Survey of Radioactivity in the Sea Near Bikini and Enewetak Atolls June 11-21, 1956 (Redwing Operation)

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UNITED STATES ATOMIC ENERGY COMMISSION SURVEY OF RADIOACTIVITY IN THE SEA NEAR BIKINI AND ENI’WETOK ATOLLS Technical Information Service Extension, Oak Ridge, Term.

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Date Declassified: November 28, 1956. This report was prepared as an account of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the COmmiSSIOm A. Makes any warranty or representation, exprese or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resu~ting from the use of any information, apparatus, method, or process disclosed in this report. AS used in the above, “person acting on behalf of the Commission” includee ~Y employee or contractor of the Commission to the extent that such employee or contractor prepares, handles or distributes, or provides access to, any hrforrnation pursuant to hia employment or contract with the Commission. This report has been reproduced directly from the best available copy. Printed in USA. Price 30 cents. Available from the Office of Technical SerV-

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SURVEY OF RADIOACTIVIN IN THE SEA NEAR BIHNI AND ENIWETOK ATOLLS Applied Fisheries Laboratory University of Washington @crated by the University of Washington under Contract No. AT(45-1)540 with the United States Atomic Energy Commission

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Ming the period of June 11 to 211 195~9 a surveY Party,:;.-$... operating from the USS Walton (DE 361), measwed the radiation““~ in plankton, water, and fish samples collected near Bikini a~+~ 1A continuous record of the radiation in the surface water was” ~’~.+,. obtained with a probe, Plankton samples from oblique tows t?.~ a depth of 200 meters and water *samples from the s~face and ~; from depths of 25, 50, 75, and 100 meters ‘“‘WgIndicated rad~actlv++~% ity at each station. Highest radiation readings In plankton .... and water samples were from stations north of Blklni Atoll. .:!%$J Radiation decreased around the periphery of the survey area. . &.$

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Plans, Equipment and operations at Sea Preparations for the Field operation of the Ship The Survey Area Delineation of Area and Proposed Track The Actual Track Collection and Preparation of Samples Plankton Samples and Water Temperatures Continuous Monitoring of Uater Methods of Analyses Gamma Ray Spectra Results and Conclusions Plankton and Water Temperatures Continuous Monitoring of Water Gamma Ray Spectra

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During the planning stage of Operation Redwing, discussions were held by staff members of the Atomic Energy Commission, Division of Biology and Medicine, and the Applied Fisheries Laboratory of the University of Washington on the probable need for biological surveys to define and evaluate the distribution of radioactive materials to be produced by the 1956 series of Following these preliminary discussions, a tentative outline of studies to be pursued during and immediately following: the test series was prepared by the Applied Plsherles Laboratory and submitted to the Division (UWL-45)~ This proposed program contained, among other suggestions, one that called for a survey and evaluation of the radioactive content of the water, plankton, and fish from areas about the test site, following somewhat the plan of Operation TrollThe specific assignment of the Applied Fisheries Laboratory to the survey project was made In a letter of March 28, 1956, from Dr. Charles Dunham, Director of the Division of Biology and Medlcl.ne. This letter addressed to Lauren R. Donaldson stated in part: Program of the Applied Flsherles Laboratory, University Of Washington, for the 1956 Test Series at Bikini and Enlwetok A~oIIs, Mrshall Islands. February 7, 1956. Harley, John H., Editor, operation Troll, NYo-4656,

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The Division of Biology and Medicine has assigned the Applied Fisheries Laboratory the following operations during and following the forthcoming test series: 1. Conduct two marine biological open sea surveys, beginning June 10 and September 1. mission of these two surveys Is to ascertain a the levels of Introduced radioactivity resulting from the tests in the water, plankton, and fish, and (b) how far the activity extends westward In the North Equatorial current. It has been recommended to the Task Force, that the ship should operate from the area of highest average fallout to the westward fringe of the detectable introduced radioactivity in the water, and that you or Allyn Seymour and the ship’s captain be briefed as to the location tf$ere fallout from each shot fell into the s+, prior to each survey. cruise should include the followtng: continuous water monitoring throughout the cruise. The New York Operations Office will construct and install the necessary instruwater samples should be taken at Oj 25) 50~ 75 and below 100 meters at selected stations. Plankton tows should be made in areas of both high and low activity. Fish should be collected wherever and whenfor undertaking these missions were made during April and May, when equipment was assembled and shipped to the Pacific proving Ground and a schedule of staff assignments was worked out. The field group, which departed for Enlwetok early In June, included Lauren R. Donaldson, Allyn H. SeYmour~

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The ship assigned by the Task Force to the first of the two surveys was the USS WALTON (Destroyer Escort 361), a 306-foot vessel whose range and accommodations were considered adequate for oceanographical work in open waters. The WALTON arrived at Eniwetok on June 5, and shortly thereafter the survey equipment was installed on board. The survey was begun on Monday, June 11, and completed on Thursday, June 21. The success of the survey Is attributable to the support of the Division of Biology and Medicine, particularly field team by the operational groups within Joint Task Force 75 for the Intelligent interest in the project demonstrated by Commander Arthur T, Emerson, Jr., captain of the WALTON, and for the very great understanding and assistance afforded by officers ‘ j The probe for >+% and constructed by and members of the crew of the vessel. continuous water monitoring was developed the Instruments Branch of the Health and New York operations Office, under the dlrecD. LeVine, Chief. The use at Eniwetok of a gamma ray spectrometer was made possible through the kindness of W. Robert (lraveson,Chief Engineer of the Electronics Section, Instruments Branch, HASL, who also assisted and instructed members of the staff in Its operation. The Eniwetok *rlne Biological Laboratory of’ the I)~VlslOn of Biology and Medlclne was Used as a headquarters, and shared with HASL personnel who were most cooperative in the exchange of the use of equipment and

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PLANS, EQUIPMENT AND OPERATIONS AT SEA -The marine survey whose results are reported herewith was one of two such projects set up by the Division of’Biology and Medicine for the purpose of collecting information on the levels and distribution of radioactivity introduced into the waters of the Eniwetok-Bikini area by the atomic testing program of 1956. A more extensive survey Is scheduled for September 1956. As originally conceived, the survey was to be made “from the area of highest average fallout to the westward fringe of the detectable introduced radioactivity in the water.” Flpal-- plans were made upon arrival In the field when a review of information available on fallout patterns indicated the desirability of a survey pattern that would provide ample sampling of water and plankton in the areas immediately about Eniwetok and Bikini as well as to the west of Enlwetok during the ten days granted for the survey. The cruise pattern thus projected, coordinated with Task Group 7.3 and reported to the Division of Biology and Medicine, anticipated the coverage of fifty collecting stations on a grid extending from a line approxinutely 18o miles west of Eniwetok to a line 30 miles east of Bikini. The north and south somewhat modified during the course of the survey because of the testing program. The survey, however, actually covered fifty-three stations between Monday, June 11, and Thursday, June 21, on a track of 3,300 miles over 78,000 square miles of

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Preparations for the Field: Preliminary nated by-the Division of Biology and Medicine and by Joint Task Force 7, specified that the survey vessel, the WALTON (DE 361), should report to Enlwetok on or about June 5 and that she should be available for the cruise for approximately ten days after June 10. The WAL7X)Nreported on schedule at Etiwetok, and was joined Immediately thereafter by members of the survey party, who began the supervision of the installation of survey equipmSurvey Equipment: The equipment used in collecting plan~- ton, sampling water, and continuous monitoring of surface water, was installed on the afterdeck of the WALTON, approximately above the port screw. The counters, a recorder, and chemistry laboratory facilities were placed below decks in the after 1. A continuous surface water monitoring probe with tank and water comections (Fig. 1), a unit designed and constructed by the HASL. 2. A power winch (Fig 2), feeding 3fi6 inch steel cable over an A-frame and davit, for the use of plankton nets (Fig. 3) and water sampling bottles (Fig. 4). A steel platform (Fig. 4) extending two feet over the .,, port side of the ship to provide space for work with nets and water sampling bottles. A temporary chemistry laboratory set up on sheet ply-

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wood work tables fastened to existing bm Names and sUpplied by electrical connections with 110 AC outlets (Fig. 5). Two nuclear radiation detection instrwents on a temporary bench built into the wardrobe space of the after 6, A bat~hermo~aph which was a part of the eqtipment Operation of the Ship: The pro~ected crtise pattern presented to the comnder of the WALTW unusual mvigatioml and ~ operational problems, and the mecktics of the sampli~ at the “ “’*”. various stations reqtired close cooperation between perso~el of the ship and of the survey team. It was calctiated that to cover the fifty proposed stations in ten day~j with a stop of”approxi~tcly 30 minutes at each % Station, and with a pause for refueling at the midpoint, the to maintain a speed ship would have As the operational procedure was worked out the tween stations at 18 knots, reduced the speed to 15 hots at ‘+ the speed to 10 knots for a batl@herrflo~aPh drop at ‘Tminus~%~.vJ” put wind 30 to 90 degrees on the port bow, cause the platiton 4 net had the effect of a sea anchor. was stopped and the starbmrd ,; ship was steadied, the port screw

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speed that would maintain the plankton net towline at an angle— of 45° with the surface of the water. For the subsequent drop of the water sampling bottles the starboard engine maintained rpm for speed of about 1 knot. After each drop the ship built Up slowly to the 18-knot cruising speed to avoid unnecessarily great variations in boiler brickwork temperatures. WALTON reported to Enlwetok for refueling on Saturday, when approximately half of the survey had been accomWith addltlowl fuel aboard, the cruise was resumed THE SURVEY AREA Deliheatlon of Area and Proposed Track: The area to be included in the survey and the projected track of the ship were determined at a meeting on June 9 in the offices of Captain H. (3.Munson, USN, representative of the commander of Task Group 7.3. Those present at the meeting Included Captain Munson; Commander N. Purley, naval liaison officer, Cm 7.1; Commander Arthur T. Emerson, Jr., captain of the WALTON; Mr. Merril Eisenbud Determinations of area and track were made after consideration of the elements of the problem, such as fallout patterns and estimated drifts of radioactive materials, and with knowledge X“*. ~ of such operational factors as the overall time limlt on the sur- ‘.,..’.’.,:,~:>? vey, the speed of the ship, and the need of the ship fors...

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T%e proposed track finally was laid out on a grid (Figc 7).~~g.,~ running northeast and runs between stations were used (a) to give southwest, jalthough calling for longer ,.jj” continuous water monitoring readings that ! were only 32 miles apart, and (b) to put the operations at sea -,.> , The Actual Track: From the point of the Initial drop to ~~@., i.“. the return to Eniwetok for fuel on June 16, the WALTON followed”>:.:.,-”,.... $0---. ,, , ,~:. rather closely the track that had been laid out in advance. “.~... During the second half of the crui~e, however, It was necessary+,!.-:~ to modify the track to avoid possible contamination of the ship ~~ }):, by tests scheduled in the area and to provlde~ in the viclnitY,~~+-‘~. ... 4 of Bikini, a more comPlete coverage of ‘he area Contatimted bY, j 1 the drift of radioactive materials. The track actually accom- v&L.;,..:?+.., pllshed by the WALTON is shown in Figure 8. COLLECTION AND PREPARATION OF SAMPLES Plankton, water, and fish samples and continuous measue ments of the activity in the surface water were taken. Plankton samplPlankton Samples and Water Temperatures: were obtained by twenty-minute oblique tows from about 200 meters of depth using a l-meter Michael Sars type net of No* ,. mesh (Fig. 3). No. 6 mesh IS equivalent to seventy-fo~ meshe per inch with apertures of 0.24 mm. This mesh retains some microplankton as well as larger forms. Organisms lo~ep than

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approximately 2 cm were removed from the samples before process-— ing. The plankton was filtered through No. I Whatman paper and planchet, dried with ship . The remainder future use. Amounts transferred to a 1.5-inch stainless steel an infrared lamp, and then counted aboard of the plankton sample was preserved for of plankton were determined volumetrically. A 50 ml portion of sea water and plankton was poured Into a Buchner funnel with No. 1 Whatman filter paper. The amount of plankton remaining on the filter paper was determined by subtracting the amount of filtrate from the original amount of sea water and plankton (50 ml). After returning to Eniwetok Mariri% Biological Laboratory the shipboard estimates of the volumes of the plankton samples were revised. The corrected volumes were calculated by multiplying the dried sample weight of the individual samples by the ratio of the average estimated volume to the average dry weight. Finally, volumes in ml were converted directly to wet weights In grams. Bathythermograph casts were made by the ship’s crew at each station during the cruise for the purpose of defining temperature change with depth. Water Samples: Samples were collected at the surface by bucket and at 25, 50, 75 and 100 meters by means of a Nansen water bottle (Fig. 4). ‘I%esurface water samples were processed aboard ship and the other samples at the EMBL. One liter of surface water was passed through a Millipore filter using Mlllipore AA paper. The filter paper was saved and counted. From the filtrate two 100 ml samples were processed

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for counting and a 500 ml sample saved for possible futue use, To each of the 100 ml samples 5 ml of saturated sodiw carbonnaturally occmring K , normally present in sea water to the ,:~..,{ extent of about 600 d/m, is elimimted from the portion w~ch ~ Radloceslm …