( Table 3 PATAPSCO Deck Log Weather Summary (Numbers in parenthesis are reference time zones) Fallout Deposition Initiation 031530 (-12) 2 Mar (-12) No rain; winds 11-22 knots. 3 Mar (-12) Slight imtermittant rain (2100-2300); wind 10-12 knots. 3 Mar (+12) No rain; winds less than 20 knots. 4 Mar (+11)Moderate thunderstorms (2000-2300); winds 12-24 knots. 5 Mar (+11)Moderate thundershowers (0800-1000); winds 22-35 knots. 6 Mar (+11)No rain; winds 17-28 knots. Arrive Pearl Harbor Naval Shipyard 071550 (+10). During these intervals of rain and relatively high winds some portion of the fallout was undoubtly removed, the question is how much? At Operation CASTLE it was observed that moderate rain reduced ship (YAG) deck contamination L approximately 50% (ref. 8). Applying this 50% reduction to the PATAPSCO Ry (deposition) value of 12.2 r/hr gives a post storm Ry (deck) value of 6.1 r/hr which is in remarkable agreement with the R, (deck) value of 4.5 r/hr estimated from the radiological survey when the ship reached Pearl Harbor. While this decrease continues as long as the rain persists, the first rain removes the most actively and an effective time of decrease in the estimated weather deck dose rate from the 12.2 to 6.1 r/hr at 042100 (+11) or H + 109 will be assumed here. Another important factor is the departure of the ships decks from idealized deposition surfaces. For a person moving about, these departures inject variable shielding which can considerably reduce the effective dose rate. It is also possible for a person to consistently occupy positions which increase his effective dose rate. For these reasons, combined with the difficulty and uncertainty in computation, no attempt will be made here to compensate for complex ‘exposure geometries. (8)