(
Within the interior of the ship, dose rates can also vary appreciably.
This gamma field can result from deck deposition altered by complex shielding
and variable distances to multiple surfaces, or more directly from activity
tracked inside the ship.
While the deck deposition component is reduced by
weather, the interior contribution ts constantly increastng as activity is tracked
in and spread throughout the ship.
Shielding factors from exterior contamination
are reported to vary between 0.0001 and 0.2 for various ships and locations
within the ship (ref. 9).
A 10% transmittance giving an Ry = 1.2 r/hr (interior)
is a high (max dose) estimate which will be assumed for the interior gamma field
between fallout deposition (H + 32.5) and partial fallout reduction at storm
arrival (H + 109).
After this time the R, = 0.9 r/hr value determined from the
Peari Harbor (survey) measurement is thought the best characterization of the
ib erior gamma field for the remainder of the time interval.
Figure 3 show the estimated variation of dose rate with time as it relates
to input data for four hypothetical cases for which total accumulated doses will
be presented in the next section.
These include an estimated "maximum" case which
assumes no reductions in the gamma field after fallout deposition; two more
realistic cases where minimal reductions have been applied to both the deck (A)
and ship interior (B) gamma fields; and a "best estimate” for a hypothetical
individual who spends eight hours per day outside on the weather decks (C).
later case (C) is a simple combination of cases (A) and (B).
This
The unit references
dose rates (Ry) applicable to these cases are summarized in Table 4.
Table 4
{
Unit Reference Dose Rates r/hr for Dose Calculations
. to Storm
After Storm
Weather Dose
Ship Interior
Hypothetical Crewman
12.2
1,2
4.8
6.)
0.9
2.6