History and Milestones in Nuclear Energy
Early breakthroughs in nuclear physics
From 1879 to 1939, discoveries in atomic and nuclear physics gradually unveiled the structure and behaviour of atoms. Early experiments laid the groundwork for understanding atomic structure, radiation, and energy. Sir William Crookes' experiments in 1879 demonstrated that electric discharges could ionise gases, creating electrically charged particles. In 1897, J.J. Thomson identified the electron, a negatively charged particle within atoms. WIlhelm Röntgen’s discovery of X-rays (1895) and Antoine Henri Becquerel’s identification of gamma rays (1896) revealed that certain materials emitted invisible, penetrating energy.¹
Building on this, the Curies isolated radium and further explored radioactive elements. Marie Curie (1867–1934) was a Polish-born French physicist renowned for her pioneering work on radioactivity. She won the Nobel Prize twice: in 1903 for Physics, shared with Becquerel and her husband Pierre, and in 1911 for Chemistry. Curie was the first woman to receive a Nobel Prize and remains the only woman to have won it in two different fields.²
Albert Einstein’s famous 1905 equation, E=mc², indicated that mass could be converted into energy, suggesting a tremendous energy source within atoms. Ernest Rutherford and Niels Bohr's models clarified that atoms have a dense nucleus of protons and neutrons surrounded by electrons. In 1930, Walther Bothe and Herbert Becker bombarded beryllium with alpha particles, producing a new radiation later identified as neutrons by James Chadwick in 1932.¹ This discovery was crucial, as it was discovered that neutrons with no charge could penetrate atomic nuclei more easily than charged particles.
The discovery of fission and chain reactions
In the 1930s, Enrico Fermi and his colleagues bombarded elements with neutrons, leading to unexpected reactions. By 1939, Otto Hahn and Fritz Strassmann identified that uranium nuclei could split into lighter elements, like barium, when bombarded by neutrons—a process later termed ‘fission’ by Lise Meitner and Otto Frisch.³ This splitting released energy and emitted additional neutrons, hinting at the possibility of a self-sustaining chain reaction. Fermi theorised that if neutrons could initiate further fission events, a powerful chain reaction might be achievable.¹
The potential military applications of fission quickly gained attention, and in 1939, notable scientists, including Einstein, warned the U.S. government about its possible use in warfare.⁴ This sparked major scientific and government efforts, leading to further exploration of uranium isotope separation, reactor development, and eventually nuclear weapons during World War II.
The Manhattan Project
With the discovery of fission and the realisation of its explosive potential, the United States launched the Manhattan Project during World War II, a massive scientific and engineering initiative aimed at developing the first atomic bomb. This project involved thousands of scientists and led to advances in uranium enrichment, nuclear reactor development for plutonium production, and weapons technology.
Key to the Manhattan Project’s success was the separation of uranium isotopes. Natural uranium contains only a small amount of uranium-235, the isotope capable of sustaining a chain reaction. Through methods like gaseous diffusion and electromagnetic separation, researchers were able to concentrate uranium-235.¹ Additionally, reactors were built to produce plutonium, another fissile material usable in nuclear weapons.
The culmination of these efforts led to the detonation of two atomic bombs over Hiroshima and Nagasaki in 1945, which effectively ended the war. The use of atomic energy for military purposes had been realised, marking the beginning of the nuclear era.
In the postwar years, the U.S. shifted its focus from military to civilian applications of nuclear energy, founding the Atomic Energy Commission (AEC) to regulate and promote peaceful nuclear developments. Over time, the AEC's roles were split, with the Department of Energy (DOE) handling promotion and research and the Nuclear Regulatory Commission (NRC) focusing on safety and regulation. On the global stage, the International Atomic Energy Agency (IAEA) was established in 1957 to promote safe, peaceful use of nuclear energy, assist developing countries, and monitor nuclear materials to prevent proliferation.¹
Post-WWII developments
After World War II, interest in the peaceful applications of nuclear energy surged. Governments and industries around the world recognized nuclear power’s potential as a reliable energy source. In the United States, the Atomic Energy Act, which was signed into law by President Harry S. Truman on Aug. 1, 1946, established the Atomic Energy Commission (AEC) to control the development and production of nuclear weapons and to direct the research and development of peaceful uses of nuclear energy.⁶
The history of nuclear energy in the second half of the 20th century and early 21st century is marked by significant developments, challenges, and milestones. Internationally, The "Atoms for Peace" initiative, proposed in 1953 by U.S. President Dwight D. Eisenhower led to the establishment of the International Atomic Energy Agency (IAEA) in 1957, promoting peaceful uses of nuclear energy. The IAEA plays a crucial role in establishing standards for nuclear safety worldwide and supports the growth of nuclear technology in developing countries while monitoring the use of nuclear materials to prevent misuse.⁷
The first large-scale nuclear power plant in the U.S. came online in 1957, in Shippingport, Pennsylvania, marking a significant milestone in the civilian use of nuclear technology.⁸
During the 1960s, nuclear power “achieved the status of a technically proven and commercially viable energy source,”⁹ and use rapidly expanded as electric utilities placed large orders for nuclear plants. By the end of the decade, nuclear power accounted for nearly a quarter of U.S. electric capacity under development. As the nuclear industry grew, so did the focus on safety. Plants incorporated multiple design enhancements and safety layers, including containment structures and emergency cooling systems, to prevent radiation release in case of accidents. The AEC’s responsibilities eventually shifted to the DOE and the NRC, with the NRC focusing on stringent safety regulations and licensing.
The 70s and 80s
During this time, nuclear energy saw both rapid growth and significant challenges. The 1970s were characterised by a “surge in environmentalism, resulting in new environmental legislation, environmental ministries and, in several countries, the founding of formal Green political parties, all anti-nuclear.”¹⁰ The 1973 energy crisis initially spurred interest in nuclear power as countries sought alternatives to fossil fuels and sought energy security. This crisis led to a wave of new nuclear plant orders, positioning nuclear power as a promising solution to the volatility of oil prices. In 1973, U.S. utilities ordered 41 nuclear power plants, a one-year record.¹¹
However, rising oil prices led to a surge in commodity prices, increasing energy costs from all sources, including nuclear, which slowed global economies, reduced energy demand growth, and lessened the need for new generating capacity, especially in industrialised nations. Meanwhile, intensified energy conservation efforts and emerging technical and safety issues in nuclear plants led to higher investment costs, longer construction times, and more stringent regulatory requirements.⁹
As nuclear power’s scientific glamour was diminished into a hard industrial reality, public awareness and concern grew, fueled by associations with nuclear weapons, radiation dangers, and environmental impact. Environmentalist movements quickly targeted nuclear power, and the media, segments of the public, and some politicians formed mostly emotional opposition. This sentiment hardened with the Three Mile Island accident in 1979, the first major accident at any nuclear power plant. The incident significantly impacted the nuclear industry's global reputation, leading to fewer new projects and many ongoing or planned projects being suspended or cancelled. The lessons learned resulted in “many improvements in the design, construction, and operation of nuclear plants, both with respect to safety and reliability.”⁹
Years later, on April 26, 1986, the world's “worst known disaster in nuclear power plants” occurred at Chernobyl, Ukraine, and resulted in loss of life and widespread radioactive contamination that crossed national borders. This further fueled public opposition and led to stricter safety standards, again reducing new nuclear projects. The psychological effect on the population was immense, as was the damage to the surrounding area and the reputation of the nuclear power industry.
The 90s
Nuclear energy faced slow but steady growth, primarily driven by improved operational efficiencies rather than new construction, which had largely stalled in North America and Western Europe. Deregulation in many electricity markets introduced new financial pressures, making nuclear power less attractive due to its high initial capital costs.¹⁰ Concerns over nuclear safety remained high following the Chernobyl disaster, but significant safety improvements and the exchange of best practices among operators helped increase the reliability and availability of existing plants. The nuclear industry also began consolidating, with experienced operators managing larger numbers of plants, thus improving overall performance.¹⁰ Expansion in nuclear capacity shifted toward Asia, where rapid economic growth and energy security needs led countries like China, India, Japan, and South Korea to increase their nuclear power investments. By the late 1990s, the first of the third-generation reactors was commissioned in Japan, a sign of the recovery to come.¹²
The 21st century
A recent revival of nuclear energy has been driven by the urgent need to meet soaring global electricity demand along with concerns about energy security and climate change. Nuclear power's capacity to provide reliable, dispatchable electricity makes it an attractive solution for ensuring stable, low-carbon energy supplies. However, this revival has not been without setbacks.
Following a 9.0 earthquake on 11, March 2011, a 15-metre tsunami struck Japan and disabled the power supply and cooling of three Fukushima Daiichi reactors, causing a nuclear accident and leading to widespread reevaluation of nuclear safety and policies globally. In June 2011, The IAEA announced that the Fukushima Daiichi plant in Japan had experienced a "melt-through" at three reactors. Significantly more dangerous than a meltdown, this is considered the worst possible scenario short of an explosion at the nuclear plant.¹³ The crisis is labelled at the highest level on the International Nuclear Events Scale.¹³
According to a World Nuclear Association safety and security report on the incident, “there have been no deaths or cases of radiation sickness from the nuclear accident, but over 100,000 people were evacuated from their homes as a preventative measure.”¹⁴ The accident resulted in low radiological exposure to the public and significantly impacted mental and physical well-being and lifestyle changes from prolonged evacuation and heightened fear.
Japanese government policy and public opinion, alongside that of many other nations, took an increasingly anti-nuclear stance following the disaster, demonstrated by Japanese Prime Minister Naoto Kan stating "Japan should reduce and eventually eliminate its dependence on nuclear energy” and that “the Fukushima accident had demonstrated the dangers of the technology.”¹⁵
The impact of the Fukushima Daiichi Accident was profound on global nuclear policy. It led to stricter regulations, enhanced safety standards, and a renewed focus on resilient reactor design. Despite this, Japan—alongside many other nations—is now making a U-turn back to nuclear energy and recently pledged to restart all its nuclear reactors.
Nuclear energy today
A modern nuclear energy renaissance is underway, fueled by the need to cut carbon emissions for climate change mitigation, rising energy demands from AI and data centres, and the drive for energy security amidst the Ukraine-Russia conflict and its impact on global energy markets. With improved public opinion, net-zero carbon targets, and pledges like the Ministerial Declaration to Triple Nuclear Energy signed by 24 nations at COP28 in December 2023¹⁵, nuclear power is regaining global momentum.
Advances in safer, cost-effective reactor technologies, such as Small Modular Reactors (SMRs), further strengthen its role as a reliable, low-carbon energy source. SMRs are advanced nuclear reactors with a power capacity of up to 300 MW(e) per unit, roughly one-third of the output of conventional nuclear reactors. They are a fraction of the size of a conventional reaction and are modular, meaning their systems and components can be factory assembled and transported for installation. Proposed designs are simpler than existing reactors and feature inherently safer characteristics, such as lower power levels and operating pressures. They also include passive systems that rely on natural phenomena like convection, gravity, natural circulation, and self-pressurisation, requiring no human intervention or external power to shut down. According to the IAEA, these additional safety features “eliminate or significantly lower the potential for unsafe releases of radioactivity to the environment and the public in case of an accident.”¹⁶ As for the current status of SMRs, there are currently over 80 designs and concepts, most in various stages of development by both the public and private sectors.¹⁶
Around the world, 440 nuclear reactors currently provide over 10% of global electricity.¹⁷ Per the World Nuclear Association, nuclear plants generate nearly 20% of U.S. electricity overall and 55% of its carbon‐free electricity as of August, 2024.¹⁸ Per the U.S. Energy Information Administration, there were 54 commercially operating U.S. nuclear power plants with 94 nuclear power reactors in 28 states as of April, 2024¹⁹ Only one new reactor launched in the past 20 years in the United States. In contrast, over 100 reactors are actively planned abroad, and an additional 300 are proposed, led primarily by China, India, and Russia.¹⁷
Nuclear energy tomorrow
As the world’s search for cleaner, more reliable fuel sources has become increasingly urgent, nuclear power is poised for a renaissance that may attract $1.5 trillion in capital investment through 2050, according to Morgan Stanley Research.²⁰
This renewed interest aligns with the introduction of advanced nuclear reactor designs, which promise enhanced safety and efficiency. While Europe and North America have plans for new reactors, the momentum is strongest in Asia, with China and India leading ambitious nuclear expansions backed by strong political will. As Jacopo Buongiorno, a professor of nuclear science and engineering at the Massachusetts Institute of Technology (MIT), proclaimed, “China is the de-facto world leader in nuclear technology.”²¹ The country expects to build six to eight new nuclear power plants each year for the foreseeable future, on pace to overtake the United States as the nation with the largest nuclear-generating power capacity by 2030.²² Overall, China has nearly tripled its nuclear capacity over the past 10 years; it took the United States nearly 40 years to add the same nuclear power capacity as China added in the last decade.²³
Demand for power is increasing, driven by electrification in developing countries and also an AI revolution the likes of which the world has never seen before. A major question surrounding the rise of AI is how much energy will be required to fully harness this groundbreaking, yet highly energy-demanding technology. According to a March 2024 Morgan Stanley report, “power demand from generative AI will increase at an annual average of 70% through 2027, mostly from the growth of data centres.” The report further suggests that companies are likely to develop renewable energy projects to meet this demand. This has since been observed, with Microsoft, Google, and Amazon each announcing deals in 2024 to use nuclear power to produce the substantial energy required to operate AI data centers.²⁵
As nuclear energy sees renewed interest fueled by AI and data centre demands, some are looking further into the future, where emerging fusion technology promises to redefine clean energy possibilities on a larger scale. Nuclear fusion, the process that powers the sun and all other stars, could theoretically provide limitless clean energy if it could be replicated on Earth.²⁶
In December of 2022, Nuclear fusion researchers achieved the historic milestone of producing a controlled fusion reaction that generated more energy than was put into the system for the first time.²⁷ Since then, numerous experiments have built upon and replicated these results, bringing viable fusion power another step closer to reality, despite economic viability being a long ways away due to a myriad of enormous technical challenges that remain. Nonetheless, many of the world's leading nations are investing heavily in the venture, such as China putting an estimated $1 billion to $1.5 billion annually into fusion and the U.S. spending around $800 million annually throughout the Biden administration, per CNN.28 However, while China’s government pours money into fusion, the U.S. has attracted far more private investment. “Globally, the private sector has spent $7 billion on fusion in the last three to four years, about 80% of which has been by U.S. companies” according to Jean Paul Allain, who leads the U.S. Department of Energy’s Office of Fusion Energy Sciences.²⁸
With mounting global demand for sustainable energy and groundbreaking advancements in fusion technology, the future of nuclear power shines brighter than ever, holding the promise of abundant, clean energy that could transform industries, power new technologies, and help meet even the world’s most ambitious climate goals.
Footnotes
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