12.171. In the United States, applicants for reactor licenses must pro­vide plans for coping with emergencies. Requirements are given in 10 CFR 50.47 and in its Appendix E. An Emergency Planning Zone (EPZ) must be specified related to a plume exposure pathway following a severe ac­cident. The radius of such a zone would depend on the typographical and access route features of a specific site but is likely to be on the order of 16 km (10 miles). However, an EPZ for a food ingestion pathway must also be considered, which may have a radius of about 80 km (50 miles).

12.172. Plans must be established for both on-site and off-site organi­zations for managing emergency situations, including protective measures, communication, transportation, and many other considerations. Lessons learned from the Chernobyl accident response (§12.187) have been helpful in identifying needs. The general trend of NRC regulations has been to favor new plant siting significantly away from population centers. However, in those European countries that are densely populated, it is not possible to have the luxury of remote siting. Therefore, reliance must be placed on a defense-in-depth design philosophy, which includes a very conservatively designed containment structure as backup.