Talk:CANDU reactor

requesting more references

I placed two {{cn}} after two statements I thought needed references -- namely:

"At the time of its design, Canada lacked the heavy industry to cast and machine the large, heavy steel pressure vessel used in most light water reactors..." "Canada also lacked access to uranium enrichment facilities, which were then extremely expensive to construct and operate..."

WRT the second assertion -- surely this was true for every nation that developed a nuclear industry?

WRT the first assertion -- this may very well be correct. But it is not what I remember when I first read about the CANDU design.

Cheers! Geo Swan (talk) 16:19, 20 March 2010 (UTC)

I don't know about the 1st, but as to the 2nd, no, I think the other nations working on nuclear power had already developed enrichment capability as part of their nuclear weapons programs.

—WWoods (talk) 04:34, 24 March 2010 (UTC)

Both assertions are true - and in fact are still true for most of the world. Whitlock (talk) 12:33, 25 March 2010 (UTC)

Pressurized or not?

I dont know if this is really an error, but I was confused when I got to this part..

"The heavy water is unpressurized, and a cooling system is required to keep it from boiling.

At the time of its design, Canada lacked the heavy industry to cast and machine the large, heavy steel pressure vessel used in most light water reactors.[citation needed] Instead, the pressure is contained in much smaller tubes, "

It seems rather contradictory. 24.141.10.136 (talk) 06:31, 17 March 2011 (UTC)

The moderator is heavy water in a large tank (calandria) at atmospheric pressure which must be kept cool by the moderator heat exchangers.

The primary fuel coolant (also heavy water) is pressurised but flows through tubes containing the fuel which run horizontally through the calandria. These tubes are a lot easier to fabricate than the thick walled pressure vessels used in Pressurised water Reactors which contain both the fuel and light water which acts as a moderator and coolant. Dabbler (talk) 14:35, 17 March 2011 (UTC)

I'm not 100% sure of your source of confusion, but maybe I can help. I'm not a nuclear engineer, but based on reading the article and looking at the colored "schematic" of the reactor, I can say this:

• heavy water is used for two purposes in the CANDU reactor. It is used as the moderator (pink on the diagram) and it is used in the primary heat carrying loop (yellow and orange on the diagram, although the orange looks to me more like a darker yellow), carrying heat from the reactor to the steam generator.

• the heavy water used to carry heat to the steam generator is pressurized, the heavy water uses as the moderator is not pressurized. (I don't know if the terminology "atmospheric pressure" adds to the confusion--to say something is at atmospheric pressure essentially means it is not pressurized--it is at the same pressure as the rest of the atmosphere around it--you don't need a special high strength tank (pressurized vessel) to contain it)

• so, the pink is at atmospheric pressure, and the tank holding it (the calandria) does not have to be built to deal with pressure higher than atmospheric--it is, in the common parlance, not a pressurized vessel

• the yellow and orange is pressurized, but note (if you can) that the orange and yellow is contained in pipes built in and through the calandria--those pipes must (and are built to) contain the pressurized moderated water

Hope that helps! Rhkramer (talk) 12:40, 17 June 2011 (UTC)

Picture of fuel bundle.

I believe that the picture of the fuel bundle with text that states '"Two CANDU fuel bundles: Each about 50 cm in length and 10 cm in diameter, and generating about 1 GWh of electricity during its time in the reactor. Photo courtesy of Atomic Energy of Canada Limited.' has a problem.

I think it should say 1 GW or 1 GWe.

1 GWh is worth about $ 80.00 ( at $ .08/KWh retail ).

Could someone who knows more check and make the change if I am correct please.

Thank you,

Rob Walker. RS Walker (talk) 17:30, 31 March 2011 (UTC)

1 GWh(e) is correct:

nominal CANDU burnup = 7500 MWd/Te

1 CANDU bundle = 20 kg U (roughly)

therefore, 1 CANDU bundle's energy output = 7500 * 20/1000 = 150 MWd = 3.6 GWh ~ 1 GWh(e)

Also, at $ 0.08/kWh 1 GWh(e) would be $80,000, not $80

Whitlock (talk) 05:59, 1 April 2011 (UTC)

Thank you for clearing that up. It makes sense now.RS Walker (talk) 19:31, 1 April 2011 (UTC) — Preceding unsigned comment added by RS Walker (talk • contribs) 19:29, 1 April 2011 (UTC)

"Relieved"? Should be some other word: "believed", "discovered"

In this sentence: "The deal for the reactor had not been opened to competition, and it was later relieved that a $20 million payment had been made to an "agent" to sell the system. Construction started in 1977 and commercial operation began in April 1983."

"relieved" is not the appropriate word. Even if there is a meaning of relieved that applies here, I have not found it, so it must be a rather obscure meaning. Better would be a word like "believed" or "discovered". As I don't know which is the case, I'm thinking of waiting until someone else comes forward who knows the facts.

Quite possibly, next time I think of it, I'll come back and, if no one has resolved the problem, I'll choose a new word, possibly at random lacking knowledge. ;-) Or maybe I'll try to indicate ambiguity today, with something like "[ believed | discovered (uncertain of the facts) ]"

Hmm, maybe that is better, unless it prompts someone to delete the sentence. Rhkramer (talk) 12:19, 17 June 2011 (UTC)

I think it should have been "revealed" and I have altered it to suit and put the comment into hiding! Dabbler (talk) 13:47, 17 June 2011 (UTC)

To no end, as it turns out. Our local CANDU apologist has removed the entire statement as being "off topic". I believe a separate section on this might be in order. Maury Markowitz (talk) 11:14, 20 June 2011 (UTC)

POV Section Tag

I have tagged this section because it uses a mixture of cost bases and it is not clear which cost estimates are used to calculate the cost overruns, early initial ones or final detailed once once the project scope was finalised? It quotes costs/kWhj without stating the base year and compares with other values and draws conclusions without allowing for inflation etc. It also compares the performance of a couple of restarted elderly units with the anticipated performance of proposed refurbished of much younger ones despite the vastly different scope of work involved. I also suggest that the Clean Air Alliance as an advocacy group is an inherently biassed source. Dabbler (talk) 17:49, 27 June 2011 (UTC)

Please tag the pecific sentences you believe are POV, with notes here on each one as to why you believe them to be POV. Many of the generalized complaints you note here are fully referenced in the article, so I want to make sure there's an actual problem to fix.

The CAA's numbers are fully referenced and are all taken from OPG, OPA, and the COP. One might suggest these sources are "inherently biassed" as well, but not in the way that is being implied here. Maury Markowitz (talk) 11:28, 28 June 2011 (UTC)

Economic performance

I think the economic performance section should be updated to include information on some of the non-Ontario units. This link from the Canadian Nuclear Association include some information on the capacity factors. It might also be good to include reference to the capacity factors or cost of competing designs to give context? — Preceding unsigned comment added by Hologram0110 (talk • contribs) 04:07, 8 December 2011 (UTC)

Design: Is This Information Necessary or Relevant?

"A CANDU power plant generates power in the same fashion as a fossil fuel power station; heat is generated by "burning" fuel, and that heat is used to drive a steam turbine, normally located in a separate "power hall". A typical coal-fired plant burns coal and air and produces mostly carbon dioxide and fly ash, the CANDU burns nuclear fuel in-situ; when the fuel is "burned up" it is removed from the reactor and stored." That entire bit there can be replaced by a single sentence including a hyperlink: "CANDU power plants generate power through the same basic design principle at the heart of all nuclear power plants." This intro is misleading and out of place in an article about a highly specific proprietary power plant design. It would be appropriate in a general article on nuclear power generation.68.6.76.31 (talk) 08:55, 23 January 2012 (UTC)

I tend to favor such introductory material be placed in-situ, it saves considerable click-itis. If we do as you suggest, then the reader would have to click out to some other article, locate the description in question, read it, and then page back. I think a single para as it is helps rather than hinders. Maury Markowitz (talk) 19:38, 5 March 2012 (UTC)

Safety coverage inadequate

The article lists safety features but does not actually discuss operational safety. This is like the Ford Explorer article mentioning that it has brakes and safety belts without mentioning that it's vulnerable to high speed tire blowout and subsequent rollover if the driver responds incorrectly (For the record, the Explorer article does cover this concern.) The article mentions that CANDU has a smaller positive void co-efficient than RBMK reactors, which gives operators more time to react to problems. However, what needs to be addressed is the effect of the CANDU positive void co-efficient in the event of a Three Mile Island type incident (ie, one in which coolant voids develop without the operators noticing) or Chernobyl type incident (ie, safety systems are disabled by accident or on purpose)

Similarly, the article mentions that CANDU plants continue to put out 7% of maximum power after shutdown and so have several cooling systems. What needs to be addressed is the ability of CANDU plants to deal with a Fukishima type incident (ie, the reactor is successfully shutdown but all power to run cooling systems is lost.)

I'm digging out some references that address this, but in the meantime invite anyone with the knowledge or references to weigh in on these points. — Preceding unsigned comment added by 2.27.196.231 (talk) 05:42, 29 March 2012 (UTC)

Fukushima response is not part of the original CANDU design since by definition it is a "Beyond design basis" event. Each utility has to assess its own response to the events that they consider appropriate. OPG did not consider 9.5 earthquakes and 30 metre tsunamis on Lake Ontario because they are physically not crediblem they did consider tornados etc. They have decided to buy diesel pumps and generators and hoses to maintain cooling in the evnt of a complete loss of the electrical grid and internal power supplies which was the worst beyond design event that was credible.

I am not saying that this should not be addressed just that each plant will have its own problems and solutions. Dabbler (talk) 11:42, 29 March 2012 (UTC)

NPOV and missing reference

"mainly from external factors" This claim requires a reference.

It is followed by a claim concerning success in China with no reference to an reputable auditor or international organization but instead public relations material from "Canteach".

I am not an opponent of nuclear power, but this is SNC-Lavalin who is the owner now and an experienced wikipedia editor needs to look at reference 10 and what it means that the prior claim has no reference.

Canadians long tolerated Atomic Energy of Canda exaggerations but since the Libya-Mexico affair, I believe that fewer Canadians have illusions about the lack of scruples of SNC-Lavalin.

In the past I worked on the world's "best selling" audit software (post-Enron) and I now have some considerable skepticism even of claims by big name auditors (that OEM firm is owned by the owners of Reuters, so we all have a lesson in having doubts about "references" when these big corporations "speak for themselves".)

G. Robert Shiplett 01:18, 30 March 2012 (UTC)