Document: NRC Regulatory Guide
Document ID: ceaeb6d7-d85a-46d3-a1b6-70059a498965
Document Type: regulatory_guide
Title: 12/2001 (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0131/ML013100014.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.78
CFR Part: 
CFR Title: 

Content:
ous chemicals from stationary sources or from frequently shipped mobile sources in quantities that do not meet the screening criteria in Regulatory Position 1.1 or 1.78-6 1.2, detailed analyses should be performed for control room habitability. Licensees may provide risk information to demonstrate that the radiological risk to the public from such toxic chemical releases is small, consistent with the Commission’s Safety Goal Policy Statement. Release of toxic chemicals that have the potential to result in a significant concentration in the control room need not be considered for further detailed evaluation if the releases are of low frequencies (10-6 per year or less) because the resultant low levels of radiological risk are considered acceptable. If demonstrated, an acceptable level of risk may be used by licensees to support license amendment requests. To facilitate risk-informed license amendments, risk information should be provided in accordance with the guidance set forth in Regulatory Guide 1.174 (Ref. 3). One key principle in risk-informed regulation is that the acceptable level of risk (defined in terms of quantitative health objectives of QHOs) is a small fraction (0.1%) of other risks to which the public is exposed. Procedures outlined in the “Framework for Risk-Informed Changes to the Technical Requirements of 10 CFR Part 50,” an attachment to SECY-00-0198 (Ref. 6), may also be used as guidelines for quantifying risks. If the level of risk associated with the release of a toxic chemical is not acceptable, detailed control room habitability evaluation should be performed. A method acceptable to the NRC staff for evaluating the habitability of a control room is described in Regulatory Position 3. 3. CONTROL ROOM HABITABILITY EVALUATION When performing a detailed evaluation of control room habitability during a hazardous chemical release using this guidance, the metric to be used for each chemical is the maximum concentration (toxicity limit) that