:

—

975, ha@ only standard flreerrenermtg-equinmenta. The firs® report gave thefsr -

-

positior ag 12-S68, 176-518 at COOLIO with: radiation intensities of 15 ar/tm
and increasing and that the LST's were carrying out decontaninatics

ae ~.

uregs A subsequent report stated theiw 0461700f readings were 23 ar/he
average
and 40or/hr high, with the highee® reading®on wind exposed surfaces. The
:
report: gave theie 0462000 position as 13}=16N, 177-397E. A further repor®,
indicated a steady decrease after 0623304 and that decontamination had beer ©
carried out during the night.

LST 762 resehed a higtt cf 40 ar/hes LSP 975,

+~

96 ar/hr. By 070800K (position 14-30M, 178-408) intensities had dropped

to an a

of 5 arfhr and « high of 15 ar/fare 4 final report, position

15~05Ny Y78-ubE, was received for 080700M indicating 762 with an average .
of 3 arfhr and a high of @ arfhr, and LSt 975 with 7 and 10 or/hr resnestively

Throughout this incident, snd considering the intensities reported, the atanis
countermeasures being taken and the preseribed route for the LST's, no specia}
action wee taken by the task force, The facts are reported primarily for
:
their bearing on the aerosol charscteristics of the water surface shot clout.,
Oa Y plus 1 day the second and final ZOU advisory wae dispatched to

CINCPACFLT.

This advisory included a preliminary report on NYXOPO Flight

ABLE (Y plus 1 day) which indicated al) populated atolls from LAS througk

TAKA loss thas 10 mr/hr from YANKES. The maximum reading was given as 13
ar/hr at BIKAR at O7131L5M and an estimate that BIKAR wae on the approximate
center line of the major fall-out patterm.

ot/he at; KYAJALEIN, UTSRIK and TAKA.

The next highest reading we 1

Subsequent atolla on Flight ABLE

indicated essentially negative results. CINCPACFLT wae advised that the

Radsafe roll-up plan for the final shot (NECTAR) would include NYKOPO Flizhe

ABLS on N plus 1 day, Flights ABLE, BAKER and CHARLIE on N plus 2 days, and

that CINCPACFLT would be advised of the results prior to departure of cogni=
sant personnel from the forward ares.

‘

On 6 May, the TG 7.3 writ on KWAJALEIN (charged by the task force with

radsafe monitor responsibilities for KWAJALEIN) reported 1 or/hr mxioun
background of that atoll at 061464,5h.

On YANKEE shot an attempt wes nade by the New York Operations Office,
ABO to place styrofcam rafts in the forecast fall-cut area. Rafts wre

plsced by air-drop in the quadrant 10° to 100°. The project failed <ue to

the few rafte recovered, and due to high water background obscuring aerial
"fly-cver” readings. This difficulty, however, pointed the way to 8 much
simpler nethod of determining the pattern, i.e., by aerial survey of the
coean water iteelf. Some work along this line was accomplished on YANKEE,

however, restrictions on available aircraft, and the absence of advance plans

for thia type measurement, limited the scope of the activities.

An apprecia=

tion of the intensities observed is indicated in the following aircraft
survey resultss

Morning of 8 May:
-

2 mr/hr at 300 feet and 3 ar/hr at 150 feet

measured on flight track 325° through 12-O3N,

165<35E, band & miles wide around this point.

Afternoon of 8 May: & mr/hr at 200 feet at 12-16, 165-595.

0-6

Select target paragraph3