CINCPAC FILE
FFl-1
Ale}
Ser 001355
“
,
31 Oct 1953
Ganger area, the proposal to munt no special effort in this benalf i
viewed with concern for the following reasons:
~
(1) On the basis of IVY reports received to date, no criterion
exists for assuming that significant fall-out hazards from atonic cloud
concentrations will arbitrerily limit such poseibilities to within the
confines of the relativelyemall danger area now established.
(2)
During IVY, almost every atoll and island in the Trust Ter-
ritory was surveyed by airborne monitoring as described in raference (b)
even though negative or insignificant residual rediation was anticipated
for the most part. For CaSTLs, it is planned to provide the same capabilities ostablished for IVY, but actusl aonitoring flights will be imile
mented only in regions where a probability of fall-out is bellavaed to
exist. Since the movoment of significant radioactive clouds is a osjor
factor in the definition of preeise areas where fall~out oy possibly
ocour, it is ovident that actual cloud tracking is essantial to dater=
mine appropriate aonitoring flights subsequent to each CASTLE shot.
Although it ie realized that similar information can be cbtained to some
degree by cloud trajectory predictions based on aetecrological observationa and continuous monitoring et fixed stations, such prognostic re
ports and those limited to predetermined locations will not establish
all possible fall-out regions in the Trust Territory. Consequently,
it would be necessary to repest the extensive serial survaye flown dur
ing IVY if cloud tracking beyond the imnediate danger area by task force
aircraft is discontinued.
(3)
During prognostication of special hasards incidant to IVY,
interference with air routes through “ake was concluded to be a possie
bility. Although no interference actually resulted from that singular
instance, CINCPACFLT has no factual data which would eliminate the pos
sibility ef this potential hazard during CASTLE. Thorefore, it is con=
sidered that cloud trecking is the only positive asans of guarding
against this hasard with a view toward punctual initiation of sppropri-
ate safoty measures in the event of its asterialization.
(a) CINCPACFLT does not concur with the consideration that the
Plan proposed in subparagraph 2c{1) above provides @ reasonable and safe
compromise for the following reasons:
(a)
In view of the fact that “B-29 flights will be conducte
upwind from the shot site and are for the purpose of forecasting fall-out
on the shot site, it is not apparent that this ceasure will aid in determining conditions in the significant downwind secter (predicted cloud
passage area).
Conditions in the populated atolls near the upwind sector
& c-)