e e Eya/v iS 8. In order ta:be able’to contime apnneamenemeaanae to carry out CASTLE CTG 7.3 has requested- Commander, Joint Task Forée SEVEN to increase the Maximum Permiss~ ible Exposure for Operation CASTLE to 7.8 roentgens: (AEC allowed exposure for 26 weeks) for (a) Helicopter pilots and plane captains, (b) Boat operating personnel of Task. Group 7.3 boat pool, (c) Flight deck crewof the USS BAIROKO, ‘and (4) © Personnel attached to the USS PHILIP, approximately 490 persons, in all. In the interest of efficiency and economy, this command has also recommended to Commander. Joint Task Force’ SEVEN that personnelnot be relieved. or detached fromTG 7,3 units | due to radiation, unless their accumulated exposure exceeds or approaches’7.8R.. This conmand is endeavoring to employ persons with high exposure in activities ° where they will receive little or no additional exposure, in insofar as practicable, 9. Since BRAVO was detonated on a reef, the subsequent contamination’ of ships’ by. - solid particles rather than water droplets, is not what ordinarily would be =... 7 expected in naval atomic warfare on the high seas, although contamination by solid particles could be expected on ships in harbors or near land, Consequently, som of the following remarks, on damage control measures have somewhat limited application in naval atomic warfare. i as ; a. Especially in locations near (within atout 50 miles of) ground zero, it is essential that damage control measures, including washdown, be placed ineffect before and not after the fallout begins to reach the ship. This conclusion is: basedon BAIROKO's experience that in such locations fallout builds up wey rapidly, (from 0,2 mr to'1Rin less than 5 minutes), wy be Presently installed washdown systems using fine spray are only partially* effective in removing relatively heavy, visible, solid particles, Heavier sprays °’ or-hoses with a large volume of water are mcessary to effectively. remove these," particles, Further, improvements in drainage are desirable to remove,the large.. volumes of water required. : ee ¥ eee a PALS OG Nes ce. Presently installed washdown systems are most effectivewhen heading ints ‘the wind, .Cross-wind headings result in much of the spray being blown from -the ™ ships structuré. Zig-zagging helps in Wetting all topside areas.and in’fachlite ating drainage. d, vd Special measures, including more extensive yashdow equipment and drainage, are necessary on bridge structures (especially horizontal endSng where critical command pe*sonnel normally are stationed, Commanding Officer BAIROKO received a relatively high dosage while conning his ship on.1 March. 10. The presently prescribed mehtods ‘of decontamination, ‘both materia) and personnel, were found to be effective. 11. The excellent report, from BAIROKO, enclosure (4), is considered worthy of special mention, It is believed that BiTROKO, -ESTES and PHILIP were.the first active ships in the Navy to be exposed to radiological fallout: on & relatively | heavy scale, os ed .