Iran’s Nuclear Ambitions
A Technological and Strategic Legacy
Historical Context: The Shah’s Era
Iran’s nuclear programme has developed across multiple political regimes and shifting international dynamics, evolving from its beginnings under the Pahlavi dynasty to its present form within the Islamic Republic. Beginning under the Shah’s modernising monarchy and evolving into a multifaceted enterprise within the Islamic Republic. This transformation reflects shifting political regimes, international alliances, and technological paradigms. While initially rooted in civilian goals and global collaboration, Iran’s nuclear ambitions have increasingly converged with its geopolitical strategy, becoming a focal point of international scrutiny.
With early support from the United States, France, and Germany, Imperial Iran’s nuclear program gained momentum during the Shah’s era through investments in Pressurized Water Reactors (PWRs), enrichment capabilities at the Urodif facility in France, and uranium sourcing in Africa. Despite favorable international relations at the time, the Shah considered access to uranium resources vital for Iran’s self-sufficiency and strategic autonomy. This initial focus on these programs laid a foundation that would persist, even as they faced international resistance and scrutiny in subsequent decades.
Iran’s nuclear program practically started in 1967 by US providing the 5 MW(th) Tehran Research Reactor (TRR) as part of the Atoms for Peace initiative. This reactor was primarily designed for research, medical isotope production, and training purposes. In the 1970s, as oil prices soared, the Shah, heavily investing oil revenue into Iran’s infrastructure, looked to channel surplus funds abroad. He acquired a 15 percent stake in the Rössing Uranium Mine in Namibia, Southern Africa—one of the world’s largest open-pit uranium mines.
While the Shah recognized the advantages of establishing a robust civilian nuclear program for Imperial Iran, there appeared to be no overt military ambitions linked to the program, at least during the Pahlavi era. However, considering the Shah’s assertive personality and regional nuclear developments in countries like Pakistan and India, it is difficult to fully discount the potential for strategic foresight. The Shah’s vision was ambitious: he planned to install twenty-six nuclear reactors across Iran over the next thirty years. Agreements were made with Kraftwerk Union (KWU), a Siemens subsidiary from then-West Germany, to construct two 1,200-megawatt reactors at Bushehr, alongside negotiations with the French company Framatome for two additional 900-megawatt reactors. In 1974, Imperial Iran reportedly invested $1 billion in a French uranium enrichment facility owned by Eurodif, a European consortium, this further included a planned nuclear research center in Isfahan.
Furthermore, as part of U.S. support for Shah’s ambitions, President Gerald R. Ford offered the Shah access to a full nuclear fuel cycle, which included the possibility of a nuclear reprocessing facility to handle spent fuel and extract plutonium. A likely model for such a facility was the Barnwell Nuclear Fuel Plant in South Carolina, a commercial reprocessing plant under development at the time by Allied-General Nuclear Services (AGNS). Although Barnwell was intended for peaceful purposes, it underscored the dual-use nature of reprocessing technology, making the U.S. cautious about its proliferation risks.
The Bushehr facility was designed to include two pressurized water reactors (PWRs), likely based on the German Konvoi design, a Generation II nuclear reactor model. Had the Konvoi reactors been installed at the time, their characteristics, particularly their high burn-up rate, would have rendered them unsuitable for producing weapons-grade plutonium. Although many authors argue that the Shah’s intentions for nuclear reactors may have included dual-use goals, there is no conclusive evidence to support this claim. Even if this were the case, the choice of reactor technology was not particularly suited for military applications. Nevertheless, it remains plausible that uranium enrichment within the program could have been pursued to serve both military and civilian purposes but certainly not through spent fuel.
In nuclear fission, uranium atoms undergo fission, releasing energy and neutrons. Some of these neutrons are absorbed by uranium-238, converting it into plutonium isotopes. However, reactors with high burn-up, like the Konvoi, produce higher amounts of plutonium-240. Plutonium-240 is undesirable for weapons production due to its high rate of spontaneous fission. For this reason, high burn-up reactors are inefficient for weapons-grade plutonium production, as they yield a plutonium mix with more non-fissile isotopes.
In contrast, reactors specifically intended for weapons-grade plutonium production are often operated with shorter fuel cycles, which limits the build-up of plutonium-240, resulting in a higher concentration of plutonium-239. Consequently, while the Konvoi reactors at Bushehr were well-suited for power generation, their design and operational parameters potentially made them impractical for any military plutonium production program. Table 1 presents a comparison of Generation II nuclear reactors, highlighting key specifications and design characteristics.
Moreover, the complex Plutonium Uranium Redox EXtraction (PUREX) process would have posed significant challenges in reprocessing spent fuel, especially given that much of the plutonium produced in reactors would contain a higher isotope mix, such as , which is less desirable for weapons. For most third-world countries in the 1970s, establishing an independent PUREX reprocessing facility was virtually impossible without external support or substantial technological advancement. The combination of technical, economic, and regulatory obstacles created formidable barriers, and only nations with strong state backing, well-developed infrastructure, and established scientific expertise could realistically pursue such capabilities.
It may be worth discussing the preparation of uranium for the enrichment process. In simple terms, uranium ore is processed into , commonly known as yellowcake. This involves leaching the ground uranium ore with either acid or alkaline solutions to dissolve the uranium. The uranium content is then separated using filtration or decantation. Finally, the uranium is purified and dried, resulting in the production of . For enrichment purposes, yellowcake is further converted into uranium tetrafluoride () and subsequently into uranium hexafluoride, which is suitable for enrichment in gas centrifuges.
To understand uranium enrichment and the effort involved, it’s essential to consider Separative Work Units (SWU). SWU quantifies the energy and resources required to separate uranium isotopes and achieve higher concentrations of , the isotope critical for nuclear fuel and weapons. This process separates uranium into two streams: one enriched in (the product) and the other depleted (the tails). Starting with natural uranium, which contains approximately 0.7% , the concentration is increased to levels suitable for nuclear reactors (3–5%) or weapons-grade material (90%). The effort depends on several factors: the starting concentration, the desired enrichment level, and the leftover concentration in the tails.
More advanced technologies, such as modern centrifuges, are more efficient and require less effort to achieve the same level of enrichment compared to older systems like Pakistan’s P-1 centrifuges from the 1970s. By calculating SWU, we can quantify and compare the efficiency of different centrifuge generations and their ability to enrich uranium for various purposes. Figure 1 demonstrates the Pakistan P-1 with some estimated parameters, comparing its performance to the P-2 and the modern IR-6 centrifuge as of 2022. The IR-6 is an advanced gas centrifuge developed by Islamic Republic of Iran. It boasts a separative work capacity approximately 10 times greater than the IR-1, enabling more efficient uranium enrichment. The IR-6 uses advanced materials such as carbon fiber, allowing it to operate at higher rotational speeds and efficiency. Its deployment has been pivotal in Imperial Iran’s ability to accelerate uranium enrichment, reducing the time required to reach higher concentrations of .
Given the inefficiency of the available centrifuges such as P-1, the substantial cost implications of such a development, and the reports on Pakistan’s nuclear program in the late 1970s, it took Pakistan nearly 20 years to conduct its first successful test at the remote Chagai Mountains. In this context, it seems highly unlikely that the Shah of Iran would have pursued any covert operations aimed at developing military nuclear applications at least for a decade to come. There were several reasons for this. Firstly, Imperial Iran at the time possessed the most advanced conventional weapons, making the development of nuclear capabilities unnecessary. Additionally, the geopolitical climate in the region could have sparked a nuclear arms race, which would have been counterproductive to the strategic goals of Imperial Iran, which sought stability and regional dominance, which is quite contrary to what Iran after 1979 invested in.
The Islamic Republic’s Nuclear Program
The Islamic Republic’s nuclear weapons development program dates back to the 1980s, most likely originating from the Iranian experience during the Iran-Iraq War, particularly after Iraq’s bombing of Iranian cities. The war prompted Iran to pursue the development of ballistic missiles capable of reaching beyond its borders, with the ability to carry both chemical and nuclear payloads. Efforts to develop a nuclear weapons capability are believed to have intensified in the 1990s, involving the Atomic Energy Organization of Iran (AEOI) and the Department of Defense. According to Iran’s nuclear archives, plans were made for at least five nuclear devices, with a target date for their development in the early part of 2003, coinciding with the development of the Shahab-3 ballistic missile. The biggest challenge the Iranian government faced at the time was developing a nuclear device small enough to fit within the Shahab-3 missile, requiring a device no larger than 55 cm in diameter and potentially needing around 25 kg of highly enriched uranium.
For several obvious reasons, countries developing nuclear weapons may opt for uranium enrichment over plutonium extraction. The primary reason for this preference is that the PUREX process, that requires large facilities equipped with hot cells and remote handling capabilities. Additionally, plutonium-based weapons generally require much more maintenance. This does not even account for the need for a nuclear reactor capable of producing just enough material for undisclosed purposes, which complicates matters further, especially when operating under IAEA surveillance. Consequently, the Islamic Republic focused its efforts on developing its centrifuge capabilities. Most likely IR-6 is used to achieve enrichment levels above 60%, with the tails from this process fed into the IR-4 to produce 20% enriched uranium. The tails from the IR-4 are then processed in the IR-5 to achieve 5% enrichment. This smart configuration not only optimizes their enrichment process but also provides the Islamic Republic with a potential bargaining chip during negotiations.
Further, plutonium-based narrative, it is important to note that the behavior of this material under high pressure is not well understood, and it undergoes several phases under varying pressure conditions, many of which are unstable and require a significant and time-consuming investment in research and development. Therefore, it is highly unlikely that the Pressurized Water Reactors (PWRs) in Iran were ever seriously considered or planned for plutonium production. To any scientifically informed observer, this seems more like a tactic to prolong negotiations, which has come at the cost of sanctions and the production of electricity that is far more expensive than other energy sources.
The Islamic Republic’s continued research into modulated neutron initiators raises further concerns. These could involve materials such as UD2, UD3, or other alternatives to uranium, designed to avoid the identifiable footprints left by fissile material. For example, materials like TiD2 are still a significant part of the ongoing concerns with the IAEA.
What next?
The most pressing question remains: if the Islamic Republic were to decide to assemble a nuclear weapon, what could be done? Can the knowledge and potential traces accumulated over the past thirty years be undone? If the Islamic Republic is using depleted uranium, lead, tantalum, or other materials in remote locations, as the IAEA is concerned, who truly has control over these activities? Additionally, the hydrodynamic calculations and experiments needed to study shockwaves could take place at any facility, or even on a computer at a university, further complicating oversight and accountability. Israel’s recent bombing of facilities may potentially delay some activities; however, it will not stop them nor change the fact that the point of no return has already passed.
Nuclear development is a legacy of both the Pahlavi dynasty and the Islamic Republic, and it is likely here to stay. However, the international community could consider focusing on fostering a pro-Western Iran, one that does not pose a threat to its neighbors, Israel, or the West. The US administration has to create an opportunity and open a new frontier in promoting Iran’s return to the Western values that once formed an integral part of the country’s legacy.