Document: NRC Regulatory Guide
Document ID: de79d411-4fc9-456e-a5a0-f4a910ca4c9a
Document Type: regulatory_guide
Title: Assumptions Used for Evaluating a Control Rod Ejection Accident for Pressurized Water Reactors (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2111/ML21119A157.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.77
CFR Part: 
CFR Title: 

Content:
legally-binding requirement nor a “generic” NRC approved acceptable approach for meeting an NRC requirement. However, licensees and applicants may consider and use the information in the secondary reference, if appropriately justified, consistent with current regulatory practice, and consistent with applicable NRC requirements. DG-1387, Page 7 C. STAFF REGULATORY GUIDANCE This section includes the staff regulatory guidance for evaluating the habitability of a NPP CR during a postulated hazardous chemical release. Any hazardous chemical stored on site within ½ kilometer (km) [1,640 feet (ft)] of the CR in a quantity greater than 45 kilograms (kg) [(100 pounds (lb)] should be considered for CR habitability evaluation. Hazardous chemicals should not be stored within 0.1 km (330 ft) of a CR or its fresh air inlets, including ventilation system intakes and locations of possible infiltration such as penetrations. Licensees are encouraged to conduct periodic surveys of stationary and mobile sources of hazardous chemicals near their plant sites to keep the site-specific inventories up to date. However, this RG also provides essential assumptions and criteria for screening out release events that need not be considered in the evaluation of CR habitability. The following criteria identify the release events that need not be considered further for CR habitability evaluation. 1. HAZARD SCREENING Whether a chemical source (stationary or mobile) constitutes a hazard that requires a CR habitability evaluation depends on prevailing meteorological conditions, the inleakage characteristics of the CR, and the air concentration in the CR as compared to the applicable toxicity concentrations shown in Table 1 and the combination of the weight quantity of chemical and the distance from the plant shown in Table 2. 1.1 Exemption Criteria for Stationary Sources Chemicals stored or situated at distances greater than 5 miles from the plant need not be considered because, if a release