several days at about 460 meters from ground zero. Working three to
five hours per day between 9 August and 25 August, they would have
been the only group to stay longer than one hour in the ground zero
area. Of the remaining personnel who approached within 460 meters
from ground zero, 25 spent 15 minutes and ten spent between 30 minutes
and one hour in the ground zero area. Only 11 people received
exposures of 3 to 5 roentgens between 20 July and 21 November. Most
received less than 1 roentgen. After 21 November 1945, no one
approached closer than the fence which was 460 meters from ground
zero, although about 200 civilian and military personnel worked at or
visited the TRINITY site through 1946 (1; 16).

According to dosimetry data, entrance logs, and other records, about
1,000 individuals were at the test site at some time between 16 July
1945 and the end of 1946. This number includes not only the
scientists, technicians, and military personnel who were part of
Project TRINITY but also many visitors. Some of the scientists took
their wives and children on a tour of the area near ground zero,
particularly to view the green glass called "trinitite," which covered
the crater floor. Trinitite was the product of the detonation's
extreme beat, which melted and mixed desert sand, tower steel, and
other debris (1; 8; 9; 16).



CHAPTER 3

RADIATION PROTECTION AT PROJECT TRINITY