Assembly of the Wevice was done in a shot czb on Ebertru, Eniwetor A toll, starting testing, by Mar. 6, early in January 1954and was completed, including the neceszary, » Wheathe a 1954, except for the installation of the, was made, disassembly of ‘the device was Started, and decision not to fire the. parts were stored in theCamco building in the CMR area on Parry. The.__,components are being shipped to the ZI for reclamation. coe One difficulty encountered duriry the assembly of the’ ~ , was the appearance of anair Piugin the line, which gaVé risto"a none xplosive bursting of several of the, “comfonents. Aporoximately one week’s effort was necessary to return the 1 ‘system to the operating condition that existed before the accident. “The device was constructed in a shot cab on EninmanIsland, BikiniAtoll, _ during the latter part of January and February. Except for the installation of the: __ §theconstruction was esc:ntially con:zleted before the “The | Se mene 4.12 "shot. i device was detonated at 0625 local time, Apr. 7, 1954. TASK UNIT 15, TIMING AND FIRING Prior to the operational phase of Operation Castle, TU-15 had planned to fire all the devices from the manned CP, Station 70 on Enyu at Bikini, and Building 311 on Parry at Eniwetok. Installations were made first at Bikini Atoll with the timing system controlled and monitored from Station 70 where the radio signals were also generated. Thefirst shot, ~ jwith its attendant radiological and personnel safety problems, demonstrated the undesirability of manning the control station at least for large devices. TU-15 reassembled and supplemented the Operation Ivy radio control equipreent and in- stalled it on board the USS Estes with the receiving and Cecoding equipment on the 300-fi Enyu tower. This system was checked out within a weekafter|L ‘and was used to fire the remaining Bikini shots. No difficulties were experienced with the hard wire or radio signals, although some Blue Boxes at great distances did not fire because (1) the transmission in general was low along the line of sight and (2) as in Mike the first light emitt2:d was of relatively low intensity and predominantly red in color. The Eniwetok shot was fired from a manned station on Parry, with the device located in the Mike crater, and again no difficulties were experienced; the television and tone monitoring systems were not used because of the cancellation of their respective shots. The only timing-system failure reported on the operation was the failure to get a 1-min radio signal by Sandia on shot. The equipment had not been dry-run, but an analysis of the failure will be attempted. The Bhangmeters are considered a part of the timing system within the EG&G division of responsibility and are reported herein. The standard Bhangmeters did not trigger on shots where the transmission was low, but a Bhangmeter in a B-36 airplane gave correct results on all shots at tactical distances and hence proved the usefulness of the device for yield measurements from aircraft. An experimental oscillographic Bhangmeter gave results on all shots and yielded much information on the relative red and blue light levels as seen by photosensitive surfaces. TU-15 had no great difficulty in maintaining timing systems for alternate firing in both atolls and was in fact prepared to radio-fire in both atolls. TU-15 would recommendthat, in the future, preparations be made to radio-fire all large devices and to expand the radio time signal system so that hard wire need only be used In congested locations and for critical experiments. In this way the most satisfactory and economical ‘ system can be used. W— 18