# Cost of building a new nuclear power plant vs expanding existing plants **URL:** \ **Category:** Factual Questions\ **Created:** [May 25, 2019, 8:20pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513 "2019-05-25T20:20:14Z")\ **Posts on this page:** 14\ **Page:** 3
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [June 1, 2019, 2:46pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/41 "2019-06-01T14:46:44Z")
> [@joema](#): > > Your number is roughly correct, however it doesn’t consider future growth in electrical consumption which would occur over the duration of such a buildup. A. On the one hand: US electrical consumption has been [declining](https://en.wikipedia.org/wiki/Energy_in_the_United_States#Consumption) in recent years. A lot of stuff is getting more efficient. This trend is expected to continue … for the most part. B. OTOH: If there’s is a large scale shift towards electric vehicles that might reverse the trend. But this is not a guarantee and should only be a secondary consideration on projecting future power demands. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [June 1, 2019, 3:53pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/42 "2019-06-01T15:53:17Z")
> [@Wesley\_Clark](#): > > …we’d need about 300 new plants to make the electricity grid 100% non-polluting (we’d be at 80% nuclear and 20% renewables)… . Not sure where you got the idea that Nuclear is non polluting. Just like an electric car is non polluting by shifting the pollution to power generation, the Nuclear Plant is non polluting by shifting the pollution to fuel mining and purification. > [@](#): > > Claims that nuclear power is a ‘low carbon’ energy source fall apart under scrutiny, writes Keith Barnham. Far from coming in at six grams of CO2 per unit of electricity for Hinkley C, as the Climate Change Committee believes, the true figure is probably well above 50 grams - breaching the CCC’s recommended limit for new sources of power generation beyond 2030. Cite : [False solution: Nuclear power is not 'low carbon'](https://theecologist.org/2015/feb/05/false-solution-nuclear-power-not-low-carbon) ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [June 1, 2019, 4:34pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/43 "2019-06-01T16:34:30Z")
> [@Wesley\_Clark](#): > > Switching all the fossil fuels in the grid to nuclear would require building about 300 new nuclear plants. I wasn’t sure what the cost would be for a new nuclear plant vs expanding the existing plants. Your OP is about baseload power, which nuclear if good for. “Switching all the fossil fuels on the grid to nuclear” doesn’t make sense. All baseload will be a smaller number. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [June 1, 2019, 5:34pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/44 "2019-06-01T17:34:10Z")
> [@am77494](#): > > Cite : [Thermal Water Pollution from Nuclear Power Plants](http://large.stanford.edu/courses/2019/ph241/clark1/) > Keep in mind that the typical Nuclear power plant is in the GW capacity where’s as you can have distributed generation with Natural Gas. In fact you can have a 0 water usage Natural Gas plant running in open cycle. There is no technical reason you can’t air cool a nuclear plant. It just raises the cost of the heat exchangers, since now they would need to be larger. Apparently, the classic “cooling tower” design is in fact an air source heat exchanger that only consumes some of the cooling water. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [June 1, 2019, 7:04pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/45 "2019-06-01T19:04:48Z")
> [@SamuelA](#): > > There is no technical reason you can’t air cool a nuclear plant. Yes there is. The condenser temperature in the steam circuit decides the overall efficiency of the steam cycle. This is also evident from basic Second law of Thermodynamics. The temperature of the source of heat (the fission reactor) and the temperature of the sink (water or air) decides the maximum efficiency possible. Air temperatures during day time is typically hotter. There is also the approach temperature problem. So say if you have air and water, both at 70F, the maximum cooling of a stream you will practically get with the water is about 75F while air coolers will only get you to about 85F. I have designed several power plants / chemical plants where the above was evident. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [June 1, 2019, 7:18pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/46 "2019-06-01T19:18:39Z")
> [@am77494](#): > > Yes there is. The condenser temperature in the steam circuit decides the overall efficiency of the steam cycle. > > This is also evident from basic Second law of Thermodynamics. The temperature of the source of heat (the fission reactor) and the temperature of the sink (water or air) decides the maximum efficiency possible. > > Air temperatures during day time is typically hotter. There is also the approach temperature problem. So say if you have air and water, both at 70F, the maximum cooling of a stream you will practically get with the water is about 75F while air coolers will only get you to about 85F. > > I have designed several power plants / chemical plants where the above was evident. I will admit I didn’t think of this angle - this would make the plant’s peak power output drop during hot days, because each nuclear reactor is a very expensive source of heat and is only licensed for a strict thermal output. Since reactors are so expensive, the owner will want to have the reactor running as much as possible at maximum licensed thermal output, and be extracting all the economically recoverable electricity from it. Still, it would work. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [June 1, 2019, 7:59pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/47 "2019-06-01T19:59:59Z")
> [@SamuelA](#): > > …this would make the plant’s peak power output drop during hot days… That’s not how nuclear power plants are operated. They are operated at base load - they pick a comfortable output and stick to it. Efficiency is not as important as safety, reliability and operability. The operators get to the plant to a safe / steady point and maintain setpoints to not the boat so much. All thermal systems and especially steam systems don’t like too much changes. > [@SamuelA](#): > > Since reactors are so expensive, the owner will want to have the reactor running as much as possible at maximum licensed thermal output, and be extracting all the … Again, I believe you are speculating. The owner (and regulators) are much more concerned about availability than to get to maximum output. Trips in a plant are expensive and turnaround times are long - very long. A stable operation is much more preferred than maximum output. > [@SamuelA](#): > > Still, it would work. You don’t design nuclear power with “it would work”. The reliability of air cooling , cost of air cooling, pressure drop through air coolers, failure modes and effect on the environment, maintainability, etc etc will need to be evaluated/demonstrated before anyone even dares to put a design like that in front of permitting boards. It takes a lot of steps from “it will work” to actually make it work. And I wonder why would anyone do that when the proven method works better. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [June 1, 2019, 8:19pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/48 "2019-06-01T20:19:18Z")
> [@am77494](#): > > That’s not how nuclear power plants are operated. They are operated at base load - they pick a comfortable output and stick to it. Efficiency is not as important as safety, reliability and operability. The operators get to the plant to a safe / steady point and maintain setpoints to not the boat so much. All thermal systems and especially steam systems don’t like too much changes. > > It takes a lot of steps from “it will work” to actually make it work. And I wonder why would anyone do that when the proven method works better. If you’re actually credentialed like you claim, you know that it would be possible to design a steam plant to operate with a variety of coldest achievable water return temperatures. Yeah, sure, there’s a lot of engineering to make it work all of the time, but in general, if you _had_ to design a type of nuclear reactor intended to operate, say, in canyons in a desert, and you had the appropriate budget and time, this is a readily achievable goal. Why might you do this? Answer is obvious - if you were trying to come up with a way to do mass deployment of hundreds of new nuclear plants, instead of making each one have a minimum chance of a meltdown at an exorbitant cost, another strategy would be to site each cluster of reactors in an uninhabited desert. Plan for meltdowns from day 1 - design the basements of the reactors to disperse the corium, place the whole plant underground, and so on. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [June 1, 2019, 10:00pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/49 "2019-06-01T22:00:00Z")
IIRC the wet bulb temperature is typically more important than the water temperature. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [June 1, 2019, 10:44pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/50 "2019-06-01T22:44:32Z")
> [@Ruken](#): > > IIRC the wet bulb temperature is typically more important than the water temperature. If you’re using evaporative cooling - the recent topic is pure “air source” plants where there is no water used (except in closed coolant loops). This is because people and population follow sources of water (and people also like coastlines so seacoasts are also crowded), and it turns out that nuclear plants create a terrible mess when they melt down and containment is breached. So the plant would use some kind of heat exchanger that would probably resemble a gigantic, multi-story car radiator. ---
**Author:** ![DWMarch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dwmarch/32/1010_2.png) [@DWMarch](https://boards.straightdope.com/u/DWMarch)\ **Post date:** [June 2, 2019, 7:01am UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/51 "2019-06-02T07:01:32Z")
> [@DPRK](#): > > OK, Wikipedia says the one 3.5 GW CANDU plant had $5.1 billion in overnight costs, $14.3 billion total capital costs. Do you have any data on the cost of expanding an existing plant, or renovating one to work for a few more decades? > > ETA the Ontario government cancelled proposed expansion there because it would cost too much… So in other words they said… no CANDU? ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [June 2, 2019, 1:54pm UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/52 "2019-06-02T13:54:46Z")
> [@SamuelA](#): > > If you’re using evaporative cooling - the recent topic is pure “air source” plants where there is no water used (except in closed coolant loops). This is because people and population follow sources of water (and people also like coastlines so seacoasts are also crowded), and it turns out that nuclear plants create a terrible mess when they melt down and containment is breached. > > So the plant would use some kind of heat exchanger that would probably resemble a gigantic, multi-story car radiator. Yes I should have quoted the earlier post that was pointing out air vs water temp. But re: air cooling, DOE had an entire program on air cooling a few years back. [https://arpa-e.energy.gov/?q=programs/arid](https://arpa-e.energy.gov/?q=programs/arid) It doesn’t work. But even if it does, how you cool the turbine loop is largely immaterial wrt the safety of the coolant loop. Air cooling, if we can make it not suck, is important for water scarcity and thermal pollution reasons for all steam turbine processes (e.g. coal, NGCC), not really for anti-meltdown reasons. ---
**Author:** ![Frankenstein\_Monster](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@Frankenstein\_Monster](https://boards.straightdope.com/u/Frankenstein_Monster)\ **Post date:** [June 3, 2019, 10:35am UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/53 "2019-06-03T10:35:56Z")
> [@am77494](#): > > That’s not how nuclear power plants are operated. They are operated at base load - they pick a comfortable output and stick to it. Efficiency is not as important as safety, reliability and operability. The operators get to the plant to a safe / steady point and maintain setpoints to not the boat so much. All thermal systems and especially steam systems don’t like too much changes. All this is true and how nuclear reactors are run in the U.S. But as a side note, in France and Germany at least, they do run nuclear reactors in load following mode. This comes with a long list of limitations, qualifications and considerations and affects EVERYTHING (design, operation, permitting, etc.etc.) but it can be done. It was important enough for the French to go through all this trouble. [Short OECD NEA report (PDF)](https://www.oecd-nea.org/nea-news/2011/29-2/nea-news-29-2-load-following-e.pdf) [Long OECD NEA report (PDF)](https://www.oecd-nea.org/ndd/reports/2011/load-following-npp.pdf) ---
**Author:** ![PastTense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pasttense/32/14550_2.png) [@PastTense](https://boards.straightdope.com/u/PastTense)\ **Post date:** [February 19, 2022, 12:15am UTC](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513/54 "2022-02-19T00:15:17Z")
> [@Corry\_El](#): > > The only example of nuclear plants to (possibly) be completed lately are Vogtle units 3 and 4, estimated $25 billion for 2\*1.1 GW units. Estimates are increasing: > Southern Co. yesterday announced another delay for its long-troubled nuclear construction project in Georgia, edging its costs closer to the $30 billion mark. > > The setback could now push the startup date for Plant Vogtle’s first reactor until early 2023 and move the date for the second one to later that year. > **[Plant Vogtle hits new delays; costs surge near $30B](https://www.eenews.net/articles/plant-vogtle-hits-new-delays-costs-surge-near-30b/)** > > The move highlights the nuclear industry's chief troubles with building large, baseload reactors: safety and cost [Previous page](https://boards.straightdope.com/t/cost-of-building-a-new-nuclear-power-plant-vs-expanding-existing-plants/834513.md?page=2)