20th century: Geological «disposal»
Since the first commercial nuclear reactors went into operation 60 years ago, «final disposal» has been the generally and globally pursued strategy for the disposal of radioactive waste produced in nuclear power plants[1]. With «final disposal» – in its various forms, such as monitored storage and limited retrieval[2] – the waste is to be permanently stored in caverns in the geological subsurface behind engineered (waste form, waste canisters and bentonite) and geological barriers (host rock formation and geological environment) for thousands of years, away from the biosphere and human habitat.
While probably no one is sad to see the hopefully definitive disposal of low and intermediate level radioactive waste through final storage, it was recognized early on that spent fuel rods in reactors still have an economically interesting content of radioactive material that can be used for further energy production. Thus, the reprocessing of fuel rods, primarily from light water reactors, in factories such as La Hague in France and Windscale in England, developed after the separation process for uranium and plutonium (PUREX process). However, there was a risk of so-called proliferation, i.e. the diversion of plutonium as a source material for nuclear weapons. To counter this risk and to reduce the large stocks of weapons-grade plutonium, mixed oxide fuel rods (MOX), a nuclear fuel produced during reprocessing, were manufactured with an increased plutonium content and burned in conventional light-water reactors. In addition, the reprocessing of nuclear fuels was prohibited by law in many countries, including Switzerland in 2003, by the new Nuclear Energy Act (NEA).
Reprocessing using the PUREX process only makes a modest contribution to reducing the amount of highly radioactive waste from nuclear power plants. Therefore, even in countries that practice (or practiced) reprocessing, work continued on projects for the storage of highly radioactive waste in deep geological repositories. However, with limited success, numerous mishaps[3] and under the constant pressure of a public (and more and more experts) who doubt the long-term protection of the biosphere through deep disposal.
21st century: transmutation of high-level radioactive waste (HLW)
The idea of bombarding highly radioactive waste with neutrons to convert it into radioactive substances with lower half-life has been discussed for decades [1].
A corresponding experiment was carried out by the Paul Scherrer Institute (PSI) in spring 2004 [2]. This «Megapie project» was successful as a laboratory project. However, implementation on an industrial scale was out of the question at the time due, among other things, to the high energy requirements and high costs.
The last few weeks have brought the public some news regarding new disposal concepts. Presentations and information from the management of the French-speaking Swiss company Transmutex in February 2025, as well as the publication of an expert report by the German Federal Agency for Breakthrough Innovations (Spring-D), show for the first time concrete alternatives to geological «final disposal», and thus positive perspectives for massively alleviating the problem of nuclear disposal of highly radioactive fuels.
Transmutex plans to commission a first reactor by 2035 to implement the separation and reuse of the radioactive substances present in the waste and to split long-lived problem isotopes in the residual waste. The answers to the effective feasibility of this concept are therefore expected in the course of the next decade.
What is already becoming apparent, however, is that Transmutex is just the tip of the technology-based options for treating highly radioactive materials. The nuclear world is on the move again and could offer completely new solutions for handling highly radioactive waste in the foreseeable future. Transmutex is talking about 10 years until a plant that would include all the treatment steps of waste conversion is up and running and ready for the market: electrochemical separation of the highly radioactive waste materials, neutron source for irradiation and transmutation of the long-lived isotopes of the waste, vitrification of the short-lived, highly radioactive residual waste and storage of the same in a geological decay storage facility. The transmutation of the waste would generate so much benefits that the process would be financially self-financing. The waste produced by the process would then have to be isolated from the biosphere for less than 1000 years, a historically manageable period.
If the problematic isotopes in the high-level waste could be transmuted using this new facility, the Transmutex process could become a real “game changer” – with enormous consequences for past and future disposal planning. It would mean the end of the deep geological repository (the classical «final repository») for highly radioactive waste with isolation times of up to 1 million years.
The fact that these developments are not on the cards in the distant future, but could happen in the foreseeable medium term, is shaking up the strategy and process maps. In Switzerland, this first concerns the general license procedure for the deep geological repository, which was submitted by Nagra in November 2024 and is currently being reviewed by the safety authorities. The most obvious question is: how will the established disposal procedure be affected by rapid developments in the field of waste conversion? How are the authorities responding to these challenges, which could fundamentally change Switzerland’s disposal path, in terms of the deep repository for high-level waste, the location for low- and intermediate-level waste, the interim storage strategy and the possible storage of shorter-lived high-level waste? One thing is certain: the planned development of the disposal of highly radioactive waste will not proceed as announced in the «Deep Geological Repository Plan»[3].
In the following chapter, fundamental questions are raised and briefly examined.
Developments and impacts of transmutation on the Swiss Sectoral Plan and the general license approval procedure
The Transmutex project is based in Switzerland and neighboring France, but it is not specifically tailored to either country. And yet both countries will be affected as soon as the first facility is up and running e.g. in faraway India, Canada or Germany.
According to the Swiss Federal Nuclear Energy Act (NEA 2003, Art. 31), the producers are responsible for the disposal of radioactive waste in deep geological repositories in Switzerland. The federal government is responsible for supervision and the licensing procedures. It also assumes the role of the waste producers if they fail to fulfill their obligations. This means that both the licensing authority itself, i.e. the Federal Office of Energy (FOEN), and the supervisory authority ENSI, have to follow national and international developments in the field of nuclear waste disposal. To what extent they are currently doing this beyond deep geological disposal, and are considering the question of waste treatment, the digestion of spent fuel rods, the separation of actinides and transmutation by neutron bombardment, is not clear from the published documents. In any case, no such information has been made public to date. The impetus for the transition from the deep geological disposal strategy to the transmutation of highly radioactive waste is therefore unlikely to come from the federal authorities. At the latest after the publication of the study by the Federal Agency for Breakthrough Innovations (SPRIN_D) in February 2025, the federal authorities – but also Nagra – will no longer be able to avoid publicly commenting on this technical development.
Of course, this raises the question of how and when the developments mentioned could and should be integrated into the Swiss waste management program. Since the fall of 2024, the general license procedure for a combined repository for all waste categories in the ««Nördlich Lägern» region has been underway as part of the «Deep Geological Repository» sectoral plan. The federal government expects a license to be granted around 2030. Until then, neither the waste producers nor the federal authorities are particularly motivated to report on the transmutation of high-level radioactive waste, although they must be well aware of the implications of this new technology, especially since Transmutex is in close contact with Nagra, as Dr. Franz Strohmer pointed out in a lecture in Stadel on May 22, 2024.[1] It is understandable that this is seriously disrupting the plans for the deep geological repository in «Nördlich Lägern» and the general license for the planned deep repository. It is also understandable that the official institutions are not particularly keen on commenting on this at the moment. Behind the scenes, however, things are looking a little different. Even the institutions with expertise in the field now know that Transmutex is a potential game changer.
In the region affected by the storage project, where the population – and possibly also municipal and cantonal authorities – will ask themselves why and whether a general license for a HLW repository should be granted at all, this development will trigger a new discussion, in particular about the sense of a final repository for highly radioactive waste. This line of argument is likely to carry weight in a referendum and could thus, despite the inertia of the institutions, have an impact on the formulated general license to be expected from the Federal Council.
A central and difficult set of questions in the transition from geological disposal to transmutation of the HLW concerns the legal aspects. The significance of new technical processes for the treatment of radioactive waste is therefore also extremely relevant in legal terms. Under the current Nuclear Energy Act (NEA 2003), the transmutation of Swiss HLW is not possible either domestically or abroad. In order to legalize transmutation by a facility in Switzerland, the law would have to be amended to allow the construction and operation of such a facility. This primarily concerns a facility for the electrochemical separation of the nuclides and a reactor for spallation and transmutation of the waste materials. For transmutation, the export of radioactive material for transmutation and the possible re-import of the resulting waste would have to be legalized. But rapid technological development also requires legislators to adapt quickly. Since legislative processes take time, it would be desirable to start work soon on possible revision of the current Nuclear Energy Act.
If technologies such as Transmutex are implemented, other effects on the disposal system will also have to be considered. If, according to EKRA concept, a deep geological repository for HLW is no longer needed, the question arises as to the direction in which the entire disposal system will move. On the one hand, this concerns the interim storage of HLW, in particular at ZWILAG site and a possible further underground interim storage facility for spent fuel elements until they are used in a Transmutex reactor or in other applications. On the other hand, how the new waste streams are to be dealt with, because a final repository will still be needed for the shorter-lived high-level waste (S-HLW). But in principle, an underground long-term interim storage facility or definitive storage in a deep geological repository is sufficient for this. Therefore, all possible options and alternatives should be considered and their consequences identified. With the planned separation of long-lived radioactive isotopes such as technetium TC-99, iodine I-129 and selenium Se-79 by Transmutex, a massive reduction in the long-term nature of downstream storage should also be expected on the anion side. Certainly, the significance of a storage site for low- and intermediate-level radioactive waste will then also need to be reviewed. It should also be permissible to question whether a dense host rock such as the Opalinus Clay could be the appropriate host rock for gaseous radioactive waste or whether other alternatives should also be discussed. And then, of course, studies on the radiological consequences of the various scenarios are also part of a comprehensive analysis of the new alternatives and options.
The costs of disposal for the various scenarios would also have to be re-examined. This is likely to be a key criterion for future decisions on the choice of a future disposal strategy, alongside the safety criteria. And finally, the question will also have to be asked whether a Transmutex reactor could also be located in Switzerland, at which site such a reactor would be possible, whether the shutdown of the two veteran reactors in Beznau 1 and 2 could also be related to this, etc. These are therefore key questions that should be addressed again, and which could best be dealt with by a new commission of specialists that is independent of vested interests. A kind of radioactive waste disposal commission EKRA II, which, in addition to technical issues, could also reflect on the role of the various actors (Nagra, safety authorities, FCNS, etc.)
So there is a lot going on in the field of nuclear waste disposal at the moment. Does this mean that we are on the verge of a turning point in energy production and waste management? And could such a development have been recognized earlier? What are the arguments in favor of such a thesis? These and similar questions will be addressed in the next article on the «turning point» or «era of change».
[1] For more information on the history of radioactive waste disposal, see for example the introductory chapters of the EKRA 2000 report (EKRA 2000: Concepts for radioactive waste disposal in Switzerland; final report. FOEN, Berne.)
[2] NEA 2003 : 732.1 Nuclear Energy Act.
[3] https://www.nuclearwaste.info/mines-de-stockage-geologique-degradees-que-signifient-elles-pour-le-principe-de-recuperabilite/?lang=fr[4] Emery, Guy, T. 2003: From Nuclear Transmutation to Nuclear Fission 1932-1939. Physics Today 56 (8), août 2003. P. 54-56; AIEA, 1997. Accelerator Driven Systems: Energy Generation and Transmutation of Nuclear Waste. Agence internationale de l’énergie atomique. IAEA-TECDOC-985. Histoire et préoccupations : voir pages 10-11.
C. D. Bowman et al. 1992: Nuclear energy generation and waste transmutation using an accelerator-driven intense thermal neutron source. Nuclear Instruments and Methods A Bd. 320.
[5] https://www.nuklearforum.ch/fr/nouvelles/transmutation-dactinides-au-psi-experience-internationale-megapie/
[6] FOEN (2008) and new versions: Sectoral Plan for Deep Geological Repositories».
[7] Manuscript of the conference on https://loti2010.ch/oeffentlicher-vortrag-und-diskussion-transmutation-als-chance-fuer-die-entsorgung-radioaktiver-abfaelle/
