nuclear waste Archives

Claudio Pescatore: The Deep-Time Reality of Nuclear Waste

2025-08-21

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 cm at 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 about 48–67 cm of required concrete for vitrified waste and about 46–72 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.

Gamma Fields: The Industrial Legacy We Cannot Afford to Forget

2025-04-28

By Claudio Pescatore

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*

The Atom & Cornelius

2025-01-27

Chairholder Cornelius Holtorf got interviewed by film-maker Vicki Lesley in her series entitled “The Atom & Us“. Vicki was the Director of The Atom: A Love Affair (2019).

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.

Nuclear Waste and Heritage Futures

2024-11-19

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.

Further reading

Research into time capsules was suggested to the Swedish Government in this 2016 report by Pescatore available online at: https://www.sou.gov.se/contentassets/9ffa0b1ff6954c58ba9e0dd8db733ffc/report_pescatore_10_nov_2016.pdf

A November-2024 technical paper by Pescatore deals with the long-term intrinsic radiation hazards of high-level nuclear wastes: http://www.nukleonika.pl/www/back/full/vol69_2024/v69n4p215f.pdf

Clau Pescatore, Affiliated Researcher and member of the UNESCO Chair on Heritage Futures at Linnaeus University

Claudio Pescatore is affiliated researcher and member of the UNESCO Chair on Heritage Futures at Linnaeus University.

Forthcoming events

2024-04-30

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

Inbjudan här

Futures Literacy Laboratory

2023-09-25

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.

Taking care of nuclear waste

2023-07-21

Now published and available in open access:

Cornelius Holtorf (2003) Taking care of nuclear waste. In: Toxic Heritage. Legacies, Futures, and Environmental Injustice. Edited By Elizabeth Kryder-Reid and Sarah May (Routledge).

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.

Alternative futures in the past

2023-02-08

Attila Dézsi published one of the most challenging and insightful articles coming out of German archaeology in recent years.

His archaeological excavation and study of the 1980 Gorleben Peace Camp, which is also the topic of his PhD research at the University of Hamburg, offers a critique of the current interest in Dark Heritage and the popular denouncement of the destructive character of contemporary capitalism. Dézsi calls instead for a much stronger appreciation of the “common heritage of hope and the power of collective action,” for “[i]t is not only destruction to which archaeologists should draw attention, but also to the past efforts of many peoples who opposed this destruction and violation.”

The Gorleben antinuclear protest village, also known as Republic of Free Wendland, was an iconic site for the German environmental movement during the 1980s. It was directed not only against the building of the nuclear waste depository nearby but also against the nuclear society and the entire capitalist system behind it. Dézsi’s research documents that the camp was partly about outspoken protest but primarily it was a collective “cry for an alternative future based on human dignity.”

The archaeological site of the village created by its inhabitants reveals an approach to the future that may be described as prefigurative: in the Republic of Free Wendland, a better future was lived already (see image below, taken from the paper, click for source and credit).

The archaeological excavation Dézsi directed showed in all lines of inquiry that “the creation of a community, socializing, and enjoyment was much more prevalent than specific manifestations of protest or resistance.”

Sites like the Republic of Free Wendland, Dézsi argues, “provide inspiration and give us the ability to grasp that alternative actions and solutions are neither impossible, nor require specialist equipment and materials – everything we need is there.”

His work also shows how the future can be addressed by an archaeology studying the past. It is not only the heritage we preserve that may provide tangible benefits of future generations, but also our very understanding of human lives in the past, including the recent past which some of us will remember. Dézsi’s research paper, which is available in open access at the link below, shows that alternative futures have always been possible.

Dézsi, Attila (2023). You May Destroy This Village, But You Cannot Destroy the Power Which Created It. International Journal of Historical Archaeology (pre-print online publication).

Remembering the Past in the Future

2022-11-23

Cornelius Holtorf attended the conference “Remembering the Past in the Future” arranged by the Expert Group on Awareness Preservation of the Nuclear Energy Agency at the OECD at the Tabloo Visitor Centre in Dessel, Belgium (22-24 November 2022).

He organised and chaired a session on “Conceptualising Remembrance Across Generations” which was attended by an audience of more than 60. His own paper was entitled “History or heritage? Understanding cultural processes over time”. Anders Högberg participated virtually in the session and presented on “Futures literacy – Why it matters to transmit information on high-level radioactive waste to future generations.” The session ended in a lively discussion on what exactly the message might be that the present needs to send to the future in relation to long-term memory of final repositories of nuclear waste.

Into Eternity

2022-04-08

Cornelius Holtorf and Leila Papoli-Yazdi attended the Sixth International Conference on Geological Repositories (ICGR-6) in Helsinki, Finland (4-8 April 2022). The conference was held in the Paasitorni, a former Worker’s Assembly Hall now a transnational serial nomination for UNESCO World Heritage.

Among the topics discussed at the conference were questions about building trust in society and managing uncertainty. One irony is that ignorance and indifference may lead to trust whereas knowledge and engagement may result from (and support) distrust.

The conference included a site visit to the Finnish low- and intermediate-level waste repository and visitor centre (ONKALO) at Olkiluoto. The site became well known through the 2010 documentary Into Eternity.

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