f
Fallout Deposition
The calculation of the shipboard (H+1) r/hr dose rate contour distances a-
Jong the hot line was accomplished after the location of the fallout intercept
had been determined. Table 2 shows the H+] hr (unit reference) dose rate values
obtained from ref. 3 together with the calculated values of the H+1 dose rates
extrapolated down range to the ship.
for this extrapolation.
Various functional forms were investigated
A power law curve of the form yzax? provided the
closest fit over the reference 3 distance and was used to obtain the extrapolated unit reference value of 12.2 r/hr for the ship at its intercept location.
Making the conservative assumption that fallout with an 18 knot downwind’ speed
could persist for roughly 10 hours at a specific geographic location (ref. 6),
deposition on the deck of PATAPSCO (12 knots) moving relative to fallout cloud
at only 6 knots might persist for 30 hours or 360 additional nautical miles
‘
wnwind.
For the purposes of the conservative dose calculations presented here
the maximum unit-reference dose rate of 12.2 r/hr at the initial intercept point
will be used with the all-down time of 021520 or H + 32.5 hours.
Table 2
Unit Reference (H+1) Dose Rate Contour Curve
Fitting and Extrapolation
Dose Rate
Contour (y)
3000
2000
1000
500
100
50
35
| 12.2
10
7
Reference 3
Distance (x)
94.8
107.0
Calculated *
Distance (x)
9)
105
127.0
‘132
296.7
-
288
364
. 160.1
=
-
167
Al}
586 |
-
627
1365
* y =(1.92 x 10°)x 78-96 with coefficient of determination, r@ = .99
(6)