This progress report discusses the activities of the P Division for the month of January 1950. The B, D, F and H pilan operated throughout the month except for outages listed under Area Activities. Power levels were as follow: B pile -- 275 megawatts (MW) D pile -- 305 MW, F pile -- 275 MW increased to 305 MW during the month, and H pile -- 275 MW increased to 330 MW during the month. The piles operated with a time operated'' efficiency of 88.8%. A total of 53.07 tons of metal at an average of 91.2% of the current goal concentration was discharged from the piles during the month. A new record canning yield of 93.9% for 4 inch canned slugs was established during January.

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A review of the present design information and studies relating to nuclear power plants indicates that the weight of the power plant components, exclusive of crew shield and nacelles, may at a particular design point be represented by an equation of the form, W{subpp} = W{subo} + K{subt}T. By use of this, a power plant parameter psi is defined as the ratio of the part of the power plant plus nacelle weight that varies with thrust to the net thrust of the power plant less nacelle drag. The funamentall part that this parameter plays in determining the gross weight of a nuclaer powered aircraft is shown. This parameter depends on the design point Mach number and altitude, and the weight and drag increments attributable to the nacelle installation.