Operation Redwing, a Preliminary Report of () (Tewa) (Deleted)

Page 1

Submitted by Task Group 7.1 This document consists Of-age(s) 1:0 of 30 copies, Series A -

Page 2

Bikini Atoll North Reef with Scientific Stations . . Rocket Determination of the Activity Distribution within the Stabilized Cloud .... Fallout Studies by Oceanography Methods. .... Collection and Characterization of Fallout with Fallout Location and Delineation by Aerial Analysis of Fallout and of Base Surge. ..... Relative Importance of the Various Radiation Sources to the Ship Shielding Problem. ..... Evaluation of Standard Navy Dosimeters in Standard Recovery Procedure for the Tactical Verification of Washdown Effectiveness as a

Page 3

Thermal Flux and Albedo Measurements from Accurate Location of Electromagnetic Pulse Source. 66 Effects of Atomic Explosions on the Ionosphere . Determination of Characteristics of Airborne Flush Mounted Antennas and Photo Tubes for Yield Analysis of Electromagnetic Pulse Produced by a Project 22.3 - High Explosive Trans Time. .......... Time Interval and Time and Pressure

Page 5

Cbserved Weather at Shot Time Fig. O-2 - Bikini Atoll North Reef with Scientific Stat~ons

Page 6

BIKIFI OBSEWED WEATHER FOR 21 JULY 1956 TEWA SHOT TIME 0546M Sea Level Pressure 1009.3 mbs Wet Bulb Temperature 780 F sea Water Temperature 840 F Surface Wind ESE 8 knots Weather No showers reported & 2/10 cumulus, bases at 2,000 ft. 1/10 cirrostratus, based at 30,000 ft. Open Sea: Wave heights 3 ft., period 6 seconds, direction 090°. Scattered cumulus clouds bases at 2,000 ft. 4-5/$ cirros based at

Page 12

Program 2 - Nuclear Radiation and Effects Program 5 - Aircraft Structures Mogmm 6 - Test of Service Equipnent and Program 9 - General Support

Page 13

The objective of this project was to document gamma exposure on Bikini Atoll using various types the initial and residual Fesidual stations were located on almost every islend in the Atoll. Initial stations were loceted on the Namu - Yurochi reef. The residual information will be included in the final report. &om 200 to 1000 r of residual radiation obliterated the initial gamma exposure results from the more distant reef stations. At the close stations the exposures were greater than 105 r causing the photo~raphic dosimeters to satur~te. Clnemicaldosimeters at these locations lxve been returned to the United States for evaluation.

Page 14

Project 2.61 - Rocket Determination of the Activity Distribution within Four rockets were fired at the capability of measuring and to e~lore the spatial distribution of gamma activity within the cloud and stem produced by the detonation of nuclear weapons of megaton yield. A six inch diameter ground launched-rocket capable of attaining 180,000 feet altitude, bearing a radiation detector and telemetering equipment was used to obtain information on the radiation field in the cloud. The first of the four rockets was fired at H + 7 minutes with the others following at ten second intervals. Radiation intensity iriormation (in the form of F. M. pulses) was telemetered to two receiving stations where the information was recorded on magnetic tape. All four rockets fired and good signal strength was received on three of the four channels. One transmitter failed shortly (about 5 seconds) after take-off and one transmitter was considerably off frequency. Accelerometers were used on two of the rockets. Their data can not be reduced in the forward area, since a discriminator will be required to separate the radiation field intensity data from the acceleration data. Data on the one channel that is readable in the foruaxd area indicate radiation fields considerably below the average encountered from the (Cherokee). However, they may correspond to those obtained at

Page 15

similar to that mede for the ‘—. I(liiwajo). Three surface vessels, the M/’VHorizon, the DE-365, and the DE-534 all remained in the fallout area for five days inking measurements and collecting semples. In all, 80 water samples were taken for Project 2.63 and 80 were Preliminary results show such that had all the fallout thet over 30,000 square miles were contaminated occurred at H+l hour, end if it had fall,~non an infinite hypothetical plane, the dose rate at a height of 3 entire erea would have exceeded 40 r/hr at that time. Several feet over the this pattern would deep moor enchor st~tions installed for this shot and all Penetration meters had been installed on two of these skiff stztions. One failed to fire, the other started and gave a good record of penetration rate. Preliminary exxminstion indicates that fallout had penetrated to the thermocline in less than a half an hour.

Page 16

Project 2.63 - Collection end Ch%acterization of Fallout with Time - To collect samples of fallout and measure radiation field intensities - with time at various distances from hi~h yield land, water and air thermonuclear detonations. To study these samples from early times with respect to gamma and beta activity, to analyze tklemfor chemical and radiochemical composition and to determine certain of their physical properties, including distributions of particle sizes. ~ Two YFNB barges and three pontoon rafts were anchored in Bikini Lagoon. YFNB-29 czrried two standard platforms with major arrays of instruments and YFN%13 carried one. Each msjor array consisted of four open-close total collectors, two always-open total collectors, one incremental collector, one gamma intensity vs time recorder, and one wind sFeed and direction recorder. The arrays on the barges were fully automatic. Each pontoon raft carried an always-open total collector, a time of arrival detector and a film pack to measure total dose. An array of 16 skiffs W2S deep-sea anchored by Project 2.62 between 10 and 30 miles from ground zero in the expected fallout area. Each carried a YAG-39 was loceted approximately 25 miles, YAG-40 approtinately 40 miles and LST-611 approximately 60 miles from ground zero; all, however, were at different azimuth angles. Each was extensively instrumented with a major array supplemented by incremental collectors and high volume filter units.

Page 17

Approtiately 90% of all project instrumentation functioned properly, and no significant demage to any station other than the one located on Namu Island was reported. Even in this case the protective cone remained upright even though crushed and a useful sample was collected. All island, barge and raft stations received fallout, as well as about half of the skiff stations; and activity levels were in general high, the hi@lest being observed on Aomoen and Namu Islands, the YFN3-29, raft #3 and the skiffs in the northwest quadrant. Surface readin~s of samples collected on island, reft and barge stations everaged 2.0 r/hr et 1200 on D+l r/hr at 0900 on D+2. The time of arrivel of fallout was All project ships received significant fallout, the with some as high as 5.0 about 7 minutes at the approximate time of hours for the LST-611.. The highest activity level measured was approximately 4.1.Or~r at H+5.2 on the deck of the YAG-39, while the maximum deck intensity obsemed on the YAG-40 was about 7.0 rfi.rat E+6.9 hours. Extrapolated to a deck condition without washdown the maximum intensity level observed on the LST-611 was approtiately 1.0 r/kJr. Activity measurements, deczy and Emma spectra measurements, and pl-.ysicalobservations of fallout material were performed at early times in the shielded Iaboratorg aboard the YAG-40. The great ~jority of thes~ta are being reduced at the present time. It is evident, ho~ever, tbat&@e active fallout particles were very similar to those observed following * shot of Operation Castle. These were of three general types: (1) unchanged coral particles, (2) p=ticles with Cao or ~(~)2 interiors ~~d a thin CaC03 exterior shell, end (3) branch clusters, resembling

Page 18

indicated the flaky agglomerated type to be about twice as active es particles of the other two types with the sme diameter. l!~c~nificant quantity of sIun-y droplets, such eS those observed for the Navajo), was found to The data obtained are being examined further and additiond analyses being performed .atI!avalRadiological Defense Laboratories; these results be included in the preliminary report.

Page 19

Project 2.64 - Fallout Lacation and Delineation by Aerial Survey - To survey the gamma radiation from fallout contaminated ocean areas using an airborne detector. To survey the areas of the sea, off Bikini Atoll, w~ch are con~- inated prior to shot, the information to provide both background radiation data and oceanographic studies of the mixing of the lagoon water into the open sea. + Three P2V-5 aircraft were equipped with g-a radiation detectors to record the dose rate arriving through the thin aircraft skin from the water surface below. A fourth aircraft was available on a non-interference basis with the security mission and was provided with detectors and Two aircraft flew over the fallout area simultaneously and observed the radioactivity and altitude (operating altitude 200-400 feet). The information on radiation dose rate and altitude was continuously recorded and telemetered to the Program ‘IWOControl Center aboard the USS ESTES. There the telemetered information was correlated with the positioning dab of the aircraft which was relayed over a communication channel between navigator and the project plotter. On D-day two aircraft surveyed near the atoll when the fallout was completed. One aircraft also surveyed near the yA&39 ad yA&AO Positions before their return to base. On subsequent days the aircraft followed a

Page 20

9 to ~ hour flight plan which included surveys over the atoll as well as flights out to the end of the iscdose plot (150 to of cont~inated water were obtained from Project 2.62 time of the radioactivity in order to extrapolate the to the fallout time. to measure the decay One aircraft was to be flown over the Bikini Atoll area, and the downwind contaminated area delineated. The survey was scheduled for The Freshet survey found downwind contamination, as expected, with a peak intensity around 0,4 mr/hr. See attached Fig. 2.64-1. The D-day survey was started late on D-day to avoid co~tamlnation% of the aircraft. The lower outside boundary was carefully delineated. On D + 1 and D + 2, two aircraft were used to survey the conkinated area. This enclosed approximately 36,CO0 squsre miles. On ?)+ 3 and D + 4, one aircraft was used to follow the contaminated area in the vicinity of the hot line. This enclosed an area of approximately 2500 squsre miles. See Fig. 2.64-3 attached. In sm~.ary, the aerial survey flights delineated the background contamination prior to the shot, surveyed the total contami~ated area on D + 1 and D + 2, and delineated the hot area not only on D + 1 and show that this area remined relatively stable throughout this time intend.

Page 24

TO obt&in fallout samples on land and to perfo~ radiopkysical and radiochemical measurements on the samples. To prepare dose rate contours of the atoll area from information getbered by this project, other projects, and FadSafe. To evaluate the role of the kse surge in transpm-t of radioactive mterisl were installed on islands in the Bikini Atoll and on the YAG’s and LST in the expected fallout zone. The IFC timing inter=ral.swere one minute, five minutes, or 30 minutes depending on location of the collector. ‘Theequipment was installed prior to the shot and was activated by EGG Blue Boxes. Samples to be used for early decay measurements were recovered on &day and the balance of the seunpleswere recovered on D+l ~nd D+2. All of the recovery was made by helicopter. Wire sipnals were used to activate the base surge detectors as a was required before shot time. tape fallout monitor, (TFM). Some of the stations also of residual radiation was made wer the respective islands by helicopter. The measurements were taken by means of a probe on a long cable suspended below the hovering helicopter. The positions of the probe were determined by comparison with ~ps and aerial photopaphs. Two project personnel were stationed in the Program 2 Control Center to consolidate data from the various projects and to assist the Program Director in maintaining a situation plot.

Page 25

f The instrumentation at the various stations is displayed in Fig. 2.65-1. The contamination resulting from this shot covered islands from Bikini to Airukiiji. Aerial survey by means of a probe suspended from a helicopter was conducted on D-day, E-l-land D+2. The readings obtained are shown in Table 2.65-1. These values were corrected to the H+l hour dose rates by using a decay ex~onent of -1.08 obtained from field gamma decay data. Fallout samples were recovered on D+l and D+2 days from all the stations on the islands with the exception of Na_muand Eokobyaadaa which were contaminated to such high levels as to make recovc .:inadvisable. The s~.pies were processed and shipped to Army Che,micalCenter for analysis.

Page 27

Tl?M- Tape Fallout Monitor 2-IFC (5 rein) BIKINI ATOLL (30 tin) MORTH PACIFIC OCEAN

Page 28

@!!&Importance of the Various Radiation Sources to To determine the relative radiation dose rates contributed by contamination of the eir envelope, water envelope, and the shipts weather surTo determine the time scattering coefficients of To field test new and dependent gamma ray still to be used in future calculations of improved detector systems. To obtain gamma radiation measurements at various points on end in the ship as a function of time for the following purposes: Check points for future shielding calculations Determination of the radiological situation at various locations aboard ship for Projects 2.63 and 2.10, to be used for operational control of the test ships. Both YAGs received levels of contamination tion of project objectives. Preliminary indications are that the rains on D + 1 will not prejudice the satisfaction of’ adequate for the satisfacencountered by the YAGs The instrumentation performed satisfactorily. Relative G~ma Radiation Fields Contrihted by Various Radiation S~urces Fig. i.71-l and 2.~-2 show the percent air contribution to the gamma radietion field on the deck of YAG 39. As in pretious events, the .

Page 29

air contribution during fallout was very significant. In the washed area, at time of maxim~ fallout the air contributed close to 100% of the garrmadose rate end about &@ of the gemma dose observed on deck, and at the time of cessation of fallout the air had contributed about 42$ of the gamma dose observed on deck. Fig. 2.71-4 through 2.71-7 show the E:mma doses and dose rates observed on the decks of the two YAGs. Fig. 2.71+ shows the estimeted ga_.madose and dose rate contributed by the air to the deck of YAG 39. Fig. 2.71-9 and 2.71-10 show the gamma dose locations in YAG 39. The variations in the dose and recorder room may be due to contaminated sea rates at several interior r:tes in the firerobm water; however, lack of has prevented examination of water contributions at this tire. Interaction of Gamma Radiation with Steel Garm radiation fields inside steel cylinders ofarious thicknesses corpared as a function of cylindeu thickness and time. Least square lines were calculated and drawn for plots on semi-log paper. (See Fig. Combined absorption and multiple scattering coefficients for steel were calculated. These coefficients are presented and compared with results from other shots in Fi ~v appear to be duplicating the (Flathead) results. Whether the rain caused..*$ tionation and thus accounts for the sudden flattening of the - (Tewa) curve remains to be determined. Participation in this shot supplied data believed to be adequate for the satisfaction …