UNCLASSIFIED SUMMARY The Problem Nuclear devices fired over sea water at previous weapons tests yielded fallout which was different from that associated with land surface detonations. The analytical methods pre- viously used on dry fallout were grossly inadequate for this slurry-like material, Certain tests at Operation REDWINGyielded slurry-like fallout. Therefore, new analytical methods were required to assess the material properly. Findings The fallout from two seawater-surface nuclear events at Operation REDWINGhas been analyzed using new quantitative techniques for the measurement of chloride and slurry droplet water content. Particle size, density and radiological properties of the slurry fallout have beenassessed satisfactorily for the first time. iii UNCLASSIFIED Lf £& B&B FB BF BE BE k 8b 2 £62 2b oe ut kl UKDUUF