LLNL's work with special nuclear materials—including highly enriched uranium, plutonium, and tritium—is conducted at the Superblock facility, one of just two defense plutonium research and development facilities in the U.S.

The Superblock supports a wide variety of activities sponsored by NNSA, DOE, and DOD. Stockpile stewardship, however, supports the majority of the Superblock programmatic activities. Stockpile stewardship activities include nonnuclear testing of components of weapons that are now sitting in the stockpile (including fundamental physics and engineering experiments on plutonium) and investigating technologies for remanufacture of plutonium parts in nuclear components.

Every year, the Livermore and Los Alamos national laboratories provide the technical basis for certification to the U.S. president that the nuclear components for which they are responsible are safe and reliable. Much of the research in the Superblock contributes to this annual process.

The Superblock houses modern equipment for research and engineering testing of nuclear materials. The facility has been continuously upgraded to ensure it meets the latest nuclear safety requirements.