Actinide Chemistry and the Battlefields of the Cold War

Abstract: The Cold War rivalry between the United States and the Soviet Union lasted for much of the second half of the 20th Century. While the superpowers never engaged directly in full-scale armed combat, a nuclear arms race became the centerpiece of a doctrine of mutually assured destruction, and prompted a mass production of plutonium, and the designing, building, and testing of large numbers of nuclear weapons. In more than 50 years of operation, the Cold War battlefields created over 100 metric tons of plutonium, produced tens of thousands of nuclear warheads, oversaw more than 1000 detonations, and left behind a legacy of contaminated facilities, soils, and ground water.  

The extent of long-term adverse health effects will depend on the mobility of plutonium and other actinides in the environment and on our ability to develop cost-effective scientific methods of removing or isolating actinides from the environment. Studying the complex chemistry of plutonium and the actinides in the environment is one of the most important technological challenges, and one of the greatest scientific challenges in actinide science today.

I will summarize our current understanding of actinide chemistry in the environment, and how that understanding was used in the decontamination and decommissioning of the Rocky Flats Site, where plutonium triggers for U.S. nuclear weapons were manufactured. At Rocky Flats, synchrotron radiation measurements made at the Stanford Synchrotron Radiation Laboratory were developed into a science-­based decision-­making tool that saved billions of dollars by focusing Site-­directed efforts in the correct  areas, and aided the most extensive cleanup in the history of Superfund legislation to finish one year ahead of schedule, ultimately resulting in billions of dollars in taxpayer savings.

About the Speaker: David L. Clark received a B.S. in chemistry in 1982 from the University of Washington, and a Ph.D. in inorganic chemistry in 1986 from Indiana University. His thesis work received the American Chemical Society’s Nobel Laureate Signature Award for the best chemistry Ph.D. thesis in the United States. Clark was a postdoctoral fellow at the University of Oxford before joining Los Alamos National Laboratory as a J. Robert Oppenheimer Fellow in 1988. He became a Technical Staff Member in the Isotope and Nuclear Chemistry Division in 1989. Since then he has held various leadership positions at the Laboratory, including program management for nuclear weapons and Office of Science programs, and Director of the Glenn T. Seaborg Institute for Transactinium Science between 1997-2009. He has served the DOE as a technical advisor for environmental stewardship including the Rocky Flats cleanup and closure (1995-2005), closure of High Level Waste tanks at the Savannah River Site (2011), and as a technical advisor to the DOE High Level Waste Corporate Board (2009-2011). He is currently the Program Director for the National Security Education Center at Los Alamos, a Fellow of the American Association for the Advancement of Science, a Laboratory Fellow, and Leader of the Plutonium Science and Research Strategy for Los Alamos. His research interests are in the molecular and electronic structure of actinide materials, applications of synchrotron radiation to actinide science, behavior of actinide and fission products in the environment, and in the aging effects of nuclear weapons materials. He is an international authority on the chemistry and physics of plutonium, and has published over 150 peer-reviewed publications, encyclopedia and book chapters.