Se Ven A vc] 7h J. Since the radioactivity will decay at high initial rate, it is possible that vital civil defense opprations may be undertaken even within the first few days witho exposure of personnel. used in relays. This is especially true Serious overEf they can be They should, of course, be carefully monitored when thus exposed. Vv. Recommendations with Respect radiation hazard, to Residual The guidance provided herein information currently available. js based on Improved knowlddge of phenomena, cover or shelter, and other factors will require these policies from time to time, In each insta will have to be made between evacuation, shelter tion of the two. Warning time, distance to a reIAtively safe area and the existence of reception facilities will bal tions, for some combina- prime considera- The possibility of moving into the fallout. area from another target must be also considered in making decision. Because larger areas will be involved, tha problems of communication, warning and transportation become creasingly complex, Since operating decisions may of necessiity be made on the basis of a large area analysis, they become increBRsingly impcertant. Methods used by meteorologists for plott wind vectors can be applied to the prediction of fallout pattefPns. FCDA Advisory Bulletin No, 178, tssued in November 1954, contaifhs a method suggested by the U.S. Weather Bureau. These methpbds will permit a rough but useful approximation of the probable difPection of falio.* and give some indication as to the area of contampnation. Improve‘ and faster methods of deriving this pattern and mpans of testing their reliability for civil defense purposes are -ll- SECRETScis der study. DOE ARCHIVES 2