When Canada began its nuclear power program, it chose to use heavy water to moderate (slow down) the fission neutrons. This choice reduces the number of neutrons that are not available for fission by reducing the absorption of those neutrons in the moderator. The improvement in neutron utilization is enough to allow a self sustaining chain reaction to occur even if the fuel source is natural uranium.
I often point to the CANDU designs during arguments with people who claim that the enrichment process uses “a lot” of input energy, adds a “huge” amount of cost, increases the risk of proliferation, or makes the uranium fuel cycle a greenhouse gas emitter. My comment to those people is – “so how do you feel about reactors that do not need enrichment?” Of course, the usual response is that those people do not like those reactors either. They often cannot give me any answers about why the new information does not affect their choice, but I attribute their silence to the fact that their manipulators have not provided any canned responses to the rarely used question.
One thing that many people in the nuclear industry do not understand or only dimly recall is the history of the battle between reactors using enriched uranium and natural uranium fueled reactors like the CANDU or gas cooled graphite reactors that were often the first commercial reactors built in countries outside of the United States. Those reactors were the natural choice of countries that owned nuclear knowledge combined with a desire to be independent of the US for their nuclear fuel supplies.
This was an important consideration since the US refused to sell enriched uranium before 1954 and after that time it required any customer to sign an agreement allowing unannounced inspections by Americans – not an international body – to verify that the material was being used for peaceful purposes. Though some of my countrymen cannot understand this concept, the idea of purchasing something with such an onerous restriction on its use was not well received. Canada, our next door neighbor, pursued the development of heavy water cooled reactors after being progressively shut out of wartime nuclear technology developments as General Groves tightened his grip on information. That was pretty galling for a close ally who had a long and distinguished history of nuclear science before the war ever started. (See, for example, Morgan Brown’s Canadian Nuclear Society – Nuclear History.)
In addition to Canadian construction of CANDUs at home, China, India, Argentina, Pakistan, Romania and South Korea chose to purchase reactors from Canada that could run on natural uranium. It is no coincidence that each one of those countries had specific reasons at the time of purchase for not wanting to be too dependent on the US.
The reason I bring this information up now is that there is a new commercial competition heating up in the nuclear business, and at least two of the current owners of CANDU reactors – Ontario and Romania – are being heavily courted by companies and countries that market light water reactors that would require the use of enriched uranium. Since neither of those countries have their own large scale enrichment facilities and since both of them are currently fully self sufficient in supplying their own nuclear fuel, choosing something other than a CANDU would represent a major policy and technology shift.
There is also a matter of technical knowledge. Canadian and Romanian scientists, engineers, operators and repair technicians all have developed a vast amount of experience with the CANDU technology. A decision selecting a completely new type of reactor and fuel system, like the EPR, the AP-1000, the ABWR or the ESBWR would require a large investment in retraining or replacing those people.
One other advantage that the CANDU design has over its light water rivals is that it was also designed to avoid using large, forged components. Canadian engineers developed the calandria and pressure tube concept so that it did not depend on the heavy manufacturing capacity that was only available outside of the country. As most readers of this blog probably know by now, there is a line developing at the doors of Japan Steel Works, the only current source of some key components for all of the light water reactor designs. CANDU purchasers can avoid that line and the project delays that it imposes. (Of course, if I ran Japan Steel Works and saw a long and growing line of orders, I might be just a bit tempted to increase my prices significantly.)
Here are two articles that are worth a read:
- Reactor contract details on way
Subtitle: Ontario to announce selection process that won’t ‘favour’ AECL.
The article was published on March 3 by TheStar.com out of Toronto, Canada.
- Price for French nuclear tech may prove too high
Subtitle: With France pushing for greater cooperation on nuclear power with Romania, the Canadians who first introduced nuclear tech to Romania argue the Gallic technology comes at a cost the country may not be willing to pay.
The article was published in March 2008 by The Diplomat out of Bucharest (thediplomat.ru).
It is likely that the collegial atmosphere that has been rather prevalent in the nuclear power industry during the past 15 years or so, when it was us against the world, may be strained a bit as we compete for the new plant orders that look like they are just around the corner. Just in case you forget who the real competition is, let me quote from the article about the Romanian decision process:
Reducing the energy dependency on increasingly expensive gas and oil is the main argument for building a second nuclear plant.
Final note: If you want a great history of the competitive development of nuclear power, I highly recommend Bertrand Goldschmidt’s The Atomic Complex: A Worldwide Political History of Nuclear Energy published in 1982 by the American Nuclear Society, LaGrange Park, Il.