Heritage Futures: Archaeological Insights for the Long-term Management of Radioactive Waste
Cornelius Holtorf, UNESCO Chair on Heritage Futures, Linnaeus University
Managing radioactive waste is a challenge that extends across many generations, requiring long-term safety measures. Archaeologists, like myself, are familiar with time scales of thousands of years as we seek to understand the distant past. A key part of our work involves questioning assumptions rooted in the present and learning to imagine past worlds that were vastly different from today. This is very difficult, but only after doing so can we draw meaningful insights from the past to inform the present. The same principles should apply when communicating information, knowledge, and guidance about radioactive waste repositories to societies of distant futures. This calls for a strengthened capacity in ‘futures literacy,’ a concept developed and promoted by UNESCO.
Futures literacy consists of three core dimensions: 1. Becoming aware of the assumptions we hold about the future, 2. Learning to imagine multiple alternative futures, and 3. Reframing the original issue and developing new strategies to address it.
In this paper, I explore this argument and discuss its implications for a long-term, safe and responsible management of radioactive waste. The paper is based on extensive research conducted by the UNESCO Chair on Heritage Futures at Linnaeus University in Kalmar, Sweden. The research has been carried out in collaboration with the radioactive waste sector in Sweden and internationally, including through participation in several expert groups of the NEA.
From the conference blurb (shortened): radioactive waste is produced in all phases of the nuclear fuel cycle and from the use of radioactive materials in industrial, medical, defence and research applications. After creation and use, many countries have a policy of interim storage, followed by permanent disposal underground in engineered repositories located in suitable geological formations. Significant quantities of data and information are generated throughout this lifecycle with many countries now exploring the concept of a digital safety case. The operational period of nuclear generation facilities often covers several decades, while disposal facilities are designed to operate for even longer. This raises significant challenges as these timeframes span multiple generations of workers and are likely to see many changes in policy and technology. Moreover, even after disposal, there is now a consensus on the importance of adopting strategies to preserve awareness of waste and disposal facility for long periods of time. The NEA Working Party on Information, Data and Knowledge Management (WP-IDKM) [to which Anders Högberg and Cornelius Holtorf belong] aims to co-ordinate these activities in a more holistic way, considering cross-disciplinary approaches and cognizant of all timescales of the information cycle.
The conference addressed “Challenges Across All Timescales”, from imminent expert retirement to one million years and more in the future. This is about Heritage Futures for real!
I presented the following paper:
Heritage Futures: Archaeological Insights for the Long-term Management of Radioactive Waste
Managing radioactive waste is a challenge that extends across many generations, requiring long-term safety measures. Archaeologists, like myself, are familiar with time scales of thousands of years as we seek to understand the distant past. A key part of our work involves questioning assumptions rooted in the present and learning to imagine past worlds that were vastly different from today. This is very difficult, but only after doing so can we draw meaningful insights from the past to inform the present. The same principles should apply when communicating information, knowledge, and guidance about radioactive waste repositories to societies of distant futures. This calls for a strengthened capacity in futures literacy,’ a concept developed and promoted by UNESCO. Futures literacy consists of three core dimensions: 1. Becoming aware of the assumptions we hold about the future, 2. Learning to imagine multiple alternative futures, and 3. Reframing the original issue and developing new strategies to address it. In this paper, I explore this argument and discuss its implications for a long-term, safe and responsible management of radioactive waste. The paper is based on extensive research conducted by the UNESCO Chair on Heritage Futures at Linnaeus University in Kalmar, Sweden. The research has been carried out in collaboration with the radioactive waste sector in Sweden and internationally, including through participation in several expert groups of the NEA.
The overall theme was “Time as a safety factor: opportunities and challenges of timely nuclear waste disposal“. It quickly became clear that this focus was inspired by the perceived need to accelerate the decision-making process to identify the site location for Germany’s repository of high-level nuclear waste. But the topics discussed during the symposium were much wider and covered perspectives from many different disciplines bringing up a wide range of issues, not the least the issue of radioactive waste resulting from uranium mining that has not always been formally included into the discussions of nuclear waste. Claudio Pescatore led a workshop on this latter topic, based on his recent research.
One highlight was the keynote lecture by Andrew Stirling, University of Sussex and formally a Board Member of Greenpeace. It turned out he was originally an archaeologist! He also made a powerful argument suggesting that the objective of finding “the best possible” solution for safe nuclear waste disposal, which the German legislation requires, misses the question whether “the best possible” solution can ultimately be satisfactory.
In my talk (in front of cirka 50 participants), I adopted this question asking whether what many think is “the best possible” way to plan for uncertain future needs is ultimately satisfactory. My point was that taking a cultural perspective linked to the capability of futures literacy can get us further…
Nuclear waste disposal is not only about physical time, safety, technology and social and political acceptance but it is also about long-term thinking, embracing cultural change, and human values and identities that are shifting over time.
Holtorf, C.: Sustainability and long-term processes: a cultural perspective, Third interdisciplinary research symposium on the safety of nuclear disposal practices, Berlin, Germany, 17–19 Sep 2025, safeND2025-6, https://doi.org/10.5194/safend2025-6, 2025.
ABSTRACT
Culture is about how people make sense of the world, of each other, and of themselves. It is diverse in scale, across space, and over time. By implication, expertise on the world, its inhabitants, and ourselves is culturally relative. Indeed, culture is often about managing difference: different ideas, different people, different languages.
Applied to the need to sustain a body of knowledge and guidance for action over the long term, a cultural approach will (have to) embrace the need to adapt to cultural changes and developments. All this means that regarding nuclear waste, what we are tasked with today is transferring to future generations, who will be living in their own cultural contexts, knowledge and guidance for action that will make sense to them, not to us. Proposed messages that lack futures literacy merely perpetuate our own frameworks of meaning and eventually become irrelevant and unsustainable. There are thus good reasons why they say that nothing ages faster than the future, and nothing is more difficult to predict than the past. In this paper, I will discuss some implications of this theoretical argument for geological disposal of radioactive waste.
Claudio Pescatore explains why high-level waste still needs shields—and memory beyond a million years:
When it comes to high-level waste repositories, the old reassurance — “radioactivity falls back close to or below natural levels” — is misleading. Yes, if you total up all the radioactivity in a repository and compare it to the original ore, the sum may look modest after ten to a hundred thousand years, depending on waste type. But people (and animals) don’t meet sums. They meet things: individual containers, cores, and fragments that concentrate radioactivity. What matters—ethically and practically—is the radiation dose at the surface of each piece as time rolls on.
Total radioactivity vs original uranium ore in Swedish spent fuel. (Report SKB-TR-97-13)
A new paper looks squarely at that reality. Rather than only computing dose, a concept for radiation specialists, it asks a tangible question: how thick must a shield be to meet modern radiation protection limit not just now, but at one million years and beyond? Using concrete as the reference, the answer comes in units anyone can picture: roughly 50–90 cmat a million years, depending on the waste and the protection target.
At one million years (and ignoring any container):
Spent fuel (SF) requires about 67–93 cm of concrete for a representative multi-ton package
Vitrified high-level waste(VHLW) requires about 53–72 cm of concrete for a full-size cylinder.
Beyond one million years, uranium-238 — lasting billions of years — makes the shielding requirement essentially constant: without containers, concrete thicknesses range from 7–42 cm for vitrified-waste cylinders and 62–87 cm for spent fuel.
Smaller isn’t safer. Even drill cores (say, 40 cm tall by 10 cm wide) or fragments still need shielding on the same order, because near-surface dose depends on what’s inside, not the item’s size. At a million years, unshielded drill cores still translate into about48–67 cm of required concrete for vitrified waste and about46–72 cm for spent fuel.
Scale matters. Numbers per item are only half the story. Program scale multiplies these requirements: for example, Sweden plans roughly 6,000 spent‑fuel canisters. In France, there will be more than 50,000 vitrified-waste cylinders.
Concrete shielding thickness at one million years for spent fuel (full canister and drill core) and vitrified high-level waste (full cylinder and drill core). Results are shown for two protection targets: 0.02 mSv/h (brief, one-hour exposure) and 0.002 mSv/h (background-like)—ballpark in the absence of project-specific requirements
What this means in human terms
Heritage, not waste alone. If descendants encounter these materials—by curiosity, drilling, erosion, or chance—they won’t face a vanishing hazard but an enduring one, beyond legal timeframes and planning horizons. Our commitment to protect future people “to levels comparable to today” becomes concrete—literally—in centimeters of real shielding.
Justice and foresight. Thinking “per item” reframes responsibility. Are we designing containers—and contingencies—that keep each piece safe, including broken pieces? The ambition is that we should.
Design humility. Landscapes move; encounters may occur. The ethical stance is not to promise a perfect fortress forever, but to equip future people with buffers that still work: robust, intelligible, possibly maintainable shields—and the memory provisions (institutional handovers, markers, archives, time capsules) to keep that knowledge alive. Also, acknowledge that these wastes never become harmless.
So what now?
Build for fragments. Don’t just model intact packages; assume cores, partial breaches, and erosion-revealed segments—and assign them shielding, too.
Specify the long-lived drivers. Make a standard reporting of the deep-time isotopic loadings, because they determine both the danger and the shield.
Design the message with the material. If safety demands 50–90 cm at a million years, our markings and archives should be designed to last—and be rediscoverable—on comparable horizons. Or that should be the ambition.
Expand the lens. Apply similar analyses to other long-lived wastes that carry significant uranium-238 loadings.
Takeaway: this isn’t a new fear; it’s a clearer ethic. We owe the future not only sealed vaults and clever signs, but credible buffers—thicknesses you can measure with a ruler—matched to how matter behaves over time. The shield is not a metaphor; it’s a promise we can make, and keep.
Further reading
Claudio Pescatore, Beyond a million years: Robust radiation shielding for high-level waste Nukleonika, 70(3): 87-93.
What if the true monuments of the nuclear age are not vaults, vitrified blocks, or warning markers—but fields of invisible light?
Gamma radiation is insidious. It leaves no ruin, no ash, no wound you can see. You don’t need to touch it. You don’t need to breathe it in. You simply pass by—and it passes into you. No trace is left on the soil. But a trace is left in you. And when the next person passes, they too receive the signal. Yet the source remains—unchanged, unweakened.
Most poisons are spent as they harm. Gamma radiation is not. It accumulates elsewhere, silently, without diminishing its source. A kind of ambient inheritance.
In a recent study, I calculated the gamma radiation field unleashed by humanity’s Uranium-238 (U-238) legacy. The results show that this field is not temporary. It is already present, slow to mature, but geologically assured and radiologically significant, beyond safety thresholds.
Mill tailings scattered across continents emit gamma radiation through uranium’s progeny. This signal will slowly fade over the next half a million years—but it will reach a baseline, unsafe value and will continue indefinitely.
Meanwhile, depleted uranium stockpiles—which emit almost no gamma today—are quietly maturing. From a few thousand years onward, their gamma output will rise steadily, eventually overtaking significantly that of tailings, peaking in two million years, and continuing unabated into geological time.
Most U-238 residues lie close to the surface—mill tailings, depleted uranium (DU) stockpiles, weapons testing sites, contaminated soils from mining and from exploded DU munitions. Even when their radiation does not cause immediate harm, it defines a long-term environmental signal whose meaning we have barely begun to grasp.
This raises questions not only of science, but of ethics, inheritance, and imagination:
What does it mean to leave behind a hazard that grows in potency over time?
How do we warn future beings of a danger concealed in ordinary soil or dust?
Should gamma radiation be seen not only as threat, but also as a marker of human agency?
Nuclear waste lasts a long time. But U-238 isn’t just persistent—it performs. It changes. It regenerates. It returns. And surprisingly, we don’t call it waste. We call it an industrial by-product.
And now we are not just leaving behind a signal—we are leaving a body.
About 4.5 million tonnes of U-238, mostly in oxide form, now reside in uranium tailings, DU, and spent fuel. It is a real, physical legacy—not symbolic, not speculative. This body must be put away—not forgotten, but deliberately placed and traced. Shielded, marked, and remembered.
We can still act. We can treat uranium’s gamma legacy not as an afterthought, but as a defining part of our industrial inheritance. This won’t undo the past—but it may shape how future generations understand what we’ve left them.
We often speak of the nuclear age as bracketed—confined by Cold War dates or the operational lifespan of reactors. But its material consequences are just beginning. Care begins by acknowledging and tending to what endures.
Claudio Pescatore is a member of the UNESCO Chair on Heritage Futures at Linnaeus University
She introduces the interview with Cornelius like this:
“Cornelius is a Professor of Archaeology, originally from Germany but now based in Sweden. But in an unusual twist, his work doesn’t focus on the past, but instead, on the future. And more particularly for our purposes, on the legacy of nuclear waste and what we in the present can leave behind to empower generations far in the future to manage this legacy safely.
“I’m fascinated by his work as these questions of nuclear knowledge and deep time have been a preoccupation of mine ever since I first got interested in nuclear issues back in the mid 2000s – and of course, they remain a live and pressing issue now, not just in the UK where I am, but in places across the globe who’ve experienced the footprints of nuclear activity, be they military or civilian.
“I find his perspective on this as an archaeologist insightful and stimulating. And on top of that, he also has a vivid tale to tell about his own personal relationship to the atom, shaped by the particular time and place he grew up in, as well as impactful encounters later in life.”
— (Cornelius writes:) I found the questions really stimulating and a good opportunity to tell about some sides of my interest in ‘the nuclear’ which I haven’t previously written about anywhere.
Reconsidering the Heritage Future of Nuclear Waste Hazards: A Permanent Legacy
By C. Pescatore, Affiliated Researcher and member of the UNESCO Chair on Heritage Futures at Linnaeus University
The question of “How long and how dangerous is high-level nuclear waste?” is rarely answered in full. Often, people are told that the radiation threat will diminish over time, as many radioactive products decay. While this is true to an extent, it only tells part of the story. The reality is more complex and far-reaching. Spent nuclear fuel is composed of roughly 95% uranium-238 (U-238), an isotope that behaves differently than the remaining 5% components that are much more actively decaying. Although its radioactivity may initially seem insignificant compared to more immediate hazards, over time U-238 will reconstitute its decay chain, leading to a resurgence of radioactive danger.
The radioactivity of U-238 does not simply decrease to insignificance; instead, it eventually increases as it reestablishes its broken decay-family, producing a host of hazardous progeny isotopes. For spent fuel, this increase becomes dominant beyond the one-million-year mark – well beyond the timeframe when many safety analyses have already been concluded. While safety cases often focus on the decay of radioactivity, they overlook the radioactive ingrowth that arises from U-238. This shift challenges conventional thinking and demands a refocusing of our long-term strategies for managing nuclear waste.
The implication is profound: the danger from high-level nuclear waste does not merely fade away. It transforms into a persistent, long-term alpha-, beta- and gamma-radiation hazard that requires sustained vigilance and robust containment strategies far into the future. This enduring risk calls into question assumptions about the timeframe for which safety must be maintained, extending our responsibilities across an almost unimaginable span of time.
Preserving Memory and Heritage for the Far Future
This brings us to the pressing question of heritage, memory, and how we communicate the information about high-level nuclear waste across extended time spans. Ensuring that future societies remember the existence and significance of these waste repositories requires a robust effort to preserve records, knowledge, and memory (RK&M).
One promising approach is the use of millennial time capsules strategically placed within or near repositories. These capsules can carry messages, warnings, and cultural artifacts that bridge the gap between our time and a distant future. Some capsules could be constructed from the same materials as the waste containers and placed within the repository to offer a final, deeply embedded source of knowledge that future discoverers might encounter, potentially guiding their understanding and actions.
Near-surface capsules could further engage communities through rituals of memory preservation and periodic inspections, creating cultural continuity and reinforcing the message of caution. Historical examples like the Osaka Castle Dual Time Capsule illustrate how science and cultural heritage can blend to transmit knowledge across generations.
Photo: Osaka Time capsule monument, Wikipedia, 12 februari 2012 https://fr.m.wikipedia.org/wiki/Fichier:Osaka_Time_Capsule.jpg
However, even with the best physical and cultural tools at our disposal, the fundamental question remains: How do we effectively communicate the danger posed by these wastes across millennia? Symbols, language, stories, and rituals may change, but the risk endures. Preserving memory is not just a technical challenge; it is a societal one, requiring us to create a living “heritage future” of caution, awareness, and responsibility – one that future generations can draw upon to protect themselves from the enduring radiation hazard that lies beneath.
Cornelius Holtorf kommer att diskutera den Svenska kulturarvskanon den 27 nov 2025 i Göteborg! Anmälan senast 20 nov 25 här.
Varje år anordnar Kulturarvsakademin Forum kulturarv som fokuserar på aktuella teman kring kulturarv. I år är temat för evenemanget “kultur(arvs)kanon”.
Hur vill vi minnas det förflutna och vilka berättelser vill vi föra vidare?
Program 13:00 Inledning, Karl Magnusson, ordförande i Kulturarvsakademin 13:15 Lars Trägårdh, professor i historia och ordförande i den kommitté som regeringen tillsatt som ska ta fram en svensk kulturkanon. 13: 45 Cornelius Holtorf, UNESCO professor i Heritage Futures, Linnéuniversitetet 14:15 Fika och mingel 15:00 Karin Nilsson, verksamhetschef och tf överintendent ArkDes 15:30 Åsa Arping, professor i litteraturvetenskap, Institutionen för litteratur, idéhistoria och religion vid Göteborgs universitet. 16:00 Paneldiskussion 16:45 Publikens talan/Avslutning av moderator
Cornelius Holtorf and Anders Högberg co-organized and co-ran (with C. Kavazanjian, UNESCO, Paris, N. Christophilopoulos, UNESCO Chair on Futures Research, Greece, and M. Packer, OECD/NEA, Paris) the first Futures Literacy Laboratory in collaboration between UNESCO and OECD/NEA.
Picture: Rebecca Tadesse, Head of Radioactive Waste Management and Decommissioning Division at OECD Nuclear Energy Agency, welcomes participants
Dedicated to exploring “The Future of Human Responses to Deep Geological Repositories” a total 17 international participants were present at the Lab which was held at the Swedish Radiation Safety Authority (SSM) in Stockholm (25 September 2023).
The Lab established the usefulness of the skill of futures literacy in the context of awareness preservation concerning long-term repositories of nuclear waste. Futures literacy encompasses both an awareness of the large significance of present-day assumptions about the future and an understanding of multiple alternative futures lying ahead of the contemporary world.
This visual essay contains impressions and reflections about long-term communication concerning long-term storage of radioactive waste and was inspired by a visit to the nuclear facilities at Olkiluoto, Finland. The site is known from Michael Madsen’s 2010 documentary Into Eternity. The images refer in various ways to selected aspects of climate change, public acceptance, uncertainty, world heritage, and the art of forgetting.
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