GAMMA DOSE RATES AT RONGELAP ATOLL,
1954-1963
INTRODUCTION
Rongelap Atoll, Marshall Islands, was accidentally contaminated on March 1,
1954 with radioactive fallout from a
thermonuclear device detonated at Bikini Atoll some 80 miles
to the west.
Eighty-two natives residing on Rongelap Island
were evacuated and repatriated in June 1957.
The atoll, its
inhabitants and its economy have been briefly characterizea‘?) ,
The decline of gamma dose rates resulting from the fallout is
et
discussed in this report.
RESULTS
Dose rates on D+ 1
Gamma dose rates at Rongelap Atoll on D+ 1
(time of
detonation plus one day) were estimated to be 3.5 r per hour
at the inhabited islet of Rongelap in the south and 35 r per
hour at uninhabited Lomuilal islet in the northern part of
the atoll (2) , Fig.
1.
These estimates were based on extra-
polations of measurements made two days after initial fallout '?) ,
The subsequent decline of gamma dose rates, based on survey
meter readings taken three feet above the ground at Rongelap
and Kabelle islets, is compared with the: theoretical decay '3)
1