RESTRICTiiD 



2 



the average be reduced to one-half its original voliuae in 22 

 days and to one-tenth its volioine in tv/o and a half months. The 

 rate of flushing will presiomably be so^iev/hat slov/er than average 

 for water in the northwestern part of the lagoon, which has a 

 relatively closed circulation, and faster in the eastern and 

 southern portion, which is i.iore exposed to tidal interchange. 



At the tiiue of test Able a patch of contaaainated water will 

 be foriiied at the strrface in the target area. The contaj^'.inatlon 

 will uove with the surface current in a WSV/ direction at a speed 

 of about 0.3 iaiot (assuLiing a 10 knot easterly wind), so that its 

 center will have i.ioved about 7 uiles fron the center of the tar- 

 get area in the course of a dajr-. At the same tiiue its concentra- 

 tion will be reduced rapidly by vertical and horizontal diffusion, 

 It is estimated that these processes will reduce the concentra- 

 tion to Vfo of the initial value in tv/o hom.-'s and to 0,0003<?'j in 

 one day (not counting radioactive decay). 



In test Baker it is likely that the radioactive products 

 will be uniformly distributed froEi surface to bottom. The patch 

 of contaminated v/ater, originally more or less circular, will be 

 elongated rapidly by currents flowing west at the surface and 

 east at the bottom. The contaminated v/ater at the surface will 

 be diluted by vertical mixing v/ith underlying v/ater at an esti- 

 mated rate of 23*^ per hour. The reduction in the concentration 

 of the bottom v/ater moving eastward from the target area is ex- 

 pected to be about 8% per hour, the difference being du to the 

 fact that the bottom current is three times as thick as the sur- 

 face current. 



Therefore part of the radioactive products v/ill be carried 

 av/ay from the target area, but part v/ill be transferred by ver- 

 tical diffusion to the other current and v/ill be ca-^ried back 

 again. Thus a strip of contaj.iinated water is developed, which 

 lengthens westv/ard with the speed of the surface current flow 

 but v/ith rapidly diminishing concentration, and eastward v/ith 

 the speed of the bottom current. The maximiEi concentration will 

 remain to the eastward of the target area. 



At the end of the first day the strip of contaminated water 

 is expected to extend from Bikini Island to a point about 7 miles 

 V/SV/ of the target. The concentration at the v/estern end of the 

 strip is expected to be about 0.01^?^ of the initial value, taking 

 into account vertical and horizontal diffusion but neglecting 

 radioactive decay. At the eastern end of the lagoon the average 

 concentration will be about Ifo of the initial value, but there 

 may be patches of upv/elling bottom v/ater v/ith a concentration of 

 10^ or more. 



m 



