4, ©, Graves, J-Division June 28, 1951 Gaelen Felt, J- Division JANGLE FALLOUT PROSLZMS SD-9))1 A. The JANGLE test program has raised, for the first time since Trinity, serious provlems of radiological safety at moderate distances from the test site. 4 meeting was held on 25 June 1951 to discuss these problems and to arrive at decisions on the relative safety of the proposed shots and on the radiation levels tobe expected. Those present were Shipman, White, Schulte, Harris, Brennan, Williams, and Heft from H-Division, and Ogle, Suydam and Felt from J-Division, The principal conclusions are given below: 1. The surface shot is considered the best shot with which to begin the program. 2. Under the worst conditions the integrated 3 -dose at 50 miles would not exceed 10 roentzgens from a single shot and for good conditions the estimated des: of avout 3 roentgens is conscrva- tive on the side of safoty by a factor of 3 to 5. levels are acceptable to H-Division. 3. The expected There is no predictable relation between radiation levels measured on the ground and the concentration of particles small enough to be retaincd in the lungs. “furthermore, the concentra- tion of small particles in a region of space near the ground is completely uncertain and is virtually independent of the point of detonation, (underground or surface), It isf elt, however, that on the average worse conditions will result from lover cloud heights than from higher. 4h, Be Conditions necessary to produce @-ray burns will be accompanied by yeray levcls higher than those tolerable to H-Division. The conclusions listed above are based on arguments presented by various people at the meeting of 25 June. Rather than append the complste minutes, I will list below those points pertaining to the above subjects; 2. ‘The data which best apply to the JANCLE problem are the Trinity data. The JANGLE shot which most nearly corresponds to Trinity is the surface burst. The theorctical model (see C below) de- veloped to fit the Trinit; data can therefore be trusted to predict results more closely for the surface shot than for the subsurface,