‘ e It should also be stated that the advantages of the Taongi weather conditions as compared to Bikini, of less rainfall and decreased shower activity are important in diagnostic experimental work as a greater assurance that optical lines of sight will remain open at shot time, especially over long distances. The possibility of transmission interlocks stopping a shot is less likely at Taongi by whatever margin of advantage exists in this regard. Fallout Asdiscussed under Item 3 above, and as seen from the JIF 7 interpolated hodographs, the ever present northerly component in the upper vesterly winds precludes the possibility of keeping the sand islands clear of contamination at Taongi after the first shot. Past operations have been very successful in being able to continue firing at Fox/George et Bikini and to re-enter scientific stations and to prepare the next shot. Many yards of concrete are required to provide adequate shielding for film data in such stations, in addition to assuring structurel strength in close proximity to the blast. The contemination picture at Taongi would be even more discouraging if one had to guarantee re-entry into land stations. The diagnostic ship method rids a considerable portion of the operation of recovery and construction complications, Another consideration at Taongl concerns contaminetion in the lagoon and the mN\ oe effects on barge mooring operations in case of no reef break-through on the first shot. Taongi lagoon has an average depth of only 50 feet and possesses an extremely emell tidel prism volume, At the present time, it is estimted the bait life of the lagoon water in exchange is_260 days. This figure, although large, is not so surprising vhen it is remembered that Taongl is totally land locked. The & knot current in the channel at low tide arises from the fact that the reef is continuous except for Poksaakku passage and this outflow is not enough to allow the lagoon level to equalize with that of the ocean. It is estimted that the minimum difference between the two is in the range of 8-10 inches. In the case of reef break-through on the first shot, the small lagoon volume becomes a beneficial factor since the exchange rate, once the tidal flow through the crater comes into action, would increase tremendously. It is felt that the crater proper from a 1 ~ 2 megaton first shot on the reef would clear itself for re-entry faster than either Eniwetok or Bikini. The storage of radioactive contaminant in any flowless stagnant pot holes below an intermediate current return layer is being looked at wery carefully. Measurements of the vertical mixing, and establishment of the surface and sub-surface current patterns will reveal any possibility of such storage. These are all factors bearing on the choice of zero points. The feasibility of building a model to aid in these determinations is being investigated.