For his leadership in separations science and technology; for improving nuclear fuel recycling and waste removal; and for leading the development process that was instrumental in the cleanup of waste at the Savannah River Site.
For environmental-effects research related to energy technologies and their use, focusing on the impacts of climate and atmospheric changes on the physiology, growth, and biogeochemical cycles of North American forest ecosystems.
For internationally recognized contributions in distributed and cluster computing, including the development of the Parallel Virtual Machine and the Message Passing Interface standard now widely used in science to solve computational problems in biology, physics, chemistry, and materials science.
For original studies of the genetic effects of radiation in mammals. A world authority on mammalian mutagenesis, he and co-workers provided the experimental basis for estimating the genetic hazards of radiation to man and for the corresponding recommendations of national and international standards bodies