Document: NRC Regulatory Guide
Document ID: 4d46a966-d280-43da-9b03-8b0abe7b29ce
Document Type: regulatory_guide
Title: Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2120/ML21204A065.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.183
CFR Part: 
CFR Title: 

Content:
ge should be apportioned between the steam generators in a manner that maximizes the calculated dose. G-5.2 The density used in converting volumetric leak rates (e.g., gallons per minute) to mass leak rates (e.g., pound mass per hour) should be consistent with the basis of surveillance tests used to show compliance with leak rate technical specifications. These tests are typically based on cool liquid. Facility instrumentation used to determine leakage is typically located on lines containing cool liquids. In most cases, the density should be assumed to be 1.0 gram per cubic centimeter (62.4 pounds mass per cubic foot). 1 Facilities licensed with, or applying for, alternative repair criteria should use this section in conjunction with the guidance that is being developed in Draft Regulatory Guide DG-1074, “Steam Generator Tube Integrity,” issued December 1998, for acceptable assumptions and methodologies for performing radiological analyses. DG-1389, Appendix G, Page G-2 G-5.3 The primary-to-secondary leakage should be assumed to continue until the primary system pressure is less than the secondary system pressure, or until the temperature of the leakage is less than 100 degrees Celsius (212 degrees Fahrenheit). The release of radioactivity should be assumed to continue until shutdown cooling is in operation and releases from the steam generators have been terminated. G-5.4 All noble gas radionuclides released from the primary system are assumed to be released to the environment without reduction or mitigation. G-5.5 The transport model described in Regulatory Positions E-6.5 and E-6.6 of Appendix E to this guide should be used for iodine and particulates. DG-1389, Appendix H, Page H-1 APPENDIX H ASSUMPTIONS FOR EVALUATING THE RADIOLOGICAL CONSEQUENCES OF A PRESSURIZED-WATER REACTOR CONTROL ROD EJECTION ACCIDENT This appendix provides assumptions acceptable to the staff of the U.S. Nuclear Regulatory Commission (NRC) for evaluating the radiological consequences