Article summary
- Darlington Nuclear Generating Station Unit 1 (DNGS-1) produces both baseload electricity and Cobalt-60, a valuable medical and industrial radioisotope that has helped improve life expectancy and healthcare since the 1950s.
- DNGS-1 demonstrates remarkable reliability, maintaining a steady power output of 863 MW (with minimal variation) through the first four months of 2025, contributing significantly to Ontario’s energy security.
- The consistent availability of high-quality electricity in Canada has created such a high level of energy security that many take it for granted, leading to potentially risky policy decisions about power generation.
- Analysis of power generation data shows that while nuclear provides steady baseload power and gas can adjust to time-of-day demands, wind power is unreliable and doesn’t align with either baseload needs or time-of-use patterns.
- The increasing reliance on intermittent power sources like wind poses risks to grid stability, as demonstrated by the April 2025 Iberian Peninsula blackout, where an overabundance of solar power and lack of synchronous generation led to system failure.
The Rise of Co-60: a medical and industrial revolution
Last time we celebrated DNGS-1’s entry into the Cobalt Club—CANDU reactors that in addition to baseload electrical power supply also make Cobalt-60. Co-60 is a hugely important medical and industrial radioisotope, and in a way is emblematic of the post–World War II economic boom, the greatest era of abundance, health, and prosperity in human history.
Co-60 is a strong gamma ray emitter, rivalled only by Radium-226 and Cesium-137 in power and portability. Unlike Ra-226, it is not ruinously expensive, and unlike Cs-137 it does not require separation of fission products. Co-60 is made inside high-flux fission reactors, by bombarding stable Co-59 with neutrons. If the reactor’s purpose is for something other than making radioisotopes, as a CANDU is, then Co-60 is a relatively easy value-added product. Radium naturally occurs in pitchblende, a uranium-rich mineral ore. To get it you have to separate the Ra-226, which is a decay product of U-238, from the ore. It is much easier to just make Co-60 in a reactor.
Co-60 supplanted Radium as a cancer-fighting material, and entered wide use in cancer treatment in the 1950s. Its value in cancer therapy as well as in sterilization is one of the reasons life expectancy across the west increased, in Canada from 71 in 1960 to over 80 in 2023.
DNGS-1: Delivering steady power and medical isotopes
We mentioned DNGS-1’s Co-60 production is a function of its power production: from midnight New Year’s Eve to midnight April 30 DNGS-1 mean power output was 863 MW, with a standard deviation of 12. That’s rock-steady, through every minute of every hour of every one of the 121 days in that period.
This kind of performance in every electricity grid across the country is literally the basis of Canada’s well-being as a nation. The Ontario grid electrical demand minimum over that period was 11,758 MW (IESO data has the minimum at 4,598 but that is likely a reporting error). Barring local/regional disruptions from ice storms, every Ontarian with a grid connection had high-quality electric power that entire time, and DNGS-1 was an integral part of the reason why. When its batch of Co-60 is harvested in 2028, it will have been because of successive periods of rock-steady power output like Jan–Apr 2025.
Energy security—the most fundamental form of which is abundant, affordable, reliable electricity—is literally why Canadians even in the most humble circumstances enjoy a level of material wealth and prosperity that is today simply unattainable for most people on earth.
The paradox of energy security
Paradoxically, our high level of energy security, having electricity of such high quality and reliability, numbs many of us to the near-miraculous benefits we get from it. We are so energy-secure, actually electricity-secure, that we take electricity for granted. This is a form of moral hazard, a situation that arises when we are so well “insured” against an event that we feel emboldened to take risks that actually make the insured-against event likelier to occur, thereby unduly burdening the insurer and making insurance more expensive.
In this case, the insured-against event is no electrical power. And the risk we are taking is indulging fantasies in which sources of electrical power incapable of providing either baseload supply or the time-of-day (TOD) and day-of-week (DOW) dependent supply that builds up from baseload become the principal source of power.
Wind power: the reliability challenge
The most popular of these baseload- and TOD/DOW-incapable sources is wind power. The plot provided the last time and repeated here below shows the central-tendency stats of the output of DNGS-1, the entire Ontario wind fleet, and the entire gas fleet through roughly 2,700 hours beginning Jan 1 2025, by Ontario Energy Board (OEB) time-of-use price period. DNGS-1 stats through all TOU periods are roughly the same—min,mean,max are all within roughly 10 MW of each other. DNGS-1 is pure baseload, and considering this is 2,700 hours, purely reliable.
Gas shows great variance from min to max, but there’s a pattern: mean, median (p50), 75th quartile, and max generally increase through each the weekday TOU periods—exactly what you’d expect throttlable generation to do.
With wind, there’s no time-dependent pattern. The shapes of the clusters look the same, regardless of TOU period. This indicates it’s not throttlable, and indeed it isn’t. This should make the mins pretty alarming: they are all close to zero, and Winter Mid-peak and Winter On-peak mins are less than Winter Off-peak. Not only is wind not baseload, it’s also not a TOD-dependent supplier.
The next plot superimposes time-of-day (the OEB TOU price periods) onto day of week. These are not trivial dimensions. Demand as you can see from the plot is extremely TOD/DOW dependent, and supply must meet demand at all times, inside very narrow frequency tolerances.
Grid stability: the critical role of baseload power
Looking at wind in the context of demand instantly shows why wind is not baseload:
- Off-peak demand mins range from 11,758 (Sat) to 12,550 (Wed)—a spread of 592 MW. All wind mins are much less than that spread.
- There is a roughly 2,000 MW difference between all Demand Winter mins and Mid- and On-peak mins; there is not much difference between those of wind, and in fact the Mid- and On-peak mins are all less.
- All demand On-peak distributions have maxes greater than Off- and Mid-peak; all wind Winter On-peak maxes are less than Mid- and Off-peak.
Gas on the other hand shows a pattern much like Demand: Mid- and On-peak mins are mostly significantly greater than Off-peak mins. You can see that it is mostly gas that meets the TOD/DOW-dependent demand above the baseload.
Gas, in other words, meets the TOD/DOW-dependent demand; wind meets neither baseload nor TOD/DOW demand. Wind happens when it happens, regardless of TOD/DOW, and yet it is considered an important energy source. Clearly Ontario could easily do entirely without wind, yet we plan to add more of it.
The more inverter-based sources like wind are in a grid, the less inertia that grid has. Inertia is a critical component of all electricity grids; it is what ensures that frequency is maintained within strict tolerances whenever there’s a sudden loss of either demand or supply. The April 28 Iberian Peninsula blackout was largely due to an overabundance of solar power and a shortage of the synchronous generation on which the grid—and, paradoxically, inverter-based sources—depend.
“No energy is more expensive than no energy”
Homi Bhabha, the Indian nuclear scientist, coined the above expression to underline the central fact of modern life: that without energy life is bleak and we live in destitution. It is in fact the very definition of destitution. In the modern world, no energy is more versatile and indispensable than electricity. Abundant grid electricity requires synchronous sources, and climate change demands that those sources be not just synchronous but non-emitting. The first without the second is the status quo; the second without the first simply does not work.
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