In this episode of Iran Watch Listen, we sat down with Dr. Bruce Goodwin, an expert on nuclear weapons design and testing. We discussed the steps required to build a nuclear weapon and what is publicly known about Iran’s weaponization efforts to date. The conversation took place on May 3 and was hosted by Valerie Lincy, Executive Director at the Wisconsin Project on Nuclear Arms Control, and John Krzyzaniak, a Research Associate at the Wisconsin Project. Read more about our guest below.

Background: Breakout vs. Weaponization

For years, Iran’s “breakout time” has been a key metric by which analysts and policy makers have evaluated the progress of Iran’s nuclear program. Breakout time is the amount of time it would take Iran to produce just the fissile material (or fuel) for a bomb if it decided to make a dash for nuclear weapons at its known facilities. One aim of the 2015 nuclear agreement with Iran, the Joint Comprehensive Plan of Action (JCPOA), was to push Iran’s breakout time to at least one year by restricting its uranium enrichment activities. Today, however, with no such restrictions in place, the breakout time can be measured in days.

A "pin dome" from the Iranian nuclear archive documents. (Credit: Institute for Science and International Security)

The breakout time only pertains to the production of fissile material, however. There are a series of additional steps, collectively called “weaponization,” that would be required to turn that material into a working nuclear weapon.

The weaponization process broadly includes coming up with a workable design, testing the components of that design, producing the fissile material, manufacturing the core of the weapon, integrating it with an explosives package, and fitting it onto a delivery vehicle (e.g., a ballistic missile or an air-dropped bomb). The timeline for these activities, most of which could be done in parallel and some of which could be easily concealed, is uncertain.

Our Discussion

According to Dr. Goodwin, for a country that is starting from scratch the two most difficult and time-consuming elements of building nuclear weapons are generating a workable design and producing sufficient fissile material.

However, Iran today is not starting from scratch. Documents from the so-called Atomic Archive, a trove of Iranian files seized by Israeli agents in 2018, reveal that between 1999 and 2003, Iran received several foreign weapon designs, had refined those designs, and had settled on a final version. Iran also developed several components of a nuclear weapon, including a neutron initiator, detonators, and high voltage firing equipment, according to the International Atomic Energy Agency (IAEA). In terms of fissile material, Iran has amassed a sizeable stockpile of highly-enriched uranium and has the capability to quickly enrich that uranium further to weapon-grade. Together, these achievements will substantially shorten the weaponization timeline if Iran decides to build nuclear weapons in the future.

Dr. Goodwin also explained that many weaponization activities would be difficult to detect. For example, Iran already has a munitions industry that designs and manufactures high explosives for conventional weapons. The facilities and the processes for making a nuclear weapon explosives package could be integrated into—and therefore indistinguishable from—these ongoing defense industry activities. In other words, this phase of weaponization could “hide in plain sight."

Other elements do not require any specialized large-scale infrastructure. For example, although a high-performance computing (HPC) capability might be necessary for designing (or improving the design of) an implosion device, Dr. Goodwin pointed out that HPC technologies are fairly prevalent. Thus, the presence of HPC infrastructure in Iran would not itself be proof of a nuclear weapons program. Finally, the equipment needed to manufacture weapon components, such as machining equipment, is standard and easy to obtain from countries such as China, or could even possibly be replaced by additive manufacturing (3D printing) techniques.

These factors combine to make Iran not only effectively a latent nuclear power—a broad category that also includes countries such as Japan and South Korea—but, due to its past weaponization work, perhaps “more latent” than most.

Expert Bio

Bruce Goodwin is a retired senior fellow at the Center for Global Security Research at the Lawrence Livermore National Laboratory. Earlier, he was the Principal Associate Director for the nuclear weapons program at Livermore from 2001 until 2013. He has been a key player in the success of the U.S. nuclear weapons program since 1981, first at Los Alamos National Laboratory and since 1985 at Livermore. While at both Labs, he was a design physicist on five nuclear tests.

Related Resources

• “Additive Manufacturing and Nuclear Security: Calibrating Rewards and Risks,” Center for Global Security Research, Lawrence Livermore National Laboratory, November 2019.
• “Nuclear Weapons Technology 101 for Policy Wonks,” Center for Global Security Research, Lawrence Livermore National Laboratory, August 2021.

Subscribe to Iran Watch Listen on Apple Podcasts, Google Podcasts, Spotify, Stitcher, or wherever you get your podcasts.