[en] Reactor cooling system effluents could, under some conditions, contribute to an increase in cloudiness and a decrease in insolation (solar radiation received at the earth's surface). The report presents the results of an evaluation of the potential impact of a Hanford Nuclear Energy Center (HNEC) on cloudiness and insolation. It is one of a series of reports prepared by the Pacific Northwest Laboratory (PNL) in the course of an evaluation of the energy center concept as it might be applied to the Department of Energy Hanford Area in Washington State