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

Click For Summary

Discussion Overview

The discussion focuses on the breakdown of fixed and variable costs associated with nuclear power plants. Participants explore the definitions of fixed and variable costs, the operational capabilities of nuclear plants regarding output scaling, and the implications for cost savings during off-peak demand periods.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants define fixed costs as those that do not vary with power output, while variable costs are linked to the amount of power produced.
  • One participant provides a rough estimate of fixed costs for an 1100 MWe reactor, including capital costs, payroll, and regulatory fees, totaling approximately $265 million per year.
  • There is uncertainty about whether fuel costs should be classified as fixed or variable, as they involve upfront purchases but are consumed over time.
  • Some participants note that nuclear power plants can adjust their output, but due to high fixed costs, it is generally more economical to operate at full capacity.
  • References to external reports from the United States Energy Information Administration are made, indicating that nuclear plants have high fixed costs and low variable costs compared to other energy sources.
  • One participant mentions that while nuclear plants can be modified for load following, this requires careful management, particularly for older reactors.
  • Comparative cost analyses suggest that advanced nuclear technology may be cheaper than solar plus battery storage in certain countries.
  • There is a lack of consensus on the disposal costs of spent fuel, as many plants have not yet disposed of any.

Areas of Agreement / Disagreement

Participants express various viewpoints on the classification of costs and the operational characteristics of nuclear power plants. There is no clear consensus on the definitions or implications of fixed versus variable costs, nor on the specifics of operational practices.

Contextual Notes

Participants acknowledge the complexity of financial calculations, including factors like interest and depreciation, which may affect cost assessments. There are also references to the evolving nature of energy costs over time and the impact of regulatory frameworks.

EnumaElish
Science Advisor
Messages
2,348
Reaction score
124
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?
 
Engineering news on Phys.org
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 can't 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.
 
  • Like
Likes   Reactions: mheslep, russ_watters and EnumaElish
EnumaElish said:
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?

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.
 
  • Like
Likes   Reactions: EnumaElish
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.
 
I'm not sure of any good numbers for the disposal of spent fuel since many plants haven't yet disposed of any.
 

Similar threads

  • · Replies 52 ·
2
Replies
52
Views
11K
  • · Replies 32 ·
2
Replies
32
Views
6K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 3 ·
Replies
3
Views
6K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 3 ·
Replies
3
Views
5K
  • · Replies 50 ·
2
Replies
50
Views
22K
  • · Replies 131 ·
5
Replies
131
Views
30K