Operation Castle, a Very Preliminary Report of the Results () (Partial) (Deleted)

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6 TEST OF SERVICE EQ~ti AND OPERATION (Cent‘d) 6.k Proof Testing on AM Ship Countemeasues. 7.2 Detection of Airtime Low Frequency So~d 13.k A 13.5 High Speed Photography end.Time

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Ga~ Intensity at Late Times I 18.2 Power as a Function of Time

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I BLAST AND SHOCK mS%~S Position, Drift and Set of Buoys. . Radioactivity in Polyethylene Bottles and ..l. 27 on Gum Pager Collectors Gamma as a function of Time 7 LONG RANGE DETECTION

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1o-1 Summary Of Time Difference Results ......l. 83 10-3 Yield from Analytic Solution ..........c 84

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6 TEST OF SEWICE EQUIP= AND OPERATION B-50 Radar Scope Picture - Path of Shock Front. 7 LONG RANGE DETXTION

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13.5-2 Model 100 Camera Streak Record ........l 1A 13.$-3 Model 100 Camera Streak Record ......... IW

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Teller Light, C,hanne~1, Camera G4HMAS AND RESIDUAL CONTAMINATION 18.2-1 Relative Power as a Function of Time - Enlnmn.

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LIST OF ILLUSTWTIONS Relative Power as a Function Searchlight Stabilization System ....

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The -was the test of an approximately mu k . Xt was fired on a barge detonation took place at appro-tely 6130 AM, Mmch 27,

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Fallout from this shot was observed to be strongly....._.... ..— different from the There was very little local throwout, so that a few hours after the shot extra activity was obse-ble only on Namu and. after the shot. Fallout collectors seem to show that nest material was either very small particles or liquid. Water waves from the shot caused some da=ge on. sweep clear over the islands. The reports followtig are prelimimry statements from the various projects end programs of Task Unit 1, Task Unit 7, Task Unit 13s and Task ~nft 15* The before and after pictues were taken by Task Unit.9. Reports concerning the work of other Task Units will be made at a later time. The reader 1s cautioned that none of the numbers reported here are final, but they should furnish a general idea of the restits–—— —

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To measure the gamma radiation exposure at various locations following a nuclear detonation. b Film and chemical dosimeters were placed In ~ Inch wall alumlnum cannlsters mounted on 2 inch aluminu stikes. The detectors were placed at a hefght of 3 ft above ground ~’ for the land stations. The beach stations were set so that the detectors were 1 ft above ma-um”hlgh tide level. mu detecting systems were calibrated agatist an 11-Mev betatron. An ana’~~;~sof the resultant produce a consistent decay emressfon

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nation sitution, or the winds and ralne patterns may have ken changed by

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Exposure Recovery Time Rate Station Type Location :4 Land Chieerete boo o * the detectors were Act rate is the rate existing at ‘he ~~re~ldgal radiatiOll--

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To obtain g- rates vs time for various distinces Cam exposure rates were obtained using scintillation detectors set one foot above ground. The ~tector outputs woro recorded as a ftmction of time on continuous recorders. Instruent stations on Bokobyaadaa and Nam had been destroyed by blast installed on Alrukliji, Airukiram and All stations operated, and showed negligible gexposue rates for the period of zero the to plus 36 hours.

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l%rticipation in n the basis of The physical installation & ‘,plann~d and effected on the Islands west of Aomoen. When the shot loaation was changed; participation was reduced to the amount Ind:cated. Detectors were Installed on the 1~~ line as shown In

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Restits of the exposed geranim are not available (samples sent to 21 for analysis). . The fission detectors that were recovered were countable in spite of the high backgroud res@ting from the late fall-out on Parry Island. hours andthe figures given are estim~es restittig from ~ project In the composite preliminary report for Castle stability of the 1403 concrete stations was distwhd (though they were not removed ). the line, and moved stations large distances, The unrecovered stations had disappeared.

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The following objectives were sought In this experiment: Magnitude and downwind extent of the prl.mary,or The physical nature of the fall-out. All available stations in the lagoon and in the atoll islands were fully instrumented. A limited number of free- . floating buoys were placed about the shot point* The calctiated positions of the buoys at shot time are given in Table 2.5a-l. This table also includes the drop position of the buoys and the computed drifts and sets of the buoys. No fall-out was found in the collectors placed in the lagoon or in those placed on the atoll isl=ds. Collections were obtained fron some of the free-floating buoys. These collections were In the polyethylene bottles and on the gum papers- TIB radlac zeter data Qf the bottles and paper are included in T=ble 20Ca-2. ‘igures have been corrected for background at tine of assay.~;~e~e. ~~e implications of the reported data cannot be reported on-site since laboratory analyses and correlations -th other measurements are required. However, all mor~t~on col~-ted Intiicatethat the contaminant arrived in the form of a fine mist or liquid aerosol. Ic{

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Drop Position of Position of Buoys of of Euoy Radioactftity of Battles Radloactlvity of 2-s-P4-TC Not Detectable 20 at 272 5 at noted recovery time

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The objectives of this project Include the collection of fall-out samples for the dooumentatim of the physical characteristics as a function of time and distance, and to provide samples fo~ chemieal and radio-chetiml analysis for Froject The following seventeen stationswere instrumented with BokororpruJ and Wkobyaatie. One instrument at each station was set to collect twenty-four samples in S-minute internals; the other collector to collect twenty-four samples in 30-minute intervals Recovery was poor due to the following reasons: Station deterioration, the r suit of the sixteen day delay between station activation and damage to instruments caused by collectorsj–hcwever, the uncertainty of the firing date precluded Approximately fifty percent of the collectors functioned

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reported at t~s time since nest of the samples are being analysed Fall-out at the upvlnd stations; Rochlkarai, inconsequential. Samples from those stations read only two or three times backgroud on R+39 Fall-out at the crosstind station Aomoen was slight

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The actwl passage of the pro$ect drone ships throu@ the fall-out is graphically presented in ~g” 10 ns 80* but It was tipossible to turn the YAG-~0 to that cowse due to a personnel error ring during demrktigo This lnactl~ted radio control of COWS. only; recmrence will be prevented.””~the futwe by an additloal% check w~ch has been intrtiuced. Attempts to keep the YAG-39 with the YAG~O failed due to mal~ction of radio paratus vhich converted a speed cwnge t+? The net effect vas that the two ships cafiot be said to have been subjected to even : vlth 3 or 4 jneremental dose ion ch.amtirs.equipped each. ~yA~-29there were 65 such stetions end on the 3L4@+0 there were ‘,-ithiti-cn-~per recorders in central recording rooms. were no failwes but perfo-ce was substandard on 6% of the

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that both ships entered the contaminattig event at about H+2 hours. Figs. 6.kA3 and 6.4A4 apply to the flight decks which received only about 30% of the average level of contamination for each ship. Msage rates on the flight decks peaked at (H +10 hours) on the YAG~. The dosage accumulated at the flight desk stations for the period to H+ 100 hours were 2 and 220 roentgens, respectively. The different amo~ts and times of arrival of contarn~ ination on the two ships precludes a direct washdovn evaluation. Accumulations on the unprotected ship vere high enough at some points to give lethal doses wlthln 2~ hours. Some not completely consistent and thus far incompletely evaluated data Indicate a ~%shdown effectiveness of greater than 90%. The qualitative nature of this figure must be emphasized, as must the extreme importance of obtaining much more conclusive data from a highly contaminating simultaneous exposure of both ships before making correl.at=n~etveen reletlve wind and contamlmtion may be inferred fron ZsoGose rate lines. See Fig. 6.~~9.

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radiation levels in below deck spaces to roughly 0.1 the , values on the weather deck. Additional shielding by the 12” thich concrete slab of the instrument recording room gave a reduction to 0.001 the above deck value on the YAG-M.b Generally, shieldlng effectiveness increased somewhat with time. Absorption data from detectors In a series of steel pipes mounted on deck, with wall thickness varying from 1/8 Inch to % inches, clearly showed a decrease in effective radiation energy over the Intenal H+5 to Ht7$hours. -~ prior to, during, ~d after decon~m~tion~ a complete radiological survey was made of both s~ps. All. readings were taken in a prescribed reamer at measured distances from previously marked stations. The TIB gamma survey meter and the was found to operate USNRDL Beta Probe proved to be the most The USNIIDL directioml gam=a instrument successfully, but its weight llmlts its & :1--I:Task Force have been used successPI-My to supplement. -=71 group regularly assigned to this dIJty.tr.csu+- On the whole, capable of recording support hes been very satisfactory. , to photograph the fall-out with equipment

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event the~~ora station wI1.1be turned on at a later hour with more hope of success. -..,-.,..’..7,.~ Adequate data have been obtained for the evalution of firehosing, hand-scrubbing and hot Ilquld jet cleaning in the decontamtition of naval ships. A gross reduction of 82% in the dose rate award the YAG~ was obtafied by use of these methods. No decontimimtion was required aboard the The radiological protective coating vas not as\ :: readily removable with the hot liquid jet as It had been during s laboratory scale tests. An on-the-spot procedure was therefore developed. This procedure success~ully removed from 90 to 95% of the paint with a corresponding removal of 75 to 9@ of the radioactive contaminant Itself. An adjacent area not coated procedure and a resultant reduction of kO to 60% of the radioAn additional reduction of 1~ in the initial dose ~7:,:. by surface renoval of wood deckizg. Total deccntazlnation throughout the weather surface of the ship was 52 mr/hr. --

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low that a~econtamlnati.on study was not warranted and the effectiveness of the washdown system could not be evaluated accurately. The YAG-kO aircraft was suff~clently contaminated to warrant an experimental decontamination s}udy. This st~Y began on R+5 and ended on R+9 days. A series of decontamiwere employed which,wlth th~ aid of one rain reduced the gamma radlatlon level at the mrfi to k5 mr/hr. At the same time, the gamma intensity level on an area on a wing sectton was reduced craft would not check out when the aircraft was turned up after the test, but no material d~ge -S detected on the yA~ Air samplers and particle collectors operated normally over the designed time interval after debarking, shutting off at H+% hourso Maximum field intensity indicated by gamma detectors on the YAG-40 occurred at about H+8 hours. However, precut sections of ventilation duct continued to be exposed to nor duct sections showed appreciable activity. T-M’otopside zillipore filters showed moder~tely high activity but here the existence of surface streaks leads to suspicion of direct fallout contamimtion rether than collection of airborne partlc~ate

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A *entatlve conclusion may be Inferred that the airborne contamination hazard is relatively less serious t-n Instrumentation on the YAG-ltOwas on the whole success~ although only partial results were obtainable on 5 out of the 19 air samplers, while 3 ative on the YAG39. All the samples to USNRDL for e~lutiono out of 5 were lnopertaken have been returned A prototype of a semi-por~ble air monitoring unit f designed for future shipboard and/or land use were evalUtedTime Intensity records of airborne beta contamination were Present Instrument gives adequate tiarningagainst airborne fizardg in external fields up tO ~ rh. This warning can be given within a minute of arrivel of hazard. Instrument appears useful also to forevarn ships, land stations, etc., of possible background level buildup. Personnel Rotection Studies and Radlolozlcal Safety During ‘theYAG recovery operations, the greatest volved with the recovery of the YAG-kO received an average Durhig the decontamination operations the total dosage

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rcceivcd b~= crews was kept to a ulninum through careful dosage control of personnel and continuous monitoring of shlp~s 1’ spaces. Of more than 400 people Involved In the operation, I only about 50 received doses of more than 2 roentgenst tith 1. seven exceeding 3 r and one recel.vlngapproximately 7 r.

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Theobjectives of this projeat are: (1) To determine structlon surfaces exposed to fall-outfrom (2) To detemlne the lffect of saltbraterwa~h-~onandslmpl. pre-protectionmeasures in minimizing contamination. A not of fourteen four-feet-squarepanels of widely used exterior construction surfaces were mounted at theirnormal orientations on each of the two drone ships (Project 6.k) which Panels wore recovered froa the ships and moved to the Parry decontamination area. Omma and station Intensity readings vere taken at sixteen locations on each panel. The panels from the vashdovn protected ship were of such 10V intensity that decontaminationvas not necessary. The panels froa the ~prOtected ship were subjeotod to Yarloushosing and scrubbing techniqueswith gamma and station Intensity readtigs taken between each decontamination pasa. Intensity readings on all panels were taken at the beginning andendof each dayts operations to be used for direct

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taken during the day~s ‘corrected tack to the $nltlal readings for that The averags lnitlal gamma Intensity and resldul gamma intensity percentages are summarized on Tablo 6.5-1 for each Preliminary data Indicates that saltvater vashdovn l% effective in mlnlmlzing co;tamlnatlonof construction surfaces , under the conditions of this test. The contamination resulting from this detonation Is of a very tenaolous nature. Uxicr the condltl~ns of this contamlnctlng eventf The contamination as deposited under the conditions of this test presents a much q ore dlfflcult removal problem than the dry contamination encountered at Op.aratlonJANGLE.

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the Mike curve fs derived from data at H+b hours similar to t present data and extrapolated to earner times by using the sl observed In Fievadatit Is obvious that the present data can be better represented by a cuzve of greater slope. From the grea rate of decrease of Intensity in the present operation it can concluded that both velocity and angular wind shear effects lX those on Mike Shot and.that the persistent Isoklnetlc layers observed In Nevada are not being found. Operationally, the eff of vind shear are anticipated by the use of plan-view projecti of the sheared cloud st?ucture derived from vinds observed i% shot a~ea as close to shot tlxe as possible. From these project altitudes and positions are chosen to give the best cloud persistence for the later sampling aircraft. The_factor of four inorease In sample obtained by th ex?~sylrereceived by the crew. 3acause of the depe~dence of t background contamination acquired by this aircraft relative to in-cloud exposure upon the nature of the coral de5ris through which it flies, it has been necessary to calculate the llcitin :n-cloud exposure while in-fMght from operational data report

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in return exposure was used to incr and hence the sample collected,&:-=:=::the external exposure and that of the shielded personnel was found to be 3.0. Itwas pogslble :anfldently to plan on an external exposure on Iandfng of about 9 roentgens because an in-flight confirmation of this ratio was.a-llable from a proto LASL. …