Chapter 2 PROCEDURE 2.1 TARGET SHIPS The positions and orientations of the target destroyers (DD’s) were chosen by the Defense Atomic Support Agency (DASA), based upon compromises of requirements from the many projatUcn arces, av ects utilizing the ships (Figures 2.1 and 2.2). The three distances of the ships from surface zero (SZ) were expected to represent regions of moderate shock damage, moderate to light shock damage, and light to no shock damage to the ships of their equipment. The innermost and outermost ships were oriented with their sterns toward surface zero in order to simulate probable escape maneuvers. The middle ship was oriented with its starboard side toward surface zero to meet requirements of other projects. The ships were located on a line downwind trom surface zero in order to maximize the radio-~ logical effects for a given distance from surface zero. They were expected to receive varying amounts of radiation contributed by the plume, cloud, and weapon debris trapped in the water near surface zero. In addition, they were expected to be contaminated to varying degrees by the fallout. The ships were subjected to continual washdown during the dynamic radiological events, because shipboard operations by the various participating projects would have been hampered by the expected high levels of residual contamination. (Washdown is a standard countermeasure aboard naval ships and would normaLly be used during fallout or other contaminating events. ) Each ship had forced-draft blowers supplying air to one fired boiler in the forward fireroom in order to supply power needed to meet the operational or experimental requirements of vari- ous projects. The experimental ingress studies of Project 2.2 aboard DD 592 also required the operation of forced-draft blowers supplying air to one unfired boiler in the aft fireroom and the operation of ventilation systems supplying air to various compartments (Reference 6). The ingress of these air supplies could be expected to create various gamma radiation sources inSide the ships and to influence the radiation fields at various stations under investigation by this Project. 2.2 INSTRUMENTATION The gamma-radiation dose rates and doses aboard the three ships were measured with GITR instrumentation and standard Rad-Safe film badges. The shipboard areas selected for investiBation represented or simulated major battle stations aboard modern destroyers. 2.2.1 Gamma-IntenSity-Time Recorders (GITR’s). Portable, self-contained, batteryPowered GITR’s were developed as part of NRDL’s laboratory program. The GITR consisted 9° a detector unit and a recorder unit (Appendix A). The detector unit could be mounted inside the recorder unit case, or it could be mounted separately and connected to the recorder unit With a waterproof cable. The detector unit consisted of two concentric ionization chambers with associated recycling electrometers, Discharge of the initially charged ionization chamber by a predetermined quan- tty of ionizing radiation, triggered the electrometer circuit, which sent a pulse to the recordWg unit and recharged the ionization chamber to complete the cycle. The pulses were recorded as on-off information on magnetic tape in the recorder unit. Three 15