CHAPTER 17 17.8 CONTAMINATION INGRESS 17.8.1. Intraduction If a ship were operating in the base-surge region or in the fallout zone resulting from a nuclear water-surface or underwater burst, air- porne radioactive particles could gain access to the ship's interior through any breaks in the ship's weather envelope. The presence of radioactive particles would result in radiation fields within the ship, since the particles might deposit on ship surfaces or remain suspended in the air within the ship. In such cases, the means of ingress de- termines the amount of activity entering the ship, and the access paths affect the amount of deposition and the concentration of activity suspended in the air within the ship. The conditions under which such ingress of activity could occur and the interaction of the ship with the radioactive particles and with the radiations emitted by those particles have been studied at field tests, by the use of simlants, and by theoretical calculations. Results of these studies will be presented in 17.8.2 and 17.8.3. The investigation of Ref.8& has indicated three possible breaks in =~ a ship's weather envelope that could provide means of ingress of contaminant to below-decks spaces: physical damage to a ship; the boiler- air system; and the ventilation-eair system. Examination of available data indicated that the primary effects likely to cause physicaldamage to a ship operating in the region of a nuclear burst are sirbdlast and underwater shock. Unlese a ship were at a range close enough to be inmobilized, the deckhous structure and lightly-constructed nonwatertight doors appear to be the only topside items likely to be damaged by airblast, and such damage would probably not be of sufficient magnitude to permit significant ingress of activity belowdecks. Unless a ship is at such close range that underwater shock causes major hull damage, it is unlikely that breaks in the weather envelope will result from underwater shock. Therefore, means of contaminant ingress which could be of significance to operable ships were concluded to be the boiler-and ventilation-air systems. Results of theoretical calculations and fieldtest measurements of the radiation fields resulting from these two sources of shipboard contaminant ingress follow. 17.8.2 Theoretical Investigations In an investigation®’or gamma radiation dose due to contaminated bottler air, theoretical calculations were made of the dose to boiler- room personnel due to contaminated air that had leaked through boiler casinge and idle burner ports into the boiler room of a destroyer. Bursts of the Shot Baker type, ranging in yield from 20 to 200 KT were considered. The investigation assumed that the ship was mobile and that all activity remained airborne. Only external-gamma and inhalation 17-105