roup had worked
with radioactive materials before and were trained in radiological
safety procedures. The Chief of the Medical Group supervised the
radiological safety operations and reported to the TRINITY director.
In addition to providing medical care to TRINITY personnel, this group
established radiological safety programs to:

o Minimize radiation exposure of personnel on the test site and in
offsite areas

o Provide monitors to conduct radiological surveys onsite and offsite

o Provide and maintain radiation detection instruments

o Provide protective clothing and equipment.

An exposure limit of 5 roentgens during a two-month period was
established. Personnel were provided with radiation detection
instruments to determine their exposures (1).

3.1 ORGANIZATION

The Medical Group consisted of physicians, scientists, and
administrators, as well as radiological monitors. Many of these
personnel were nonmilitary, but all worked on the Manhattan Project
under the administration of the Army Corps of Engineers Manhattan
Engineer District.

The Medical Group was divided into two monitoring groups, the Site
Monitoring Group, which was responsible for onsite monitoring, and the
Offsite Monitoring Group. Each reported to the Chief of the Medical
Group, and each communicated with the other during the monitoring
activities. In addition to these two groups, a small group of medical
technicians provided radiation detection instruments to Medical Group
personnel (1; 10).

3.2 SITE MONITORING GROUP

The Site Monitoring Group consisted of a chief monitor, three other
monitors, and several medical doctors. This group had the following
functions (1; 10):

o Conduct ground surveys of the test area and mark areas of
radioactivity

o Conduct surveys of the Base Camp and roads leading into the test
area

o Provide protective clothing and equipment, including film badges and
pocket dosimeters, to personnel

o Monitor all personnel for radioactive contamination and provide for
their decontamination

o Maintain a record of radiation exposures received by personnel.

The Site Monitoring Group monitored the radiation exposures of
personnel in the test area. The time spent by personnel in radiation
areas was limited, and radiation detection instruments were provided
to permit continuous monitoring of exposure rates. In many cases, a
monitor from the Site Monitoring Group accompanied project personnel
into