Project Trinity 1945-1946 | Page 5

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