LANL report finds humidity inside sealed plutonium storage containers falls as they age
The finding bears on a proposed change that would let some containers be stored 100 years instead of 50.
LOS ALAMOS - Humidity inside sealed plutonium storage containers drops as the containers age, according to a Los Alamos National Laboratory report issued Oct. 20 and posted by the Department of Energy's Office of Scientific and Technical Information.
LANL researchers Elizabeth J. Kelly and Josh Narlesky analyzed humidity readings from 120 containers opened for examination from fiscal 2009 through 2024 at the Savannah River Site in South Carolina. The average measured humidity fell by an estimated 5.72% of its value each year, a statistically significant decline.
Moisture matters because it can help corrode the inner of the two welded stainless-steel containers that seal in the plutonium. The containers are packaged under a DOE standard that allows storage of plutonium metals and oxides for up to 50 years. A proposed revision would extend that to 100 years for containers without the potential for internal corrosion.
The oldest container examined was about 21.5 years old, so the report treats its 50-year figures as a model projection. The authors say a follow-on report will combine these results with long-term lab testing.