DRAFT
es,
contaminated water moves over relatively clean water and clean
water flows in above the lower contatinated portion.
Simultancous-
ly, vertical turbulence acts to homogenize the ent#ts laycr above
the thermocline, thereby diluting the contaminated water.
ror fallout over a small area from a nominal kiloton weapon
the primary mixing process is the latter effect discussed above,
the vertical shear.
‘orizontal shear in the currents cver a
sm4ull area is generally, although not always, rclative:y suall.
California coast, measurements of herizontal disnersior
ke
U
Cff the
hy,
The horizoutel molecular diffusion is eiso minor.
vo
both horizontal shear and aiffusion gave an averaze rate of ore
foot per minute for areas up to 10 miles across.
mee
7
ogee co *
North
In toe
e
‘9
Equatorial Current region where current sreods ure stronger thon
4
6s
off California, this rate woul
probably be two or
th:i-ea tines
as great; nevertheless, tne effect cf the process would be of 2
second ordere
For both small and large contaminated cesanic
O
oO
n
Eete
Large, heavy part:
roe
areas the rates of vertical mixing are essentially equal.
in the fallout (c.g., coral) must
Sink fairly rapidly ana secount for rediocactivity found cn the
Geep ocean bottom in the PPG.
sut much of the Talloue redio-
activity is on ssialler coral particles, or ash material and is
dissolved into the water ebove the thernocline.
Coral particles
that are 100 microns in diam. ter would sink et the rate of 30 to
100 meters per hour; these would reach the thermocline in 2 or 3
ar
hours time on the average and may lose much of their radiogectivity.
Both the measurements made at CASTLE and by the Japanase one ww
two months after C,STLE showed mach greater concentration of
activity above the thermocline than anywhere else in the water
column.
aK