BBC Inside Science – How to bury radioactive waste – BBC Sounds

At the heart of the problem lies the inherent nature of radioactive waste. As Professor Clare Corkhill from the University of Bristol elucidates, this waste is a byproduct primarily of nuclear power generation, but also from medical applications, industrial processes, and defence activities. While low-level waste (such as contaminated clothing or tools) and intermediate-level waste (resins, chemical sludges, metal fuel claddings) can often be managed with shallower repositories or robust shielding, it is the high-level waste that presents the most formidable conundrum. This waste, comprising spent nuclear fuel and reprocessed liquid waste, is intensely radioactive, generates significant heat, and remains dangerous for hundreds of thousands, even millions, of years. The isotopes within it decay at vastly different rates, meaning a comprehensive solution must account for timescales that dwarf human civilisation itself. Professor Corkhill’s insights highlight that despite its relatively small volume, high-level waste poses a "small but mighty problem" due to its extreme toxicity and unparalleled longevity.

For decades, the global scientific community has converged on deep geological repositories (DGRs) as the most viable long-term solution. These facilities aim to isolate radioactive waste deep within stable geological formations, far removed from the biosphere, for the duration of its hazardous lifespan. The BBC Inside Science programme takes listeners on a crucial journey to Onkalo, Finland, where Victoria Gill visits the world’s first national facility poised to provide just such a long-term solution. Onkalo, meaning "cave" or "cavity" in Finnish, is located deep within the stable granite bedrock of the Olkiluoto island, western Finland. It is a pioneering project, designed to permanently entomb Finland’s spent nuclear fuel at depths of approximately 400 to 450 metres. Due to begin operations this year (2026), Onkalo represents a landmark achievement in nuclear waste management, moving from theoretical concept to tangible reality.

The engineering marvel of Onkalo involves a multi-barrier system designed to provide layers of protection against the migration of radionuclides. First, the spent fuel is sealed inside robust copper canisters, a material chosen for its exceptional corrosion resistance. These canisters are then encased in bentonite clay, which swells when it absorbs water, creating a tight seal and limiting water flow around the canisters, thereby inhibiting the movement of any escaped radionuclides. Finally, these packages are placed in deposition tunnels excavated within the ancient, stable bedrock of the Fennoscandian Shield, a geological formation that has remained largely undisturbed for billions of years. The entire repository will eventually be backfilled and sealed, effectively creating a natural and engineered fortress against the outside world. The expectation is that this system will contain the waste for the hundreds of thousands of years required for its radioactivity to diminish to safe levels. Gill’s visit underscores the meticulous planning, extensive geological surveying, and advanced engineering required to construct such a facility, a testament to Finnish scientific and technological prowess.

However, even with the most robust geological isolation, a profound challenge remains: how to prevent future civilisations, potentially far removed from our current understanding and technologies, from inadvertently or intentionally disturbing the waste. This intergenerational communication dilemma is explored in depth by journalist Mark Piesing and artist Gair Dunlop from the University of Dundee. Dunlop, who for several years has co-convened the international, interdisciplinary Nuclear Culture Research Group, highlights the complexity of deterring trespass over timescales stretching hundreds of millions of years.

The problem is multifaceted. Human languages evolve and die, rendering written warnings unintelligible after mere centuries, let alone millennia. Our current societal structures, political systems, and even our species might undergo radical transformations. How do we convey "danger" or "stay away" to beings whose perceptions, knowledge, and values are utterly alien to ours? The Nuclear Culture Research Group, alongside other international bodies, has grappled with this unique semiotic and anthropological puzzle.

One proposed solution involves creating enduring physical markers – vast, engineered landscapes or monuments that convey a sense of dread or warning through their sheer scale and unusual forms, transcending linguistic barriers. Imagine a "landscape of thorns" or "forbidding blocks" that visually scream "danger." Another concept, often termed the "atomic priesthood," suggests establishing a self-perpetuating institution or cultural group whose sole purpose would be to preserve the knowledge of the waste’s location and hazard, passing it down through generations via oral tradition, ritual, and symbolic narratives, much like ancient religious orders.

Mark Piesing’s journalistic work on this issue delves into historical precedents and speculative futures. He touches upon the work of the Human Interference Task Force, established in the 1980s by the US Department of Energy, which explored various deterrence strategies for the Waste Isolation Pilot Plant (WIPP) in New Mexico. Their recommendations included the use of multiple warning signs in different languages, including dead languages, and even pictorial warnings designed to evoke universal human fear responses. The challenge is not just to convey "danger," but to convey the reason for the danger – that something buried here is profoundly harmful and must not be disturbed.

Gair Dunlop’s work with the Nuclear Culture Research Group pushes these boundaries further, embracing artistic and philosophical approaches. The group explores how art, storytelling, and cultural practices can contribute to long-term memory and warning. Could myths, legends, or even a sense of taboo be intentionally cultivated around these sites? They consider how visual arts, soundscapes, or even genetic modifications (e.g., "radiation cats" that change colour in the presence of radiation, though this is largely metaphorical) could serve as warning signals. The interdisciplinary nature of their work — bringing together artists, scientists, linguists, anthropologists, and historians — underscores that this is not merely an engineering problem, but a profound humanistic one. The goal is to create messages that are robust, unambiguous, and resilient to the inevitable cultural drift and potential collapse of advanced civilisations.

The implications of Onkalo’s impending operation extend beyond Finland. Many other countries with nuclear power programmes, including Sweden, Canada, the UK, and the USA, are also pursuing DGRs. Sweden’s SKB is developing a similar facility for spent nuclear fuel near Forsmark, also within the Fennoscandian Shield. The UK is currently in the process of identifying a willing community and suitable geology for its own DGR. These projects face not only immense scientific and engineering hurdles but also significant public engagement and political challenges, as communities grapple with the long-term presence of such facilities. The Finnish success story serves as a vital blueprint and a powerful motivator for these global efforts.

The BBC Inside Science episode powerfully conveys that burying radioactive waste is far more than just digging a deep hole. It is a monumental act of long-term stewardship, requiring not only cutting-edge science and engineering but also an unprecedented level of foresight, ethical consideration, and imaginative communication. It is a testament to humanity’s capacity for ingenuity and our profound responsibility to generations yet unborn. The solutions being forged in places like Onkalo, and the discussions fostered by groups like the Nuclear Culture Research Group, represent a collective promise to mitigate the risks of our technological advancements, ensuring that the legacy of nuclear power does not become an insurmountable burden for those who will inherit our planet hundreds of thousands of years from now.