Recently, a team of British scientists used the renowned London Underground topological diagram to streamline the visualization and comparison of densely packed data related to the various ways nuclear fuel can be recycled.
A revolution in how the London Underground is represented
In 1931, the industrial designer Harry Beck devised the London Underground’s topological diagram. It stands as one of the most influential pieces of graphic art and industrial design of the 20th century, having completely transformed how public transport networks are depicted around the world. Before Beck, the subway map superimposed the metro lines onto a city’s ordinary map. Yet this posed two major problems.
Indeed, because downtown stations are clustered very closely together, they tended to become illegible on a crowded map, while peripheral stations, farther apart, stretched the map toward large blank areas. With an aesthetic inspired by electrical circuits that disregarded real geographic distance, Beck could focus on the essentials: the order of stations, the transfers, and the clarity of each line.
Six nuclear fuel recycling scenarios
A team of researchers from the Dalton Nuclear Institute at the University of Manchester (United Kingdom) has recently revived the idea behind the 1931 map. As evidenced by their publication in Sustainability on August 31, 2026, this concerns a cartographic study aimed at simplifying several nuclear fuel cycle scenarios on a single diagram (see below).
The first scenario is the direct line “Open Cycle,” the simplest pathway. It involves extracting natural uranium, then enriching it, for a single-use in a reactor. It is followed by cooling in a pool and then deep geological storage — the fuel is thus treated as ultimate waste. This solution implies a huge waste of resources. Indeed, spent fuel still contains about 96% of energetic materials, including uranium and plutonium that could be reused.
The remaining five scenarios pertain to other approaches, namely single-pass recycling in Light Water Reactors (LWRs), the multi-recycling of plutonium, the fully closed fuel cycle (Fast Neutron Reactors – FNRs), the transmutation of minor actinides, and finally thorium or molten-salt cycles.
Why this kind of representation?
For the researchers, placing these six lines side by side lets governments visualize geopolitical and financial trade-offs. By shedding the constraints of physical proportionality in order to focus on interconnections, the scientists have provided a clear reading framework. This framework thus seems ideal to help policymakers assess the sustainability and future of nuclear energy.
“The results of this critical analysis show that recycling has positive effects on the use of natural resources, the environmental footprint, the management of high-activity radioactive waste, and energy security. However, the adoption of closed cycles faces challenges related to safety, security, proliferation, and economic aspects; but our preliminary analysis indicates either that solutions exist, or that these elements are not decisive factors in choosing the fuel cycle.”, the study notes.
According to the study’s authors, recycling more of the fuel should help reduce reliance on new uranium resources while also improving the sustainability of nuclear energy. Yet, given that nuclear power is already a durable and low-carbon energy source, the prospect of closing the fuel cycle is certainly a positive development.
