DECONTAMINATION AND PROTECTION

Test panels, four ft square, of 14 building materials were mounted on the weather surfaces of two remotely controlled liberty ships and on a stationary barge. One of the ships was protected by a washdown system. All surfaces were contaminated significantly with tenacious fallout. Vertical surfaces facing upwind became equally or more highly contaminated than horizontal or pitched surfaces, probably due to wind currents impacting the tenacious contaminant onto surfaces normal to it. A sequence of hosing and vigorous scrubbing operations resulted in contamination reductions of 40 to 70, but with reductions on most surfaces being less than 50. The most effective decontamination method was scrubbing. Under the conditions of this test, painting and joint sealing had little effect while the washdown countermeasure reduced the initial contamination over 90. It is concluded that contamination from fallout encountered in these tests presents a serious decontamination problem on buildings and paved areas and further development of effective countermeasures is necessary.