Nuclear Physicist Explains - What are CANDU Reactors?

Nuclear Physicist EXPLAINS - What are CANDU Reactors?

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In this video, I explain CANDU Reactors from the perspective of a nuclear physicist. I go through CANDU Reactors and what they are and compare them to current Light water reactors.

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[YourFriendlyNuclearPhysicist]

I have a special connection with CANDU reactors as this was the reactor type that got me fascinated about nuclear energy and almost a decade later, here I am! ☢️👩🏽‍🔬
I hope you’ve enjoyed this video! Let me know what your favourite reactor type is!⚛️

[calvinhobbes]

I worked my US navy career in the nuke program .... learned what I know about CANDU on my own as a hobby. I think it's another example of Canada doin' it right. The Calandria system is amazingly safe and the control systems are simple and effective. I've been a fan of Canada ever since the Avro Arrow was developed. I'm probably not gonna be changing my mind any time soon.

[philplasma]

As a Canadian I knew about Candu reactors only in the sense that I knew they existed. Thank you for explaining in such detail how they work and how they compare to LWRs.

[kyle]

It is worthwhile noting that a CANDU is a Calandria vessel (not pressure vessel), where there are multiple horizontal fuel channels consisting of a pressure tube to contain the fuel 'bundles' and Calandria tubes which separate the fuel channels from the moderator. This is how it is able to be re-fuelled online because you only have to open a single fuel channel to do so. Back when Canada designed the CANDU there was no capability for Canada to construct large pressure vessels like what other countries were using such as the PWR. I also want to correct you in that South Korea does have an operating CANDU at the Wolseong Nuclear Power plant.

[robertkomar]

I got my engineering degree in Canada specializing in nuclear power many decades ago, and learned a fair bit about CANDU reactors back then. I have to say that you did a great job explaining the technology, both pros and cons. No fake news here :).

[franciscotoro]

It is also worth noting that this technology makes Canada the largest producer of medical istopes in the world. The fact that one of the facilities had to shut down for maintenance actually created a global shortage of this material.

[michaelmills]

I grew up in a town right next to a CANDU site with 8 reactors and had family and friends who worked there. To me, the most interesting thing about CANDUs is that their design enables passive failure modes. Natural Uranium doesn't have enough neutrons to sustain a reaction by itself, hence why the heavy water is required. This also means that if the supply of heavy water is cutoff, or if light water is introduced, the reaction will stop. This allows the design to use safety features that don't require active intervention or power, preventing situations like Fukushima. Based on the comments I had from people who work there, the workers have to spend much more time just keeping the reaction going instead of working to keep the reactor from going boom.

[quantummotion]

Hi Elina! Great presentation of the Candu reactor! I had the pleasure to work for a CANDU operator (then Ontario Hydro) and the designer ( Atomic Energy of Canada). One slight correction. South Korea does operate Candu...these are the Wolsung 1 and 2 NPP as well as they bought designs of our MapleX research reactor. Regardless, this was a great summary of the technology. One interesting bit of history - when the Soviet Union fell, and the former Soviet republics were reducing their nuclear weapons number, Canada's CANDU reactors were used to consume the fuel from the nuclear warheads, as you mention, the use of heavy water allows for the use of multiple fuel types.

[ccibinel]

One key point of CANDU which was not addressed is tritium production. Tritium is essential for fusion research and while it is theoretically possible fusion can become self sustaining with tritium blankets it is another very difficult engineering problem (because fusion didn't have enough of those already). The CANDU reactor is how the world will get tritium for initial research and is essential to potentially cracking viable fusion.

[alexandrufrateanu]

Hello, Elina and greetings from Romania 🙂I have driven past Cernavoda NPP a lot of times but I did not know we were the only CANDU reactor operators in Europe.😃

Interesting that Ceausescu’s communist regime chose Canadian designs and not soviet ones.
But I think its ’ because Ceausescu was paranoid about not being dependent on foreign countries, and since Romania has its own heavy water production facility and natural uranium reserves, it would have made sense.

[canaanval]

Another thing to mention is the the production of Cobalt-60, CANDU reactors have produced to majority ever used! Also the Bruce site is now producing other rare radioactive elements!

I grew up in Inverhuron, right next to Bruce...there is a very informative visitors centre there for anyone really intersted in CANDU reactors😃

[zwebsterz]

Fantastic presentation of the CANDU reactor which I had no idea that existed. You northerners have consistently invented/created ingenious products. Chalk this one up as another winner as well! Thanks for the lesson.

[mirskym]

In terms of safety, you didn't mention that every CANDU station has a building attached to the reactor building that is under vacuum and has water sprayers. In case of a LOCA (loss of coolant accident) it sucks up and condenses any radioactive steam. This is one of the safety barriers to releasing radioactive material to the environment.

[BrunodeLima]

Refueling a nuclear reactor while in operation, now I feel silly as an IT professional for calling "hot swap" what we do to server's components

[richarde]

Thank you for the videos, I used to be very ignorant and anti nuclear but your videos have changed my mind.

[Fuad_]

7:28 Didn't India produce its weapons grade plutonium from heavy water reactors?Doesn't online refueling make it a bit easier to remove fuel after low burnup?

7:41 Correction:D20 has lower thermal neutron absorption cross section compared to H20

[David_C_]

Thanks so much for this video, as a Canadian I knew of the CANDU and roughly how it works but I didn't knew all the details as to why we had them or why they weren't popular elsewhere.

[eh]

I grew (Winnipeg - had a tour of the CANDU simulator in Pinawa, MB) up believing that the 2 biggest safety features (esp in light of 3 Mile & Chernobyl) is the heavy water moderator lends to non-weaponizable materials (as you noted) but also because if a runaway condition should happen, dumping the coolant/moderator/water actually stops the reaction - it fails safe.

[test]

Thanks Elina for the clear cost/benefit explanation. As a student in UT, we were told there was a small Candu reactor under the physics building. I always wonder why it wasn't more popular...now I know. You made my day!

[frede]

Great video but you got some parts wrong. Heavy water is indeed a better moderator, but the reason is that it absorbs LESS neutrons, leaving MORE neutrons to be absorbed by the uranium which results in a better neutron economy.
This, and online refueling, is also the reason that MORE plutonium is being produced in a CANDU which is not a problem but creates higher demands for non-proliferation measures.