During the report period, fallout data was collected by LRL by both
the Berkeley and Livermore sites. These sites are 45 miles apart in the
San Prancisco Bay Area in central California.
The Livermore data is confined to the collection of dust aerosols,
as concentrated from air at 4 CFM on filters, and may be roughly divided
into two categories of samplings: "daily" and "weekly." The daily
sample ig taken at a single on-site location whereas the weekly samples
were taken at 11 places located 2 to l2 miles from the site.
The Berkeley data involves samples taken by various means:
a) A "daily" dust aerosol concentrated from air at
4 CFM on filters.
b)
"Horizontal" fallout trays, at 5 locations on
the project and one about 7Opmiles afield to the
N. W.
¢)
Vertical cloth screens, vane~guided to be normal to the
to the prevailing wind, at the same six locations
as
in
"b)."
a)
Rainwater samples, on site.
e)
Tap-water samples, on site (public water supply. )
f£)
Gamma gurveys at 3’ above outdoor pavement, at
author's residence 3 miles off'site.
Items "a)" and "a)" have become routinized; "b)"” and "c)" are
exploratory in nature and the data are sparse; "e)" and "f)" were terminated
prior to the conclusion of the pertod. A description of the methods
employed will be found with the data in the appendix.
Herewith will be found copy of letter (MDT-611-58) presenting informa-
tion covering a period of especial interest, namely Oct. 15--Nov. 10,
1958.
This letter was a reply to the request of Gordon M. Dunning,
Chief, Radiation Effects of Weapons Branch, DBM, AEC, Washington, D. C.,
in connection with the fallout incident which suffered some national and
Califorhia publicity. Its data covers some information of non-LRL
origin and differences in treatment of data are noted.
Attentéon is called to a correction in the factor employed for
converting LRL Livermore counts~per-minute to pre/m. A critical
re-examination of the counting equipment and procedures dictates the
figure "17,9" should have read’2h.8." This would have increased the
magnitude but not the trends of the concentrations reported.
Examination of the information indicates the following:
1)
A parallelism exists between the two sites in
the daily samples, as to trend. (This testifies
that the isotopes involved are not of local but
rather are of external--or "fallout"--origin. )}