A Look into the Legacy of U of T’s Nuclear Reactor
The term “nuclear reactor” typically conjures images of large-scale energy production or, perhaps, the potential for disaster. Yet, when mentioned in the same breath as the University of Toronto (U of T), it takes on a different connotation—one of academic pursuit and scientific inquiry. While one might think that an active nuclear reactor within U of T would be a more well-known piece of history, it seems that SLOWPOKE’s legacy has slipped quietly into the periphery of institutional memory. With help from fonds within UTARMS and instruments recovered from the lab where the reactor was built, now stored in UTSIC, we can try to unearth more about this long-forgotten device. What we see is that SLOWPOKE’s legacy extends beyond its operational lifespan– It becomes part of the technofossil record, a marker of the Anthropocene where human-made objects are embedded into the stratigraphy of the planet.
The University of Toronto’s SLOWPOKE reactor, a compact nuclear research reactor, was a marvel of engineering and safety design. Initially installed in 1971 as SLOWPOKE-1 and upgraded to SLOWPOKE-2 in 1976, it featured a core made from highly enriched uranium in the form of uranium-aluminium alloy, which was later transitioned to low-enriched uranium dioxide (UO2) fuel to meet newer safety standards. (RMC, 2019).
The core’s assembly was encased in a zirconium alloy cage, which housed the fuel pins. These pins were packed with pellets of sintered UO2, known for its stability and high melting point, making it an ideal reactor fuel. Surrounding the core was a beryllium reflector, a material chosen for its excellent neutron-reflecting properties, which enhanced the reactor’s efficiency and safety. The entire assembly sat within a pool of light water, which acted as a moderator to slow down the neutrons, as well as a coolant to remove the heat generated by the nuclear reactions. This design allowed for passive cooling through natural convection, eliminating the need for complex and potentially failure-prone active cooling systems. (Hilborn et al., p. 2-8, 1972).
Yet, perhaps the most intriguing vestiges of the reactors are not the reactors themselves but the instruments and equipment that were integral to their operation.
These scientific artifacts, now housed in the University of Toronto Scientific Instrumentation Collection (UTSIC), serve as a material bridge to U of T’s nuclear past. They are not merely remnants; they are the physical narrative of an era when the university ventured into the atomic age, embodying the spirit of innovation and the pursuit of knowledge that defines U of T to this day. Through UTSIC, these instruments and pieces of equipment continue to tell the story of the SLOWPOKE reactors—a story that, while perhaps not widely known, is indelibly part of the university’s rich scientific heritage.
My initial curiosity about SLOWPOKE happened when I saw this Geiger counter. A Geiger counter, known for its distinctive crackling sound when detecting radiation, was a necessary device for any nuclear facility. The counter operates by detecting the ionization produced by radiation in a gas-filled tube. When radiation enters the tube, it ionizes the gas, leading to a discharge that is registered as a count. (Korf, 2013).
Geiger counters carry a lot of historical weight, as their presence implies the existence of nearby nuclear endeavours. A safety device, yes, but one that carries dangerous implications of invisible radioactive threats. Their very necessity speaks to the potent forces at play within such facilities. So, how did the collection acquire this one? Was it from one of the nuclear power plants nearby in Ontario? You can imagine my surprise when I found out that it, in fact, was from a nuclear reactor that once existed here at U of T.
This particular Geiger counter, Model 107C, included a metal frame encased in a brown leather box. Based on the descriptions from the collection, the device seems to be in relatively fair condition. (UTSIC, Jowlabar). It now resides permanently in the UTSIC collection as a reminder of our nuclear past.
In the study of the Toronto meteorite, the SLOWPOKE reactor played a crucial role by employing Instrumental Neutron Activation Analysis to ascertain the meteorite’s elemental composition. A diminutive fragment of the meteorite, with a mass of merely 0.07 grams, was subjected to this analysis. The findings from this initial investigation closely mirrored those obtained from subsequent examinations using larger samples, underscoring the precision of the SLOWPOKE reactor’s capabilities. (Kissin, Wilson, 2006).
When considering the meteorite sample as a technofossil in relation to the SLOWPOKE reactor, we can think of it as an object that has been altered by human technology and has the potential to serve as a geological marker of our current era. The SLOWPOKE reactor, used for neutron activation analysis, leaves a distinct signature on the meteorite, which could be detected by future scientists or archaeologists. This signature would indicate not only the presence of human technological intervention but also the level of sophistication and scientific understanding of our time. The instruments surrounding the SLOWPOKE reactor contribute to this signature, making the meteorite sample a part of our technological legacy—a technofossil that encapsulates a moment in our scientific advancement.