410395
January 11,
1357
Dr, Allyn H, Ssymour
Marine Blologist, Biclogy Department
Division of Biology anc Medleinc
U.S. Atomic Enerzy Commission
1901 Constitucion Avenue Now.
Washington 25, D.C.
,
BEST COPY AVAILABLE
Dear Al:
uring a conversation while Sc and I were in Washington
last month, you mentioned that the activity levels in the
water at Rongelap were higher in July 1956 than the levels
reported in UWEL-43 obtained at earlier visits.
looked up the data anc summarized it.
Ed has
The best evidence seems to indicate that the ineress
noted in the July 1956 samples 1s Jue to the recontamination
of Rongelap from the 1956 series of weapons tests.
c Jfeny
of the newly acded recdloactivity is such that it will soon
be insignificant when compares with that from the 1954 serics,
The cecay of activity of the particulate matter anc tne
iltrate of &@ cistern water and a lagoon water sample col-
cated at Rongelap Islan! in July 1956 was followed.
Although
he eounting error is too large to permit a precise evaluation
’ the decay rate, it Ls clear that the half life immetiately
.fter August 22 (first counting date) was between 20 aad 40
says, indicating the presence of short half-life radionuclivies.
The count of January 1957 resulted in values which compare to
those found in Oetober 1956 and reported in UWFL-43, Table 13,
as follows (values in d/mAliter):
Collection Date
Counting Date
det.
'55
Oct. '55
Cistern water
particulate matter 75°17
Cistern water
filtrate
.
+
310-199
Lagoon water
a
yarticulate matter
Lagoon water
riltrate
+
GO=120
July ‘56
Aug. '56
— 390t17
July '5¢
Jan. '57
+
91=10
a
110-73
910f100
+
1410-12
'
2ho0te210
2000#200
Sincerely, |
64480
+
24-5
ro
auot1cs