Talk:CANDU reactor

I have read that intense radiation in the metallic fuel tubes leads to gases developing in the metal, weakening it and reducing its strength. The result is that the effective lifetime of the tubes is dramatically reduced, eliminating the supposed financial benefits of the CANDU approach. Comments?

Comment on the above: This is eventually a problem with all classes of nuclear reactor. The higher neutron fluxes of the Fast Breeder make it a special problem there, and it will be even worse for a fusion plant. But I haven't heard of it being a particular problem with the CANDU.

I'm skeptical about the claim that heavy water is toxic. It's not radioactive, and chemically it is almost identical to ordinary water, the main difference being in reaction rates and even this is very small. Otherwise separation would be easy and cheap!

Sorry, I should have signed the above two comments before. I'm new here. Andrewa 23:15 Mar 3, 2003 (UTC)

From heavy water:

Heavy water is toxic, since it inhibits cell division, but only in very large quantities: approximately 50% of the water in one's body must be replaced with heavy water for poisoning to occur. The symptoms of deuterium poisoning are similar to those of radiation poisoning or chemotherapy.

So it doesn't look like all that dangerous a material, since you'd have to spend days drinking it to get relatively minor symptoms. Bryan

Hmmm. We might then take this discussion to the heavy water article, which I should have looked at before.Andrewa 10:17 Mar 5, 2003 (UTC)

OK, I posted comments on that discussion page too. No reaction, so I've had a go at updating that page, and put pointers to it on this page and the deuterium page. I wonder are there any other references to deuterium poisoning?

Obviously, a politically sensitive issue. Andrewa 16:43 Mar 6, 2003 (UTC)

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[1] talks about a 99.75% purity instead of 99.975% as in the article. If somebody else has another information source, let's consider there's a typo in the wp article.--Chealer 09:43, 2004 Nov 10 (UTC)

Fixed as 99.75%, citing www.nuclearfaq.ca, also fixed the gadolinium error -Wikibob | Talk 20:27, 2005 Mar 5 (UTC)

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There seems to be more to discuss here, especially the next version of CANDU that uses enriched uranium fuel. In parallel with this a recent study from MIT recommends that reactors use a "once through" fuel cycle that does not involve enrichment. Should we consider a major update now? --Randal Leavitt 16:20, 3 Dec 2004 (UTC)

costs

It would be interesting to see what's a cost of building a CANDU-type reactor and how does it compare with other types of nuclear reactors? Does anyone have such information? --rydel 18:25, 16 Dec 2004 (UTC)

There is little reliable information on nuclear costs, particularly in the US context, mainly because no new plants have been built for such a long time there. Construction costs in Japan and other countries are difficult to compare to American ones (the Japanese construction industry is notoriously inefficient). One of the appendices of this MIT study has one of the more comprehensive analyses of the topic, but is perhaps overly conservative when it comes to construction costs of new generation reactors. For information on new-generation designs, you could try this DOE study on the topic. Material from these studies would probably be well worth adding to some of the nuclear power related articles. --136.186.1.116 29 June 2005 04:45 (UTC)

Removed section on variants...

This is interesting, but it's currently not correct Wikipedia style:

An interesting variant of the CANDU used a high-temperature organic coolant rather than pressurized water as the primary coolant of the fuel assemblies. This simplified the design even further by removing high pressures from the fuel-tubes. The organic coolant was cooled in a steam-generator to generate power. The author believes that this design lost favour because the organic coolant was a toxic chlorinated hydrocarbon. The design might be revived if adapted to use a biologically-inert fluorocarbon.

If somebody replaces the the author believes with a citation, or modifies it some other way, it can go back in. --136.186.1.116 29 June 2005 04:36 (UTC)

There may have been a safety concern with the organic coolant, but the main reason for the dominance of the heavy-water version was its successful demonstration as a commercial plant in Ontario. I was say put the section back in, minus the last two sentences and with a new sentence to this effect added, as in

An interesting variant of the CANDU used a high-temperature organic coolant rather than pressurized water as the primary coolant of the fuel assemblies. This simplified the design even further by removing high pressures from the fuel-tubes. The organic coolant was cooled in a steam-generator to generate power. Due to the success of the heavy-water-cooled CANDU plants in Ontario, however, the organic-cooled design never progressed beyond the prototype stage.

Whitlock 29 June 2005 05:29 (UTC)

IAEA Safeguards

Is the statement that all CANDU reactors are under IAEA safeguards accurate? I know they're supposed to be according to Canadian policy, but it doesn't seem like the Qinshan Phase III reactors in China are under IAEA safeguards. They are not on any of the IAEA safeguarded site lists, and there is no documentation from AECL, Canadian government or Chinese government about the verification and inspection regime for these sites. Yes there's a 1994 nuclear cooperation agreement, but what about the actual controls and inspections on the ground being implemented? Can anybody point to info on this? As it stands, I don't think it's accurate to say that all CANDU reactors are under IAEA safeguards, because they aren't according the IAEA. --RBruneau 25 October 2005

In 1988, China signed an agreement with the IAEA subjecting a number of facilities in China to IAEA safeguards, and also guaranteeing that China will require recipients of Chinese nuclear exports to accept IAEA safeguards. Currently, China has two facilities under IAEA safeguards: (1) its Qinshan-1 nuclear power reactor and (2) the HWRR-2 research reactor at the China Institute of Atomic Energy (CIAE), Beijing. In addition, the three-module centrifuge plant being built with Russian assistance at Hanzhong and the CANDU power reactors to be provided by Canada will be under IAEA safeguards. In 1991, China further declared that it would report to the IAEA any export or import of nuclear materials and all exports of nuclear equipment. However, although China has placed all of its nuclear exports under IAEA safeguards, it does not require full-scope safeguards. Nuclear Threat Initiative Website

But I agree the passage in question needs to be looked at in detail. DV8 2XL 10:28, 26 October 2005 (UTC)

Also, India has built a number of reactors, not under IAEA safeguards, that were derived from the CANDU design and are used for power generation. What happens with these is anyones guess. DV8 2XL 11:27, 26 October 2005 (UTC)

According to the "Agreement between the Government of Canada and the Government of the People's Republic of China for Co-operation in the Peaceful Uses of Nuclear Energy" of 1994 (I've only found this in hardcopy):

"Article VII

... 3. With respect to nuclear material subject to this Agreement, compliance with the provisions of paragraph (2) of this Article shall be verified by the Agency (i.e. the IAEA). In Canada, such compliance shall be verified by the Agency pursuant to its safeguards agreement with Canada in connection with the NPT. In China, this requirement is satisfied where nuclear material subject to this Agreement is subject to China’s voluntary offer agreement with the Agency. (my emphasis)

Agreed Minute

During negotiations of the Agreement between the Government of Canada and the Government of the People’s Republic of China for Co-operation in the Peaceful Uses of Nuclear Energy signed on the 7th of November 1994, the Parties agreed to the following, which shall be an integral part of this Agreement:

...With reference to Article VII of this Agreement, if the safeguards referred to in paragraph (3) of Article VII are not applied by the Agency within the territory of either Party, the Parties shall, at the request of either Party, forthwith consult with each other and reach mutually acceptable solutions which will ensure compliance with the provisions of paragraph (2) of Article VII." (my emphasis)

As NTI notes in the quote provided by DV8, China is under no obligation within their safeguards agreement with the IAEA to subject their domestic facilites to safeguards in any comprehensive way. They provide a list of certain facilities that the IAEA can then select from to implement safeguards. As with the voluntary offer agreements with the other NWS, the IAEA almost never actually implements any of those safeguards. (See the agreement here: IAEA INFCIRC/369) So for the Canada-China agreement to rely on China's safeguards agreement with the IAEA isn't saying very much. Thus the need for the Agreed Minute, which makes the likely situation a "mutually acceptable solution" outside IAEA safeguards.

The most recent list (Dec 31, 2004) of Chinese facilities under IAEA safeguards is in the annex to the IAEA's annual report. There is only 1 nuclear power reactor listed, and it's not a Qinshan Phase III CANDU.

RichB 16:10, 30 October 2005 (UTC)

OK. Let's get this sorted out. Two things need to be done:

• Do we call CANDU designs that were nor built by AECL "CANDU's" for the sake of this passage?
• Can we list which of these are not under IAEA safeguards?

DV8 2XL 17:41, 30 October 2005 (UTC)

I think what you propose here would be valuable. That nuance is important, as is the simple statement that other countries are building HWRs based on CANDU designs. Finding verifiable sources of info regarding the "copied" nature of the designs may be hard. For example, in 2000 China was accused of stealing plans for Canada's Slowpoke reactor and selling it internationally, but verifying that claim is difficult. I will give it a shot for the CANDUs.

RichB 19:57, 1 November 2005 (UTC)

Okay, re: Qinshan Phase III. After tracking down some more stuff and having a chat with people at the Canadian regulator (CNSC), this is the lowdown:

As I mentioned above, the 1994 nuclear cooperation agreement requires China to include the CANDUs in its safeguards "voluntary offer" agreement with the IAEA. However, the actual list of facilities included is kept confidential between China and the IAEA, so 100% verification to us outsiders of the inclusion of CANDUs is only possible if the IAEA actually chooses to implement safeguards there. In discussions with Canada, China has made it clear that the CANDUs were on their voluntary offer list, and Canada seems satisfied with that as they haven't requested an additional agreement as is possible under the Agreed Minute of the 1994 agreement.

So the Qinshan Phase III CANDUs (built by AECL in cooperation with other companies), are not under IAEA safeguards but ARE under an IAEA Safeguard Agreement (at least according to the Chinese). I will take a stab at updating the main piece based on this.

RichB 19:57, 1 November 2005 (UTC)

We can't forget the fact that India operates 12 Pressurized Heavy Water Reactors (PHWRs) reactors and another 6 are under construction and they are all CANDUs or CANDU knock-offs, a fair number of those are not under safeguards and this goes back to my origninal concern - are CANDUS a PHWR sold by AECL- or is candu (lowercase) a generic term for PHWR of a certain design. This is an importaint issue as Canada transfers technology with the sale of a CANDU system. DV8 2XL 23:06, 1 November 2005 (UTC)

It's correct that the two CANDUs built in China are on the IAEA Voluntary Offer list, but are not safeguarded by the IAEA. From the IAEA's point of view the situation is similar to that of the other nuclear weapons states (US, UK, France, Russia), where non-proliferation activities have similar relevance. I've changed the phrase to say "are subject to IAEA safeguards", instead of "are under".

Regarding terminology, only PHWRs sold by Canada are CANDUs. Therefore the domestically-designed and built PHWRs in India are not CANDUs (regardless of any similarities).

Whitlock 15:37, 2 November 2005 (UTC)

Thank you Dr. Whitlock for clearing that issue up. I totaly agree that CANDU should be treated a a trademark of AECL and not as a generic name. I brought the subject up because I felt the issue needed to be clarified. DV8 2XL 21:25, 2 November 2005 (UTC)

Even so, Indian (and other) CANDU-derivatives are similar enough that they should be discussed here (that, or we make a separate derivatives page, but that seems silly given that most of the info here applies).

In general, this page has a point-objection-rebuttal quality rather than a neutral quality. Mindless nuclear minion 18:31, 18 November 2005 (UTC)

The Indian CANDU-derivatives are discussed in the article and I don't believe there has been a suggestion to remove the references. I was only responding to the direct question as to whether you can call them "CANDUs". Whitlock 17:20, 22 November 2005 (UTC)

Yes, and you also clarified the status (w.r.t IAEA) of the Chinese reactors. Thank you on both counts.

Do you know what the status of the Indian reactors are? As I recall India is not even signatory to the nuclear non-proliferation treaty. Same for Pakistan. Mindless nuclear minion 15:10, 23 November 2005 (UTC)

India's indigeneous PHWRs are not under IAEA safeguards, unlike the two CANDUs at Rajasthan and the one CANDU at Karachi, Pakistan. The IAEA website lists all safeguarded facilities.Whitlock 16:35, 19 December 2005 (UTC)

Canadian deuterium-uranium reactor

This is what "CANDU reactor" stands for, sometimes with and sometimes without the hyphen. Should it redirect here, or should the article be moved to the full name? -- Kjkolb 22:56, 12 December 2005 (UTC)

CANDU stands for "CANada Deuterium Uranium". (Not "Canadian", and no hyphen) Whitlock 16:35, 19 December 2005 (UTC)

It looks like you're correct, according to the official website. A lot of sources give wrong versions (Canada with the hyphen, or Canadian with or without the hyphen), even the Federation of American Scientists has it wrong. I hate creating redirects for misspellings because then people won't realize they're misspellings. I'll leave them undirected. Thanks, Kjkolb 06:48, 21 December 2005 (UTC)

Plutonium for the bomb

Canada's connection to India's nuclear bomb

The plutonium for the 1974 test was produced at BARC in the Cirus research reactor, a 40-megawatt reactor supplied by Canada that began operating in 1960. This reactor can produce about 9 to 10 kilograms of weapon-grade plutonium a year.

Canada supplied the Cirus on condition that it be used for peaceful purposes only, but Canada did not require International Atomic Energy Agency (IAEA) safeguards on the reactor or an accounting of the amount of plutonium the Cirus produced. India claims that its agreement with Canada did not preclude the use of Cirus-produced plutonium for "peaceful" nuclear explosions.

The Cirus plutonium was chemically separated from the irradiated uranium fuel in the nearby Trombay plutonium separation plant, which began operating in 1964. Trombay was shut down in 1974 for refurbishment and enlargement, and it reopened in the early 1980s.

Because India could not legally use Cirus plutonium in nuclear weapons, it had to wait until the mid-1980s for plutonium that was truly free of international restrictions. On August 8, 1985, one day before the fortieth anniversary of the bombing of Nagasaki, India commissioned the 100-megawatt Dhruva reactor, an indigenous project that was basically a scaled-up version of Cirus. This reactor can annually produce about 20 to 25 kilograms of weapon-grade plutonium, which is separated in the enlarged Trombay facility. But the Dhruva reactor experienced start-up problems, and it produced little plutonium until the late 1980s.

In late 1985 or early 1986, India began separating unrestricted and unsafeguarded plutonium at a second plant at Tarapur, north of Bombay, which had begun operating several years earlier--processing fuel from the Cirus and safeguarded power reactors. The unrestricted plutonium was in spent fuel discharged from the Madras atomic power stations (MAPS). Although the quality of this plutonium--and its suitability for weapons--is unknown, this activity at the Tarapur plant signaled that India could obtain plutonium from its own power reactors that it is entirely free to use in nuclear weapons.

The Tarapur plant's history of operational difficulties has limited the potential supply of plutonium, but senior Indian nuclear officials say that these problems have been overcome, and that a new plant under construction at Kalpakkam will separate even larger quantities.

Currently, most of India's supply of weapons plutonium is believed to have been produced in the Dhruva reactor and separated at Trombay, with only a small amount of high-quality plutonium produced in unsafeguarded power reactors and separated at Tarapur. Cirus plutonium may in fact also be available for nuclear weapons, since the reactor is neither safeguarded by the IAEA nor inspected by Canada. Because information related to the amount of plutonium produced in the Cirus is a closely guarded secret, we cannot determine whether some of it has been dedicated to weapons.

India is estimated to have had an inventory of about 290 kilograms of weapon-grade plutonium available for the manufacture of nuclear weapons by the end of 1991. [4] About one third of this amount is from the Dhruva reactor; nearly all the rest is from Cirus. Based on Indian Department of Atomic Energy's annual reports, we believe that almost all of this plutonium is in separated form.

In the absence of information about the amount of plutonium needed for an Indian bomb, we assume about 6 kilograms of plutonium for each weapon, a higher than normal value. If India uses Cirus plutonium, then it probably has enough for about 50 weapons.

By the end of 1995, India could have a stockpile of about 400 kilograms, with the bulk of the additional 100 kilograms produced in the Dhruva reactor. In all, this would give India enough plutonium for 65 weapons.

India is also moving toward realization of large-scale use of uranium 233 as fuel for its power reactors. Uranium 233 is a fissile isotope of uranium that requires about as much material per bomb as plutonium. Uranium 233 is made by irradiating natural, non-radioactive thorium in a reactor, and India attaches a high priority to the development of thorium/uranium 233 fuel for its power reactors. Irradiation of thorium in the Cirus, Dhruva, and the MAPS reactors has resulted in the production of kilogram quantities of uranium 233.

Chronology

Adding in a section about the history of CANDU, from NPD to Darlington...just a short blurb on each station really. Still under construction... Burtonpe 16:29, 17 January 2006 (UTC)

Pressurised Heavy Water Reactor

I made an article on Pressurised Heavy Water Reactors to highlight the differences between the Canadian and Indian projects. I then adjusted the redirects accordingly. I was getting sick of the 'Indian-made CANDU's fueling nuclear weapons' allusions that were showing up here. --DV8 2XL 18:05, 10 February 2006 (UTC)

What exactly are the differences between the CANDU and the Indian MAPS PHWR? According to one of your own posts above, you agree that the Indian reactors are CANDU-derived. They are often referred to in the media as CANDU-clones. We have a reference that says these Indian reactors were used to make plutonium. It's true that the CANDU has probably not contributed directly to proliferation, (because the CIRUS was better at it,) but there is evidence that this technology can be misused that way despite the IAEA and economic considerations. This is relevant to an NPOV article about the CANDU. In order to win public trust, we must be honest and fair in representing our industry.--Yannick 20:15, 12 February 2006 (UTC)

As per the above discussion with User:Whitlock and User: Mindless nuclear minion and myself it was established that CANDU is a product, not a design-type. Furthermore the PHWR's built by India - while indeed using CANDU's as a starting point - have now diverged to the point where they can no longer be considered knock-offs. In any case the ignorance of the media in this regard does not constitute a reason to perpetuate this error here. The bald fact is that most light-water reactors bear a resemblance to General Electric or Westinghouse designs, yet their names are not invoked every time a US reactor is mentioned. As for public trust the whole issue of CANDU's relationship to the Indian nuclear weapons program was and is dissemination spread by anti-nuclear groups in an attempt to soil the reputation of what is in fact, the most proliferation-resistant commercial power reactor technology on the market to-day. --DV8 2XL 20:33, 12 February 2006 (UTC)

What is the difference between the CANDU and the MAPS that makes one proliferation-resistant and the other capable of producing plutonium? The trademark CANDU is applied to Pickering, Bruce, Darlington and CANDU-6 reactors even though they have significant design differences. At what point did Wintel computers diverge enough that we stopped calling them IBM clones? At what point do we stop calling a PHWR a CANDU clone? I think those questions depend on popular usage, and that means we can't ignore the media. And considering how similar this article is to an AECL marketing brochure, I don't think the anti-nuclear groups have found this page.--Yannick 00:54, 13 February 2006 (UTC)

"At what point do we stop calling a PHWR a CANDU clone" The point in this encyclopedia where it was decided to have a separate article on Hoover the company and vacuum cleaner the appliance, despite the fact that in many English-speaking communities the former is a synonym for the latter. Ultimately this is a trademark issue; CANDU is a trademark of AECL, case closed - other reactors built by others are PHWR's. Under no circumstances will you get any traction here or anywhere else in Wikipedia with the argument that a media error should be perpetuated in these pages. --DV8 2XL 01:56, 13 February 2006 (UTC)

Contradictions

One of the following is incorrect or misleading and should probably be removed. In the "Advantages" section, an item reads:

"CANDU can even be operated to "burn" former nuclear weapons material (MOX fuel cycle) to a less-reactive state effectively rendering it useless for warheads while at the same time turning the relatively easily handled weapons grade material into highly radioactive waste."

then, at the end:

"As mentioned above, by burning it as fuel, CANDU could actually render existing stocks of weapons-derived plutonium less reactive and less toxic."

The resulting material is either "highly radioactive waste" or "less toxic", but it's probably not both. --Rhombus 22:53, 28 February 2006 (UTC)

Good call; I have made the appropriate changes. --DV8 2XL 23:38, 28 February 2006 (UTC)

Weapons Grade Plutonium

I have removed the paragraph that attempts to make a case for CANDU reactors being good at making "weapons grade plutonium". Previously I have edited versions of this text in order to bring it back into the realm of fact; but a recent major edit brought back the fiction and it's best that this diseased limb be pruned. There is nothing inherent about CANDU technology that makes it better or worse in this department. If there are opinions to the contrary out there, please discuss it fully and perhaps do a bit of research before publishing your opinions as fact. You may feel free to email me in this regard. Thank you.

Whitlock 03:58, 16 April 2006 (UTC)

What I want you is not to sell this machine to a country that does not respect human rights.

It seems the discussion should not just be about production of plutonium, but also of tritium. For example, as discussed by Pervez Hoodbhoy and Martin Kalinowski:

"tritium is produced inadvertently in the CANDU reactors possessed by India and Pakistan. The high neutron flux in these reactors converts some of the heavy water into tritium. Smaller amounts of tritium can be extracted from spent fuel rods or control rods.

India may be using its research reactors at Dhruva and Cirus to breed tritium from lithium 6, and it is known to have removed tritium from heavy water tritiated during normal operation of its CANDU reactors."

"The nuclear subcontinent: The tritium solution", Bulletin of the Atomic Scientists July/August 1996 pp. 41-44 (vol. 52, no. 04)

RichB 15:45, 18 April 2006 (UTC)

Your point? --DV8 2XL 15:53, 18 April 2006 (UTC)

My point is that Candus are a concern both for "horizontal" as well as "vertical" proliferation, and this possibly makes them (and similar heavy water moderated reactors) unique from other reactor types in terms of proliferation risk. --RichB 17:43, 18 April 2006 (UTC)

But the bald fact is they have not been used as such; (see below)light-water reactors have. --DV8 2XL 17:50, 18 April 2006 (UTC)

It was not fiction at all about the production of Pu-239. A nuclear weapon requires high purity Pu-239 since Pu-240 being a good neutron source will increase the speed of the reaction and decrease significantly the efficiency of the weapon to a point that the explosion will not be of much intensity. The longer U-238 is irradiated with neutrons, the higher the percentage of Pu-240 created. So, for producing weapons grade plutonium, one needs a reactor that can be refueled online or that can be stopped often. If one has to disguise such a reactor as a civilian one, then the online refueling is the only option.

Canada tries to aggressively market Candu to many countries, including ones that do not respect human rights, causing uneasy feelings to their neighbors because of Candu's ability for the twin military and civilian role. Its complex piping also reduces its reliability and so those that really care about the production of electricity only, choose PWRs and BWRs which are by far the most popular designs worldwide.

See this is where a little bit of knowledge coupled with not much thinking will get you. What sort of fuel do those reactors use? Enriched fuel. Once you have an enrichment plant, nothing is stopping you from going all the way. With a CANDU no one needs enrichment, thus any country using CANDUs and building such a facility is immediately suspect of weapons manufacturer. North Korea and Iran are not getting Pu from CANDUs, and it has been clearly established that India and Pakistan did not use theirs as a source - given that they had better reactors for that purpose.

Indeed! "Given that they had better reactors for that purpose."

As far as I can see this is just dragging a Red Herring - you have nothing but speculation to back your claims. --DV8 2XL 17:38, 18 April 2006 (UTC)

It's true that Canada never designed Candu for military applications. But the Russian RBMK, another reactor that can be refueled online with natural uranium, represents an evolution from a purely military reactor.

It seems to me that the best bet is the EPR coupled with an agreement for high quality fuel from its manufacturer and an agreement for spent fuel reprocessing. And if you are a real democracy, you can be sure that these agreements will always be honored.

Also, if you read the Candu article, not many such reactors were sold outside Canada. If the Candu marketing was successful, your red herrings would be very real.

And if my Aunt had a beard she'd be my Uncle. Speculation has no place on Wikipedia - state facts and back them up with citations. --DV8 2XL 18:48, 18 April 2006 (UTC)

The fact that a Candu has never been used for the production of weapons grade plutonium is not a proof that it cannot be used easily and clandestinely for such a project. And if the prospective buyer was your neighbor and insisted on Candu by manipulating the specifications for its proposed power plants to exclude other designs, you'd be worried too.

It may be useful to frame this debate with three separate questions

It may be useful to frame this debate with three separate questions:

1. Do Candu reactors produce “weapons-grade plutonium” or other weapon materials such as tritium easier/faster/better than other designs?
2. Are Candu reactors more difficult to safeguard than other designs?
3. Have Candu reactors been used to produce weapons material?

I think they are all relevant, as we are not just talking about actual incidents of proliferation/diversion to weapons purposes but the risk of such incidents occurring. Comparison with other designs should happen within all three questions. Risk assessment is not conjecture and speculation; it is an assessment of the nitty-gritty details of how Candus can be safeguarded and how they can potentially be used for weapons purposes. What would be valuable in response are details of how these risks have been / can be mitigated. --RichB 19:50, 18 April 2006 (UTC)

1. As Dr. Whitlock mentioned above, the answer is no. Producing weapons-grade plutonium involves the whole reprocessing cycle - not just breeding the Pu. The small saving in time exposing the fuel in a CANDU is not a major advantage - the reprocessing plant and the recovery and fabrication of the warhead is the same. As for the tritium - all that you need for a weapon can be gotten from other sources.

It's not about saving time! It's about using what you've got!

Do you have any idea what you are talking about? Because this remark seems to suggest you do not.

1. No, I can't see how they would be as this comes down to fuel inventory monitoring which is the same for all types. In fact, as I have said above, the fact that no enrichment facilities are needed to make the fuel makes monitoring the fuel cycle somewhat easier.

Really? Using natural uranium, allows one to use material mined in their own country. Are all uranium mines monitored?

Whereas if one built an enrichment plant you would use imported uranium? Balderdash!

1. No one has presented to date any credible evidence that an explosive nuclear device has been made from ex-CANDU fuel or material irradiated in a CANDU reactor. The Powers that have CANDUs and have made bombs have used 'research reactors' to breed fuel because this is a more efficient way of doing it. --DV8 2XL 20:21, 18 April 2006 (UTC)

Yes, but if you don't have a suitable "research reactor" to speed things up, a Candu will do nicely. It's really irrelevant whether they have been used for such a purpose or not. What's relevant it's whether they are capable or not.

That's pure sophistry. ANY reactor standard design is capable, so that line of argument is nonsense. Keep in mind that the two current high-risk proliferators seem to be using light water reactor fuel for their programs and the same thing is (was) true for the South African and Israeli programs as well. This charge against CANDUs is totally groundless. --DV8 2XL 13:44, 20 April 2006 (UTC)

I'm very sorry to see that you carefully avoid some facts by presenting other facts and by rejecting hypothetical questions by saying that this or that has never happened.

• Can a stake knife be used to kill? -- You answer that all knives can kill. -- Or that the ones you make have never been used for this purpose.

But let's go back to our reactors. If I'm a country that wants to build a few nuclear bombs and I don't want anyone to know and my technology is limited, what is the best route? The EPR or the Candu?

• The EPR needs refueling every 18-24 months. By that time, my plutonium will be high in Pu-240 and won't be useful. But, stopping my 1600MW reactor often to get high percentage Pu-239 will be noticed. Also, my foreign supplied fuel rods will have to be sent back to their manufacturer for reprocessing and they know how to count. Using my own fuel rods will require enriching facilities which will also be noticed.
• The Candu can be refueled online and thus bypasses the above problems of someone noticing. It uses natural uranium and again noone will notice something out of the ordinary if I insert a few rods of my own. By building a small reprocessing facility just for my few own rods, I have good chances of noone noticing. Surely, I'll send my regular spent fuel abroad for reprocessing keeping the supplier happy that I'm up to nothing. It might take long to get my bombs, but I have survived so far without them. Patience it my secret of success.
• Surely, a small military natural uranium fired reactor is the best way to go. I might not even need heavy water as I could use a graphite moderated one. But we are talking more radioactive waste that cannot be sent abroad. And the more the facilities, the better the chance someone will notice.
• * You say that I have no idea what I'm talking about. But the reality is that I do and that hurts your chances of selling your machine and making profit. I'm sure the advanced Candu cost a bundle to develop and by just replacing Canada's aging reactors with it does not cover the costs. But you have to see it from my perspective: I don't want my local military government getting its hands on such a piece of equipment. Whereas, if they get the EPR, they might solve my evergy problem too!

You're engaging in nothing but hollow speculation here and drifting away from anything you can prove. Verifiable facts are what drives Wikipedia, and the verifiable fact is nobody has used CANDUs for this service; but light water-reactors have been. Take your beefs to some place that traffics in "what-ifs" they have no place here. I will not debate with someone with an agenda, in these pages. It's not what this for. --DV8 2XL 08:50, 21 April 2006 (UTC)

Accidents

How about including a list of accidents that CANDU reactors have been involved in? Here's a list of problems that have occured with Pickering's Candu reactors as of 2001:

On August 1, 1983, Pickering reactor 2 had a loss of coolant accident after a pressure tube suffered a metre-long rupture. The station was shut down and the four reactors at Pickering A were eventually retubed at a cost of about $1 billion.

On November 22, 1988, an operator error damaged 36 fuel bundles. The cooling system was contaminated by radioactive iodine that was vented into the environment over several weeks following the accident.

On September 25, 1990, Pickering reactor 2 experienced large power shifts in the reactor core. Staff spent two days trying to stabilize it before shutting it down. The AECB later criticized the utility for not shutting down immediately.

On August 2, 1992, Pickering reactor 1 had a heavy water leak from a heat exchanger that resulted in a release of 2,300 trillion becquerels of radioactive tritium into Lake Ontario.

On April 15, 1996, Pickering reactor 4 had a heavy water leak from a heat exchanger that resulted in a release of 50 trillion becquerels of tritium into Lake Ontario.

http://www.parl.gc.ca/37/1/parlbus/commbus/senate/com-E/ENRG-E/REP-E/repintjun01-e.htm

http://www.sierraclub.ca/national/programs/atmosphere-energy/nuclear-free/reactors/nuclear-and-clim-chg-6-01.html

Also, here's a link to a pdf document on how to identify and classify accidents in nuclear power plants:

http://engphys.mcmaster.ca/~unene/un803/2006/Chapter2-DesignBasisAccidents.pdf

The above is part of the course notes for a course in "Nuclear Reactor Safety Design" http://engphys.mcmaster.ca/~unene/un803/

from the Canadian University Network of Excellence in Nuclear Engineering (I think the course is offered at McMaster University, Hamilton, Ontario, Canada but I'm not sure)

(TaffyDownUnder 23:40, 24 May 2006 (UTC))

There is already a list of civilian nuclear accidents, and none of these qualify for that article. The fuel channel rupture might be notable enough to add here, or maybe at Pickering Nuclear Generating Station -- the rupture provided the impetus to a large inspection programme -- but I can't source my claim, maybe Dr Whitlock might. -Dan 01:24, 26 May 2006 (UTC)

I have to agree with Dan. This is dealt with in the other topic, and these don't make the cut. --DV8 2XL 02:23, 26 May 2006 (UTC)

Props to Maury

User:Maury Markowitz has done some outstanding work on this article of late and I would like to take this opportunity to extend thanks for a job well done. --DV8 2XL 11:57, 29 May 2006 (UTC)

There remain a number of factual errors and other problems with this article however. A significant re-write is required, and until I or another qualified contributor get to this: Reader Beware. Whitlock 15:06, 29 May 2006 (UTC)

Okay, having completed some major adjustments the text is generally factual, although less egregious issues still persist. Whitlock 04:50, 31 May 2006 (UTC)

Nuclear Nonproliferation

I originally removed Nuclear Proliferation (now changed to Nuclear Nonproliferation, which is more appropriate) as a separate section since it was superfluous -- a lot of words were used to basically say what could be expressed in one sentence: "CANDU reactors meet a similar level of international certification as other reactor designs". To raise and then destroy a number of speculations makes good discussion, but it doesn't belong in an "encylopedia". The section also contained a number of errors, such as using nonproliferation as main attraction for purchasing CANDU.

I still think the subject doesn't merit it's own section, but I'm easy. I deleted a lot of the superfluous material, however. I still don't believe the stuff about tritium in fusion weapons belongs, but I'll make that concession. Whitlock 13:59, 31 May 2006 (UTC)

Thanks for your continued maintenance of this article. I would agree they don't belong if the speculations were originally raised and dismissed here. I don't know if that's actually the case or not. For instance this bit:

...this made the international community somewhat happier with the sale of CANDU systems to countries like India and Argentina, whose claimed peaceful intentions were not entirely clear at the time.

If this could be made specific (i.e. who in this so-called international community said they were happier of the sale to which country whose claimed peaceful intentions was not entirely clear at what time) then would that not be appropriate? I'm thinking this bit is not original speculation either:

...while the CANDU design does not require an enrichment facility, it does, like any other reactor, produce plutonium as a side-effect of its operation...

As such it may very well be appropriate and in fact leads naturally into the Indian plutonium discussion. As for:

The neutron economy of the reactor also makes it possible to use a CANDU as a breeder reactor...

and for:

...Tritium is used in the "fusion trigger" in an H-bomb. Although few countries considered to be a proliferation risk are capable of producing an H-bomb... tritium recovery remains a concern...

Here I have really no idea that anyone seriously has suggested someone doing either of these or not.

But speaking of tritium, did a section on CANDU and tritum get lost in the reshuffle somewhere, or was I imagining that (maybe I inhaled too much tritium myself) -Dan the OPG mindless minion 15:34, 31 May 2006 (UTC)

Well this section has been clipped twice now, and is approaching the three-edit revert war limit. I will explain my reasons for including the section here, before re-adding the information again.

For many years, AECL pushed the CANDU as a "safe" system for sale to questionable countries who's nuclear ambitions were rightfully suspect. They claimed that the lack of enrichment facilities meant that one could not surrepticiously use "extra-enriched" fuel for bomb-making purposes. I had someone from AECL (hmmm, maybe NRC/Chalk, I could look it up) say this in a well-attended speech to my nuclear physics class circa 1987.

Of course, it was Canada that ended up giving India the bomb. While it is true that the lack of an enrichment facility makes one type of bomb more difficult to build in secret, plutonium production remains a real problem. Yes, it was not a CANDU that provided the Indian plutonium in question, but nevertheless the process they used could be duplicated on the CANDU, and apparently has been on their own PHWR's based on them.

As the posts above note, the ability for the CANDU to be refuelled "online" presents a very real problem. Single fuel elements can be removed quickly, when the inspectors are not around, and then replaced with new fuel prepared in a site not subject to oversight. In fact, it's the use of natural uranium fuel that makes this "easy"; even small amounts of ore diverted to secondary sites allows for preparation of single fuel elements in fairly limited facilities (as opposed to an enrichment site).

The tritium concerns are twofold: 1) sale of tritium to nations capable of using it in H-bombs, and 2) direct use of tritium for "boosted fission" weapons. These are real concerns, notably the later, which is a relatively simple way to dramatically boost yields of otherwise fairly conventional designs. The British, years behind in bomb design, were able to produce a 1 MT boosted fission devices (Green Bamboo/Orange Herald) with relative ease, and I have no doubt the Indians are capable of producing the same design, and I believe this is what they did in their recent tests.

The long and short is that the CANDU produces plutonium and tritium in a way that makes it easier to extract compared to other reactor designs. And while Jeremy's FAQ notes a Los Alamos report claiming it is difficult to extract plutonium from spent fuel, it covers LWR's only, and ignores the fact that the CANDU fuel can be removed before the Pu-240/241 concentration starts making things difficult.

Let's get specific here: Jeremy, you note in your FAQ this series of apparently rhetorical questions:

Even if you possess spent power reactor fuel in storage, is the expense and complexity less than that associated with a weapons-plutonium or uranium-enrichment route? Furthermore, if you are a signatory to international safeguards, would you risk detection in so obvious a manner when other options can be pursued in smaller, cheaper, even indigenously-designed (and therefore unsafeguarded) facilities [13]?

As far as I am aware, all of the plutonium produced by Israel, India, Pakistan and France is derived from heavy water reactors. That suggests that exporting heavy water for any use is itself a serious proliferation risk. Furthermore it appears that at least some of this plutonium, at least in the case of Pakistan and India, was indeed extracted from spent nuclear fuel, as opposed to dedicated breeder-type systems like CIRUS. BARC is a PUREX-cycle systems,

I think that pretty much answers that. Your dismissal of Taylor's comments on this topic strikes me as particularily questionable.

Claiming that this entire section can be reduced to "CANDU reactors meet a similar level of international certification as other reactor designs" strikes me as rediculous. Not only is the statement basically content-free (eg: "CANDU reactors do not blow up much"), I consider it to be misleading as well.

Look, I'm not some champaign socialist or green weenie, I'm a failed physicist who fully supports nuclear power. That said, I think it's important that the article points out that the CANDU does present a proliferation risk at least as great as other reactor designs. I tried to balance that with statements suggesting that possibility does not imply that these things have actually been done, but you characterized them as "raise and then destroy a number of speculations". I'm sure if I had stated them as outright facts, which they appear to be, I would have been critisized for unverified statements instead.

Maury 19:01, 31 May 2006 (UTC)

The bottom line here is that these edits must meet the terms of WP:V (which at this point they do not) and therefor violate WP:NOR and WP:NOT --DV8 2XL 19:21, 31 May 2006 (UTC)

Well then, I will have to ask you to provide a list of exactly which items in my text you feel require V. I'm sure I can provide "high level" references for most/all of them in a few moments. To start us off:

Proliferation Vulnerability Red Team Report, SAND 97-8203, notes that, contrary to the DOE's claims mentioned in Jeremy's FAQ, plutonium extraction from spent fuel is a trivial process that could be handled by a six man team in under two months.

This is further proved by the wealth of reports on the PUREX-based unit Pakistan is operating to extract plutonium from spent fuel. Minimum Nuclear Deterrence Postures In South Asia: An Overview October notes that best estimates suggest they produce 1.5 bombs worth of Pu via this process every year.

That the CANDU makes extraction when the PU ratios are favourable requires no V IMHO. It's obvious.

That the CANDU also has a better neutron economy, and thus is more favourable for breeder-type reactions, is also obvious. It's also factually proven by India's current efforts to produce thorium-fed reactors.

A Very Special Relationship, mentions details of the Green Bamboo/Green Grass tamper-boosted devices, and how easy it was to develop them (tritium risk)

Heavy Water - Properties, Production and Analysis, an Indian book, notes their successful attempts to extract tritium from the heavy water in their PHWR's. The Bulletin of the Atomic Scientists has also covered this several times, here for instance

India themselves claimed that one of their 1998 tests was in fact an h-bomb, although I have seen speculation that it was actually a boosted fission device similar to Green Grass.

Dan, I believe this particular item addresses your last question.

Anything I've missed?

Maury 20:17, 31 May 2006 (UTC)

At the risk of sounding pedantic, listing such things here is not how it's done. Providing verifiable sources for statements in the main article falls on the poster - anything that is not referenced is subject to removal. If you put this material back in the onus is on you to cite your sources properly. Keep in mind as well that this is an article on CANDU reactors - a product of AECL not on HPHW reactors or on heavy water reactors in general. We should limit our remarks in the main article to that which is relevant to this particular product. --DV8 2XL 20:32, 31 May 2006 (UTC)

That's fine DV8, but you stated here that you object to the material in question for lack of V. I asked you to provide the examples that you think require V, so that I could provide V. When I provided example V's, you now claim that I shouldn't put them here.

So I will try again: please, tell me exactly what items you wish me to find V for, I will find the V, and put it in the main article. Fair enough?

Maury 21:35, 31 May 2006 (UTC)

Maury, I agree with your comment that "it's important that the article points out that the CANDU does present a proliferation risk at least as great as other reactor designs." This was precisely my intention in the first sentence of the section on Nuclear Nonproliferation. The risk is, by definition of meeting IAEA safeguards criteria, no greater and no smaller than any other technology meeting these same criteria. The details of why this is so, given the on-line refuelling capability of CANDU vs. the batch short-irradiation option of an LWR, and the relative detection risks of each, should not be discussed in a public forum, incl. Wikipedia. At the same time, speculation about these matters based on personal knowledge is (as I said) fine, but also not appropriate in a Wikipedia article. -- Whitlock 20:36, 31 May 2006 (UTC)

The risk is, by definition of meeting IAEA safeguards criteria, no greater and no smaller than any other technology meeting these same criteria.

Meeting a risk requirement suggests nothing whatsoever about the relative risks. Valium and Xanax both meet safety requirements, yet the later is much safer than the former. According to your statement above, since they both meet the safety requirments, that fact alone would allow you to claim that Vallium is "no greater and no smaller" a risk than Xanax. This claim is clearly specious.

The details of why this is so, given the on-line refuelling capability of CANDU vs. the batch short-irradiation option of an LWR, and the relative detection risks of each, should not be discussed in a public forum

I can't imagine why this would be so. Please explain your reasoning here.

• Hmm, I'm not sure what is meant by this. What exactly should we not be discussing? -Dan 15:19, 1 June 2006 (UTC)

At the same time, speculation about these matters based on personal knowledge

Please be specific about exactly which items you believe are "based on personal knowledge", and I will be happy to either provide references from the literature to support them, or remove them entirely.

Maury 21:35, 31 May 2006 (UTC)

Maury I dislike it when people treat me like an idiot. If you do not have sources in the main body of the article to back up your edits I will remove the unverified text as per WP:V. It is as simple as that. --DV8 2XL 22:11, 31 May 2006 (UTC)

Let me assure you that I had no such intention or desire. Nothing you have said makes me question either the validity of you comments or your reasons for posting them. I am actually a little surprised that you took them as some sort of insult, but I suppose this sort of thing is expected in the limited bandwidth of a a text-based medium.

I didn't ask for clarification to be an ass, I'm asking you because I really don't know. REALLY. I wrote everything in the article in as neutral a form as I could, precisely so I wouldn't end up in a reference war. Yet my attempt has apparently failed. To date, only Dan has actually pointed out anything specific to take issue with (the "international community").

I'm still at a loss. The concerns are tritium production and the ease of removing fuel while the reactor is running. The later is mentioned in the article without anyone complaining about a reference being needed, the former I have a reference for if that is what you are asking about. But I'm not sure if this IS what you are asking about.

Maury 00:43, 1 June 2006 (UTC)

• And for that matter, there was no suggestion that you were some sort of hippie green cryptocommie or what have you. At least that was certainly not my intention, if it came across that way, I am sorry. I do reject the idea that this sort of thing is unavoidable on this sort of medium. -Dan 15:19, 1 June 2006 (UTC)

Oh, not at all Dan, I just put that in as a sort of pre-emptive strike... it's all too easy to dismiss someone in e-mail as being "one of those" as soon as you say anything negative about, well, anything. Nuclear power is certainly one of the larger touchstones, so it pays to be careful...

Anyway, I have re-written the section, (yes, with references) so I hope everyone will have a look and comment. I will be re-working the section on the Pu extraction again, as it appears that India is indeed doing this (yes, even from the CANDU's), but it is not clear whether the Pu used in their recent tests came from extraction or breeding at their other plant. We'll likely never know for sure, and with the recent US agreement the best we can say is it is unlikely this will happen in the future anyway. Maury 16:03, 1 June 2006 (UTC)

I've tightened up the wording in this section and removed some statements that I think are questionable (see below). In the end this has become a wishy-washy section that says little of any value, but then that's Wikipedia. Basically, all existing reactors produce plutonium, and safeguards are what's important (India's indigneous reactors, historically unsafeguarded, happen to be PHWRs). There are many ways to produce tritium, and India practices a few of them, including the efficient lithium-6 process and the not-so-efficient heavy-water extraction process (but very efficient if your goal is worker safety).

Two items removed, which can perhaps be re-inserted if cleaned up and referenced:

Concerns over the source of the plutonium in the Shakti tests led, in 2005, to an agreement between India and the US to place all civilian plants under full IAEA safeguards.

Any new and proposed aggreements do not cover "all" civilian plants, and the motivation is not so much the source of Shakti plutonium (that was Dhruva), but plutonium controls in general, and trade aggreements with the U.S.

In 1985 what was then Ontario Hydro sparked off an intense debate in Ontario due to their plans to sell excess tritium to the US for use in their nuclear stockpile. In the end, sales to the US weapons labs were banned in August 1989...

The tritium was never intended for the U.S. nuclear stockpile. I've modified this text in the article, but didn't know about the last bit - I'm not sure what it means (in light of the original intention not being for military sales), and it needs some kind of reference - which, unless I missed it, is not the one provided at the end of the paragraph. Whitlock 06:04, 2 June 2006 (UTC)

Background section

I have removed this as a better job is done elsewhere, and no other specific reactor design article feels the need to describe general reactor physics in this detail/ --DV8 2XL 06:11, 2 June 2006 (UTC)