Document: NRC Regulatory Guide
Document ID: 769c53ca-7692-4fdf-9301-9fd64e37aa8f
Document Type: regulatory_guide
Title: Evaluations of Explosions Postulated To Occur on Transportation Routes Near Nuclear Power Plants (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2110/ML21105A439.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.91
CFR Part: 
CFR Title: 

Content:
robability of potential accidents at nearby facilities or the frequency of hazardous cargo shipment may show that the attendant risk is sufficiently low. The NRC staff determined that if the frequency of an explosion at a nearby facility (fixed facility), or the exposure rate1 associated with a transportation route for material in transit, can be shown to be less than 1x10-7 per year, then the risk of damage caused by explosions is sufficiently low. The following equation defines the exposure rate for potentially explosive material in transit: ݎ= ݂݊ݏ (5) where, r = exposure rate n = explosion rate for the substance and transportation mode in question, in explosions per mile or kilometer f = frequency of shipment for the substance in question in shipments per year s = exposure distance in miles or kilometers (see Appendix A to this guide, exposure distance calculation, from UFC 3-340-02, Figure 2-7) If the substance in question is shipped on more than one transportation mode near the plant, exposure rates calculated for the modes should be summed. If an adequate database for estimating the explosion rate for a substance is lacking, an estimate can be made by using nationwide statistics for the particular transportation mode: ݊= ݊ଵ݊ଶ (6) where, n1 = accidents per mile or kilometer for the transportation mode n2 = cargo explosions per accident for the transportation mode Because the events under consideration have a low frequency of occurrence, estimates based on average frequency may have wide confidence bands and conservative estimates may be preferred. If estimates of explosion rate, frequency of shipment, and exposure distance are made on a realistic or best-estimate basis, an exposure rate less than 1x10-7 per year is sufficiently low. If conservative estimates are used, an exposure rate less than 1x10-6 per year is sufficiently low. If it cannot be shown that the distance to the fixed facility or transportation route is great enough, or that the