Hiroshima Report 2023(12) Irreversibility
The draft final document of the NPT RevCon stated, “States parties recognise that further work is required to ensure the irreversibility of nuclear disarmament and, as a first step, are encouraged to build an understanding of the application of irreversibility measures in attaining and maintaining a world free of nuclear weapons and to exchange information on the application of the principle of irreversibility in relation to the implementation of their Treaty obligations.”
Meanwhile, in their working papers submitted to the NPT RevCon, Norway and the United Kingdom raised the following issues related to the concept of irreversibility in nuclear disarmament.
Despite enjoying broad support among the Treaty on the Non-Proliferation of Nuclear Weapons community, there is no common definition or unified understanding of the principle of irreversibility. In developing an improved understanding of the principle, it will be useful to make a distinction between two equally important but different facets of the overarching principle of irreversibility in the disarmament context. These are “irreversible steps towards disarmament” and “irreversibility in a weapon-free world”. Both are clearly important, but they are not the same thing, and one does not necessarily lead to the other. Disarmament could be achieved without having irreversible steps, and individual irreversible steps do not necessarily lead to disarmament by themselves. The United Kingdom has co-authored a paper with Norway on the principle of irreversibility, on how it has been understood and on where further work can be taken forward. The United Kingdom invites all States to work with us to deepen our understanding of irreversibility and what it means in practice.314
A) Implementing or planning dismantlement of nuclear warheads and their delivery vehicles
As with their previous nuclear arms control agreements, the New START obliges Russia and the United States to dismantle or convert strategic (nuclear) delivery vehicles beyond the limits set in the treaty, and to do so in a verifiable way. The New START does not stipulate that retired nuclear warheads be dismantled, but the two states have partially dismantled retired nuclear warheads as unilateral measures. As mentioned above, in 2021, the Biden administration declassified the number of dismantled U.S. nuclear warheads. According to a State Department fact sheet, the United States dismantled 184 nuclear warheads in 2020, and 11,638 warheads from 1994 through 2020.315
The other NWS did not release any information regarding nuclear weapons dismantlement in 2021. However, France and the United Kingdom have dismantled their retired nuclear warheads and delivery vehicles. France also mentioned, in its national report submitted to the NPT RevCon, that it had begun dismantling its M4 SSBN.316
B) Decommissioning/conversion of nuclear weapons-related facilities
No remarkable activity or progress was reported in 2022 in terms of decommissioning or converting nuclear weapons-related facilities.
In 1996, France became the only country to decide to completely and irreversibly dismantle its nuclear test sites, which were fully decommissioned in 1998.317 In its national report submitted to the NPT RevCon, France reported that it has engaged in decommissioning operations for the former fissile material production facilities for nuclear weapons, including its uranium enrichment facility, reprocessing facility and plutonium production reactor.318 The United States also reported the following: “In 1980, the nuclear complex was made up of 14 sites. Today, it consists of eight, and its workforce has been reduced by two-thirds since the end of the Cold War.”319
C) Measures for fissile material declared excess for military purposes, such as disposition or conversion to peaceful purposes
In October 2016, Russian President Putin issued a Presidential Decree on suspending implementation of the Russian-U.S. Plutonium Management and Disposition Agreement (PMDA), which entered into force in July 2011.320 This situation has not been resolved.
In the meantime, as mentioned in the Hiroshima Report 2021, the United States formally terminated construction of the Mixed Oxide Fuel Fabrication Facility (MFFF) at the Savannah River Site in South Carolina in 2018. The NNSA has proposed to repurpose the MFFF to produce plutonium pits.
314 NPT/CONF.2020/WP.35, December 10, 2021.
315 NNSA, “Transparency in the U.S. Nuclear Weapons Stockpile.”
316 NPT/CONF.2020/42/Rev.1, August 1, 2022.
317 NPT/CONF.2015/10.
318 NPT/CONF.2020/42/Rev.1, August 1, 2022.
319 NPT/CONF.2020/47, December 27, 2021.
320 This decree stipulates, inter alia, that 34 tons each of surplus U.S. and Russian plutonium extracted from dismantled nuclear warheads shall be converted into mixed oxide (MOX) fuel for use in civilian nuclear reactors.
