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What is the fixed cost vs. variable cost breakdown for a nuclear power plant?

  1. May 12, 2017 #1


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    I am trying to understand the fixed cost of a nuclear power plant relative to variable cost.

    By fixed cost I mean "cost that does not vary with the amount of the power outputted over a given time period."

    By variable cost I mean "cost items that vary with the amount of the power outputted over a given time period."

    Does the whole plant have to be either on or off? Or can its output be scaled down pretty much on a continuum? Or perhaps on a discrete scale? In either case, what are the cost savings during scaled-down times, e. g. off-peak demand, relative to total cost of operating?
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  3. May 15, 2017 #2
    I am not a financial type so Take the following with a grain of salt.

    Let's look at an 1100 MWe reactor. Assume it cost $8 billion, and runs at 90% capacity.

    First, the $8 billion capital cost, spread evenly over the initial 40 year license, would be $200,000,000 per year. I know finance is more complicated than that, what with interest, depreciation, etc. but that $200 million gives a rough idea of the cost. That's fixed.

    Then, the payroll. If the unit has 600 employees at say $100,000 per year salary, that's $60,000,000 per year. That's fixed.

    The NRC charges licensees about $5 million per year. That's fixed.

    So that adds up to $265,000,000 per year fixed costs.

    Now, the fuel. The fuel cost is about 3/4 of a cent per kw-hr. For the 1100 MWe reactor that's about $65 million per year. Is this a fixed cost? Well, kind of, since the power company buys the fuel for the cycle all at once, they are making payments on it whether the plant operates or not. On the other hand, a load of fuel will last for a certain burnup so it really isn't fixed cost.

    I cant think of too many other big ticket items that are not fixed; there are things like burnup on the incore instruments (a few million to replace every few cycles). I'm sure there are others that might be identified by those closer to daily operations than I am.

    I don't really know what the maintenance costs are and how closely tied they are to power production.

    Looking forward to hearing from others.
  4. May 16, 2017 #3
    The United States Energy Information Administration has some cost estimates for nuclear and other types of power plants on page 2-10 (PDF page 44) of this report. As can be seen, nuclear has high fixed costs and low variable costs. In fact, the interest rate on construction bonds are one of the largest costs for a nuclear power plant.

    Nuclear power plants can adjust output, but due to their high fixed costs it makes the most sense to operate them at full output. French nuclear power plants are modified to be load following, but that requires careful coordination because plants with older cores have low/no ability to increase output if adjusted downwards due to loss of reactivity.
  5. May 16, 2017 #4
  6. May 17, 2017 #5


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    Per the 2016 referenced, the capital cost of solar plus battery storage is about the same as nuclear in the US, and the variable O&M for nuclear is 3X cheaper than solar plus battery storage. In several other countries, China, S. Korea, Russia, India, advanced nuclear is far cheaper than solar plus battery storage.
  7. Jul 6, 2017 #6
    I'm not sure of any good numbers for the disposal of spent fuel since many plants haven't yet disposed of any.
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