Letter to S L Warren, Subject: Enclosure: Observations and Suggestions Resulting from Participation in Tests Able and Baker (Crossroads)

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PRIVACY ACT MATERIAL REMOVED THE OHIO STATE UNIVERSITY t Howard L. Bzvu, Prendcnt DEPARTMENT OF MEDICINE Ofnci axd Rxiulich Laboaatomb* Manhattan District Project University of Rochester Rochester, New York Deer Doctor Zarren: Enclosed <Te copies of the letter and report sent you in late August after ny return fron Bikini. I pm sorry that you had not received then previously and hope they nay still be useful. In the light of more recent experience, minor modifications in the report wo ild be in order, but in general ray impres sions ore still essentially the same ps after ry return from Operation Crossroads. It was a pleasure to see you again ?t the Radiological meetings in Chicago. Mrs. Myers and I both enjoyed the movie and comments by Colonel Cooney and your own impressions aftervp.rd. I hope when you are in this vicinity you will plpn to ppy us e visit and look over our facilities and investigations in the field of nuclear physics as applied to our medical and biological researches. PRIVACY ACT MATERIAL REMOVED BEST AVAILABLE COPY

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PRIVACY ACT MATERIAL REMOVED BEST AVAILABLE COPY w Oakland Arwjr Base, Calif. Bear Colonel barren) last few days I was aboard the Hawen before re turning by second air-lift. I hope they will not reach you too late to be of value to you in your suaoariaation of the operation. If they are not clear in all respect* or need further elaboration, please let no know. I an very grateful to you for your invitation to take part in the tests and for your efforts toward ranking the participation of all of ua as pleasant and as profitable as possible. The tine spent away from ny own work was well repaid by the contacts X arde, the helpful seminar of fine lectures arranged by Colonel de Loriner, and the nost educational two aonths Jam-packed with adventure I have ewer experienced. X was particularly Impressed by and appreci ative of the fore-thought and preparation which went into Baking the teats ae safe and fool-proof os possible. In this regard X think Captain Lyon deserves special cocoandation for the splendid Job he did on Annex E. It wna a genuine pleasure to have served under your direction and a privilege to have been a participant in Operations Crossroads. PRIVACY ACT MATERIAL REMOVED BEST AVAILABLE COPY

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PRIVACY ACT MATERIAL REMOVED in Teat Able end Test Baker A. Civilian Atomic Bomb Monitoring Corps 1 va* aware that the monitor* were probably chosen beoeise they were phyalcians or aciffiitlst* experienced, in radiation or radio logy, or both, a* well as that they rrere selected from widely scattered commit lee throughout the country. It seemed to me that the training we received and the first-hand experience we gained with phenomena associated with atonic bomb explosions would be best exploited and most useful to our nation in time of the inevitable atomic bombings of our cities if we were organized into a nationwide corps of monitors Instantaneously available for service daring and following such attacks. 7e could have a civilian status such as that of Air-Bald hardens and members of the Civilian Defense Corps during World War II. TTe should be provided with suitable identifying insignia and credentials to enable ua to perform our duties as expedition*- ly os possible. A travel and cocsnanicntion priority for such emergency uce should be assigned ua so that we could contact a central headquarters immediately at any time and be directed to travel to those cities or areas in our own communities which had greatest need for monitoring. We should hare in our possession at all tine* several recently tested instruments ( see below) both for replacement and for deputies trained on?-th*-spot for their use under our direction. We should also have several hundred signs Do Hot Stay Her# Over with the blank to be filled in by the monitor in minutes or hours with black wax crayon. The experience we gained at Bikini should be considered as our initial training period. We should be assembled at a source of large amounts of radioactivity, such ns a pile, periodically every two or three years for refresher purposes and to acquaint un with the proper use of the latest instrameutn supplied us as they evolve. Since several scores of German scientists were crrptured by a potential enemy and are undoubted ly now being exploited by that nation for the davlopnent of methods PRIVACY ACT MATERIAL REMOVED BEST AVAILABLE COPY

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of production of atomic ‘bonba, m ma7 anticipate that an atomic bomb attack on our cities amy be Launched at any time, swiftly and without warning, probably by rocketa or by placements by saboteurs. Therefore the propooed. Civilian Atonic Bomb Monitoring Corps should be organized (and probably expanded) aa soon as possible. Close monitors who served in Operation Crossroads night serve as the nucleus of such a corps. A large number of new monitors should be trained at Test Charlie to be added to the first group. A large supplementary list night be recruited fron those qualified by extensive monitoring experience on the Manhattan District. B. P-T Boat Hsseas and Monitoring Units I was stationed aboard PGA 24 for Test Able and aboard PGM 32 for Test Baker. As you know, all of the gun-boats became badly contaminated with radioactivity after Test Baker which limited their usefulness somewhat in that the crews had to be evacuated at night because the excessive radio activity could not be dissipated by running the ships at sen. Moreover, these vessels have a minimum speed of about eight knots which is too great for probing into sharply delineated areas of highly radioactive water such as we enoountared. Thirdly, fairly large crews are required to man them. On the other hand, the LCP(L)1s became liabilities when their single motor failed and they were likely to drift Into high radioactivity. Therefore I should like to suggest that in time of war for purposes of rescue of salvagable crews of ships on the fringes of atom-bombings (for morale if nothing more) ns well as monitoring functions, that a boat intermediate in else be provided. Probably a P-T boat or a modification of it would serve the purpose. Such a craft should have the approximate a) Two conpletsly independent engines, screws, etc. it could be hoisted out of the water and the paint contaminated during the day could be removed readily and a new coat of specially designed paint be spi lled during the night in readi ness for next day* s activities. c) Be speedy and very caneoverable so that rescues could be affected in a short time in waters that would be too "hot* to operate in with slower boats. PRIVACY ACT MATERIAL REMOVED As you are well aware, the multiplicity of instruments served only to confuse us. However, their number and variety was a good thing since it enabled a critical evaluation of performance In the field to be made. It is of course essential that three separate instruments be available for the performance of a satisfactory monitoring Job! PRIVACY ACT MATERIAL REMOVED BEST AVAILABLE COPY

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PRIVACY ACT MATERIAL REMOVED 2. A cusulative dose neter Apparently the film .bodges we used tere aatiofactory insofar ae erjana rrd-iation was concerned, although X have no bania for Judging their efficacy See D. below for comment a concerning beta radiation* X thought the pocket electroscope type dosimeters supplied ua were quite satisfactory. The Pro taximeter was worthies#. The confusion nearly all lay with the vario'^f types of rate meters. The X-263 was very unsatisfactory for the following reasons* a) It too often failed to function entirely* Nearly everyone finally tried to get hold of three or four of the* to assure himself that at least one would be working by the time he had reached hie b) It did not read directly in “r- per day. c) It became very erratic nod was often misleading on the 20* scale when It was essential that it function well. d) It did not measure high enough radiation intensities. On the credit side the X-263 was* a) light and easy to carry. b) Very sensitive (Uore so than necessary). e) The he«d-phone feature was a good one. For monitoring nftsr atomic bombings of our cities it will be neces sary that a fool-proof rate meter be available that will embody nil, least, of the following! 1. It must measure'up to 200 ',ru per day. 2. It must have a thin enoxvyi window that fairly low energy beta rays will be measured along with the gaiaoa rays. This is an 3. At rates above 1 "jr* per ho’ir a safety warning bell or busser should sound continuously. 4. The lower limit of sensitivity would not need to be less than about 0.01 "r" per day. 3. The dial should have a lighting device behind it for reading in the dark. 6. Hew batteries easily installable. 7. It must be sturdy and may weight up to four or five times that of the X-263 if carried in the hand or more if designed to be strapped on the back. In order to have the range indicated above, the meter mat have several acnles which must operate froa the same zero setting with easy switching between scales. There is good agreement .among physicists experienced in measuring rndlntion Intensities that an ionization chamber is much core reliable than a counter device, especially when portability is dooired. PRIVACY ACT MATERIAL REMOVED BEST AVAILABLE COPY

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PRIVACY ACT MATERIAL REMOVED ionisation chamber, type. To be sufficiently sensitive it should have had n 10^2 scale in addition to the I0^t 10^ rsnd 109 scaleo. It ahould not be difficult to design the meter to read in "r" per day. Other than these minor deficiencies it ms on excellent portable rate meter. D. Dangers of Bets Radiation My apprehension concerning the almost complete disregard of the dangers of beta radiation eae shared by many others including Dr. John tion of a given energy produces the tissue-damaging ionisation in quanti ties approximately 100 times as great at that resulting from gsama radiation of the same energy. In conversations with one of the colonels, who wna actively directing some of the work, concerning the danger* of beta radiation, he was of the opinion that no danger existed because the akin is not penetrated by betas to more than about one sllllseter. This la strictly not the caee. To illustrate let us use data concerning fission products published by the Manhattan District in Science 107. 6gf (half-life = 17 minutes) and this isotope emits a beta with anxiaaa energy a 3»1 aev. There is also present in leaser amount Ru-lOo (halflife - 1 year) which gives rise to Kh-lo6 (half-life * JO seconds) and this isotope salts a betr with maximum energy • 3«9 Mew, Also, many other strong beta-emitters are present. How, try extrapolation of some of Ksflsme Curie's data indicate that betas with energies of 3»1 3«9 Mev. will penetrate tissues not tc the extent of only 1 am# but to approximately 15 to 20 millimetersi After monitoring with Dr. John Lawrence under Lt. Shallow1 a direc tion aboard PGM 32 on 3nker Day, I returned to the Haven that night where Dr. Hardin Jones discovered that my clothing had become highly contaminated by beta-emitters. This contamination persisted in some what lessening degree up to the tine my clothes were finally accepted by the laundry on Baker plus 5* v'ith the above lead at hand I explored the PQi 32 for beta contamination with a "Cutie Pie" with window open on Baker plus 1 and found that the screen (probably actually the grease and lint accnanloted on it) covering the air intake port of the naln ventilator system of the ship was badly contaminated. The beta plus gnmma/gnnaa ratio was of the order of about 6 or more (the reasurements were recorded on daily data sheets hended in by Lt. Shallow). This beta contamination persisted at least to B«iker plus 9 when I left PGU 32 the last tloe. Zven the X-263, which was very insensitive for soft betas, indicated a beta plus garaoa^gamna ratio of about 3« PRIVACY ACT MATERIAL REMOVED BEST AVAILABLE COPY

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PRIVACY ACT MATERIAL REMOVED _ BEST AVAILABLE COPY 0 The contpjRinAtlan of my clothes Titd the .icroen (th«» nnah of which only by the Baker bomb. Aside froa injuries to the r?kln gad underlying stmotures fron contamination of the clothes nnd hair, I would be concerned with that which entered the luntfs since a EU'n nt rest on the ships would have breathed in about hoO-500 liters of the contaainated air per hour. I do not believe th.«,t the fila bad£e values for bet^* plus gaBBn compered with gejnas alone had much si^niflcaice because the sensitive fila was en cased in thick paper plus a Betel foil that would have stopped coopletely nuch soft bets radiation which, however, could still have been suffici 1 as not an sleraist. Colonel rr^rren, and 1 am fully cognisant that hind-night is such better than fore-sight. It is ay opinion that probably no permanent rsdiation injury was sustained by any of the participants. I do believe though that many of us probably received ouch core penetrating, ionizing radiation than the Instruments of very low bet«e>sensitlvity were able to record. I have included this section principally because cany of ua were very apprehensive and because I believe that air-borne beta radiation. stabilised by the dusts of our atom bonbed cities any be several tines core dangerous than the attendant gamma radiation. Prnftical application of this opinion in preparation for such eventualities would be to design the instrucenta provided the Civilian Atonic Bomb Monitoring Corps proposed above, or other monitoring igency, so that both tha rate neter and cumula tive dose irseter recorded beta radiation (insofar an possible) along with the gacaa radiation. E. Peculiar Baker Day Phenomenon There was observed a peculiar well delineated base over the target area by several of ua aboard FGa 32 as we approached the Ingoon entrance about two hours after the B„ker bomb burst. The fact that the halo-like effect renal nod very symmetrical throughout the four or five hours during which it gradually decreased in sise end faded in intensity would indicate that it nay have been associated with some sort of radiation. Sven when most intense, it would have been difficult to record photographically end success would probably have resulted only if the encern would have been directed parallel to and not more than a hundred feet or bo above the surface of the lagoon. Its approilmate shape and relationship to the target area at about HOC and lUjO la sketched below. BEST AVAILABLE COPY Ut/UCLA

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