WASHINGTON – This week marks the 20th anniversary of President Bill Clinton’s announcement that the United States would pursue negotiations for the Comprehensive Nuclear Test Ban Treaty (CTBT) and maintain the U.S. nuclear arsenal without nuclear explosive tests. President Clinton stated that the maintenance of a safe and reliable nuclear stockpile was “a supreme national interest” of the United States, and that the Department of Energy and the national nuclear design laboratories had assured him that the United States “can meet the challenge of maintaining [its] nuclear deterrent under a CTBT through a science-based Stockpile Stewardship Program (SSP).” On September 24, 1996, the United States was the first nation to sign the CTBT. The United States Senate has not yet ratified the CTBT.

A science-based Stockpile Stewardship Program pushed the limits of modern science and engineering. It required transitioning from single nuclear weapons tests to what effectively is virtual nuclear testing, where every nuance in a nuclear weapon must be understood and evolved through the nuclear detonation process. When the idea was first proposed, after the 1992 explosive nuclear test moratorium was enacted, there were many skeptics who thought solving these enormously complex scientific and engineering challenges might not be possible. Today, nuclear explosive testing has been replaced by an annual assessment process that examines each weapons system in scientific and engineering detail in a manner that is instilled with scientific rigor and allows peer review. The SSP has proven itself.

“This 20th anniversary is an important milestone. The science-based Stockpile Stewardship Program was and remains successful thanks to the vision and determination of its proponents and the significant investment in the necessary tools, facilities, and people. The men and women employed by the national nuclear labs and production plants have achieved this goal with decades of hard work, ingenuity, and unmatched science and engineering,” said Lt. Gen. (Retired) Frank G. Klotz, Under Secretary for Nuclear Security and Administrator, National Nuclear Security Administration (NNSA). “Our Nation maintains the safe, secure, and effective nuclear deterrent necessary for national security. Today, we have a greater understanding of how nuclear weapons perform than we did when we were actually conducting nuclear explosive tests.”

What does this new understanding of the nuclear stockpile include? “The nuclear security enterprise is pushing frontiers in computational science, experiments, and theories,” according to NNSA Chief Scientist Dimitri Kusnezov. “With detonation temperatures and pressures reaching those found in the sun, the SSP drove new methods to make and visualize integrated predictions with world-leading high-performance computing and suites of fundamental experiments pushing the limits of lasers, optics, diagnostics, materials properties, and engineering designs. The labs have developed new techniques for understanding the dynamic behavior of materials. We were driven to make scientific predictions of combined phenomena that range over a million-billion times in size – from nuclei to full up weapons. The resulting experts and tools now allow flexibility to explore situations that previously could not be tested, from impacts of aging or replacement parts to non-proliferation and counter-terrorism issues. Looking ahead, nuclear security will continue to shape the conversation in areas including next generation exascale computing, advanced manufacturing, and materials science.”

The National Academy of Sciences has twice conducted exhaustive studies of U.S. preparedness to use the SSP to maintain the U.S. nuclear weapons stockpile without nuclear explosive testing. Its 2012 study found that the “United States has the technical capabilities to maintain a safe, secure, and reliable stockpile of nuclear weapons into the foreseeable future without nuclear-explosion testing.” 


Established by Congress in 2000, NNSA is a semi-autonomous agency within DOE responsible for enhancing national security through the military application of nuclear science. NNSA maintains the safety, security, and effectiveness of the U.S. nuclear weapons stockpile without nuclear explosive testing; works to reduce global danger from weapons of mass destruction; provides the U.S. Navy with safe and effective nuclear propulsion; and responds to nuclear and radiological emergencies in the U.S. and abroad.

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