This memo discusses the effects of advancing to higher power levels of the 105 Piles (D-Pile). It is concluded that there is no technical reason against a cautious advance to higher powers; the units can be run at higher levels than their rating of 250 MW, or the additional reactivity that they will gain with time may be taken entirely in the form of lower peak temperatures and radiation levels. The decision as to what course to follow between these extremes involves such issues as the best use of uranium and the most effective separation of adequate amounts of product of proper quality.

It was proposed to prepare a volatile polonium compound which could be used alone or with another gaseous compound as a neutron source. The objective was to obtain a neutron source which would give off few neutrons in the expanded state, but when condensed would act substantially as a thick target and emit perhaps ten times as many neutrons. Originally, polonium hexafluoride was suggested; with such compound the fluorine atoms would constitute the target. the predicted boiling point of polonium hexafluoride is about -40 {degrees}C. There was reason to believe, however, that lower relatively non-volatile fluorides would be formed rather than the hexafluoride. Polonium alkyls were therefore proposed as alternatives. The predicted boiling point of Po(CH{sub 3}){sub 2} is about 110 {degrees}C. This compound in itself would probably not be suitable as a target material but it could be mixed with other gases such as carbon tetrafluoride, boron trifluoride, etc., as targets. As a longer range possibility, Po(CF{sub 3}){sub 2} was also suggested. This compound would act as its own target and would moreover have the same F/Po ratio as PoF{sub 6}; its boiling point could be expected to be 30{degrees} - 60 {degrees} lower than that of polonium dimethyl. …

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