OPERATION CROSSROADS -
DATE:
TIME:
PPG time
25 Jul 1946
0835
TOTAL YIELD:
Baker
GMT
24 Jul 19h6
2135
Sponsor:
SITE:
LASL and DOD
PPG - Bikini - Near How
11° 37' #10" N
165° 29' 28" E
Site elevation:
23 kt
HEIGHT OF BURST:
Sea
level
-90 ft
TYPE OF BURST AND PLACEMENT:
Underwater - cable-supported
90 ft above lagoon floor.
Time to lst minimum:
Time to 2nd maximum:
Radius at 2nd maximum:
223
FIREBALL DATA:
Lagoon was 180 ft deep.
CLOUD TOP HEIGHT:
CRATER DATA:
Diameter:
Depth:
7,600 ft MSL
3,300 ft maximum
1,800 ft minimum
25 ft
REMARKS:
The contamination pattern is unreliable.
The dose-rate readings
used for the pattern were obtained from the total dose measured by
film badges collected between D+tlO days and D+15 days.
The radioactivity
on the target vessels diminished
At its greatest
extent the base surge extended about 2,000 yd upwind, 3,000 yd crosswind
and 4,COO yd downwind.
"The contamination resulted from fallout or
radioactive rain from the mushroom head reinforced somewhat by condensation
of the base surge.
Ideally there should have been an annular infinitivedose pattern as a result of fallout from the outer edges of the mushroom
head.
This ideal pattern was changed because of the intermittent behavior of the rain-out and because of the varying ability of the different
target ships to retain the fallout activity."