Subtitle: No Benefits From Smaller Modular Nuclear Plants
Are there any benefits from small, modular nuclear power plants? As background, this series on nuclear power has shown that
large, “cathedral” nuclear power plants of 1,000 MWe or greater cost as much as
$10 billion each to construct. The high
capital costs require a high power sales price, making the new generation of
nuclear power plants uneconomic. See Part Two, Part Three, and Part Six for particulars.
This article explores the costs that can be expected if smaller, modular
nuclear power plants are installed.
There is a contingent of nuclear power proponents that insists that
costs per kW can be reduced by building smaller plants, more of them, and
building them in controlled factory conditions. But, are those assertions true?
Modular Small Nuclear Plant source: Energy.gov |
The short answer is, No.
Supposedly, the benefits are shorter construction times, less inflation,
less interest on loans, all of which lead to lower costs. But, loss of economy of scale overwhelms such
benefits. Consider 1200 MWe vs 600, 400,
300, and note that Dept of Energy defines Small Modular Reactors as 300 MW or less. Each of the smaller size plants must be delivered much more quickly to
achieve any savings in materials inflation and interest on construction loans. A
shorter construction period very likely cannot be done due to fabrication and
delivery of large items: the reactor, steam generators, turbines, and pumps.
There
is, perhaps, a case for some capital savings for a smaller plant if only one
steam generator can do the job instead of two or more. For example, the 1600 MW plant under
construction in Finland has four steam generators for its one reactor. The recently-closed plants in California at
San Onofre each produced a bit more than 1000 MW, and each reactor has two steam
generators. Those steam generators, at approximately 500
MW per steam generator, caused problems that led to the plant shutting
down. Therefore, a 600 MW plant with one
steam generator probably cannot be done, or at least, no one would take that
risk. But, a 400 MW plant could have one
reactor and one steam generator and still remain within the proven size of
approximately 400 to 500 MW per steam generator. That single bit of savings, however, would
not be enough to overcome the cost increase per kW created by the loss of
economy of scale.
The initial premise is that a 1,000 MWe nuclear plant would
cost $4,000 per KW as its overnight cost (the cost to construct if it could all
be built in one month, or “overnight”), and materials and labor escalation or
inflation over six years increases the cost by $3,000 per kW, and finally, interest
on the construction loan increases the cost by another $3,000 per KW. The total is then $10,000 per kW. The sources for these costs is explained in
detail in Part Three. (Note, EIA shows 2013 overnight costs for a new
nuclear plant as $5,530 per kW). See
Table 2 from this link.
Costs for a smaller plant can be expected to follow the “Point 6” power
rule for economy of scale, such that the cost of Unit B is found by the formula
Cost B = Cost A x (Size B / Size A) ^0.6.
An example illustrates using overnight costs only, where Size B is 400
MW, Size A is 1200 MW, and Cost A is $4,800. Then,
Cost B = $4,800 x
(400/1200)^0.6 = $2,483 per kW overnight
cost.
Then, for a total power output of 1200 MW, three of the 400
MW plants are required. The total overnight
costs for the three plants is then 3 x 2483, or $7,449 per kW. The goal here is to have a final cost less
than $12,000, which is the single-plant size of 1200 MW times the cost per kW
of 10,000. With the overnight cost already at $7,450
(rounded slightly, which is fine using such rough numbers), one is left with
only 4,550 available for inflation and escalation, plus interest. If we
make the very rough allocation of escalation or inflation is the same as
interest on the loan, that then results in each category being half of 4,550,
or 2,275.
Then, we can compute the
number of years that the modular plant must require for construction, at
inflation of 5 percent per year. Calculations show that approximately 5.5 years
at 5 percent per year yields the desired result. To save any on the final costs, then, the
modular plants must be built in less than 5.5 years. Stated
another way, savings are realized only if the plant can be brought online in 3
or 4 years from notice to proceed.
The question is, then, can it be done? Once again, the nuclear industry is
scrambling, trying to find a way to justify itself. Small, modern design, modular-constructed
nuclear power plants have never been built in the US, indeed, they are not even
approved by the NRC. The first projects
would suffer all the problems of first-of-a-kind projects, and likely have no
cost reductions at all.
The same analysis can be performed for smaller plants, such
as 300 MW, where four plants would be required to produce 1200 MW of power, and
200 MW, where six plants would be required.
The results are as follows. The
300 MW plants must be constructed in 4 years to have zero savings, with any
savings produced only if construction time is 2 or 3 years. The 200 MW plants must be constructed in 2.1
years to have zero savings over the cathedral design. It seems highly unlikely that small, modular
plants can be built on such short timescales.
The analysis is dependent on the inflation or escalation rate
for equipment, labor, and services over the life of the project. If the inflation rate is higher, as many
forecasters predict must be the case, then the situation is worse. The amount of time required to build the
plant and yield a cost savings will be less and less as the inflation rate
increases.
Conclusion
There are no benefits to the smaller, modular nuclear power
plants that some nuclear power proponents advocate. The loss of economy of scale requires much
shorter construction times for any savings to be had.
Update: 4/17/14 - Modular reactor developer cuts development, funding by 90 percent due to lack of customers and lack of investors. (Imagine that...) "Babcock & Wilcox will slash its spending on the mPower small modular reactor project, having failed to find customers or investors." also, from same article: "In February this year (2014) Westinghouse announced it would scale back its development of its 225 MWe small modular reactor design, having lost out in the DoE competition." see link from World Nuclear News, 4/14/14 -- end update
Update 2- 4/19/14: - Navy-style small reactors are mentioned by nuclear advocates as proof that smaller reactors are viable. Those reactors do indeed function for the purpose. However, the issue is one of cost and the price require for electric power on a grid powered by nuclear reactors. The US Navy has many nuclear powered ships and submarines that work very well. Those reactors are not designed like commercial power plants. Also, the economy of scale applies here. It appears that the largest of the military reactors are approximately 165 MWe, however the USS Ronald Reagan, a new aircraft carrier, has two nuclear reactors each producing just under 100 MW of shaft power. Such small reactors would require very high-priced electricity. -- end update 2
Update: 4/17/14 - Modular reactor developer cuts development, funding by 90 percent due to lack of customers and lack of investors. (Imagine that...) "Babcock & Wilcox will slash its spending on the mPower small modular reactor project, having failed to find customers or investors." also, from same article: "In February this year (2014) Westinghouse announced it would scale back its development of its 225 MWe small modular reactor design, having lost out in the DoE competition." see link from World Nuclear News, 4/14/14 -- end update
Update 2- 4/19/14: - Navy-style small reactors are mentioned by nuclear advocates as proof that smaller reactors are viable. Those reactors do indeed function for the purpose. However, the issue is one of cost and the price require for electric power on a grid powered by nuclear reactors. The US Navy has many nuclear powered ships and submarines that work very well. Those reactors are not designed like commercial power plants. Also, the economy of scale applies here. It appears that the largest of the military reactors are approximately 165 MWe, however the USS Ronald Reagan, a new aircraft carrier, has two nuclear reactors each producing just under 100 MW of shaft power. Such small reactors would require very high-priced electricity. -- end update 2
Part One – Nuclear Power Plants Cannot Compete
Part Three – Nuclear Power Plants Cost Far Too Much to
Construct
Part Four – Nuclear Power Plants Use Far More Fresh Water
Part Five – Cannot Simply Turn Off a Nuclear Power Plant
Part Six – Nuclear Plants are Huge to Reduce Costs
Part Seven -- All Nuclear Grid Will Sell Less Power
Part Eight – this article
Part Nine -- Nuclear Plants Require Long Construction Schedules
Part Ten - Nuclear Plants Require Costly Upgrades After 20 to 30 Years
Part Eleven - Following France in Nuclear Is Not The Way To Go
Part Twelve - Nuclear Plants Cannot Provide Cheap Power on Small Islands
Part Thirteen - Nuclear Plants Are Heavily Subsidized
Part Fourteen - A Few More Reasons Nuclear Cannot Compete
Part Fifteen - Nuclear Safety Compromised by Bending the Rules
Part Sixteen - Near Misses on Meltdowns Occur Every 3 Weeks
Part Seventeen - Storing Spent Fuel is Hazardous for Short or Long Term
Part Eighteen - Reprocessing Spent Fuel Is Not Safe
Part Thirteen - Nuclear Plants Are Heavily Subsidized
Part Fourteen - A Few More Reasons Nuclear Cannot Compete
Part Fifteen - Nuclear Safety Compromised by Bending the Rules
Part Sixteen - Near Misses on Meltdowns Occur Every 3 Weeks
Part Seventeen - Storing Spent Fuel is Hazardous for Short or Long Term
Part Eighteen - Reprocessing Spent Fuel Is Not Safe
Part Nineteen - Nuclear Radiation Injures People and Other Living Things
Part Twenty - Chernobyl Meltdown and Explosion
Part Twenty One - Three Mile Island Unit 2 Meltdown 1979
Part Twenty Two - Fukushima The Disaster That Could Not Happen
Part Twenty Three - San Onofre Shutdown Saga
Part Twenty Four - St. Lucie Ominous Tube Wear
Part Twenty - Chernobyl Meltdown and Explosion
Part Twenty One - Three Mile Island Unit 2 Meltdown 1979
Part Twenty Two - Fukushima The Disaster That Could Not Happen
Part Twenty Three - San Onofre Shutdown Saga
Part Twenty Four - St. Lucie Ominous Tube Wear
Part Twenty Five - Price-Anderson Act Protects Nuclear Plants Too Much
Part Twenty Six - Evacuation Plans Required at Nuclear Plants
Part Twenty Seven - Power From Nuclear Fusion
Part Twenty Eight - Thorium MSR No Better Than Uranium Process
Part Twenty Nine - High Temperature Gas Reactor Still A Dream
Part Thirty - Conclusion
Part Twenty Eight - Thorium MSR No Better Than Uranium Process
Part Twenty Nine - High Temperature Gas Reactor Still A Dream
Part Thirty - Conclusion
Roger E. Sowell, Esq.
Marina del Rey, California
4 comments:
You are right: cost is proportional to the surface (materials), power is proportional to the volume of the core. But the same rule is applicable to the passive cooling efficiency:
Cost_B = Cost_A x (Size_B / Size_A)^n
PCE_B = PCE_A x (Size_B / Size_A)^n
PCE - Passive cooling efficiency
n = 0.5 - 0.7
300 MW nuclear power station is more costly than 1200 MW, but smaller reactor is safer. Deterministic safety is achievable for all small enough reactors. Alvin Weinberg pointed out already 50 years ago that probabilistic safety is nice, but deterministic safety is a real safety. Moreover playing with probabilistic safety the reactors are getting safer and safer but they are more and more expensive, they have more and more safety systems.
It is high time to come back to small reactors and deterministic safety concepts.
A more comprehensive price analysis of small modular reactors would take into account the pervasive savings due to increased safety. The inherent safety is real affecting everything from insurance, cost of clean-up, cost of lives saved, reduced environmental impact, and yet your analysis conveniently leaves out any analysis or discussion of improved safety. Your entire series reads as if you already know the conclusion, you are just advocating for the unaffordable cost conclusion you seek.
Anon Y Mous, from August 13.
Actually, the answer is no amount of increased safety, even if they did exist as you state without any factual support, can overcome the inherently high cost of construction.
The sheer amount of nuclear-grade welding in thick, high-pressure metal for the SMRs is prohibitively expensive.
The great number of items of equipment further doom the SMR concept. The cost per kWh sold must be prohibitively expensive.
I have zero pre-conceived conclusions. I strive to follow the valid facts to the logical conclusions.
I should add that the NuScale SMR concept is now under safety review at the NRC. Published documents on the SMR 50 MW module (complete reactor, steam generators, steam turbine, electrical generator) shows the inherent very high costs of construction.
An update to the original article will be added on this.
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