SESSIOMHI

9

Hf

gamma dose to the Rongelap people was made on the basis of estima-

tion of time of arrival of the fallour (which was believed to be at about
four to five hours after the detonation), the length of time of fallout
(which was calculzi*ed to be around 12 hours), and by the readings that
were taken on the Islands at the time of tne evacuation, roughly two
days later. There was a telemetering device on Rongerik, as was
pointed out this morning, which gave valuable information on the
time of arrival there of the cloud of fallout and the 30-minute period
that it required to go off scale. In addition, on Rongerik there were
many film badges and the readings from these film badges afforded
valuable information on the dose and agreed reasonably well with the

other estimations.

So, this really gives a better indication of the biological 2ffectiveness, and we might take the Rongeliap dose of 175 rads of whole-body
radiation and say that it actually represented possibly 260 rads or so
as compared with ordinary laboratory type of radiation. In the case
of the Rongerik group, from 78 to 120; the Alinginae, from 70 to 100;
and Utirik, from 14 to 20.

DUNHAM: What do you mean by the ordinary type of radiation?
CONARD:
BRUES:
_

CONARD:
the gro..nd.

I mean uni-directi_nal type of radiation.

The numbers you give are rads in air?
Yes.

These were based on readings three feet above

BRt<S: And midline doses within the person.....
CONARD: ..... were derived using the factor of 1.5. The skin
dose was i.npossible to really calculate. As you know the beta spectrum -n fajlout has quite a smear of different energy components along
wit! 3-sme soft gamma. The energy spectrum of the beta radiations

-

Gamma radiation in a fallout field produces a more penetrating
type of raniation than occurs with ordinary laboratory uni-directional
radiation. Due to the geometry of the planzr fallout field, the midline
dose is increased by a factor of about 1.5.

e
a Scr she

In the case of the Japanese fishermen, the doses calculated were
around 170 to 700 racs based on extrapolation back to Day 9.

Select target paragraph3