Daily river temperature cycling has existed at reactor area river pumphouses from the beginning of operations. Of small account at first and due only to the daily air and solar radiation cycle, the phenomenon became significant with the initiation of daily river flow cycling at priest Rapids Dam to meet changing power generation requirements. The problem was compounded by the construction of the N reactor, placing a water intake and outfall at approximately half the previous distance between the K and D reactors. The decidedly non-uniform effluent distributions in the river at the shorter distances has caused apparent daily temperature swings at 181-D. This distribution was determined by the use of rhodamine B dye. Estimates of the relative contributions over a range of river flow to the temperature cycling at 181-N were made. A similar evaluation of the relative contributions at low river flow only at 181-D from K and N reactor operations has been requested by Douglas United Nuclear, Inc. This report is made to satisfy that request.

This report details 200 Area activities for the month of May 1966.

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This is the concept for a series of post-shot investigations at the Piledriver site, Area 15, Nevada Test Site (NTS), to gain information on: Chimney geometry and associated wall rock conditions resulting from a deeply buried (1500 ft) nuclear explosion in granite; The characteristics and distribution of rubble and radioactivity in the chimney; and Data pertinent to in-situ leaching.

This monthly document provide source and special nuclear material composition of ending inventory reports for the month of April 1966.