Document: NRC Regulatory Guide
Document ID: 14983af3-17d8-4f7b-866e-8d603a0f811c
Document Type: regulatory_guide
Title: Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for Pressurized Water Reactors (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003739614.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.4
CFR Part: 
CFR Title: 

Content:
that may be used to evaluate the design basis LOCA of a Pressurized Water Reactor (PWR). It should be shown that the offsite dose consequences will be within the guidelines of 10 CFR Part 100. (During the construction permit review, guideline exposures of 20 rem whole body and 150 rem thyroid should be used rather than the values given in § 100.11 in order to allow for (a) uncertainties in final design details and meteorology or (b) new data and calculational techniques that might influence the final design of engineered safety features or the dose reduction factors allowed for these features.) C. REGULATORY POSITION 1. The assumptions related to the release of radioactive material from the fuel and containment are as follows: a. Twenty-five percent of the equilibrium radioactive iodine inventory developed from maximum full power operation of the core should be assumed to be immediately available for leakage from the primary reactor containment. Ninety-one percent of this 25 percent is to be assumed to be in the form of elemental iodine, 5 percent of this 25 percent in the form of particulate iodine, and 4 percent of this 25 percent in the form of organic iodides. b. One hundred percent of the equilibrium radioactive noble gas inventory developed from maximum full power operation of the core should be assumed to be immediately available for leakage from the reactor containment. c. The effects of radiological decay during holdup in the containment or other buildings should be taken into account. d. The reduction in the amount of radioactive material available for leakage to the environment by containment sprays, recirculating filter systems, or other engineered safety features may be taken into account, but the amount of reduction in concentration of radioactive materials should be evaluated on an individual case basis. e. The primary reactor containment should be assumed to leak at the leak rate incorporated or to be incorporated as a technical specification