin the state of the art, may be considered at the time that the standard issubjected to periodic review. It may be reaffirmed, revised, or withdrawn atany time in accordance with established procedures. Users of this standardare cautioned to determine the validity of copies in their possessio
11、n and toestablish that they are of the latest issue.The American Nuclear Society accepts no responsibility for interpretations ofthis standard made by any individual or by any ad hoc group of individuals.Requests for interpretation should be sent to the Standards Department atSociety Headquarters. A
12、ction will be taken to provide appropriate response inaccordance with established procedures that ensure consensus on theinterpretation.Comments on this standard are encouraged and should be sent to SocietyHeadquarters.Published byAmerican Nuclear Society555 North Kensington AvenueLa Grange Park, Il
13、linois 60526 USACopyright 2006 by American Nuclear Society. All rights reserved.Any part of this standard may be quoted. Credit lines should read “Extracted fromAmerican National Standard ANSI0ANS-6.4.2-2006 with permission of the publisher,the American Nuclear Society.” Reproduction prohibited unde
14、r copyright conventionunless written permission is granted by the American Nuclear Society.Printed in the United States of AmericaForewordThis Foreword is not a part of American National Standard “Specification for RadiationShielding Materials,” ANSI0ANS-6.4.2-2006.!The need for this standard was id
15、entified in mid-1977 by Working Group ANS-6.4.At that time, it was recognized that an increasing number of different material0design shielding concepts were being introduced into nuclear power plants tosolve neutron and gamma-ray streaming problems. For protection against neu-tron streaming, materia
16、ls varying from water-filled rubber bags, rubber balls,special concretes, treated plastics, and silicone gels were proposed, while lead-filled silicone rubber and gels were proposed for gamma-ray streaming. Withsuch a variety of materials, some only a year or two after initial commercialintroduction
17、, a clear need was discerned to standardize the specification of thesematerials to assist the material manufacturer in the type of information he orshe needs to provide to the user.The focus of the working groups initial work was to orient the standard towardthe reporting requirements used by materi
18、al suppliers rather than toward thepreparation of specifications by designers and end users. This focus has beenmaintained through the development of this standard as that representing thetrue needs of nuclear power plants in this area. The standard was reaffirmed in1997 and again in 2004, at which
19、time a working group was appointed andcharged with revision of the standard.Working Group 6.4.2 of the American Nuclear Society Standards Committee hadthe following membership at the time of this revision:R. E. Faw Chair!, IndividualC. C. Graham, AmerenUE Callaway PlantS. J. Haynes, Sandia National
20、LaboratoriesT. M. Lloyd, EnergySolutionsJ. D. Olson, Black the word “should” is used to denote arecommendation; and the word “may” is usedto denote permission, neither a requirementnor a recommendation. To conform with thisstandard, materials that are to be consideredfor use as a radiation shield sh
21、all be evaluatedagainst the physical and nuclear properties thatthe standard sets forth. Accuracy of the deter-mined values shall be provided. Unless other-wise specified, it will be assumed that all valuesare at a pressure of 1 atm. Units used in spec-ifying properties shall be in the SI system ass
22、pecified in this standard but may be ex-pressed in other convenient units as well.3 Terms and definitionsThe following terms and definitions are pro-videdtoassureuniformunderstandingofthese-lectedtermsasareusedinthisstandard.Alargenumberofadditionaltermsthatareusedarede-finedinthefollowingdocuments:
23、“StandardTer-minology Relating to Methods of MechanicalTesting,” ASTM E6-06 1#;1!“Terminology Re-lating to Density and Specific Gravity of Solids,Liquids,andGases,”ASTME12-70R1991,with-drawn 1996!2#; “Standard Terminology of FireStandards,”ASTME176-05a3#;“StandardTer-minology Relating to Rubber,” AS
24、TM D1566-064#; “Cement and Concrete Terminology,” ACI-116R-00 R2005!5#;andGlossary of Terms inNuclear Science and Technology1986!6#.Arrhenius model: A model commonly used inaccelerated aging tests that relates the rate ofreaction of a material to temperature by a sim-ple exponential function, r H110
25、05 AexpH11002H90210kT!,where r is the reaction rate, A is a materialconstant frequency factor!, H9021 is the activationenergy of the material eV!, k is Boltzmannsconstant 0.8617 H11003 10H110024eV0K!, and T is theabsolute temperature K!.bremsstrahlung: Gamma radiation emitted byan electron when it i
26、s deflected by the Cou-lomb field of an atomic nucleus of charge Z;thefraction of energy radiated as photons by anelectron of initial energy E MeV! is approxi-mated numerically by ZE01000.equivalent test:Atest method utilized in placeof a standard or reference test that achievesthe same end result.i
27、nduced radioactivity: Radioactivity due tothe interaction of an external neutron radia-tion field with the nuclides of a material.operating range: The range of values overwhich a parameter, indicative of environmen-tal conditions, is stated to vary during the ex-pected life of a material as it perfo
28、rms itsintended function.photoneutron: Neutron released from anatomic nucleus in a photonuclear reaction witha gamma ray of sufficiently high energy. Thethreshold energy required of the gamma ray is;2 MeV for beryllium and deuterium but .8MeV for other elements.specific gravity: For the purposes of
29、this stan-dard, specific gravity is considered numeri-cally equal to density expressed in units g0cm3.trace element: An element found in smallquantities usually ,1%! within a material.trace radioactivity: Radioactivity due to traceamounts of naturally occurring radioisotopescontained within a materi
30、al.1!Numbers in brackets refer to corresponding numbers in Sec. 8, “References.”14 Introduction and generaldescription4.1 IntroductionThepropertiesdiscussedinthisstandardarecon-sidered to be the most important ones for radi-ation shielding materials primarily as used innuclear power plants; however,
31、 they should notbeviewedascomprisinganall-inclusivelist.In-cluded in Sec. 5 are the nuclear properties andin Sec. 6 are the general physical properties.Users of this standard should recognize that interms of the shielding function of a material,some properties are more important than oth-ers because
32、 of the direct impact they have. In-cluded among these are density and the nuclearproperties. Other physical properties, e.g., sta-bility, strength, and fabrication, are needed todefine fully the conditions and capabilities ofcandidate materials but are of more peripheralinterest to the shielding fu
33、nction. This stan-dard does provide guidance for the consider-ation of those more peripheral properties byreferencing examples of American Society forTesting and Materials ASTM! standards thatare available. However, there may be other stan-dards that provide a fundamental and moredetailed discussion
34、 of these properties and howthey are used. Such standards are properly theworking tools of engineering disciplines otherthan radiation shielding, and the ultimate de-cisions relating to such properties reside withthese other engineering disciplines.4.2 General descriptionInformation on the general d
35、escription of amaterial such as its physical state, type, andintended use should be used in the initialidentification of potentially appropriate mate-rials for a specific application. Such informa-tion is generally supplied by material vendorsbut needs to be supplemented by the specificproperties di
36、scussed in this standard. Anyknown environmental restrictions shall beidentified.5 Nuclear properties of materials5.1 IntroductionThe selection of an appropriate shielding ma-terial is most strongly influenced by its nu-clear properties, i.e., its ability to provide therequired attenuation of neutro
37、n radiation orgamma radiation, or both, per unit thicknesswithout creating deleterious nuclear, physical,or chemical side effects. These nuclear proper-ties are dependent on the isotopic compositionof the material.This section of the standard sets forth two al-ternate sets of data requirements that
38、serve todefine the nuclear properties of the candidateshielding material. One requirement applies tothe case where the supplier provides a com-plete elemental composition of the candidatematerial and is more fully described in Sec. 5.2.The alternative requirement applies when thesupplier provides at
39、tenuation and other nu-clear information directly, which is more fullydescribed in Sec. 5.3. The intent of the stan-dard is to encourage the material supplier touse the first alternative whenever practical.That the first alternative may also be advan-tageous from the viewpoint of the material sup-pl
40、ier is illustrated in Ref. 7#.5.2 Elemental compositionThe supplier shall provide a detailed materialcomposition; the data shall be in the format ofthe density of each element of the compoundg0cm3or kg0m3!. In the case of any elementwhose isotopes are not naturally abundant, suchas depleted uranium,
41、 the composition of thiselement shall be subdivided into compositionby isotope. If lithium or boron is a componentof a neutron shield material, the isotopic abun-dance shall be provided since there is a largedifference in the neutron cross-section proper-ties between the isotopes of these elements a
42、ndsome variation in the naturally occurring iso-topic abundances in available material. Forshields containing an appreciable proportion ofhydrogen and where the neutron field to beshielded is largely thermal neutrons, it is alsoappropriate to indicate the molecular form inwhich the hydrogen atoms ex
43、ist.5.2.1 Environmental considerationsThe elemental composition of the materialandisotopic breakdown for special elements such asin Sec. 5.2! shall be given along with the phys-ical and chemical conditions under which suchcompositionisapplicable.Theseconditionsmightbe temperature, pressure, humidity
44、, physicalform, age, etc. Variations of elemental composi-American National Standard ANSI0ANS-6.4.2-20062tionswiththeseconditionsshouldalsobegiven,either in accord with Sec. 5.2.4 of this standardor with a later section. The basis, i.e., type ofstandard or equivalent test, used in determin-ing the c
45、omposition should also be provided.5.2.2 Trace elementsTrace elements can be very important in theselection of a shielding material if the materialis intended to be used in the presence of aneutron field. This importance stems from thevery large differences among the elements intheir neutron interac
46、tion probabilitiescross sec-tions! that lead to the formation of activationproducts that emit gamma rays. Trace ele-ments, therefore, shall be provided by the sup-plier as part of the elemental composition ofthe material.2!5.2.3 Trace radioactivityTrace radioactivity is detrimental when theshield ma
47、terial application is a low-level count-ing room, health physics laboratory, or analyt-ical laboratory. Examples of trace radioactivityisotopes are40K in concrete,204Pb in shieldingmaterials containing lead,209Bi in certain melt-able alloys, and numerous long-lived radioiso-topes in thorium and uran
48、ium. Trace radioactiveisotope content shall be included in the compo-sition of materials intended to be used for suchapplications.5.2.4 Test documentationThe supplier should describe the laboratorymethods utilized to measure the material com-position or reference an existing industry stan-dard proce
49、dure, such as those published by theAmerican National Standards Institute. Thephysical and chemical conditions existing atthe time of measurement should be stated. Insome cases, the weight percentages of the ele-mental constituents will remain constant overa wide range of temperature, pressure, and otherenvironmental changes; in other cases, the ele-mental makeup will change e.g., loss of waterwith increasing temperature!. The suppliershould provide, in accordance with this sectionor later sections of the standard, definitive in-formation on how the composition var
