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Fast vs thermal reactor cost

  1. Jul 10, 2017 #1
    Is a "fast" reactor more economical in terms of capital investment than a thermal one? I am asking this because I assume a fast reactor only needs a smaller startup U235 source of on average 20% enrichment but can later run on its own produced fissile material and would normally for the rest of its life use natural uranium U238 or Thorium as it's fuel source, is there significant savings made due to the fact that the natural U and Th are not enriched and so don't go through the enrichment facilities through which normal thermal reactor Uranium fuel goes.?

    This thought struck my mind after reading up on centrifuge enrichment and also gas diffusion process I saw that on average such a plant needs its own nuclear reactor/s to power the energy it needs for the isotope separation process like the French Tricastin NPP which if I understand correctly powers a nearby enrichment facility which is located on site.
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  3. Jul 10, 2017 #2
    Don't forget that the enrichment plant is producing fuel for many reactors. I understand the energy used to enrich the fuel is ~ 2% of the energy produced when that fuel is used.

    Someone else can answer the economic question on thermal vs fast reactors.
  4. Jul 10, 2017 #3
    To be able to understand more easily the question I want to ask is how much MWh of electrical energy are needed to supply a full fuel load of a 1000MW electrical output PWR or BWR plant since they are the most common reactors out there. I do know there is this measurement for enrichment as SWU and that a single fuel load is changed not altogether but in steps since core regions burn up faster than the outer ones yet still speaking in terms of electricity in to enrich and electricity out as the available power to load is simpler to my mind.

    surely fast reactors must be more demanding in terms of materials and engineering so that would probably drive their cost higher in terms of building the plant.
  5. Jul 10, 2017 #4
    There are some numbers here:

    The overall EROI is calculated as 59 for a 40-year plant life and 70 for a 60-year life. Note that the enrichment values assume centrifuge operation which I believe is a lot less energy intensive than the older gas diffusion tech.

    On the other hand, "During the 20-year Megatons to Megawatts program, as much as 10 percent of the electricity produced in the United States was generated by fuel fabricated using LEU from Russian HEU." https://en.wikipedia.org/wiki/Megatons_to_Megawatts_Program

    That means half the reactor fuel used in the US required no energy input for enrichment, it was downblended from the Soviet weapons uranium.
  6. Jul 11, 2017 #5
    Fuel costs are not the main part in the price of energy generated in NPPs. If you look it from this angle, fast reactors are far less economical since almost all of them are one-of-a-type one right now.

    If you consider the the price of the fuel generated too, then - well, right now even the reprocessing is barely viable. And fuel generated in fast reactors needs to be reprocessed first before it can be used in other reactors.
  7. Jul 13, 2017 #6
    well technically fast reactors could simply be used like ordinary reactors only instead of regular refueling these could fuel themselves as enough fissile material is extracted from the blanket it can be then put in the primary fission core or so.
    I assume there is some reason why fast reactors are one of a kind experimental devices instead of routine reactors being built according to plan and certain design.
    I assume it has to do with two factors, firstly that we now know we have enough uranium to fuel our current needs for some time and the second factor could be that fast reactors are technically more challenging both with respect to materials endurance and other factors??

    does someone here know what's going on with the molten salt concept? I realize while reading it has some good potential in terms of fast reactors with onsite fuel reprocessing due to the molten liquid nature of the fuel.?

    oh and I guess that the second biggest investment right after building a NPP and getting the licensing done is the decommissioning of the plant after it's planned life cycle ends, probably fuel enrichment is only a small fraction of the cost if compared to these.
  8. Sep 17, 2017 #7
    The various cost issues are irrelevant in the USA, because its impossible to built a commercial reactor at any price.

    E.g., look at South Carolina and Georgia.
  9. Sep 18, 2017 #8


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    Of course, it is not impossible at any price, just at a high price that is not competitive with alternatives.. If a NPP could be built for a reasonable price, including fuel cost, and be competitive with alternative, e.g., natural gas-fired combined cycle plants, then folks would build them.

    Large NPPs (≥ 1100 MWe) do seem to have a high cost, as the recent situation at Summer demonstrated. They seemed off to a good start. It is hoped that SMRs will have lower upfront capital costs with units brought online in stages so that the first units will be generating revenue as others are completed. We'll see.

    Fast reactors are a different genus. The cores are very different. The US and France have had difficulty with commercial fast reactors, while the Russians seem relatively successful. Assessing the economics of a commercial fast reactor is difficult, since none have been built in the US. EBR-II generated of over 2 billion kilowatt-hours of electricity, but it was more a research reactor facility than a power station.
  10. Sep 19, 2017 #9
    You might be missing the point: Cost comparisons have no meaning in the nuclear game, because the players want infinite costs.

    The problem of non-completion is more about psychology and financial greed than engineering. This problem afflicts ALL nuclear facilities- including the MOX facility at Savannah River, the cleanup campaign at Hanford, and radioactive waste disposal sites. (Yucca Mountain is a good example!) The mindset in the USA and the U.K. now regards building nuclear facilities as a source of endless cash— the goal is to keep the development going at billions of dollars per year for an unlimited number of years, enriching executives and bureaucrats in the process. That is the case at Hanford, at Savannah River and the Vogtle plant in Georgia. True, the new build at the Summer plant in So. Carolina was recently shut down after hosing the ratepayers for a mere $3 or 4 billion(!) and driving Westinghouse into bankruptcy, but that’s an exception to the perpetual gravy train.

    New reactor builds in the U.K. are just a couple of years into the cash-cow process, but already show schedule delays exceeding one decade and projected mouthwatering overruns of tens of billions of euros or pounds. They will never be completed. Even France can no longer complete a nuclear plant, with its current builds 6+ years behind schedule and 7 billion euros over budget.
  11. Sep 20, 2017 #10


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    No question about your point that the incentives for the industry have become disfunctional. When the end of the job means permanent unemployment, slow completion and unhappy outcomes are guaranteed.
    That said, is not a large part of the problem the failure by governments to recognize that the commercial nuclear industry no longer exists in the western world?
    It was done in by a decades long drought of no new orders and no business to keep the design and construction teams together. Consequently all are building high end nuclear plants as a learning experience, which is very costly. The customers might have been better served to buy older, established designs, except that those no longer pass regulatory scrutiny.
  12. Oct 7, 2017 #11


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    And yet well over a hundred reactors have been built in the US. Another came online a year ago. The one nearest me has O&M less than 2 cents per kWh. Building reactors in the US has historically not been impossible. Abroad, some 58 reactors are underway.

    So conditions have changed via some combination of the factors involved, the current regulator, the industry, and/or the new design.
    Last edited: Oct 7, 2017
  13. Oct 8, 2017 #12
    The reactor that came online a year ago was the Watts Bar reactor. It was the first reactor to come online in the USA in twenty years! And its construction started about forty years ago!
  14. Oct 8, 2017 #13


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    Absent ongoing practice, skills atrophy, in reactor construction as in everything else.
    There may be a rebirth of nuclear in the western world at some point, but it would take a crisis that drives the needed massive investment to recreate the missing capabilities. That opens a window for some different approaches, but thus far no one has been able to implement any of the alternative designs.
    In this environment, discussions of costs are not credible, because there is no current track record for either conventional or fast reactors costs.
  15. Oct 8, 2017 #14


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    And? WB was not under construction for 40 yrs.
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