improvement in the techniques used in predicting thermal effects. However, the data obtained should assist in revising the procedures used to calcuJate thermal effects and, thus, result in more accurate predictions. The formulas and procedures utilized to predict blast effects at overpressures less than 1.0 psi were satisfactory; in general, good correlation was obtained between measured and predicted values. AS a result of the experiments, sufficient data are available to determine the responses oi the B-36 aircraft to nuclear detonations and to define with reasonable accuracy the maximum delivery capabilities of the aircraft. Furthermore, the data and experience obtain- Figure 6.1 The YAG~-39 with the washdown system operating. ed from both experiments wili be useful to assist in the establishment of general methods for the determination of nuclear effects as related to weapon-delivery capability, structural vulnerability, and lethality problems. €.2 CONTAMINATION AND DECONTAMINATION STUDIES The basic vehicles exposed to the fallout from the Castle detonations were two con- verted Liberty ships: the USS Granville S. Hall (YAG-39) and the USS George Eastman (YAG~40). In addition to simulating conditions aboard ship during and after fallout, these ves: els served to mount devices to collect fallout on their weather surfaces for contamination-decontamination studies and to house instrumentation for studies of fallout material. Their weather surfaces served as a radiating source for various shielding studies. The basic difference between the two ships was the installation and operation of a washdown system aboard the YAG-39 only. It was planned to have the two ships experience the same magnitude of fallout and thereby evaluate the effect of washdown. Figure 6.1 is a photograph of YAG-39 with the washdown system operating. The ships were instrumented extensively for the measurement of gamma dose and dose rate at a total of 137 stations. Each instrument consisted of four ion chambers which provided for covering a dose-rate range from 0.1 mr/hbr to 10,000 r/hr. The detectorrecorder system recorded dose increments in the ion chambers as deflections on the 79