ANS 5 10-1998 Airborne Release Fractions at Non-Reactor Nuclear Facilities (Includes Appendix A 2013 Appendix B and Appendix C)《非反应堆核设施中的空气释分》.pdf
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1、REAFFIRMED January 15, 2013 ANSI/ANS-5.10-1998 (R2013) ANSI/ANS-5.10-1998 (R2013)with 2013 Appendix A Update American National Standard ANSI/ANS-5.10-1998 Appendix A (updated 2013) (This Appendix is not a part of American National Standard for Airborne Release Fractions at Non-Reactor Nuclear Facili
2、ties, ANSI/ANS-5.10-1998.) Airborne Release Fraction Values Available in the Literature A1. Literature Sources The primary literature source for the Airborne Release Fraction is DOE-HDBK-3010 (DOE 1994), which covers the range of experimental parameters that are cited in the literature and contains
3、references to the experimental basis for the ARF and RF values cited. Other experimental studies used, but not cited in DOE-HDBK-3010, are referenced as appropriate. A2. Guidance in Application of Values in Tables The values cited in Table A1 are taken from experimental studies that utilize specific
4、 materials and types and levels of stress. Each specific material has characteristics that are influenced by the type and level of stress imposed resulting in the separation and suspension of the material. Both the characteristics of the material and type/level of stress affect the airborne release.
5、 The ambient airflow around the suspended material affects transport. Thus, specific values must be chosen with great care. In many cases where the material is inert to the chemical environment, the airborne release value can be representative of the airborne release for all similar physical materia
6、ls. Such is the case for suspension of chemically-inert compounds in powder form by aerodynamic forces at normal temperatures and for the fragmentation of brittle materials by crush-impact forces. In other cases, such as the generation of volatile materials due to chemical reactions (e.g., iodine ge
7、neration), the airborne release value is sensitive to the chemical and physical environment and not directly applicable to other volatile materials. Even droplets of aqueous solution can be modified by the environment they are suspended in by the effects of evaporation or the condensation of the sol
8、vent during airborne transport. The release mechanisms are also different for combinations of materials and stress. Pre-formed particles (powders) under aerodynamic stress behave differently depending upon whether the material is a pile that projects into the flow field (typically considered fugitiv
9、e emissions), in a smooth layer within the boundary layer on a heterogenous substrate, in a sparse layer, or in a homogeneous layer. The value for airborne release selected must be based upon the combination of material characteristics and type and level of stress. The type and level of stress is ty
10、pically determined by the postulated scenario and the postulated/calculated behavior of the other materials involved (e.g., fire, explosion, earthquake, high winds, process malfunction). On a “worst case” basis with little analysis of the behavior of materials, equipment, or structures, “bounding” c
11、alculations are appropriate. In these cases, the physical limits of the materials are used, such as the total heat of combustion expressed as a TNT Equivalent for explosions. Bear in mind that the TNT Equivalents so estimated for gaseous mixtures or for non-explosive solids may be gross exaggeration
12、s of the actual conditions. Nonetheless, if the calculated values for the level of stress are within the bounds of the experimental data, the ARFs and RFs can be applied to physically similar materials. For more detailed calculations of the potential airborne release, analysis of the limiting materi
13、als (e.g., strength of barriers, oxygen availability for fires, rupture pressure for pressure-volume/over-pressurization events), and the responses of materials, barriers, and equipment to the type and level imposed, must also be considered. Where experimental data for the material-of-concern and th
14、e stress combination are available, the data may be interpolated to provide a closer estimate of airborne release. If the material-of-concern is chemically/physically similar to the materials used in the experimental study, such an American National Standard ANSI/ANS-5.10-1998 interpolated result ma
15、y also be applicable. If the material-of-concern is dissimilar, the level of stress exceeds the range used in the experimental study, or the material-of-concern or type of stress has not been studied, the user should make the commitment to perform experimental studies and have the results reviewed a
16、nd published prior to the extensive engineering analyses of the response of materials to the applied stress. Such extensive engineering analyses are of little benefit without the experimental data to provide more realistic estimates. In some cases where experimental studies have used materials with
17、similar characteristics but have deviations that would produce conservative estimates in the specific case addressed (e.g., a finer size distribution of a dry, cohesionless powder is used in the experimental study), the interpolation could be applicable. Extrapolation of the results from experimenta
18、l studies must be approached with greater caution. If the release mechanism is known and does not change over the range of interest, extrapolation of the experimental data may be useful (e.g., fragmentation of brittle solids by crush-impact forces) but all parameters that affect the results must be
19、considered. In the example cited, fragmentation of brittle solids by crush-impact forces, both the physical characteristics of the impacted material and the configuration are important. In the experimental studies, it was ensured that all the brittle materials were subjected to crush-impact forces b
20、ecause the plate applying the force covered the entire surface of one side of the specimen. The fragmentation and size distribution of the fragments are a function of the energy density applied per unit volume or per unit mass. For the configuration where the impacting object is less than the entire
21、 surface, one must address the question of the volume impacted (the volume in which the shock/pressure waves propagate and are reflected through the material to result in fragmentation). An additional consideration for particles is the effect on both the supension and the transport of the suspended
22、materials of the sizes of individual particles and the size distribution of the entire sample. The size units used in this table are normalized by use of micrometers of Aerodynamic Equivalent Diameter the diameter of a sphere of material with a density of 1 g/cm3that has the same terminal (settling)
23、 velocity as the particle. This is appropriate inasmuch as both the airborne transport and inhalation are functions of the aerodynamic characteristics of the particle. The size distribution of the airborne particles are a function of the formation process and the duration airborne. When initially fo
24、rmed, particles are typically log-normally distributed and their distribution can be defined by the Aerodynamic Mass Median Diameter (AMMD) and the Geometric Standard Deviation (GSD) (the slope of the curve on log-probability graph of the cumulative mass versus size). If the preformed particles (pow
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