The state of the nuclear stockpile

For more than 25 years, Laboratory directors have penned an annual assessment letter.

By Thom Mason | July 26, 2021

Thom Mason Mask Opt
Laboratory Director Thom Mason. Los Alamos National Laboratory

For 25 years now, Los Alamos National Laboratory has completed an annual assessment of the weapons systems in our nation’s nuclear stockpile. Each September, the process culminates in a letter from the Lab director to the secretary of energy, the secretary of defense, and the chair of the Nuclear Weapons Council. This letter informs the president of the United States of our confidence that the stockpile remains safe, secure, and effective now and into the future as a result of our dedicated sustainment and modernization efforts.

In the mid-1990s, the early years of the letter, the concept of science-based stockpile stewardship—maintaining the stockpile using science instead of nuclear testing—was in its infancy but had momentum among the Los Alamos workforce, which viewed stockpile stewardship as a challenging technical problem. Advanced testing facilities were built and began to realize their potential as experiment data was fed into increasingly powerful supercomputers that could simulate the inner workings of a nuclear weapon.

As the stockpile stewardship program evolved into the comprehensive, broad-reaching program of today, so did the letter. 

The process and content of the annual assessment letter has also evolved from an initial rudimentary concept. Early versions of the letter were heavily influenced by the knowledge of and experiences from the recent nuclear testing program, which was fresh in the collective consciousness of the Laboratory workforce of the mid-1990s. Several of these early letters were unclassified and only a few pages long. The letters focused solely on certification, which is understandable because the idea of science-based stockpile stewardship was still developing.

As the stockpile stewardship program evolved into the comprehensive, broad-reaching program of today, so did the letter. The letters crafted from the mid-2000s to 2010 explain the technical content as well as the discussion around emerging scientific research and tools that could assess the stockpile without performing underground nuclear tests. These tools included advanced computational platforms and capabilities and advanced experimental testing facilities. Additionally, production plants—throughout what we now call the nuclear security enterprise—continued and improved their surveillance (inspection) efforts to determine how our systems were aging.

For the past 10 years, the annual assessment letter has recognized significant advancements in capability and introduced weapon life extension programs, alterations, and modifications, which each address aging and performance issues, enhance safety features, and improve security. Often the letter captures the status of the execution of such updates because they represent timely examples of success and advancement.

The 2020 annual assessment process was completed despite hurdles caused by the coronavirus pandemic. Weapons and computer code designers, administrative assistants, and others had to comply with Laboratory guidelines for social distancing and telework while meeting reporting deadlines. I addressed those challenges in the 2020 letter: “Every Laboratory activity has been affected to some degree this year.”

The 2021 assessment is underway, and although the Laboratory (and the world) is still affected by the pandemic, we remain vigilant in our assessment of the nuclear stockpile.