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:
ources of hazardous chemicals such as those listed in Table 1 are known or projected to be present within a 5-mile radius of the plant, and in quantities less than those shown in the table of examples in Appendix A for a given toxicity limit and stable meteorological conditions, these sources need not be considered in the evaluation of control room habitability. Appendix A to this guide also contains a simplified procedure for adjusting the quantities given in the table to appropriately account for the toxicity limit of a specific chemical, the meteorological conditions of a particular site, and the air exchange rate of a control room. The calculations in Appendix A are included as examples of the guidance. Any hazardous chemical stored onsite within 0.3 miles of the control room in a quantity greater than 100 pounds should be considered for control room habitability evaluation. Hazardous chemicals should not be stored within the close proximity (generally within 330 feet or less) of a control room or its fresh air inlets, including ventilation system intakes and locations of possible infiltration such as penetrations. Small quantities for laboratory use, 20 pounds or less, are exempt. The maximum allowable inventory in a single container stored at specified distances beyond 330 feet from the control room or its fresh air inlet varies according to the distance and the control room type. If there are several chemical containers, only the failure of the largest container is normally considered in the evaluation unless the containers are interconnected in such a manner that failure of a single container could cause a release from several containers. 1.2 Screening Criteria for Mobile Sources If hazardous chemicals such as those listed in Table 1 are known or projected to be shipped by rail, water, or road routes outside a 5-mile radius of a nuclear power plant, the shipments need not be considered further for evaluation for the same reason stated in the screening