PROJECT TRINITY
1945-1946
by
Carl Maag and Steve Rohrer
United States Atmospheric Nuclear Weapons Tests
Nuclear Test Personnel Review
Prepared by the Defense Nuclear Agency as Executive Agency for the
Department of Defense
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CONTENTS:
LIST OF FIGURES
LIST OF ABBREVIATIONS AND ACRONYMS
REPORT DOCUMENTATION PAGE
FACT SHEET
PREFACE
CHAPTERS:
1 INTRODUCTION
1.1 Historical Background of Project TRINITY
1.2 The Project TRINITY Site
1.3 The Project TRINITY Organization
1.4 Military and Civilian Participants in Project TRINITY
2 THE ACTIVITIES AT PROJECT TRINITY
2.1 Preshot Activities
2.2 Detonation and Postshot Activities
2.3 Activities after 16 July 1945
3 RADIATION PROTECTION AT PROJECT TRINITY
3.1 Organization
3.2 Site Monitoring Group
3.3 Offsite Monitoring Group
4 DOSIMETRY ANALYSIS OF PARTICIPANTS IN PROJECT TRINITY
4.1 Film Badge Records
4.2 Gamma Radiation Exposure
REFERENCE LIST
LIST OF FIGURES
1-1 Location of Alamogordo Bombing Range
1-2 TRINITY Site and Major Installations
1-3 Tent Used as Guard Post at Project TRINITY
1-4 Truck Used as Guard Post at Project TRINITY
1-5 Organization of Project TRINITY
2-1 The TRINITY Shot-tower
2-2 The TRINITY Detonation, 0530 Hours, 16 July 1945
2-3 The South Shelter (Control Point)
2-4 Inside One of the Shelters
2-5 The Base Camp, Headquarters for Project TRINITY
2-5 The Base Camp, Headquarters for Project TRINITY
2-6 Project TRINITY Personnel Wearing Protective Clothing
2-7 "JUMBO" after the TRINITY Detonation
LIST OF ABBREVIATIONS AND ACRONYMS
The following abbreviations and acronyms are used in this volume:
AEC Atomic Energy Commission
DOD Department of Defense
LASL Los Alamos Scientific Laboratory
MAUD [Committee for the] Military Application of Uranium Detonation
MED Manhattan Engineer District
R/h roentgens per hour
UTM Universal Transverse Mercator
REPORT DOCUMENTATION PAGE
SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered):
UNCLASSIFIED
1. REPORT NUMBER: DNA 6028F
2. GOVT ACCESSION NO.:
3. RECIPIENT'S CATALOG NUMBER:
4. TITLE (and Subtitle): PROJECT TRINITY 1945-1946
5. TYPE OF REPORT & PERIOD COVERED: Final Report
6. PERFORMING ORG. REPORT NUMBER: JRB 2-816-03-423-00
7. AUTHOR(S): Carl Maag, Steve Rorer
8. CONTRACT OR GRANT NUMBER(S): DNA 001-79-C-0473
9. PERFORMING ORGANIZATION NAME AND ADDRESS:
JRB Associates
8400 Westpark Drive
McLean, Virginia 22102
10. PROGRAM ELEMENT. PROJECT, TASK AREA & WORK UNIT NUMBERS:
Subtask U99QAXMK506-08
11. CONTROLLING OFFICE NAME AND ADDRESS:
Director
Defense Nuclear Agency
Washington, D.C. 20305
12. REPORT DATE: 15 December 1982
13. NUMBER OF PAGES: 76
14. MONITORING AGENCY NAME & ADDRESS(if different from Controlling
Office):
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16. DISTRIBUTION STATEMENT (of this Report): Approved for public
release; distribution unlimited.
17. DISTRIBUTION STATEMENT (of the abstract entered In Block 20, If
different from Report):
18. SUPPLEMENTARY NOTES: This work was sponsored by the Defense
Nuclear Agency under RDT&E RMSS Code B350079464 U99QAXMK50608 H2590D.
For sale by National Technical Information Service, Springfield, VA
22161.
The Defense Nuclear Agency Action Officer, Lt. Col. H. L. Reese,
USAF, under whom this work was done, wishes to acknowledge the
research and editing contribution of numerous reviewers in the
military services and other organizations in addition to those writers
listed in block 7.
19. KEY WORDS (Continue on reverse side if necessary and Identify by
block number):
TRINITY
Los Alamos Scientific Laboratory
Alamogordo Bombing Range
Manhattan Engineer District
Manhattan Project
Personnel Dosimetry
Radiation Exposure
Nuclear Weapons Testing
20. ABSTRACT: This report describes the activities of an estimated
1,000 personnel, both military and civilian, in Project TRINITY, which
culminated in detonation of the first nuclear device, in New Mexico in
1945. Scientific and diagnostic experiments to evaluate the effects
of the nuclear device were the primary activities engaging military
personnel.
FACT SHEET
Defense Nuclear Agency
Public Affairs Office
Washington, D C. 20305
Subject: Project TRINITY
Project TRINITY, conducted by the Manhattan Engineer District (MED),
was designed to test and assess the effects of a nuclear weapon. The
TRINITY nuclear device was detonated on a 100-foot tower on the
Alamogordo Bombing Range in south-central New Mexico at 0530 hours on
16 July 1945. The nuclear yield of the detonation was equivalent to
the energy released by detonating 19 kilotons of TNT. At shot-time,
the temperature was 21.8 degrees Celsius, and surface air pressure was
850 millibars. The winds were nearly calm at the surface; at 10,300
feet above mean sea level, they were from the southwest at 10 knots.
The winds blew the cloud resulting from the detonation to the
northeast. From 16 July 1945 through 1946, about 1,000 military and
civilian personnel took part in Project TRINITY or visited the test
site. The location of the test site and its major installations are
shown in the accompanying figures.
Military and Scientific Activities
All participants in Project TRINITY, both military and civilian, were
under the authority of the MED. No military exercises were conducted.
The Los Alamos Scientific Laboratory (LASL), which was staffed and
administered by the University of California (under contract to the
MED), conducted diagnostic experiments. Civilian and military
scientists and technicians, with assistance from other military
personnel, placed gauges, detectors, and other instruments around
ground zero before the detonation. Four offsite monitoring posts were
established in the towns of Nogal, Roswell, Socorro, and Fort Sumner,
New Mexico. An evacuation detachment consisting of 144 to 160
enlisted men and officers was established in case protective measures
or evacuation of civilians living offsite became necessary. At least
94 of these personnel were from the Provisional Detachment Number 1,
Company "B," of the 9812th Technical Service Unit, Army Corps of
Engineers. Military police cleared the test area and recorded the
locations of all personnel before the detonation.
A radiological monitor was assigned to each of the three shelters,
which were located to the north, west, and south of ground zero. Soon
after the detonation, the monitors surveyed the area immediately
around the shelters and then proceeded out the access road to its
intersection with the main road, Broadway. Personnel not essential to
postshot activities were transferred from the west and south shelters
to the Base Camp, about 16 kilometers southwest of ground zero.
Personnel at the north shelter were evacuated when a sudden rise in
radiation levels was detected; it was later learned that the
instrument had not been accurately calibrated and levels had not
increased as much as the instrument indicated. Specially designated
groups conducted onsite and offsite radiological surveys.
Safety Standards and Procedures
The safety criteria established for Project TRINITY were based on
calculations of the anticipated dangers from blast pressure, thermal
radiation, and ionizing radiation. The TR-7 Group, also known as the
Medical Group, was responsible for radiological safety. A limit of 5
roentgens of exposure during a two-month period was established.
The Site and Offsite Monitoring Groups were both part of the Medical
Group. The Site Monitoring Group was responsible for equipping
personnel with protective clothing and instruments to measure
radiation exposure, monitoring and recording personnel exposure
according to film badge readings and time spent in the test area, and
providing for personnel decontamination. The Offsite Monitoring Group
surveyed areas surrounding the test site for radioactive fallout. In
addition to these two monitoring groups, a small group of medical
technicians provided radiation detection instruments and monitoring.
Radiation Exposures at Project TRINITY
Dosimetry information is available for about 815 individuals who
either participated in Project TRINITY activities or visited the test
site between 16 July 1945 and 1 January 1947. The listing does not
indicate the precise military or unit affiliation of all personnel.
Less than six percent of the Project TRINITY participants received
exposures greater than 2 roentgens. Twenty-three of these
individuals received exposures greater than 2 but less than 4
roentgens; another 22 individuals received between 4 and 15 roentgens.
PREFACE
From 1945 to 1962, the U.S. Government, through the Manhattan Engineer
District (MED) and its successor agency, the Atomic Energy Commission
(AEC), conducted 235 tests of nuclear devices at sites in the United
States and in the Atlantic and Pacific Oceans. In all, an estimated
220,000 Department of Defense (DOD)* participants, both military and
civilian, were present at the tests. Project TRINITY, the war-time
effort to test-fire a nuclear explosive device, was the first
atmospheric nuclear weapons test.
* The MED, which was part of the Army Corps of Engineers, administered
the U.S. nuclear testing program until the AEC came into existence in
1946. Before DOD was established in 1947, the Army Corps of Engineers
was under the War Department.
In 1977, 15 years after the last above-ground nuclear weapons test,
the Centers for Disease Control** noted a possible leukemia cluster
among a small group of soldiers present at Shot SMOKY, a test of
Operation PLUMBBOB, the series of atmospheric nuclear weapons tests
conducted in 1957. Since that initial report by the Centers for
Disease Control, the Veterans Administration has received a number of
claims for medical benefits from former military personnel who believe
their health may have been affected by their participation in the
weapons testing program.
** The Centers for Disease Control are part of the U.S. Department of
Health and Human Services (formerly the U.S. Department of Health,
Education, and Welfare).
In late 1977, DOD began a study to provide data to both the Centers
for Disease Control and the Veterans Administration on potential
exposures to ionizing radiation among the military and civilian
participants in atmospheric nuclear weapons testing. DOD organized an
effort to:
o Identify DOD personnel who had taken part in the atmospheric nuclear
weapons tests
o Determine the extent of the participants' exposure to ionizing
radiation
o Provide public disclosure of information concerning participation by
military personnel in Project TRINITY.
METHODS AND SOURCES USED TO PREPARE THIS VOLUME
This report on Project TRINITY is based on historical and technical
documents associated with the detonation of the first nuclear device
on 16 July 1945. The Department of Defense compiled information for
this volume from documents that record the scientific activities
during Project TRINITY. These records, most of which were developed
by participants in TRINITY, are kept in several document repositories
throughout the United States.
In compiling information for this report, historians, health
physicists, radiation specialists, and information analysts canvassed
document repositories known to contain materials on atmospheric
nuclear weapons tests conducted in the southwestern United States.
These repositories included armed services libraries, Government
agency archives and libraries, Federal repositories, and libraries of
scientific and technical laboratories. Researchers examined
classified and unclassified documents containing information on the
participation of personnel from the MED, which supervised Project
TRINITY, and from the Los Alamos Scientific Laboratory (LASL), which
developed the TRINITY device. After this initial effort, researchers
recorded relevant information concerning the activities of MED and
LASL personnel and catalogued the data sources. Many of the documents
pertaining specifically to MED and LASL participation were found in
the Defense Nuclear Agency Technical Library and the LASL Records
Center.
Information on the fallout pattern, meteorological conditions, and
nuclear cloud dimensions is taken from Volume 1 of the General
Electric Company-TEMPO's "Compilation of Local Fallout Data from Test
Detonations 1945-1962, Extracted from DASA 1251," unless more specific
information is available elsewhere.
ORGANIZATION OF THIS VOLUME
The following chapters detail MED and LASL participation in Project
TRINITY. Chapter 1 provides background information, including a
description of the TRINITY test site. Chapter 2 describes the
activities of MED and LASL participants before, during, and after the
detonation. Chapter 3 discusses the radiological safety criteria and
procedures in effect for Project TRINITY, and chapter 4 presents the
results of the radiation monitoring program, including information on
film badge readings for participants in the project.
The information in this report is supplemented by the Reference
Manual: Background Materials for the CONUS Volumes." The manual
summarizes information on radiation physics, radiation health
concepts, exposure criteria, and measurement techniques. It also
lists acronyms and includes a glossary of terms used in the DOD
reports addressing test events in the continental United States.
CHAPTER 1
INTRODUCTION
Project TRINITY was the name given to the war-time effort to produce
the first nuclear detonation. A plutonium-fueled implosion device was
detonated on 16 July 1945 at the Alamogordo Bombing Range in
south-central New Mexico.
Three weeks later, on 6 August, the first uranium-fueled nuclear bomb,
a gun-type weapon code-named LITTLE BOY, was detonated over the
Japanese city of Hiroshima. On 9 August, the FAT MAN nuclear bomb, a
plutonium-fueled implosion weapon identical to the TRINITY device, was
detonated over another Japanese city, Nagasaki. Two days later, the
Japanese Government informed the United States of its decision to end
the war. On 2 September 1945, the Japanese Empire officially
surrendered to the Allied Governments, bringing World War II to an
end.
In the years devoted to the development and construction of a nuclear
weapon, scientists and technicians expanded their knowledge of nuclear
fission and developed both the gun-type and the implosion mechanisms
to release the energy of a nuclear chain reaction. Their knowledge,
however, was only theoretical. They could be certain neither of the
extent and effects of such a nuclear chain reaction, nor of the
hazards of the resulting blast and radiation. Protective measures
could be based only on estimates and calculations. Furthermore,
scientists were reasonably confident that the gun-type uranium-fueled
device could be successfully detonated, but they did not know if the
more complex firing technology required in an implosion device would
work. Successful detonation of the TRINITY device showed that
implosion would work, that a nuclear chain reaction would result in a
powerful detonation, and that effective means exist to guard against
the blast and radiation produced.
1.1 HISTORICAL BACKGROUND OF PROJECT TRINITY
The development of a nuclear weapon was a low priority for the United
States before the outbreak of World War II. However, scientists
exiled from Germany had expressed concern that the Germans were
developing a nuclear weapon. Confirming these fears, in 1939 the
Germans stopped all sales of uranium ore from the mines of occupied
Czechoslovakia. In a letter sponsored by group of concerned
scientists, Albert Einstein informed President Roosevelt that German
experiments had shown that an induced nuclear chain reaction was
possible and could be used to construct extremely powerful bombs (7;
12)*.
* All sources cited in the text are listed alphabetically in the
reference list at the end of this volume. The number given in the
text corresponds to the number of the source document in the reference
list.
In response to the potential threat of a German nuclear weapon, the
United States sought a source of uranium to use in determining the
feasibility of a nuclear chain reaction. After Germany occupied
Belgium in May 1940, the Belgians turned over uranium ore from their
holdings in the Belgian Congo to the United States. Then, in March
1941, the element plutonium was isolated, and the plutonium-239
isotope was found to fission as readily as the scarce uranium isotope,
uranium-235. The plutonium, produced in a uranium-fueled nuclear
reactor, provided the United States with an additional source of
material for nuclear weapons (7; 12).
In the summer of 1941, the British Government published a report
written by the Committee for Military Application of Uranium
Detonation (MAUD). This report stated that a nuclear weapon was
possible and concluded that its construction should begin immediately.
The MAUD report, and to a lesser degree the discovery of plutonium,
encouraged American leaders to think more seriously about developing a
nuclear weapon. On 6 December 1941, President Roosevelt appointed the
S-1 Committee to determine if the United States could construct a
nuclear weapon. Six months later, the S-1 Committee gave the
President its report, recommending a fast-paced program that would
cost up to $100 million and that might produce the weapon by July 1944
(12).
The President accepted the S-1 Committee's recommendations. The
effort to construct the weapon was turned over to the War Department,
which assigned the task to the Army Corps of Engineers. In September
1942, the Corps of Engineers established the Manhattan Engineer
District to oversee the development of a nuclear weapon. This effort
was code-named the "Manhattan Project" (12).
Within the next two years, the MED built laboratories and production
plants throughout the United States. The three principal centers of
the Manhattan Project were the Hanford, Washington, Plutonium
Production Plant; the Oak Ridge, Tennessee, U-235 Production Plant;
and the Los Alamos Scientific Laboratory in northern New Mexico. At
LASL, Manhattan Project scientists and technicians, directed by Dr. J.
Robert Oppenheimer,* investigated the theoretical problems that had to
be solved before a nuclear weapon could be developed (12).
* This report identifies by name only those LASL and MED personnel who
are well-known historical figures.
During the first two years of the Manhattan Project, work proceeded at
a slow but steady pace. Significant technical problems had to be
solved, and difficulties in the production of plutonium, particularly
the inability to process large amounts, often frustrated the
scientists. Nonetheless, by 1944 sufficient progress had been made to
persuade the scientists that their efforts might succeed. A test of
the plutonium implosion device was necessary to determine if it would
work and what its effects would be. In addition, the scientists were
concerned about the possible effects if the conventional explosives in
a nuclear device, particularly the more complex implosion-type device,
failed to trigger the nuclear reaction when detonated over enemy
territory. Not only would the psychological impact of the weapon be
lost, but the enemy might recover large amounts of fissionable
material.
In March 1944, planning began to test-fire a plutonium-fueled
implosion device. At LASL, an organization designated the X-2 Group
was formed within the Explosives Division. Its duties were "to make
preparations for a field test in which blast, earth shock, neutron and
gamma radiation would be studied and complete photographic records
made of the explosion and any atmospheric phenomena connected with the
explosion" (13). Dr. Oppenheimer chose the name TRINITY for the
project in September 1944 (12).
1.2 THE PROJECT TRINITY SITE
The TRINITY site was chosen by Manhattan Project scientists after
thorough study of eight different sites. The site selected was an
area measuring 29 by 39 kilometers* in the northwest corner of the
Alamogordo Bombing Range. The Alamogordo Bombing Range was located in
a desert in south-central New Mexico called the Jornada del Muerto
("Journey of Death"). Figure 1-1 shows the location of the bombing
range. The site was chosen for its remote location and good weather
and because it was already owned by the Government. MED obtained
permission to use the site from the Commanding General of the Second
Air Force (Army Air Forces) on 7 September 1944 (12). Figure 1-2
shows the TRINITY site with its major installations.
* Throughout this report, surface distances are given in metric units.
The metric conversion factors include: 1 meter = 3.28 feet; 1 meter =
1.09 yards; and 1 kilometer = 0.62 miles. Vertical distances are
given in feet; altitudes are measured from mean sea level, while
heights are measured from surface level, unless otherwise noted.
Ground zero for the TRINITY detonation was at UTM coordinates
630266.** Three shelters, located approximately 9,150 meters (10,000
yards) north, west, and south of ground zero, were built for the
protection of test personnel and instruments. The shelters had walls
of reinforced concrete and were buried under a few feet of earth. The
south shelter was the Control Point for the test (12). The Base Camp,
which was the headquarters for Project TRINITY, was located
approximately 16 kilometers southwest of ground zero. The principal
buildings of the abandoned McDonald Ranch, where the active parts of
the TRINITY device were assembled, stood 3,660 meters southeast of
ground zero. Seven guard posts, which were simply small tents or
parked trucks like the ones shown in figures 1-3 and 1-4, dotted the
test site (9).
** Universal Transverse Mercator (UTM) coordinates are used in this
report. The first three digits refer to a point on an east- west
axis, and the second three digits refer to a point on a north-south
axis. The point so designated is the southwest corner of an area 100
meters square.
1.3 THE PROJECT TRINITY ORGANIZATION
The organization that planned and conducted Project TRINITY grew out
of the X-2 Group. LASL, though administered by the University of
California, was part of the Manhattan Project, supervised by the Army
Corps of Engineers Manhattan Engineer District. The chief of MED was
Maj. Gen. Leslie Groves of the Army Corps of Engineers. Major General
Groves reported to both the Chief of Engineers and the Army Chief of
Staff. The Army Chief of Staff reported to the Secretary of War, a
Cabinet officer directly responsible to the President. Figure 1-5
outlines the organization of Project TRINITY.
The director of the Project TRINITY organization was Dr. Kenneth
Bainbridge. Dr. Bainbridge reported to Dr. J. Robert Oppenheimer, the
director of LASL. A team of nine research consultants advised Dr.
Bainbridge on scientific and technical matters (3).
The Project TRINITY organization was divided into the following
groups (3):
o The TRINITY Assembly Group, responsible for assembling and arming
the nuclear device
o The TR-1 (Services) Group, responsible for construction, utilities,
procurement, transportation, and communications
o The TR-2 Group, responsible for air-blast and earth-shock measurements
o The TR-3 (Physics) Group, responsible for experiments concerning
measurements of ionizing radiation
o The TR-4 Group, responsible for meteorology
o The TR-5 Group, responsible for spectrographic and photographic
measurements
o The TR-6 Group, responsible for the airblast-airborne condenser
gauges
o The TR-7 (Medical) Group, responsible for the radiological safety
and general health of the Project TRINITY participants.
Each of these groups was divided into several units. Individuals were
also assigned special tasks outside their groups, such as
communications and tracking the TRINITY cloud with a searchlight (3).
1.4 MILITARY AND CIVILIAN PARTICIPANTS IN PROJECT TRINITY
From March 1944 until the beginning of 1946, several thousand people
participated in Project TRINITY. These included not only the LASL
scientists, but also scientists, technicians, and workmen employed at
MED installations throughout the United States. According to entrance
logs, film badge data, and other records, about 1,000 people either
worked at or visited the TRINITY site from 16 July 1945 through 1946
(1; 3; 8; 15; 16).
Although supervised by Major General Groves and the Army Corps of
Engineers, many Manhattan Project personnel were civilians. Military
personnel were assigned principally to support services, such as
security and logistics, although soldiers with special skills worked
with the civilians (7; 12). Most of the military personnel were part
of the Army Corps of Engineers, although Navy and other Army personnel
were also assigned to the project (4; 12).