This standard provides criteria for defining Airborne Release Fractions (ARFs) for radioactive materials under accident conditions (excluding nuclear criticalities) at non-reactor nuclear facilities. The criteria in this standard provide requirements for selecting ARFs based on the calculated or assumed forms of radioactive material released. This standard may be applied to determine the ARFs for certain applicable reactor plant events for which alternative methodologies are not mandated by regulatory requirements. Because the predominant physical forms of radioactive materials in non-reactor facilities are solids and liquids, the standard focuses on these forms. Criteria are also provided for gases and materials that can be converted into the form ofa vapor.

Purpose. This standard addresses criteria for selecting appropriate ARFs to estimate the airborne release from accident phenomena that can subdivide and suspend radioactive materials from various initiating events. The purpose of this standard is to provide a uniform approach for the selection of ARFs used in consequence assessments based upon the degree of definition of the relevant parameters (Le., the type and level of the suspension mechanism applied to the material- at-risk and the behavior of other materials and equipment that may affect the airborne release) and the complexity of the initiating event.

The criteria for selecting ARFs are presented in Section 3. Section 4 discusses the limitations of the standard. Background information on the analytical process commonly employed to calculate source terms is necessary to understand fully all aspects of the ARF selection process; sample problems illustrating the application of ARFs to some accident scenario analysis are also helpful.¹

¹Infonnation on this topic is provided in Appendix B.