VERIFICATION OF SHIPBOARD WASHDOWN COUNTERMEASURE

Project 2.10 was conducted to verify the effectiveness of a washdown system as a radiological countermeasure for ships. The evaluations were made possible by the requirement for washdown-equipped ships to be stationed within the region of tactically significant fallout in order to support several projects in the fallout characterization program of Operation Redwing. To fulfill the instrumentation requirements of Program 2, the Bureau of Ships test ships, YAG39 and YAG-40, were employed. Washdown effectiveness was measured by a comparison of gammaradiation field measurements taken in the unwashed control area forward and the washed after portion of each ship. The test ships participated in five shots and at least one of them was sufficiently contaminated in four of these to make washdown evaluation feasible. Maximum levels of gamma radiation encountered range from 266 mr/hr at 11 hours after Shot Flathead to 21.2 r/hr at 4.6 hours after Shot Tewa.