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:
associated with normal operations or iodine spikes should be included. Activity from projected fuel damage should not be included. DG-1389, Appendix D, Page D-2 D-4.3 All radioactivity in the released coolant should be assumed to be released to the environment instantaneously as a ground-level release. No credit should be assumed for plateout, holdup, or dilution within facility buildings. D-4.4 The iodine species released from the main steamline should be assumed to be 95-percent cesium iodide as an aerosol, 4.85-percent elemental iodine, and 0.15-percent organic iodide. DG-1389, Appendix E, Page E-3 APPENDIX E ASSUMPTIONS FOR EVALUATING THE RADIOLOGICAL CONSEQUENCES OF A PRESSURIZED-WATER REACTOR STEAM GENERATOR TUBE RUPTURE ACCIDENT This appendix provides assumptions acceptable to the staff of the U.S. Nuclear Regulatory Commission (NRC) for evaluating the radiological consequences of a steam generator tube rupture (SGTR) accident at pressurized-water reactors. These assumptions supplement the guidance provided in the main body of this guide.1 Source Term E-1. Regulatory Position 3 of this guide provides assumptions acceptable to the NRC staff regarding core inventory and the release of radionuclides from the fuel. E-2. If no or minimal2 fuel damage is postulated for the limiting event, the activity released should be the maximum coolant activity allowed by technical specification. Two cases of iodine spiking should be assumed: E-2.1 A reactor transient has occurred before the postulated SGTR and has raised the primary coolant iodine concentration to the maximum value (typically 60 microcuries per gram (μCi/g) dose equivalent (DE) iodine (I)-131 (DE I-131)) permitted at full-power operations by the technical specifications (i.e., a pre-accident iodine spike case). E-2.2 The primary system transient associated with the SGTR causes an iodine spike in the primary system. The increase in primary coolant iodine concentration is estimated using a spiking model that