United States Nuclear Regulatory Commission - Protecting People and the Environment

Allowable Shipment Frequencies for the Transport of Toxic Gases Near Nuclear Power Plants (NUREG/CR-2650, SAND82-0774)

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Publication Information

Manuscript Completed: October 1982
Date Published: October 1982

Prepared by:
David E. Bennett, Nuclear Facility Analysis Division
David C. Heath, Fuel Cycle Risk Analysis Division (Cornell University, College of Engineering)
Sandia National Laboratories
Albuquerque, New Mexico 87185
Operated by Sandia Corporation
for the U.S. Department of Energy
Under Contract No. DE-AC04-76DP00789

Prepared for:
Division of Systems and Reliability Research
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Under Memorandum of Understanding DOE-40-550-75

NRC FIN A-1214

Availability Notice

Abstract

One part of the safety analysis of offsite hazards for a nuclear power plant is consideration of accidents which could release toxic gases or vapors and thus jeopardize plant safety through incapacitation of the control room operators. The purpose of this work is to provide generic, bounding estimates of the maximum allowable shipping frequencies for the transport of a chemical near the plant, such that the regulatory criteria for the protection of the operators are met. A probabilistic methodology was developed and then applied to the truck and rail transport of an example chemical, chlorine. The current regulatory criteria are discussed in detail. For this study, a maximum allowable probability of occurrence of operator incapacitation of 10-5 per year was used in the example calculation for each mode of transport. Comprehensive tables of conditional probabilities are presented. Maximum allowable shipping frequencies are then derived. These frequencies could be used as part of a generic, bounding criterion for the screening of toxic hazards safety analyses.

Unless a transport survey assures shipping frequencies within 8 km of the plant on the order of or lower than 4/week for rail or 35/week for truck, the control room should be isolatable and the shipping frequency then determines the degree of isolation needed. The need for isolation implies the need for toxic chemical detection at the air intake.

For a self-detection case in which the smell threshold is significantly lower than the incapacitation threshold and the control room is isolatable, the corresponding shipping frequencies are 11/week for rail or 115/week for truck. Self-contained breathing equipment is assumed to be used after 5 minutes.

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