At 6:45 a.m. on March 1, Tawakoni observed the first Castle detonation, test BRAVO, from a distance of approximately 50 miles southeast. Tawakoni was responsible for retrieving YAG-39 following test Bravo. In preparation for its retrieval, the YAG's Crew transfered fram Molala to Tawakoni that afternoon. At 5:10 p.m. the tug proceded to inspect the YAG. One hour and thirty five minutes later Tawakoni had George Eastman in tow, ant they departed for Eniwetok.
The towing line of George Eastman had been carefully laid out on the deck and the end of the towing line was suspended over the side with a special device so that the tug could take the tow line aboard without sending anyone onboard the ship.
Tawakoni with George Eastman in tow, arrived at Eniwetok on March 2. At 1:06p.mp during the return trip, a whaleboat had been lowered into the water to enable a boarding party to boardthe YAG. However , whether or not anyone actually boarded the ship is unknown. once the experimental ship was moored in Eniwetok Lagoon, Tawakoni departed to return to Bikini.
The sequence of events for test ROMEO was similar to that of BRAVO day. When ROMEO was detonated on March 27, Tawakoni was 32 miles southeast of ground zero. About three and one half hours after the 6:30 a.m. detonation, the YAG.s crew transfered from Molala to Tawakoni. At 6:12 p.m. Tawakoni proceeded on course to intercept the YAG. At 9:41 p.m., the tug made its approach. It appears that sometime later that night or the next day, George Eastmans crew reboarded their ship. on March 29, George Eastman, under its own power, was sailing toward Eniwetok in the company of Tawakoni. Both ships anchored at Eniwetok that morning.
At 6:20 a.m. on April 7, Tawakoni was 27 miles southeast of shot KOON. Approximately nine and one half hours after Koon, Tawakoni picked up passengers in Enyu Channel. At 7:28 p.m. the tug anchored in the lagoon.
The fourth Castle test, UNION, was detonated on April 26 at 6:05 a.m. Tawakoni was anchored at Eniwetok some 200 miles west of bikini. On April 30 Tawakoni was moorerd alongside YAG 39 for 40 minutes. It may have been involved in decontaminating George Eastman after the YAG's participation in UNION.
Sometime after the April 26 test and before YANKEE which was detonated May 5 at 6:10 a.m. , Tawakoni replaced USS COCOPA ATF 101 in support of the underwater pressure measurements project. The experiment required the installation and recovery of moorings and buoys and servicing of clocks and batterys in instrumented buoys.
At 6:10 a.m. on May 5, when the fifth CASTLE event, Test YANKEE occured, Tawakoni was operating 58 miles southeasdt of the detonation point. The next day the ship was underway for a decontamination project. The details of the project are unknown.
Tawakoni departed the Marshall Islands on May 8 With a district lightwer in tow. When the final Castle event , Test NECTAR, was detonated on May 14, Tawakoni was enrout to Pearl Harbor, arriving there May 18.
Tawakoni was officially released from Operation Castle on May 11. At that time the highest level of contamination recorded aboard the ship was 0.2 mr/hr.
An examination of CASTLE dosimetry data indicates that, in general, a crews overall operational exposure was based on a selected number of periiodically badged individuals. Individual film badges were to be issued when an individual was involved in an assignment that would have increased his potential for exposure. Additionally, there are instances when recorded exposure readings were assessed.
The CONSOLIDATED LIST OF CASTLE RADIOLOGICAL EXPOSURES is regarded as the final summation of an individual's identified cohort badges, individual badge readings and assessed doses. Based on this report, the recorded mean radiation exposure reading for the 80 listed Tawakoni crewmen is 1.26 rem gamma with a range of exposure from 0.28 to 3.180 rem gamma. These readings are within present national occupational radiation exposure standards which permit 5 rem per calendar year.
-- Keith Whittle, May 22, 1998