1、Designation: D5928 18aStandard Practice forScreening of Waste for Radioactivity1This standard is issued under the fixed designation D5928; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in paren
2、theses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the screening for , , and radiation above ambient background levels or user-definedcriteria, or both, in liquid, sludge, or solid
3、 waste materials.1.2 This practice is intended to be a gross screening methodfor determining the presence or absence of radioactive mate-rials in liquid, sludge, or solid waste materials. It is notintended to replace more sophisticated quantitative analyticaltechniques, but to provide a method for r
4、apidly screeningsamples for radioactivity above ambient background levels oruser-defined criteria, or both, for facilities prohibited fromhandling radioactive waste.1.3 This practice may not be suitable for applications suchas site assessments and remediation activities.1.4 The values stated in SI u
5、nits are to be regarded as thestandard.1.5 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
6、 of regulatory limitations prior to use.1.6 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
7、 Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear Materials3. Terminology3.1 For terminology related to radioactive materials, seeTerminology C859.4. Summary of Practice4.1 Asample is held within 6 mm of the
8、 detector window ofa radiation survey meter, and the visible or audible reaction ofthe meter, or both, is noted. The user defines an application/project-specific “negative” and “positive” result criteria. A“negative” test result indicates radiation levels are below theuser-established criteria; a “p
9、ositive” test result indicates theradiation levels are above the user-established criteria.5. Significance and Use5.1 Most facilities disposing or utilizing waste materials areprohibited from handling wastes that contain radioactive ma-terials. This practice provides the user a rapid method forscree
10、ning waste material samples in the field or laboratory forthe presence or absence of radioactivity at user-establishedcriteria. It is important to these facilities to be able to verifygenerator-supplied information that radioactive or mixedwastes have not been included in shipments of waste material
11、s.6. Interferences6.1 Needle deflections or audible clicks of the survey meter,or both, occur due to naturally occurring omni-directionalbackground radiation. This level of ambient background radia-tion should be periodically assessed. See Section 10.6.2 Possible sources of interference include pace
12、makers,X-ray-generating equipment, radium-based luminescent dials,polonium-based static eliminators, and smoke detectors con-taining a radioactive isotope-sensing mechanism. Such inter-ferences can usually be traced to their source using the portableinstrument specified in this practice.6.3 A large
13、amount of potassium in the waste sample mayproduce a positive result due to the natural presence of theradioactive isotope, potassium-40.6.4 The sensitivity of this practice to beta and gammaradiation may be dependent on sample volume.Asmall samplevolume with readings near background levels may give
14、 a falsenegative result.1This practice is under the jurisdiction of ASTM Committee D34 on WasteManagement and is the direct responsibility of Subcommittee D34.01.05 onScreening Methods.Current edition approved Sept. 1, 2018. Published September 2018. Originallyapproved in 1996. Last previous edition
15、 approved in 2018 as D5928 18. DOI:10.1520/D5928-18A.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.Copyrigh
16、t 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 Principles for theDevelopment of International
17、 Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16.5 Some radioactive isotopes, such as tritium/hydrogen-3and carbon-14, may not emit radiation of sufficient energy to bedetected. If suspected to be present in the waste, anoth
18、erprocedure should be used that is appropriate to their determi-nation.6.6 Liquid samples, as well as moisture in solid samples, aregood attenuators of radiation and will hinder detection of manyradionuclides unless they emit high-energy gamma radiation.The possible inability to detect alpha particl
19、es and low-levelbeta emissions that may be attenuated, in many cases, shouldnot be a serious shortcoming in this practice because theseemissions are often accompanied by higher-energy gammaemissions.6.6.1 Moisture-laden, americium-241-bearing waste wouldbe a case where there is a high probability of
20、 non-detection dueto attenuation.6.7 Survey meter contamination can cause artificially low orhigh results when reading standard sources or ambient back-ground. If this occurs, the survey meter performance shall beconsidered unreliable and should be appropriately decontami-nated by qualified personne
21、l, or disposed of in accordance withapplicable regulations.6.8 The radiation monitor should be operated in accordancewith the manufacturers instructions.7. Apparatus7.1 Radiation Survey Meter, with a halogen-quenched un-compensated Geiger-Mueller tube with thin mica end window.It is advisable to cho
22、ose an instrument model that has aninternal counter (cpm) or is capable of operating in a scalermode.38. Reagents and Materials8.1 The check sources used in the development of thispractice may be U.S. federally exempt and may not requirelicensing. Sources other than the following (that is, cesium-13
23、7) are appropriate for this practice. The sources, types ofactivity, levels of activity, and half-lives used in the develop-ment of this practice are as follows:Source Type Activity Half-Life (t12)polonium-210 alpha 3.7 kBq 138.4 daysstrontium-90 beta 3.7 kBq 28.6 yearscobalt-60 gamma 37 kBq 5.3 yea
24、rs8.2 Check sources should be replaced at least every threehalf-lives.9. Sample9.1 Because stratification of liquid samples is possible,thoroughly mix the sample by shaking or stirring prior totesting. Strongly multiphasic samples should have each layertested separately. Solid samples should be thor
25、oughly mixed bya method appropriate to their size and physical characteristics.10. Calibration and Standardization10.1 Check the battery power source of the survey meterprior to use. If the battery check indicates that the batterycharge is not in the optimal power range, it must be replacedprior to
26、use.10.2 Check the survey meters performance at least dailyusing the , , and check sources. This is done by observingthe survey meter response when held within 6 mm of eachcheck standard. At a minimum, check sources should be 2times the ambient background. The check sources listed in 9.1far exceed t
27、his requirement.10.3 The survey meter should be factory calibrated per themanufacturers requirements.10.4 Assess the level of ambient background radiationperiodically. This may be prior to each test, daily, weekly, ormonthly depending on user requirements.10.4.1 Set the survey meter to its X1 or mos
28、t sensitivesetting and enable the audible alarm, if unit is so equipped.10.4.2 Record the number of audible meter clicks over aperiod of 60 s (counts per minute). Repeat this procedure twomore times, and take the average of the three repetitions usingthe following formula:Average ambient background
29、radiation5Measurement No. 11Measurement No. 21Measurement No. 3310.5 Unexpectedly high readings for ambient background orstandard sources imply that the survey meter is contaminated.See Section 6 on Interferences.10.6 The user must clearly define the criteria to be used forreporting “negative” or “p
30、ositive” test results. These criteriamay be project or application specific. A common definingpoint used is “two to three times the ambient backgroundlevel.”11. Procedure11.1 Perform the necessary steps presented in Section 10.11.2 Allow the survey meter to stabilize for 10 to 15 s at itsX1 or lowes
31、t appropriate setting.11.3 Place the end window of the survey meter within 6 mmof the sample. Depending on the physical characteristics of thesample container (for example, the container is such that thesample is 6 mm from the opening), it may be necessary towithdraw a representative portion of the
32、sample to an alternatesample container, watch glass, or other appropriate vessel toallow the end window to be placed within 6 mm of the sample.Do not allow the survey meter to come into direct contact withthe sample. This may contaminate the meter and may damagethe end window.11.4 Record the counts
33、per minute for a period of 60 s(counts per minute). Repeat this procedure two more times, andtake the average of the three repetitions using the formula in10.4.2.3The meter used in the development of this practice was the Monitor 4manufactured by SE International, Inc., Summertown, TN. Through the e
34、ndwindow, this unit is capable of detecting and indicating alpha radiation (down to2.5 MeV with a typical detection efficiency of 80 % at 3.6 MeV), beta radiation(down to 150 keV with a typical 75 % detection efficiency), gamma radiation, andX-rays (down to 10 keV), with the survey meter set on its
35、lowest energy range of0.1 Sv/h. A number of vendors produce survey meters that are suitable for thispractice.D5928 18a211.5 If the counts per minute are above the user-definedcriteria, then the sample may contain radioactive material.NOTE 1The user should recognize the potential interferences men-ti
36、oned in Section 6.11.6 If radioactivity levels above the user-defined criteriaare observed, the background levels should be redetermined asdescribed in Section 10. The sample should then be retestedbeginning with 11.2.11.7 If radioactivity levels are confirmed to be above theuser-defined criteria, s
37、ample testing should be discontinued,and the appropriate health and safety professional or siteregulatory officer should be contacted for further instructions.11.8 If radioactivity levels are below the user-definedcriteria, the test result may be recorded as not detected.12. Precision and Bias12.1 P
38、recisionNo statement is made about the precisionbecause this screening practice produces only a positive ornegative test result.12.2 BiasNo statement is made about the bias because thisscreening practice produces only a positive or negative testresult.13. Keywords13.1 radioactivity; screening method
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