[Insight & Opinion] Permitting Nuclear Submarines but Banning Commercial Nuclear Power Plants Is Unreasonable

Surprise U.S. Approval for Nuclear Submarine Development and Fuel Request
Agreement Revision Uncertainty and Policy Consistency Debate

An unexpected variable emerged during the South Korea-United States summit, which was held on the occasion of the 2025 Asia-Pacific Economic Cooperation (APEC) summit. President Lee Jaemyung announced that South Korea would also develop nuclear-powered submarines. In a public request to the United States to "supply nuclear fuel," U.S. President Donald Trump stated via social media that he had "approved the construction of nuclear-powered submarines."

South Korea's interest in nuclear-powered submarines began during the first North Korean nuclear crisis in 1993, triggered by North Korea's declaration of withdrawal from the Nuclear Non-Proliferation Treaty (NPT). At the time, under the direction of then-Minister of Science and Technology Kim Sijung, South Korea even obtained blueprints for small reactors for nuclear-powered submarines from politically, economically, and socially unstable Russia. The SMART reactor, which the Korea Atomic Energy Research Institute began developing independently in 1997 and for which it obtained the world's first standard design approval in 2012, was the result of these efforts.

Interest in nuclear-powered submarines was temporarily put on hold under the Sunshine Policy of the Kim Daejung administration but was revived in 2003 under the Roh Moohyun administration as the "362 Project" (nuclear submarine construction project). The plan was to invest 3.5 trillion won to deploy three attack nuclear submarines by 2017. However, the 362 Project had to be halted due to diplomatic conflicts over nuclear fuel supply and other issues. During the Moon Jaein administration, North Korea strongly opposed the mention of "reviewing the necessity of nuclear-powered submarines" in the Defense White Paper, and the United States refused to supply nuclear fuel, citing non-proliferation principles.

The nuclear-powered submarines that South Korea aims to develop are fundamentally different from the nuclear weapons being developed by North Korea. The only change is replacing the diesel engine that powers the submarine with a small nuclear reactor. The heat energy generated by the reactor is used to produce electricity, which then powers the submarine. The advantages include no noise, greater submerged range, and faster speed compared to conventional submarines.

The history of nuclear-powered submarines began even before the commercial nuclear power plant at Calder Hall in the United Kingdom in 1956. The United States began development in 1946, and in 1954 built the "Nautilus" (SSN-571), the world's first nuclear-powered submarine. Equipped with two pressurized water reactors, the Nautilus could remain submerged for more than several months. The Soviet Union also succeeded in developing a nuclear submarine in 1958. The United Kingdom, France, India, and China also possess nuclear-powered submarines, and Australia will acquire U.S.-made nuclear-powered submarines.

Developing and possessing nuclear-powered submarines is not only a technical challenge for South Korea. It is unclear whether the international community will recognize South Korea's nuclear-powered submarines as "peaceful use of nuclear energy." The nuclear agreement with the United States may need to be revised, and resistance from China and North Korea is likely to be significant. Securing a stable supply of nuclear fuel for the submarines will also not be easy. In particular, if highly enriched uranium is used as fuel, the situation will become even more complicated.

Domestic public opinion is also far from favorable. This is especially true as the newly established Ministry of Climate, Energy and Environment is pushing for "Nuclear Phase-Out Season 2." Both President Lee and Minister of Climate, Energy and Environment Kim Sunghwan are firmly convinced that "the dangers of nuclear power are an objective fact." They remain unmoved by the reality that abandoning nuclear power would make it impossible to reliably supply electricity needed for artificial intelligence (AI), security, and industry. The contradiction of permitting the military use of dangerous nuclear technology while prohibiting its use for industry and daily life is unconvincing.

Lee Deokhwan, Professor Emeritus at Sogang University, Chemistry and Science Communication