HEADQUARTERS
TASK GROUP
7.4 PROVISIONAL

APO 187, c/o Postmaster
San Francisco, California.
14 April 1954

MEMORANDUM FOR THE RECORD

SUBJECT: Evacuation of Rongerik After Shot BRAVO, Operation CASTLE

1. Twenty-four (24) airmen and one (1) Warrant Officer of the Weather Reporting Element (Provisional), Task Group 7.4 were assigned to operate a weather station for JTF SEVEN on Rongerik Atoll, Marshall Islands. In addition this detachment operated a recording radiation rate meter for the New York Operations Office, AEC. The purpose of the device was to maasure and record any radioactive fall-out which might occur after an atomic detonation on either Eniwetok or Bikini Atolls during Operation CASTLE. This radiac station was one of several situated in the Pacific Ocean area as part of a general fall-out activity. The instrument was capable of detecting a maximum activity of 100 mr/hr. Above that figure the instrument was inoperable. Mr M. R. Breslin, JTF SEVEN was the local representative of the New York Operations Office, AEC.

2. Three (3) Army enlisted men assigned to Task Group 7.1 were stationed on Rongerik to operate an Ionosphere measurement station for Project 6.6. These personnel shared messing and housing facilities with the Task Group 7.4 detachment.

3. Shot BRAVO was fired on 1 March 1954 at approximately 0640 local time on CHARLIE Island located in the northwest corner of Bikini atoll. The ZERO point was approximately 130 nautical miles from Rongerik Atoll.

4. The following is a chronological sequence of messages and deci- sions leading up to and through the evacuation of the personnel on Rongerik Atoll on 2 March 1954:

a. Message No.1: From Weather Detachment at Rongerik to JTF SEVEN, 1500, 1 March 1954 - "Attention Mr. Breslin, Info Comnder, Weather Reporting Element, Provisional. GR 12 MIKE over 100 CHARLIE - Over 100."

Above message received AACS Communications Center, Eniwetok at 1543, 2 March, and delivered to US Army Communications Center, Eniwetok at 1547 (local time) for transmission to JTF SEVEN. Because the "Info . Commander WREP GR 12" was in the body of the message, the Weather Element Test Services Unit, TG 7.4, was not informed (text unreadable).

b.Message No. 2: From Weather Detachment, Rongerik, to JTF SEVEN, 2015, 1 March - "For JTF SEVEN Eniwetok. Pass to Mr Breslin. Auto monitor present reading is 100 plus repeat present reading is 100 plus, pen off chart and has been in this position since 0250Z. Request acknowledgemt of receipt from Breslin. Signed Commander."

Above message was received 2040 (local timr) by AACS, Eniwetok and delivered to Army Communications Center, Eniwetok for further transmission to JTF SEVEN at 2050. Major Fellie F. Robinson, Weather Reporting Element, Task Group 7.4 was read the mssage by the AACS at 2049 (local time). The message was discussed with Colonel M. B. Hammond, Commander Test Services Unit, TG 7.4. It was decided to obtain more information before any action should be taken. An attempt was made to locate Mr Breslin of the NYOO, AEC, on Parry Island to determine the meaning of "100 plus". He was not on the island but Colonel Dave Miller TG 7.1 stated that the top range of the instrument was 100 mr/hr. It was then decided to call on other Task Group personnel to assist in evaluating tbe problem and determine the correct course of action. How- ever, it was considered advisable to send Message No.3 to Rongerik as a precautionary nmasure - "From Weather Reporting Element, to Rongerik, 0015 2 March 1954: 'Cease all operations immediately aad all personnel remain inside metal buildings until further notice. Maintain rotating shift radio communications with one DR for further instructions. Robinson sends.

C. At approximately 2300 Colonel K. H. Houghton, Technical, Advisor, TG 7.4, was called by Lt Colonel Watkins and requested that he attend a meeting to consider the radiation conditions at Rongerik. At approximately 2330 a meeting was held at Lt Colonel Hammond's quarters. In attendance were Lt Colonel Hammond, Colonel Houghton, Lt Colonel James Watkins (Commander, Test Aircraft Unit), Major Robinson and Captain Chrestensen, Rad-Safe Officer, Test Support Unit, TG 7.4. Responsibilities for the down cloud area monitoring and the Rad-Safe instrumentation avail- able at Rongerik was discussed. It was determined that Task Group 7.4 should take steps to determine for themselves what the true radiological situation was at Rongerik and not wait for JTF SEVEN notification. It was deemed undesirable to attempt to get a water landing aircraft into Rongerik before daylight (approximately 07OOM, 2 March 1954). If a PBM or SA-16 aircraft were sent direct to Rongerik from Eniwetok an advantage of only l/ 1/2 hours would be gained over utilizing the regular Kwajalein- Rongerik resupply run that was scheduled for 08OOM on the morning of 2 March. A MATS aircraft was leaving at 03OOM on 2 March for Kwajalein from Eniwetok and it was decided to send Captain Chrestenson as a rad- monitor on that aircraft and have him pick up the regular Rongerik run at that station.

d. Captain Chrestensen departed Kwajalein by Navy SA-16 at 0830, 2 March and arrived over Rongerik at 0945. The aircraft did not land immediately but made passes over the island at 500 ft altitude. The average reading on the 4T-lB radiac Instruments were 200 mr/hr. Another pass at 250 ft altitude was 340 m/r, The aircraft climbed to 5000 ft to attempt direct radio communication with the USS Estes or Eniwetok. Transmissions were garbled and intermittent. The following message (message #4), however, was received by the ACC, &iwetok, at 1043, 2 March from Navy aircraft #1902 "Should Rongerik Island be evacuated at Request immediate answer". The message-as received did not make much sense but Lt Colonel Crosby, TG 7.4 Operations, queried Lt Colonel Richard House, Rad-Safe Officer, JTF SEVEN. House's information based on shipboard contamination (USS Estes-USS Bairoke) in the target area and fall-out prediction indicated that Rongerik should be in the same contamination level as the ship or approximately 300 mr/hr. The effect should be transient and disappear in a few hours. He counseled no evacuation. Crosby then sent a message to Navy aircraft 1902 informing them not to evacuate Rongerik. This message was sent to Navy aircraft 1902 at lll7M on 2 March 1954 (Message #5).

e. The request from Crosby was received by Navy 1902 and Chrestensen sent back that his only radiological reading was "340 mr/hr at 250 ft altitude." This message was received at TG 7.4 as "340 mr/hr at 250 ft. This was discussed by Crosby and Houghton and Chrestensen was informed at 1126, D/l, to disregard message to not evacuate and again requested the radiological situation in more detail (Message #6).

f. Chrestensen finally landed at 1130, 2 March, and made a quick rad survey of the island and work spaces. It was as follows:
Inside buildings 0.6 r/hr
Outside buildings 1.8 r/hr (waist height)
Outside buildings 2,4 r/hr (sand surface)
Surface of one bed in tent l.2 r/hr
One Inch from ground surface 3.2 r/hr

g. Eight (8) men was loaded on the Navy aircraft and started for Kuajalein. As the aircraft departed Chrestensen was informed by the pilot that additional information on the rad situation was requested by TG 7.4. A reading of 3.2 r/hr at one inch was sent (not received). At 1125 Crosby received a TWX stating that the Navy aircraft had taken off eight (8) personnel. (Message #7 & 8).

h. At 1439 a classified message was received from JTF SEVEN LN0 at Kwajalein stating "Upon advise of Captain Chrestensen, Adm Clark is returning same aircraft to Rongerik to evacuate remaining personnel - Hughes sends." At 1440 a confidential message was received from JTF SEVEN IN0 Kuajaleln addressed to JTF SEVEN Eniwetok and TG 7.4 Eniwetok: "Per Crosby's request following submitted. Captain Hughes was requested to assist by Adm Clarke. Following is summary. Navy 1902 DF-1 with Chrestensen on board requested imperative they have frequencies of USS Estes. They were unable to contact on 126.18. Navy 1902 queried should Rongerik be evac- uated at once. Navy 1902 then requested PBM for evacuation and stated they were going in to pick up eight (8) persons. Chrestenson advised that readings at one inch 3.2 r. Navy 1902 landed 1349M, 8 people have been evacuated. Twenty people still to be evacuated. Chrestenson insists remaining personnel must be evacuated immediately. Hughes sends."

i. On the basis of the above TWX Crosby and Houghton ordered immediate evacuation and a TWX was sent to Commander, Naval Air Station, Kwajalein at 1445, D+l, requesting their assistance in the removal of personnel from Rongerik as soon as possible.

j. Chrestensen arrived at Kwajalein with the eight (8) evacuees at about 2400 and the last 20 evacuees arrived about 1900, 2 March. Shortly after arrival, Chrestenson sent via JTF SEVEN LNO, Kwajalein, to CTG 7.4, info to JTF SEVEN, the following mssage: "Suggest immediate survey of inhabited islands of Rongelap. High possibility exists that ixmdiate steps must be taken to evacuate natives. Signed Chrestenson."

k. Upon their arrival to Kwajalein, the evacuees were decontam- inated and placed under care of the Station Medical Officer.

Karl H. Houghton
Colonei, USAF (MC)
Technical Advisor to the Commander

cc: Co1 Houghton
cc: Co1 Crosby
Declassified
DOD DIR 5200.10

Harold Wainscott
Email: haroldw@kih.net

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