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> Also, it looks like Darlington Nuclear Generating Station originally planned to build 4x 1200MV Advanced CANDU reactors. These were cancelled and replaced with a plan to build 4x BWRX-300 reactors.

https://www.theenergymix.com/rip-smrs-is-it-the-end-of-the-l...

> Despite the public spending largesse, and after heroic promotional efforts by Ontario Power Generation and the federal and Ontario governments, there are no reports of private investment in the Darlington SMR—not even after Prime Minister Mark Carney’s high-profile Canada Investment Summit last week—and none have been ordered in Canada or elsewhere.

> Yikes. Estimated cost of 15.2B USD for 1200MW of capacity. I am taking bets: How much will this project overrun its estimates? My guess: 25-50%. I don't get it. Why are these better than just building one big reactor with 1000MW+ of capacity?

It's my understanding that they want to be able to mass produce these kinds of smaller reactors, to drive the cost down over time.

So, the 1st one isn't competitive. But, hopefully, the 100th or 1,000th will be.

Please review this comment after 5, 10, 15, 20 years. I doubt that Planet Earth will have 1,000 SMRs built by this time, nor will the 1,000th be wildly cheaper than the 1st.

What comments were being made about French designs at the time?

Also, at 300MW it isn't exactly small - that's the same order of magnitude as regular reactors.

Anyway 30% is my number, but the more pressing issue is time. How long until they actually fire it up?

https://news.ontario.ca/en/release/1006993/ontario-delivers-...

Canadian nuclear industry is very good.

I agree. For their entire history of building and operating commercial reactors, they have only built CANDU variants. In this regard, yes, they are spectacular. However, this is a brand new non-CANDU design.

When I read about how CANDU (heavy water moderated reactor) works I started wondering why we ever build any other kind of large scale reactor.

Runs on natural uranium. Can burn waste too, and plutonium, and even thorium (mixed in, not pure, but still). It’s like a flex fuel reactor. It’s very safe and reliable.

Why do we bother with any other design? Except maybe fast breeders or fission fusion hybrids but those are whole new directions.

One design limitation that I have heard about it is that is can be used as source for weapons grade Plutonium for nuclear weapons development. Both the CIRUS and CANDU reactors supplied to India and Pakistan, respectively, in the 1960s and 1970s, were used in the nuclear weapons program of both countries ( https://web.archive.org/web/20050224145816/http://archives.c... ). Canada specifically requested Pakistan to not use the Plutonium it derives from the CANDU research reactor, but it declined after yet another war with India where it was trounced badly. India even went on to customise the CANDU reactor clones it developed to even produce Tritium, as a by-product, from it ( https://ccnr.org/india_tritium.html ) which apparently is important to develop hydrogen bombs and increase the yield of nuclear weapons in general.

> One design limitation that I have heard about it is that is can be used as source for weapons grade Plutonium for nuclear weapons development.

Which nuclear reactor technology, whether it uses natural or enriched uranium, cannot potentially be used for weapons development? AIUI, anything that starts with uranium leads to or through plutonium.

> Canada specifically requested Pakistan to not use the Plutonium it derives from the CANDU research reactor, but it declined

This is the most Canada and Pakistan thing in history.

Isn't that true of a lot of reactor designs though? You can produce plutonium in a BWR, PWR, etc.

You can also synthesize plutonium in particle accelerators without a nuclear reactor, but only in very small quantities and very slowly.

" Plutonium (specifically, plutonium-238) was first produced, isolated, and then chemically identified between December 1940 and February 1941 by Glenn T. Seaborg, Edwin McMillan, Emilio Segrè, Joseph W. Kennedy, and Arthur Wahl by deuteron bombardment of uranium in the 60-inch (150 cm) cyclotron at the Berkeley Radiation Laboratory at the University of California, Berkeley. "

https://en.wikipedia.org/wiki/Plutonium#Discovery

There are interesting designs for Subcritical reactors. A nuclear fission reactor operating without achieving criticality, but with additional neutrons from a particle accelerator.

https://en.wikipedia.org/wiki/Subcritical_reactor

Cyclotrons are poorly suited to making plutonium. The neutrons per energy increases dramatically with higher energy particles; a 1 GeV beam of protons on a thick uranium target makes 60 neutrons per proton. The nuclear reaction here is called "spallation", where the protons shatter nuclei into many fragments, including free neutrons.

It can also be continually refuelled without shutting down.