Chapter I: Front Matter

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

Destroy this report when it is no longer needed. Do not return to sender.

PLEASE NOITIFY THE DEFENSE NUCLEAR AGENCY, ATTN: STTI, WASINGTON D.C. 20305, IF YOUR ADDRESS IS INCORRECT, IF YOU WISH TO BE DELETED FROM THE DISTRIBUTION LIST, OR IF THE ADDRESSEE IS NO LONGER EMPLOYED BY YOUR ORGANIZATION.

Since declassified

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):
15. SECURITY CLASS. (of this report): UNCLASSIFIED
15a. DECLASSIFICATION/DOWNGRADING SCHEDULE: N/A Since UNCLASSIFIED
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.