1. Based on
available dosimetric and demographic information:
a. It is
estimated that between March 28 and April 15, the collective dose
resulting from the radioactivity released to the population living
within a 50-mile radius of the plant was approximately 2,000
person-reins. The estimated annual collective dose to this population
from natural background radiation is about 240,000 person-rems. Thus,
the increment of radiation dose to persons living within a 50-mile
radius due to the accident was somewhat less than one percent of the
annual background level. The average dose to a person living within 5
miles of the nuclear plant was calculated to be about 10 percent of
annual background radiation and probably was less.
b. The maximum
estimated radiation dose received by any one individual in the
off-site general population (excluding the plant workers) during the
accident was 70 millirems. On the basis of present scientific
knowledge, the radiation doses received by the general population as a
result of exposure to the radioactivity released during the accident
were so small that there will be no detectable additional cases of
cancer, developmental abnormalities, or genetic ill-health as a
consequence of the accident at TMI.
c. During the
period from March 28 to June 30, three TMI workers received radiation
doses of about 3 to 4 rems; these levels exceeded the MRC maximum
permissible quarterly dose of 3 rems.
d. The process of
recovery and cleanup presents additional sources of possible radiation
exposure to the workers and the general population.
2. There were
deficiencies in instrumentation for measuring the radioactivity
released, particularly during the early stages of the accident. However,
these deficiencies did not affect the Commission staff's ability to
estimate the radiation doses or health effects resulting from the
accident.
3. The health
effects of radiation dose levels of a few rems or less are not known.
Estimates of the potential health effects of the TMI accident are based
on extrapolations from the known health effects of higher levels of
radiation.
4. The major health
effect of the accident appears to have been on the mental health of the
people living in the region of Three Mile Island
and of the workers at TMI. There was immediate, short-lived mental
distress produced by the accident among certain groups of the general
population living within 20 miles of TMI. The highest levels of distress
were found among adults a) living within 5 miles of TMI, or b) with
preschool children; and among teenagers a) living within 5 miles of TMI,
b) with preschool siblings, or c) whose families left the area. Workers
at TMI experienced more distress than workers at another plant studied
for comparison purposes. This distress was higher among the
nonsupervisory employees and continued in the months following the
accident.
