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Small nuclear power plants.

  1. Apr 3, 2006 #1
    I've always thought that a small nuclear reactor installation that would power an average size county (as opposed to a large city county) would be more efficient that the large installations such as Three Mile Island. Less expensive to construct and operate. Anyone care to comment on feasibility, advantages, disadvantages. I am not an expert.

  2. jcsd
  3. Apr 3, 2006 #2
    I'd think it would be more cost effective to have fewer locations and build bigger. France ITER is building the biggest right now. Fewer places to guard, less red tape and fewer waste routes etc.

    My two cents
    Last edited: Apr 3, 2006
  4. Apr 3, 2006 #3


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    Such a small modular design of 10 MWe has been designed and proposed by Toshiba for Galena, Alaska.

    Licensing Status in US - Currently Inactive:
    from NRC
  5. Apr 3, 2006 #4


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    ITER is an international research program to demonstrate the latest technology in fusion. Commerical fusion power systems have yet to be perfected.
  6. Apr 3, 2006 #5


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    How is that going by the way? When are they going to be up and testing?
  7. Apr 3, 2006 #6
    Oh, ok. I thought that was the name of the French company building that reactor. :confused:
  8. Apr 3, 2006 #7


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    I would think that since some of the biggest costs in building a nuclear power are political/regulatory, that larger would almost always be more efficient, since the cost of jumping through the hoops would be about the same regardless of size.
  9. Apr 3, 2006 #8


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    Iter homepage - http://www.iter.org/index.htm [Broken]
    schedule - http://www.iter.org/when.htm [Broken]

    Areva is the big French nuclear energy concern. They design and build the plants, make the fuel, and operate much of the fuel cycle.

    http://www.areva.com/servlet/ContentServer?pagename=arevagroup_en/home [Broken]

    Areva was formed after the merger of Framatome with Siemens's nuclear power portion.

    Russ is correct. There is a large front end cost associated with site licensing, which invovles a huge effort in terms of characterizing the plant site and surrounding area, including the siting of transmission lines, etc.

    Then there is the certification of the nuclear power system and the power plant supporting the nuclear reactor and power conversion systems.

    And then there is the waste and spent fuel issues.

    The licensing process has been streamlined recently, but it is not less rigorous - safety and environmental protection is still paramount.

    Currently the proposed next generation reactors (Gen 3+) would be added to current plant sites. There is one site which has been proposed, which was approved for a nuclear plant, but the plant was cancelled before start of construction.

    Size has its benefit and large utilities prefer units on the order of 1000 - 1500 MWe.
    Last edited by a moderator: May 2, 2017
  10. Apr 4, 2006 #9
    Thank you all very much.

    I was rather surprised at the response. It seems most everyone fell back to the large reactors such as TMI and the pitfalls and requirements involved in those type of installations.

    Consider, one of the biggest problems we have is damaging the environment. This won't harm the earth, it will only harm us. I've spent time in the Antarctic and have observed the shrinking coast lines and glaciers. It is happening. The heating of the earth is directly dependent on the population. Little short of reducing the population will have any effect. However, if we can heat all the homes and businesses with electric power, with no emissions, it can have an effect. Nuclear reactor development for power is pretty much stagnated.

    Small, maybe about a nuclear carrier size or a little larger, reactor should drastically reduce the problems. An installation of that type should take an area about the size of two houses, with open land around it for security. This type of installation can pretty much be developed off-site and trucked in except the buildings of course. With a few of these up and going it should get pretty standard. This should reduce building and operating costs drastically. No big cooling towers, no large complex, etc. Think carrier or submarine size.

    This just might jump-start the industry. There will be problems but that's what nuclear engineers are for.

    Small county size nuclear reactors for electrical power just for that county might work.

    Maybe some of the nuclear engineers out there might take another shot at this. Feasibility, advantages, disadvantages.
  11. Apr 4, 2006 #10


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    You are making the assumption that the cost and difficulty of operation scales with the
    size / power of the reactor - and that's not true.

    Whether your reactor is big or small - you still need the skilled cadre of operators.

    Whether your reactor is big or small - you still have to have meet all the legal
    requirements for Environmental Impact Statement, license filings.....

    With nuclear power plants, as in most industrial installations; there are certain
    "fixed costs" that don't scale [ go up or down ] with the size of the facility.

    Therefore, in order to better amortize these "fixed costs" - the LARGER the
    facility the more efficient - in that you get more product for your given fixed costs.

    Dr. Gregory Greenman
  12. Apr 4, 2006 #11


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    ITER = International Thermonuclear Experimental Reactor.

    Dr. Gregory Greenman
  13. Apr 4, 2006 #12


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    Let's look at 1000 MWe. One can have one plant on one site, or one could have 100 sites at 10 MWe each. Each site requires a team of operators and maintenance staff. A large plant might require 500-800 employees. Each small plant might require 10-20-50 employees - or 1000 - 5000 employees.

    Each small site would probably occupy the same area as the large plant - an exclusion zone. So one plant ~0.5 square mile vs 50 square miles for 100 plants.

    Regardless of the size of the plant, one is also stuck with thermodynamics and system efficiency, which for steam plants is about 33-34%, which means that about 66-67% of the thermal energy is discarded/rejected to the environment directly. Higher temperatures would increase efficiency, but at the cost of wear and tear on the equipment. Possibly a combined cycle plant Brayton/Rankine could be used, but that requires two thermal to mechanical conversion systems, and perhaps two generator trains, unless one can optimize the rotational speeds of the gas turbine (Brayton) and steam turbine (Rankine) sets.
  14. Apr 4, 2006 #13


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    You don't know the power of a carrier reactor - they are NOT that small!!!

    One of the problems is that your exclusion area around the reactor doesn't scale
    with power. As long as you need to set aside an exclusion area - you might as well
    get the most for it. This augers for a LARGE reactor not a small one.

    Those big cooling towers are one of the MOST cost-effective parts of a nuclear
    power plant. You have to brush up on your physics here. Suppose you have a
    given demand for power. You can either meet that demand with one large power
    plant or 10 smaller ones. If you go the small power plant route - the smaller amount
    of heat that needs to be dumped will necessitate that you use a rather small forced
    circulation cooling tower. So you end up expending [ i.e. "wasting" ] some of your
    power in running the forced circulation for the cooling tower.

    If you have a large heat load - then you can use the natural circulation of those big
    hyperbolic cooling towers. With the big heat load you can get the waste heat to
    drive its own cooling flow.

    Building big towers like that is not very expensive. Although they may be large -
    they are not very complex.

    Maybe submarine size - but carrier reactors are fairly large.

    The carrier U.S.S. Enterprise is powered by 8 submarine sized reactors - and even
    at that it doesn't have the power of the Nimitz class carriers.

    The experience of small county sized reactors in the past has been VERY POOR!!

    The idea of community sized reactors has been tried before - the Piqua, Ohio plant
    for example. Or even a moderate sized city like Sacramento trying to run its own
    power plant Rancho Seco.

    The problem is that you need a LOT of expertise in running and managing these
    facilities. Small operations just don't have the type of quality "corporate knowledge".

    It takes a lot of money to get and train the best cadre of operators and managers.
    It's not a job for a small operation - NOT if you want to do it RIGHT!!!

    SMUD - the Sacremento Municipal Utility Districts operated Rancho Seco which
    was a single unit installation that was a twin of the dual reactors at the Oconee
    plant operated by Duke Power.

    At the time, Oconee was one of the BEST performing reactor plants - it routinely
    was at the top of the NRC list in terms of capacity factor. Rancho Seco was a twin
    of these units and could have achieved similar performance. Alas, SMUD just didn't
    have the expertise to operate Rancho Seco as efficiently as Oconee did. They didn't
    have the people and expertise.

    Again it's a problem of amortization. If you have a cadre of good people capable of
    making good decisions concerning plant operation - you'd like to be able to use those
    people to make good decisions for more than one plant - and to have those good
    decisions and practises give you the most power. Again - that augers for a LARGE
    plant; not a small one.

    The past experience for nuclear plants, as well as ANY complex industrial plant is
    that LARGE plants operate better and more efficiently than small plants.

    Additionally, large steam cycles - the steam turbine cycle - operate more efficiently
    in large systems than in small. The use of more reheat stages, etc which are cost
    effective in large plants give you better thermodynamic efficiency than one can
    realize in a small thermodynamic steam cycle.

    Small plants have only one advantage - you lose less output when the plant goes
    down unexpectedly. However, with properly managed large plants - that's not a big

    When a new nuclear power plant is proposed - the operator is going to have to go
    through all the hurdles of licensing the plant. More than likely there will be intervenors
    and years of court battles. After all that - a 100 Mwe power plant goes into operation.
    If you need 1000 Mwe - you've got 9 more identical battles to fight. If you build the
    1000 Mwe plant - you fight the battle once.

    Even in engineering, or should I say ESPECIALLY in engineering - you realize
    "economies of scale".

    You've made a lot of assumptions as to where the problems are - such as the size/cost
    of buildings and land and cooling towers. Those aren't the problems. In fact, those are
    are rather mundane non-problems. If you want to make concrete suggestions as to
    how to best proceed - I would suggest researching what the real problems are that
    have stymied the nuclear industry; instead of making a bunch of assumptions.

    Summarizing - small plants are NOT a good idea.

    Dr. Gregory Greenman
    Last edited: Apr 4, 2006
  15. Apr 4, 2006 #14


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    One thing that hasn't been mentioned here is the transmission and distribution issues. Though the country's transmission grid (the high-voltage, high tension lines) needs to be upgraded, it is in place and it works. Since the vast majority of the country's power requirements are relatively centralized, the structure of the current grid system doesn't really need to be changed.

    Take Philadelphia and southeastern PA, for example. A large fraction the area's power comes from the Limerick nuclear plant (2200MW), roughly 30 miles outside the city. Supplying power to a similar area with smaller reactors would require dozens of Enterprise-sized reactors (~25MW each) scattered around southeastern PA. Sure, you could get rid of the high voltage transmission by locating them at the larger substations, but that doesn't gain you much since the transmission lines are already there and aren't very long anyway.

    It is much more practical to simply locate one or two large nuclear plants a few miles outside of every major population center in the US.
  16. Apr 4, 2006 #15
    Thank you all again. Very interesting comments.

    Dr. Morbius, I stated in my first post that I wasn't an expert and I wasn't making a bunch of assumptions. I did offer some points of possible discussion and I do appreciate the efforts to respond. For everything there is a starting point.

    The industry seems stagnated and I doubt if it will ever start up again. It is probably one of the few things that just may have had an impact on the excess heat. Changes are slow so the generations to come will adapt. Arizona ocean front property may yet be a reality.
  17. Apr 4, 2006 #16


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    Read the thread "Prospect for Nuclear Power Industry in US"

    There are currently 12 COL's in various stages of preparation - that is for 12 new nuclear reactors.

    Over the last decade, many nuclear power plants have been uprated to the maximum original design capacity (using existing margins).
  18. Apr 4, 2006 #17


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    I'm just pointing out that when you hypothesize that a smaller plant may be more
    efficient - you are making an assumption. You have to be assuming something -
    otherwise what is your basis for saying that the small plant may be better?

    The assumption that you are making - and it's quite a natural assumption to make
    is that cost and other factors scale with the size - i.e. rated output of the plant.

    It does seem rather natural to make that assumption - if you need twice the power
    output, then you need twice the reactor power, and that reactor will be twice as
    expensive as one half its size....

    The problem is that in a field like nuclear power, there are an awful lot of fixed costs.
    The instant you want to build A reactor - then you've immediately saddled
    yourself with a whole bunch of responsibilities and problem. In a way - that's just
    the "buy-in" cost for playing in the "game".

    That said - since these costs don't scale with plant output power - e.x. you don't
    need 10X the number of security guards for a 1000 Mwe plant than you do for a
    100 Mwe plant. Therefore, it is advantageous to get the most output for the
    expenditure you need to make.

    Some costs scale - but in a field like nuclear power, there are a lot of fixed costs.
    You will be more efficient if you amortize the fixed costs over a larger output.

    Dr. Gregory Greenman
  19. Apr 4, 2006 #18
    Thank you Dr. Morbius.

    It took some doing but I think I found the current status and possibilities.


    This is pretty recent which is probably why I didn't find it before.

    Small installations can be built less costly and can be run with less operators. Single county reactors are a real possibility. (Remember I said "as opposed to a large city county.") A far greater efficient method has to be found to recover the heat rather than releasing it. In the US we need to find a way to cut the red tape. I know there is a great argument to be made here concerning red tape=safety. I understand that. Nevertheless a way has to be found or a lot of our descendents will never get born (is that a paradox or contradiction) or as Spock said on Star Trek, "Millions of people died that never died before.".

    Nuclear engineers arise and go forth.

    Again, than you all very much. I'm always surprised at the depth of knowledge on this board.
    Last edited by a moderator: Apr 22, 2017
  20. Apr 4, 2006 #19


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    On a per unit basis, this is correct - somewhat. One still needs the same number of operators for a small plant as a large one, although the staff may be smaller at a small unit.

    On the other hand, if one looks at the total capacity, for say 1000 MWe, one would need 10 plants of 100 MWe with 10x staff, and that would likely greatly exceed the staff of a 1000 MWe plant.

    The capital cost for ten turbine sets, ten 100 MWe generators and ten transformers and ten transmission systems would greatly exceed the cost of 1 turbine set, one 1000 MWe generator set and one transformer and transmission system. So to provide the same power, the building small individual plants would be detrimental, not beneficial.

    The thermodynamic cycle is completely independent of the plant size, and that is from where greater benefit would come.

    As for the knowledge in this forum - some of us are actual nuclear engineers and physicists! :cool:
    Last edited: Apr 5, 2006
  21. Apr 4, 2006 #20
    That's what I love about this site.
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