Helena Rydén, Author at UNESCO

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.

Om framtidsskapande

2025-06-18

Artikel i tidskriften Byggnadskultur (som är svenska byggnadsvårdsföreningens tidskrift). In Swedish.

Anders Högberg, Professor of Archaeology UNESCO Chair on Heritage Futures

Rethinking Futures

2025-05-22

In May, Anders Högberg was invited as keynote speaker at the National Library of Sweden. The invitation came from their Department for Research and Collection Management, which hosted a joint staff day. Högberg presented his research on heritage processes as futures-making practices. In his presentation Anders emphasised that we need new knowledge in order to rethink futures in novel ways. The discussion that followed on the presentation, largely focused on how we can create change to achieve this, what opportunities it might bring, but also which challenges we need to address in order to succeed.

National Library of Sweden. Photo Maria Aho

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*

New article on urban transformation, heritage and social sustainability

2025-04-03

Bebyggelsehistorisk Tidskrift (Nordic Journal of Settlement History and Built Heritage): Urban transformation, heritage processes and social sustainable futures by Ulrika Söderström & Anders Högberg.

Short summary:

In this study, we use three case studies to discuss heritage processes as future-building practices. Through examples from urban regeneration processes in three Swedish cities, we discuss how these processes have contributed to social sustainability. The case studies are the Caroli neighbourhood in Malmö (transformed 1967-1973), the Valnötsträdet neighbourhood in Kalmar (transformed 2008-2018) and the ongoing transformation of Kiruna city. Our findings show that the cultural heritage processes activated in urban regeneration processes do not always promote socially sustainable future-making practices. We conclude that an engagement in different forms of future-making is crucial for heritage processes to contribute to long-term sustainable urban development. We suggest that this requires a way of thinking and acting that includes change and transformation. Our findings are conceptualised in a model that we hope can be used to understand heritage processes as future-making practices in urban transformation projects.

Bebyggelsehistorisk Tidskrift is a Nordic forum for research and debate on the history of the built environment. It is the Nordic region’s leading academic journal on the history of the built environment. The periodical presents the latest research on the history of the built environment, and also provides a forum for discussing the discipline in practice when buildings and heritage environments are being conserved.

https://bebyggelsehistoria.org/en/bebyggelsehistorisk-tidskrift-english/

Open access (Doctoral Thesis by Ulrika Söderström) https://lnu.diva-portal.org/smash/record.jsf?pid=diva2:1901953

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POSTSCRIPT 13 April 2025. Here is a graphical summary of the paper prepared by ChatGPT:

Conference by the Swedish National Heritage Board

2025-03-24

Anders Högberg held a keynote lecture at the conference “Kulturarvsforskning i Sverige 2025” – Cultural Heritage Research in Sweden 2025, organised by the Swedish National Heritage Board 20-21 March 2025 in Stockholm. Keynote paper: ‘Cultural heritage research 2025 – some thoughts on where we stand and questions for the future’.

Ulrika Söderström also presented her dissertation at the conference: “Cultural heritage as a resource in socially sustainable urban development: A designed living environment for the future”.

More about the dissertation here

Kulturarvsforskning i Sverige 2025 -Riksantikvarieämbetet (The Conference Programme in Swedish)

*Ulrika Söderström,* *Doctor of Archaeology UNESCO Chair on Heritage Futures*

Conference on restoration and conservation in Gothenburg

2025-03-03

On the 25th of February 2025 Gustav Wollentz presented and participated in a panel discussion at the conference “The Houses, the History, and the Future” (Husen, historien och framtiden) that was organized in Gothenburg by Gothenburg University and multiple other partners in the region. There were around 140 heritage professionals attending the conference, mostly working with, and researching on, the conservation and restoration of buildings.

Gustav contributed to the final part of the conference, where future challenges and opportunities were in focus. Gustav presented the work on Strategic Foresight he has been carrying out together with ICCROM, including the Horizon Scanning looking 15 years ahead, and the work for the pan-European ARCHE project, with the goal to produce a new Strategic Research and Innovation Agenda for Heritage in Europe.

In the presentation, Gustav focused on four specific opportunities for action related to future change:

Heritage to shape more desirable, sustainable and just futures,
Heritage to increase wellbeing,
Heritage to understand and reveal the humanity in individuals,
Heritage to cope with loss and change.

The presentation and panel discussion were very well received and there was a large interest to further explore Strategic Foresight.

For those interested in the ICCROM Horizon Scanning, it is available here: https://www.iccrom.org/publication/anticipating-futures-heritage

For those interested in the Foresight-work within the ARCHE project, the report is available here: https://www.heritageresearch-hub.eu/app/uploads/2024/04/ARCHE_D2.1_Report-on-Future-Trends-on-Cultural-Heritage-RI-3.pdf

*Gustav Wollentz, UNESCO Chair on Heritage Futures*

Future Day at Linnaeus University

2024-12-12

On December 3, 2024, the university management invited to a theme day in Växjö about Linnaeus University and the future. A recording of the event is available here https://play.lnu.se/media/t/0_tb0d3lc4

Cornelius Holtorf participated live in a panel discussion with Marie Hedberg, Pro Dean at the Faculty of Social Sciences and Jörgen Forss, Vice Dean at the Faculty of Technology. Marcelo Milrad from the Faculty of Technology joined via link. The panel was chaired by Kerstin Årmann from the Office of External Relations.

Future Day at Linnaeus University 3 December 2024 — Cornelius Holtorf in a panel discussion at the Future Day, Linnaeus University.

Workshop in Gothenburg

Anders Högberg and Gustav Wollentz from the UNESCO Chair on Heritage Futures were on the 22 November 2024 invited to conduct a workshop on future awareness for the management group at the Department for Nature and Cultural Heritage in the Region Västra Götaland. During the day we met 12 persons, and the workshop lasted for four hours. It took place at the Museum of Natural History in Gothenburg.

The main question we explored was: What will the museums’ societal role/mission look like in 2050? This question was approached through a series of sub-questions, for example with the aim of identifying societal challenges and how these can be proactively met through actions today.

The workshop was based on dialogue and the exchange of different perspectives and experiences. By such an approach, participants took on a more open approach to different types of futures in relation to the museums’ societal role and mission. In the exchange after the workshop, it was highlighted as particularly important to be able to approach the future as open where several different alternatives are conceivable. Participants expressed it as liberating not to see the future solely as an extension of the present, and to be able to seriously engage in considering alternatives for the future.

*Museum of Natural History in Gothenburg*. *Photo Gustav Wollentz*

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.

UNESCO