Interesting video on the CANDU reactor
February 6th, 2008
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For those who do not know, the CANDU family of nuclear reactors is based on a design which was developed in Canada beginning in aboot 1960 and which has continued to be refined and updated, most recently to the Advanced CANDU Reactor. What’s unique aboot the reactor is that it was designed to operate using deuterium oxide (AKA: heavy water) as the moderator. Heavy water can be processed from normal water by established methods and offers a big advantage when used as a neutron moderator: It has a much lower tendency to absorb neutrons than standard “light water,” ay.
This allows reactor which can run on fuels not suitable for light water reactors, in particular, unenriched “natural” uranium. What this means to operators is that they do not need to rely on large complex enrichment facilities, which exist in only a few countries and are considered an especially potent proliferation hazard. The fuel can be manufactured from uranium using standard metallurgy fabrication methods. The reactor can also used low enrichment uranium (Aboot 1.5% or less), recycled weapons material, spent fuel from light water reactors and is even capable of operating in a thorium fuel cycle, ay. The spent fuel is also low in plutonium and generally less radioactive than other reactors, making handling easier. This makes it great for any countries which are looking to get into nuclear energy but lack the infrastructure of other nations. The CANDU is the perfect reactor to start with for a domestic nuclear program, ay.
Here’s a video which shows another innovative feature of this reactor. It can be fueled without shutting it down by a system that removes the plug from one of the fuel tubes in the reactor and inserts new fuel bundles, pushing the spent ones oot. It only takes aboot two hours to complete the automated process. For countries which may have only a number of generating stations, this is another advantage, as a shutdown would tend to have more of an impact, ay.
This entry was posted on Wednesday, February 6th, 2008 at 12:09 pm and is filed under Good Science, Humor, Nuclear. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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February 6th, 2008 at 12:40 pm
You can also breed weapons grade plutonium with nothing more than a CANDU reactor and unenriched uranium, he said with a wicked grin. That makes the CANDU reactor a perfect reactor to start a nuclear weapons program too.
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February 6th, 2008 at 12:59 pm
I’ve looked into the CANDU proliferation concerns. It produces very little plutonium and the plutonium it produces is pu-240 rich at that in it’s normal fuel cycle.
It could produce plutonium if it were modified such that uranium rods were cycled through at a high rate for breeding of weapons grade plutonium, but it seems that would be very ineffecient and require very frequent reprocessing and refabrication. It seems to be one of the reactors less suited for that in general.
It does produce tritium under normal operation though, but not all that much by comparison to conventional methods of breeding it from lithium-6. I suppose the candu could make lots of tritium with lithium rods inserted, but that’s not much use if you don’t already have a weapon.
And of course, either way, plutonium is more difficult for weaponization than HEU
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February 6th, 2008 at 1:53 pm
Candu reactors don’t produce much plutonium when operated as a power reactor but they can be used to breed plutonium with some modifications to the fuel cycle. They will put out about 50kg a year of plutonium which is usable for weapons (less than 15% pu-240) and less that of the high-grade weapons stuff. That is, if they are used for the dedicated purpose of making plutonium.
So there is a proliferation concern. But as you do mention, plutonium is not as easy to weaponize. So the nation would need reprocessing and fabrication and a weapon design and all that, which is a challenge, but still getting the plutonium is the hard part, so a candu could get you more than half way there if you so desired.
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February 6th, 2008 at 2:10 pm
For that mater any lightwater reactor can be use to breed Pu as well. That’s the type North Korea used. The CADNU is a proliferation concern is a Red Herring.
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February 6th, 2008 at 5:10 pm
It is generally acknowledged that the Plutonium for India’s first atomic bomb came from its Canadian CIRUS reactor. The Cirus relies heavily on CANDU technology, but the Heavy Water originally came from US sources. Pu239 for Israeli bombs comes from the heavy water moderated Dimona reactor that is very similar to CANDU technology. Other heavy water reactors, for example one in Iran, are suspected of producing weapons grade plutonium. A great deal depends on exactly what you do with the fuel, and how long you keep it in the reactor.
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February 6th, 2008 at 5:29 pm
I still don’t see the point. You can make plutonium with a heavy water reactor? Sure. The US used heavy water reactors to breed plutonium at the Savanah River site. You can also use graphite moderated reactors. You could use a light water reactor if you really wanted to.
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February 6th, 2008 at 5:35 pm
It’s probably the on-power fuel handling that makes people think they might be a better choice for Pu-239 production, but it’s not really a huge practical advantage.
Really the important truth is that power reactors have simply not been used to develop nuclear weapons.
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February 6th, 2008 at 5:40 pm
“The CIRUS relies heavily on CANDU technology”
No
Charles, how does an open pool reactor resemble a heavy water high pressure reactor?
Breeding weapons grade Pu with any reactor requires a supply of enriched uranium. Natural uranium makes a mix of Pu isotopes that really cannot be used for bombs (except in the imaginations of some antinuclear types.)
Consider the following: If all a country had was HWPR’s they would have no reason to have enrichment facilities. Because when all is said and done it isn’t the type of reactor that is being used, but the enrichment technology that is the key dual-use factor in proliferation risk.
At any rate this argument has become sterile, and in the end was a ploy to discredit CANDU’s on the international market. Furthermore, the future dose not belong to ether LWR or HWR reactors, but to molten salt designs which beats both of them hands down in any selected parameter. Arguing which one is better is equivalent to debating whether Stromberg carburetors are superior to SU carburetors when both are yesterday’s technology.
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February 6th, 2008 at 5:49 pm
Much as I like the molten salt system, it’s still on the horizon and none yet have been deployed. I don’t know how long it will be before the molten salt system would be avaliable as a turnkey reactor avaliable to those with limited nuclear resources but the CANDU has proven successful in that role and it’s avaliable right now.
It’s a good interm solution for the foreseeable future.
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February 6th, 2008 at 6:10 pm
Well as Charles himself pointed out on his blog Nuclear Green in todays post the issues with MSR’s are mostly political. Which is the same problem that all nuclear is laboring under.
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February 6th, 2008 at 6:26 pm
All the oot and aboot are a little over done.
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February 6th, 2008 at 8:14 pm
BTW the organic liquid that was selected as a coolant in CANDU-WR-1 was called OS-84, a mixture of terphenyls treated catalytically with hydrogen to produce 40 percent saturated hydrocarbons. The terphenyls are petrochemical derivatives that are readily available and are already in use as heat transfer media.
OS-84 resemblance to maple syrup is purely incidental.
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February 7th, 2008 at 12:17 am
All those moving parts! How is the refuelling machine maintained?
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February 7th, 2008 at 2:14 am
The machines are serviced in maintenance bays that are separated from the reactor room by isolation doors. The machines can be repaired with the reactor at full power.
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February 7th, 2008 at 9:41 am
Josh said:
There are but the machines are actually pretty reliable. The rotating magazine system is extremely reliable and the system has been refined for many years. It works very well. There’s a bit of a trade off for the automation but it simplifies the refueling in general because they don’t need to shut down the reactor and open the core or anything like that. The automated system actually ends up saving a lot of headaches in the long run.
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February 7th, 2008 at 7:50 pm
mmm… maple syrup neutron moderator…
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February 9th, 2008 at 7:18 pm
Oh, I get it! I was wondering what was with all the “ay” at the end of the sentences. Now I see that you were trying to sound ‘Canadian.’ Just for the record, it’s spelled, “eh,” and it’s always followed by a question mark. Like this, eh? You’re such a Hoser! Also, no one I know, anywhere in Canada, pronounces “out” as “oot,” or “about” as “aboot.” I have no idea where that started, but it ain’t Canadian.
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February 9th, 2008 at 10:04 pm
‘oot and aboot’ is the way it sounds to Americans Paul – and Québécois francophones like me
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October 20th, 2009 at 4:24 am
I can not see the video. How is the procedure?
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