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

Canadian nuclear industry is very good.

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.

It can also be continually refuelled without shutting down.

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.

> 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.

> 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.

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.

"On August 20, 1942, a trace quantity of this element was isolated and measured for the first time. About 50 micrograms of plutonium-239 combined with uranium and fission products was produced and only about 1 microgram was isolated."

So small were the amounts of early produced plutonium, than new methods to study it had to be used.

https://www.scientificamerican.com/article/ultramicrochemist...

Of course we have now military plutonium production reactors.

Yes, they had to do it that way, because they had no better way at the time.

Today, if you wanted to make Pu with an accelerator you'd use energies nearly 2 orders of magnitude higher. At such high energy, the particles lose energy mostly in nuclear collisions, not to ionization.

https://podcasts.apple.com/ca/podcast/decouple/id1516526694?...

Found this podcast on the topic to be interesting

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.

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