CHAPTER 17
account for the low observed levels. ‘Thus, it is possible that at early
times, radiation levels in the water around surface zero could add to
the radiation field aboard a ship traversing the area. However, it is
concluded that available data from surface bursts do not provide ea
reasonable basis for predicting dose rates around surface zero at early
times.
The underwater-burst data indicate that within 2000 %%of surface
zero and within the first 15 min after burst, doses of several hundred
roentgens could be eccumilated from contact with the first few feet of
surface water.
However, after 1 hr after burst, activity in the water
probably would be of no significance aboard ship, and by several hours
after burst, activity levels in the water from either water-surface or
underwater detonations would probably be lower than 1 r/hr.
17.7.4 Shipboard Dose~Rate Dato from Contaminated Water
Shipboard dose and dose-rate data have been obtained at various
weapons tests. In compartments below the water line, the recorded
gemma doses and dose rates that were considered to be due only to contaminated water surrounding the ship were negligible in all cases;
in fact, they contributed less than 1% of the levels measured at exposed
C
locations. Simultaneous measurements of dose rates in the water around
a ship and dose rates aboard that ship are required for reliable esti-
mates of the contribution of waterborne radiation.
Such measurements
are available for only a few shots. However, efforts have been made to
distinguish the contribution of waterborne radioactivity from the con-
tributions of other sources for several additional tests.
1.
Water-Surface Bursts
ration
(YAG's 39 and GO)
ulate portions of
area on each ship
Castle: For Operation Castle, two Liberty Ships
were modified to have various parts of each ship sinNavy combatant ships. For instance, the recorder-room
similated compartments below the waterline, adjacent
to the shell, and was well-shielded from the weather surfaces by a le-
inch concrete slab. Doses and dose rates measured in these rooms were
attributed only to radiation penetrating the ships’ skins, and not to
radiation from sources above, such as fallout. Dose rates in the
recorder rooms after Shot 5 (Yankee) peaked at only 0.07 to 0.08 r/hr
between 6 and 7 hr after burst, and the total doses measured to 12 hr
were only about 0.5 r.
During the same period, doses of over 100 r
were recorded at unprotected topside stations on the same ships.
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