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50 Mile Evacuation of Japan Nuclear Plant: Making Sense of Evacuation Distances

Monday, March 21st, 2011

Author: Jack Long, Director of CBRNE Preparedness, IEM

Since the US Nuclear Regulatory Commission recommended on March 16 that US residents who are within 50 miles of the damaged Japanese nuclear power plants should evacuate, there has been a lot of speculation as to why the NRC would recommend such a large evacuation zone when the guidance for the plume exposure pathway emergency planning zone in the United States is for an area approximately 10 miles in radius.

First, the NRC recommendation was based on specific US guidelines for radiation exposure and some sophisticated calculations of the possible radiation doses based on what is known or suspected to be happening at all of the Fukushima plants, so this NRC recommendation is very site-specific and incident-specific whereas planning guidance is based on a wide range of possible accident scenarios.

Secondly, the US guidance for emergency planning for commercial nuclear plants never established 10 miles as any kind of outer limit or maximum evacuation zone.  Rather, the US guidance is designed to require highly detailed response plans and preparedness for a 10 mile radius zone since that area is at greatest risk and has the least amount of time to evacuate. (more…)