20, 000 gallons of water over the tower. However, the dose rate could not be reduced to less than 1000 mr/hr. On 22 May another decontamination attempt was made, This time 60, 000 gallons of water were pumped over the tower, but the east side of the tower still showed gamma readings of 1000 mr/hr, On 1 June the tower was washed down with water and scrubbed with brushes, and the maximum reading on the east side was 450 mr/hr. To protect the tower from fallout a disposable canvas cover was placed over the top cab of the tower and a tent over the generators on the lower platform. On subsequent shots the gamma intensities were reduced somewhat; however, the Scaevola event contaminated both the lower and upper cabs with alpha. At the close of the Operation the tower was again washed down and the radiation intensities were 80 mr/hr gamma and 50, 000 c/m/55 cm? alpha. For future operation it is recommended that the tower be covered with a disposable canvas cover prior to each event. 6.5 Alpha Decontamination 6.5.1 General Due to a low yield event on Site Yvonne a considerable area was heavily contaminated with alpha. The same GZ area had to be used for a subsequent event, and it was necessary to partially decontaminate the area, The area between Stations 1310 and 1610 on Site Yvonne was des- ignatedasa FULL RADEX alpha area, The Rad-Safe check point set up near the personnel pier is shown in Figure 6.1. 27 Two decon trucks,