ATTACHMENT 10 REPORT OF PARTICIPATION IN SELECTED VOLUNTEER PROGRAM OF DESERT ROCK V-ILLEGIBLE 25 APRIL 1953 Prepared by: Captain Robert A. Elmers, USN Headquarters, Armed Forces Special Weapons Project DECLASSIFIED BY ORDER OF THE SEC ARMY BY TAG PER 3 ILLEGIBLE MEMORANDUM FOR AFSWP FILES SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE ILLEGIBLE, and Description of Effects on 50 ILLEGIBLE Burst as Observed at 2,000 Yards from Ground Zero 1. The undersigned participated in the Selected Officer Volunteer Program of ILLEGIBLE ILLEGIBLE Book 7-7 held on Saturday, 25 April 1953 at the Nevada Proving Grounds. Arrangements for my participation were made with the Exercise Director, Brigadier General W.C. Bullock, by Colonel ILLEGIBLE of AFSWF Field Command in accordance with request from this headquarters. The AFSWF report had stipulated that my proposed participation, if arranged, should not be permitted to result in the displacement of any officer who might previously have been selected for this group by the Army. This condition was met without difficulty, since several of the Army officers originally selected had been unable to attend the exercise. In requesting my participation, Colonel ILLEGIBLE also informed the Exercise Director's representative (Colonel Thelma) that I would be acting in the capacity of a representative of AFSWF rather than of the Naval Service. 2. The volunteer group selected for this shot consisted of a total of eight officers. The other seven were all from the Army, and included Colonel K.P. ILLEGIBLE and Lt. Colonel J.E.K. Hines of the staff of the Special Weapons Course at Ft. Leavenworth and Colonel M.M. Irvine of ILLEGIBLE. In the interest of continuity, General Bullock designated it Lt. Colonel Don Davis, Inf, USA, as the group leader. The latter and functional in a similar capacity for the previous shot. A complete list of the officers in this group is appended hereto (Tab A). 1 Security Information SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE 7-7, and Description of Effects ILLEGIBLE ILLEGIBLE and Observed at 2,000 Yards from Ground Zero 3. Prior to final acceptance as a member of the group, each officer was required to personally and individually compute the effects to be expected in an open trench on the basis of the expected yield of 35 to 40 ILLEGIBLE, and to recommend a distance for positioning the group which would not exceed the effects criteria which had been established for this exercise. Each officer also was required to exercise a certificate confirming his volunteer status. Attached hereto (Tabs B and C) are copies of the forms used for this purpose. In submitting my own forms, I recommended a distance of 2,000 yards. 4. General Bullock reviewed the ILLEGIBLE at a briefing conference held in his office on the day before the shot. Since there was substantial agreement between all of the officers of the group as to the 2,000 yard distance, this distance was approved by the General. Trenches previously had been prepared at 500-yard intervals, so that the final decision could be made with some flexibility on the basis of the weather conditions and any other last-minute considerations having any bearing on the predicted efforts. At the final briefing, General Bullock also informed us that although there had been a rather complete press release on the *The actual yield, as of the time of preparation of this report (26 May 1952), as reported to have been between 50 and 55 ILLEGIBLE. 2 SECRET SECURITY INFORMATION SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE V-7, and Description of Effects of ILLEGIBLE Burst as Observed at 2,000 Yards From Ground Zero. volunteer program following the first ILLEGIBLE ILLEGIBLE ILLEGIBLE exercise, more recent security restrictions precluded public release of the exact distance at which we would be positioned relative to ground zero or of any of the other details of our position and observations. 5. We were given physical examinations at the camp ILLEGIBLE the day before the shot, and also were interviewed by psychologists from the Army contract group known as the "ILLEGIBLE ILLEGIBLE ILLEGIBLE Office" (ILLEGIBLE). 6. The final weather prediction on Friday evening indicated fairly strong cross-winds (from the west) at both the 10,000 and 20,000 feet elevations, and very little ground wind. This was considered to be about as favorable as we could expect from a contamination standpoint. The actual weather at shot time was as predicted. 7. The personal equipment issued to us for use on shot day consisted of standard Army field helmets and liners, gas masks, flashlights, and canteens. We each receive three file badges and were instructed to place one in a ILLEGIBLE pocket, pin one to our back or place it in a hip pocket and tape the third inside our helmet. In addition, various types of ILLEGIBLE, and several survey ILLEGIBLE, were distributed throughout the group. We also were issued cotton for use in keeping dirt out of our ears. 8. On the morning of the shot, we rode to the forward area on ILLEGIBLE of the ILLEGIBLE of the regular troop observer convey. The Army psychologists accompanied us as far as the main troop positions at the 4,000-yard point. Our group continued on alone by truck to the general vicinity of the 2,000 yard position arriving there about one hour before shot time. Communication was established by field telephone with Colonel ILLEGIBLE, the Deputy Commander for Operations, who was with the main body of troops. He relayed the usual AEC time announcement to us. We remained above 3 SECRET SECURITY INFORMATION SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE V-7, and Description of Effects of ILLEGIBLE Burst as Observed at 2,000 Yards From Ground Zero. ground until about 15 minutes before shot time, at which time we entered our trenches. There were two trenches in line, each about 20 feet long, 3 feet wide and 6 feet deep, with their adjacent ends separated by about five yards of concentrated earth. One was reinforced with a solid rock lining on the front and rear ILLEGIBLE and cross-braced with wood timbers at about 4-foot intervals. The other one was ILLEGIBLE. Each trench had a row of sandbags placed flat on the ground around its top perimeter, and had a loose fill sloped to about a 45o angle at each end to facilitate ILLEGIBLE in ILLEGIBLE. We were permitted to choose our respective positions. I chose the ILLEGIBLE trench, along with two other officers of the group. Both trenches were bare of any equipment accept for several shovels. See Tabs D and E for photographs of the trenches, taken after the shot. 9. The telephone was placed in the ILLEGIBLE trench, but those of us in the other trench could hear the time signals without difficulty as the talked called them out. Just before shot time, we all squatted close to the forward wall in order to obtain maximum shielding, and faced away from ground zero as a precaution against spelling. Due to the alight time lag involved in relaying the time signals by telephone, the actual detonation occurred when our talker had reached a count-down of about 3 seconds before zero time. 10. The following is a summary of the variable effects as we observed them at 2,000 yards from ground zero, in the positions described: a. Light - The intense white light was the first manifestation of the explosion, and seemed to persist for at least six seconds, as it 4 SECRET SECURITY INFORMATION SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE V-7, and Description of Effects of ILLEGIBLE Burst as Observed at 2,000 Yards From Ground Zero. continued well beyond the time of arrival of the shock wave. I was wearing Navy safety goggles with clear glass lenses, as I was carrying a high-range experimental type of radiation survey meter and had hoped to get an early reading of the prompt nuclear radiation by opening my eyes very slightly. This proved to be impossible; I not only could not see the meter scale or pointer, but could not even see the profile of the instrument, the bottom of the trench, nor any other surrounding objects. There was nothing but white light on all sides. However, I had no sensation that it was hurting my eyes; it merely blanked out all vision for the duration of the fireball. When the fireball finally cooled off and the light gradually diminished, I had no ILLEGIBLE of any monetary flash-blindness; so far as I could tell, my eyes ILLEGIBLE to the rather dim early morning light (which was further reduced by the very heavy dust cloud) as fast as the fireball disappeared. b. Earth Shock. This was the second manifestation of the explosion to be felt at our position, and in our case never exceeded a rather slight trembling ILLEGIBLE. I was squatting on the balls of my feet with one shoulder braced lightly against the forward wall of the trench. In spite of this rather ILLEGIBLE position, at no time did I lose my balance due to ground motion, nor did I feel any appreciable ground shock against my shoulder. This was in apparent contrast to the experience of some of the members of the volunteer group at an earlier shot (V-1) who, although at a 500-yard greater distance from ground zero, reported considerable ground motion. Several persons with when I discussed this afterwards expressed the opinion that this difference probably was due to varying geological at the two locations. 5 SECRET SECURITY INFORMATION SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE V-7, and Description of Effects of ILLEGIBLE Burst as Observed at 2,000 Yards From Ground Zero. of the shock wave required slightly less than 4 seconds to reach our position. It was loud enough to be startling, but not at all painful. In this latter respect, I did not find it as annoying, for example, as the "crack" of a three-inch AA gun. It was more of a "boom" than a sharp crack. It was accompanied by a shower of light pebbles and heavy dust, but no other missiles of any kind were felt or observed at our range. I could not recall afterwards having had any ILLEGIBLE of increase of pressure from the positive phase of the shock wave, or reduction due to the negative phase, but this might easily have been obscured by the startling effect of the noise. Calculations made afterwards for yield of 50 ILLEGIBLE indicated that the overpressure at this position was about 4 psi on the surface, with a possible increase to 5 psi at the bottom of the trench due to reflections. There was no appreciable caving or spalling of the trench either from ground shock or air blast." d. Heat - There was no sensation of heat in the trench; not even on my face, which was entirely exposed except for the small area covered by the frames of my safety goggles. e. Nuclear Radiation - The first reading which I was able to obtain on my survey meter was exactly 100 r/hr. I estimate this to have been at about 8 seconds after the detonation, as soon as the light had diminished ILLEGIBLE for me to regain my sight. At this time, the pointer on the instrument was moving smoothly downward. The decrease in the ___________________________________ The soil in this area consisted of hard ILLEGIBLE. A looser material might not have stood as well. For further evidence on this, see AFSEP Report ILLEGIBLE, "ILLEGIBLE Type ILLEGIBLE ILLEGIBLE Shelters"; also see tab marked "Supplement". I carried an IM-71/PD ("CASPER") miniature ion chamber survey meter, which has a range of 0.02-500 r/hr. 6 SECRET SECURITY INFORMATION SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE V-7, and Description of Effects of ILLEGIBLE Burst as Observed at 2,000 Yards From Ground Zero. reading was fairly rapid at first - down to 50 r/hr during the next ten seconds or so - but the note of decrease then gradually slowed down so that it required about one additionalminute for it to drop down to a reading of between 20 and 25 r/hr. I was calling the readings over to the group leader in the other trench, and at this point he directed us to leave the trenches. I watched the meter as I climbed out, and it moved up to 40 r/hr as I left the trench for the open ground. We stopped briefly to examine some sheep which had been tethered in a dugout, in shallow trenches, and in the open in the vicinity. As we did so, I noticed that the meter reading was gradually increasing, so that it was again up to about 50 r/hr. by the time we started walking down the road away from ground zero. It was then about 4 or 5 minutes after the burst. During all this time, particles of sand or other debris was continually raining down on our helmets; the sound ILLEGIBLE light alerting. 11. As we walked away from ground zero, the survey meter reading steadily decreased, but whenever we stopped to look at something, it would gradually increase again which indicated that a substantial amount of fall-out was still being deposited at those distances (between 2,000 and 2,500 yards from ground zero). After we had walked for about a quarter of a mile, we were met by our two evacuation trucks; by this time the instrument reading was down to about 10 r/hr. The reading ___________________________ A study of the cloud motion pictures of this burst indicates that the height of the cloud was roughly 5,000 feet at the end of the first 20 seconds, and that 60 seconds later it had risen to about ILLEGIBLE feet. 7 SECRET SECURITY INFORMATION SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE V-7, and Description of Effects of ILLEGIBLE Burst as Observed at 2,000 Yards From Ground Zero. continued to decrease rapidly as we moved away from ground zero by truck, and was down to less than 1 r/hr. by the time we reached the main body of troops at the 4,000 yard position. 12. It was difficult to read our quartz fiber dosimeters immediately after the shot because of the heavy dust cloud, but early readings obtained by flashlights indicated that of the total average dosage of ILLEGIBLE received by the members of the group, about 10 or 11 ILLEGIBLE, was in the form of prompt radiation (received within less than a minute after the explosion), and the balance was residual radiation received during the withdrawal from the position. Most of the 0 to 10 r self-reading dosimeters carried by the group went slightly off-scale, but a higher range dosimeter which I was carrying (1M/91/PD) read 10 r when I left the trench and ILLEGIBLE r back at ILLEGIBLE. 13. Tab F is a tabulation of the film badge readings for the group. About the only "pattern" noticeable in this list is that in most cases, the "chest" reading is the lowest and "hip" reading is the highest. This is not surprising, since the chest film badges were in our breast pockets and were shielded from ILLEGIBLE-shine by our bodies in the squatting positions which we assumed at the time of the burst. The "head" badges. although closer to the top of the trench, were shielded by our steel helmets. In addition to the film badges, each officer carried one phosphor glass locart type of dosimeter (DT-60/FD) and one holder containing several Polaroid self-developing film badges (DT-60/PD) which I had obtained from the radian instrument evaluation group at Camp Mercury. When checked 8 SECRET SECURITY INFORMATION SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE V-7, and Description of Effects of ILLEGIBLE Burst as Observed at 2,000 Yards From Ground Zero. afterwards, the phosphor glass readings did not correlate individually with the film badges, but the average reading for the group (13.6r) checked exactly with that of the film badges. This agreement was as good as could be expected, since the DT-60's were designed for a range 0-600r, and could not be expected to be very accurate at these relatively low readings. All of the Polaroid badges checked less that 30r, which was the lowest step on their scale. 14. The principal effect visually observed above-round after we had emerged from the trench were: a. Sheep - Those in the vicinity were singed to a dark brown color on those portions of their bodies which had been exposed to line-of-sight thermal radiation, but they were all on their feet and showed no other evidence of physical injury. b. Trees - A large ILLEGIBLE tree just outside our trench was partly broken off and on fire. It can be seen in the upper picture on Tab D. Other ILLEGIBLE trees were burning on all sides of our position. c. Dust - The dust was sufficient to make the visibility very poor beyond a hundred yards or so in any direction, but was not heavy enough to be suffocating. I did not feel the need of putting on my gas mask, and did not use it. 15. A stop was made for a monitoring check at the ILLEGIBLE Rock station across from the ILLEGIBLE ILLEGIBLE on our way back to camp. It was found that ILLEGIBLE off our clothing and shoes with a ILLEGIBLE was sufficient to bring the reading down to an acceptable level. 9 SECRET SECURITY INFORMATION SUBJECT: Report of Participation in Selected Volunteer Program of ILLEGIBLE ILLEGIBLE V-7, and Description of Effects of ILLEGIBLE Burst as Observed at 2,000 Yards From Ground Zero. 16. Following our return to camp, we were given an "ILLEGIBLE interview" by the Army psychologists, and filled out questionnaires, Tab C. With respect to the question concerning the ability of troops to carry on immediately after emerging from trenches under those conditions, it was the ILLEGIBLE of opinion that there should have been no difficulty except a radiation in efficiency for about the first five minutes ILLEGIBLE to the heavy dust cloud and resultant poor visibility. 17. Tab H is enlarged from a frame of a motion picture at 13 seconds after the blast, taken from a camera station seven miles to the east of ground zero. The position of our trench relative to the early cloud and fireball is indicated to scale by the white arrow, i.e., at a point 2,000 yards to the left of ground zero. R. A. ILLEGIBLE CAPTAIN, U.S. Navy 5 June 1953 10