INTROOUCTION Following the accident at Three Mile Island, the U.S. Nuclear Regulatory Commission (NRC) required that each nuclear reactor operator submit an evacua. tion time estimate for an area with a radius of about 10 miles surrounding the plant (NRC, FEMA 1980). Previously, such estimates were prepared only f?r low-population zones (LPZs), which generally extended from only 1 to 6 m1les from the reactor. Because of the small areas and numbers of people involved, evacuation times for LPZs

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... uld be estimated using relatively simple models. When NRC increased the area subject to evacuation, these simple models frequently proved inadequate . Consequently, a generic model was needed for estimating evacuation times for relatively large areas and for accurately representing the population, transportation network, and specific characteristics and problems posed by each power plant and the surrounding region. This paper describes a computer model, designated CLEAR (Calculates Logical Eya~uation And Response), developed by the Pacific Northwest Laboratory (PNL)~aJ to simulate vehicle departure and movement on a transportation network in order to determine time estimates for an emergency evacuation. The NRC requested and sponsored the development of the CLEAR model to provide a means of verifying the evacuation time estimates submitted by its applicants and licensees. To date, the CLEAR model has been used primarily as an analytical tool for simulating an emergency evacuation following an accident at a nuclear power plant. However, the methodology is equally applicable to simulating evacuations preceding or following other types of events such as toxic waste spills, toxic gas leaks, fires, hurricanes and other natural or man-made incidents. In order tO test the model, evacuation time estimates for a power reactor facility and the surrounding area were calculated using the CLEAR model and then compared with time estimates prepared by three other groups using various techniques. The site chosen for this test was the Beaver Valley Nuclear Power Plant in Pennsylvania. The time estimates used for comparison were prepared by Wilbur Smith and Associates under contract to the Federal Emergency Management Agency; the utility company, Duquesne Light, as requested by NRC; and the Pennsylvania Emergency Management Agency. The results of the comparison are discussed in the final section of this report. In an effort to fully describe the CLEAR model, a copy of the computer code and the corresponding flow chart are provided in Appendices I and II, respectively. In addition, an example of the input and output for a specific transportation network and population distribution is provided in the remaining appendices. (a) Operated for the Department of Energy by Battelle Memorial Institute.