UNESCO

Chair on Heritage Futures

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?

  1. Build for fragments. Don’t just model intact packages; assume cores, partial breaches, and erosion-revealed segments—and assign them shielding, too.
  2. Specify the long-lived drivers. Make a standard reporting of the deep-time isotopic loadings, because they determine both the danger and the shield.
  3. 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.
  4. 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.

https://sciendo.com/article/10.2478/nuka-2025-0009 (open access)

Claudio Pescatore
Claudio Pescatore is a member of the UNESCO Chair on Heritage Futures at Linnaeus University

Archaeology of Garbage

2025-08-01

A new interview published in Brazil featuring the Chair’s affiliated researcher Dr Leila Papoli-Yazdi tells the significance of the archaeology of garbage, not the least for the future:

By connecting her research to the idea that archaeology can “build futures”, Leila reveals the potential of garbology as an interdisciplinary and transformative practice that illuminates not only the past but also the challenges of the present and the possibilities for a more just and sustainable future.

Full reference:

Papoli-Yazdi, Leila, Tiago Silva Alves Muniz, Camilla Agostini (2025) Archaeology of garbage: from disaster archaeology to social entrepreneurship. Vestígios – Revista Latino-Americana De Arqueologia Histórica, 19(2), 317-326. https://doi.org/10.31239/j677sr71

This interview explores Professor Leila’s pioneering work in the archaeology of garbage, tracing her journey from disaster archaeology in Iran to the establishment of Europe’s first start-up focused on garbology. Initially working in Tehran, Leila faced challenges linked to Iran’s political climate and the adaptation of traditional garbological methods to urban environments. Upon moving to Scandinavia, she encountered new professional and cultural dynamics, eventually co-founding Garbonomix – a company dedicated to analyzing consumption habits to support economic resilience. She discusses the interdisciplinary potential of garbology to improve both individual and community well-being, linking academic insights with practical applications. Furthermore, Leila reflects on the stigmatization of contemporary material studies in archaeology, noting the field’s often nationalistic orientation that overlooks recent histories. Her work advocates for a more inclusive, human-centered archaeology that addresses modern issues like poverty and environmental sustainability. Through her engagement with both academic and consulting roles, Leila demonstrates how archaeology can extend beyond traditional frameworks, encouraging practitioners to collaborate with marginalized communities and contribute to social resilience.