Nuclear reactors have been used on submarines for decades. McMurdo base in Antarctica was powered by a nuclear reactor for 10 years which ended in the 70s.
As a result of continuing safety issues (hairline cracks in the reactor and water leaks), the U.S. Navy Nuclear Power Program decommissioned the plant in 1972.
Or course, one would hope that more modern design would be safer.
So, I'm calculating a material buckling for S6G that's only one-fourth that of the described SMR, and I know S6G is highly enriched. Why is the SMR so close to parity for power density, especially if it's using natural circulation?
I'm getting bleary eyed from a day that has gone on too long, but how does something approximately 33x33x42 feet equal 140k ft^3? Same question with the first one too. The cubic-feet measurement is including something else, right? What might that be?
Oops...thanks for the catch. Used diameter instead of radius when calculating the volume of each cylindrical object. So, the cubic footage is off...but for both.
So, corrected:
For comparison, the reactor described here outputs 50 megawatts, and is 15 feet in diameter and 76 feet long (~13,500 cubic feet).
The S6G reactor in Los Angeles class submarines outputs 150 megawatts and is 33 feet in diameter and 42 feet long (~35,000 cubic feet).
50 MW is small for all the red-tape necessary to operate a nuke plant. 1500 MW is nice if you're going to need over 1,000 staff. I'm not sure how much headcount they could eliminate with a better design.
I'm assuming the plan is that a 15x50MW install isn't going to use 15x the 1x50 personnel and site prep. Otherwise there'd be no way they're viable except for smaller requirement installs.
It sounds like a neat idea, and potentially safer(?). But I don't understand why they're claiming it'll be cheaper:
> But one company thinks that by going smaller, they could actually make nuclear power more affordable.
And later in the article:
> The company believes that 570-MW project can be completed for less than $3 billion. By comparison, a new 1,150-MW reactor at Watts Bar in Tennessee cost around $4.7 billion and began operation in 2016 after years of delays.
Based on those numbers, the construction cost of the modular reactor system is almost 30% more expensive per MW. Are they anticipating the operational costs to be lower, thus saving money in the long run? But the article claims they're trying to save on the construction costs:
> Companies such as NuScale hope to offset the higher costs by saving on the cost of construction
Which isn't true, based on the numbers the article quotes.
On a related note, I wonder if refueling these modular would be more difficult/costly because of their smaller size and the submersion design?
> The savings would likely kick in as they manufactured more and more of the vessels.
Maybe, but I would have thought that would have either factored that into the quoted cost estimates, or that they would have said something like "and similar future plants would cost X". (where X is lower).
Those cost savings won't be immediate, and will likely have to wait until production facilities are expanded once there are sufficient orders to warrant it. And not just immediate orders, but ones for a few years out as well.
Sure, but surely they can make some sort of estimates, depending on quantities, typical economies of scale, etc. Of course, I don't know accurate they'd be in the end, but it shows they've thought about it in more detail than "oh yeah, it'll totally be cheaper later on."
I think the savings come from modulatization. The first reactor needs an expensive plant, but dropping in a second or third at the same location, into the same tank, would cost much less.
> The first reactor needs an expensive plant, but dropping in a second or third at the same location, into the same tank, would cost much less.
I don't think that explains it, based on the article. Each individual module produces 50 MW, so a 570 MW plant would already involve 11+ individual modules/reactors. So presumably the modularization effect is already taken into consideration for the cost estimate of the 570 MW plant.
I would expect a 22 module reactor to be cheaper per MW. How much cheaper is the question to ask. With out that information it's impossible to compare prices accurately.
Much likely depends on the customer. In the long term, i think they are targeting the military/facility market where a small reactor could provide heat without the expensive turbines needed to generate power. One of these could easily keep an airbase warm through an alaskan winter.
The USS Enterprise (the carrier, CVN-65, not the fictional one) had modular nuclear plants. It had eight submarine-sized reactors. Later US nuclear carriers had only two, larger, power plants. Although the military likes modularity and redundancy, the headaches of staffing and operating eight plants were not worth it.
Very true. Important to note that the 8 plants also allowed for testing different combinations of pumps, steam generators, and other plant equiptment. Rickover got a testbed for future plants integrated into an operating carrier.
And carriers need a throttled power supply based on operations (steam to move, steam for catapults etc). Reactors don't like being throttled. So having eight probably meant they could keep more of them running at full, turning them off when not needed rather than try to run them at reduced power.
This is pure speculation, but I wonder if by cheaper they mean simply cost, rather than cost per MW. Perhaps if you are going to build a traditional nuclear reactor, you might as well build the 1,150MW, $5 billion reactor, even if you only need 570MW. Thereby generating a bunch of excess energy that you need to sell and transmit somewhere else.
If you are a special case (US military base, remote area) and you only want 1 or 2 NuScale modules, and therefore is cheaper.
I think you're right. There are few customers willing and able to bet the farm on huge nuclear megaprojects. The Small Modular Reactor concept emerged as a response to this. The massive nuclear buildouts are happening in China where the capital and patience exists and there's incentive to invest in hundreds of GWe of long-term sustainable clean-air baseload power.
As a nuclear industry person, I wish NuScale very well. I just don't think they're targeting world-scale energy.
The name of the game in nuclear innovation is to bring down costs while improving safety and minimizing proliferation and waste. Costs are dominated by construction (fuel costs are <10% of a nuclear venture because nuclear fuel is so energy-dense) so ideas like modularization and standardization are intriguing. Many nukes are built by assembling lots of pre-fab modules to try to take advantage of this. But sometimes the modules show up and don't fit together, costing more and causing long delays. So it will take a while for modular construction to be really figured out enough to make a big impact.
For what it's worth, from my view one of the most exciting ideas is to build big nukes on big ships. Sounds crazy but hear me out. You construct in a shipyard which is very controlled and standardized so you can pump them out rapidly and cheaply with high QA. You park them 10km offshore of your customer and run underground cables so there are zero people in your exclusion zone for worst-case accidents. If something goes wrong, you're in the water so you can't run out of cooling and the protective fission product barriers always stay intact. You even design to let it sink, stay intact, and have a pre-planned recovery operation worked out. If you have a fleet of 20 customers, you can have one extra plant that relieves another to go home for maintenance and refueling, allowing very high capacity factors. Russians and Chinese are building nukes on ships already (mostly to power oil rigs and remote areas), and we know the navy nukes work great. Could be fun.
Cool idea. Though, wouldn't such a ship-based system be vulnerable to, say, hurricanes? If you're tethered to shore and suppling a population with (their expected) power - you can't exactly maneuver out of the hurricane's path without interrupting service(?).
Thanks. That's a key question. Inclement weather is a challenge, but not an unmanageable one. Case in point, behold the Prelude [1], Shell's new 500m long floating LNG facility (and the biggest ship in the world). It is designed to handle a category 5 cyclone off the north-western coast of Australia (the crew may be evacuated beforehand though). You can design ships to handle pretty much anything, for a price. Finding the balance is required.
Another new concern of offshore nuclear is the physical protection. Can some terrorist in a mini-sub get near it and sink it? With high frequency sonar and whatnot this should be doable. It's probably harder to get to a big ship than to a land-based plant. And again the worst case would be the sink and recover plan.
I don't care for the idea of contaminating the ocean with nuclear radiation in the case of something going wrong with the reactors. That seems like a really bad idea.
The ocean is really, really, really, really big. Also, "radiation" isn't a substance that can be mixed into things like a poison (with the sort of exception of neutron radiation).
"radiation isn't a substance" but plumes and liquids carry the Cesium and other elements. Immensely little contamination in catastrophic events has been through radiation; Most has been through inhaling, eating, depositing radioactive dust.
The expected savings for small modular reactors (SMRs) are tied to construction and continuing operation costs. Better economies of scale would drastically alter the costs for the reactors themselves, but you won't see those until you're looking at orders for a few dozen units. That won't come about for a while, unfortunately. And there are still a lot of regulatory burdens to deal with that will slow initial orders.
That said, SMRs are an incredibly exciting innovation in nuclear energy production. Until now, you've had to build at a large scale. Nothing else made sense economically, and most of the regulatory process presupposes such a scale, but it also limited the markets where you could build to larger ones. More flexible scaling (using multiple, smaller reactors to mix and match what fits an area's forecasted demand in the future) and a lower initial cost can make nuclear a more appealing option for more regions.
Despite the higher cost per MW, SMRs are a lot more flexible compared to traditional nuclear power plants where--by definition--you have to build at a very large scale. SMRs can make nuclear a more appealing energy source for regions with lower electricity demand. And the initial costs are significantly lower even without better economies of scale. They might not be as efficient, but that's not the only factor involved in cost analyses. Remote areas, where traditional nuclear plants are way too large and transportation infrastructure necessary for other conventional energy alternatives isn't sufficient, are particularly appealing use cases.
As for refueling, that depends on the reactor design. Various SMRs designs have refueling cycles of around ~1-10 years[0] (most are somewhere in the middle), and some of the small ones like Gen4's LMR are sealed with no on-site access.[1] It's shipped back to the factory for refueling. And while that sounds like a pain in the ass, it's much less of one than having to deal with storing spent fuel on-site. Those implications will also likely result in some major regulatory changes for SMR plants.
Not sure if I've got apples to apples here, but...
This thing fits on the back of a semi truck, and is supposed to be 50 megawatts capable.
The Hooper solar power plant in Colorado's San Luis valley is also 50 megawatt, and spans 320 acres.
Edit: Well, apples to apples for actual "energy density" vs photo voltaic cells. Not making a statement about which is better either...just an interesting comparison.
Nuclear power plants have very large "clearing areas" for safety and security reasons. In fact, one of the reasons Elon Musks cites for investing in solar rather than nuclear power is that the power area density is actually comparable. Here's some criticism of that claim, but it agrees that it's within about an order of magnitude (which is impressive given that nuclear is probably dozens of orders of magnitude denser in power at the scale of the reactor).
tyingq lists Hooper at 50MW/320 acres, or 156kW/acre. The Paluel nuclear plant is 5200MW (4x1300MWe reactors) over 400 acres ("160 hectares" according to https://www.edf.fr/groupe-edf/producteur-industriel/carte-de...), or 1300kW/acre, so it's within an order of magnitude yes.
As long as we only consider nameplate capacity and ignore capacity factor of course, which greatly favours solar as it has a much lower capacity factor than nuclear. If you factor that in the difference grows by ~4x (PV in dry southern US states has a capacity factor of ~20%, US nuclear plants are around 90%).
Also less regulation. When you want to make money off the idea, being able to buy any land you want and start filling it with solar panels is a pretty great model.
Are you concerned about the acreage?
Luckily there is a report for you out there that looked at the potential for solar energy in the US. In short, it is about 1000x higher than what would be required to provide the US with power.
I wonder how the energy density of one of these compares to a traditional reactor. That's what I would intuitively correlate with safety. Solar and wind, for example, are very safe mainly because they has such a low energy density.
Safety is in the eye of the beholder. Turbines do fail, sometimes with fire and explosions. When so spread outt, hundreds of turbines, forest fire is a risk. A nuke plant, being smaller, can be better covered by safety systems than an expansive wind farm. But the practical differences between the two techs are so great that direct comparison is probably pointless imho.
This was described in depth in a recent Nova program called "The Nuclear Option"[1][2]. In it they referenced multiple other more safe methods than the most common type of reactors in use today which use technology designed decades ago. Sodium based reactors were new to me entirely and appear much more safe than existing designs, also capable of using depleted uranium.
Note: I'm not a nuke supporter just a curious guy.
I watched it too and can elaborate a bit on this since I'm in the SFR business (anyone want one?).
When an nucleus fissions, not all the heat comes out at once. Roughly 7% of the energy comes out later, distributed in time as a decaying exponential [1]. The really key safety challenge of nuclear is cooling that after the chain reaction is stopped (because 7% of 3 billion Watts is 210,000,000 Watts). So if the power goes out (like in Fukushima), traditional plants rely on active cooling systems like diesel generators, fuel cells, steam turbines, etc. to run pumps that cool the fuel, preventing the fission products from emerging.
There are some nuclear reactors that can handle the decay heat without active cooling systems. They're mostly low-pressure/exotic coolant systems, including liquid sodium metal, molten salt (FLiBe, NaCl, etc.), molten lead, etc. These can just naturally circulate and dump heat thorough ambient heat exchangers outside. And some gas-cooled Pebble Bed reactors can do it too because their fuel can get hot enough to just conduct it out.
Worldwide, we have by far the most experience with sodium-cooled fast reactors (400 reactor-years). As pointed out in NOVA, two weeks before Chernobyl, the small sodium-cooled EBR-II in Idaho demonstrated station blackout conditions without scram and it just shut itself down and cooled itself.
But sodium metal has a problem. It is quite reactive with air and water, so dealing with it can be an operational challenge. We know how to deal with sodium leaks in sodium-water steam generators (arguably the most "exciting" component in a SFR) and sodium fires, but they can still be expensive. The French SuperPhenix SFR suffered a series of political and weather-related challenges that ended up giving it a terrible operational record. The Japanese SFR Monju has a bad history too with some 10 year outages and whatnot. But EBR-II and FFTF in the US operated fantastically until Bill Clinton finished shutting down their funding following the long slowdown of nuclear research that came after the failed and super-expensive Clinch River Breeder Reactor Project, and the Russians now have the best and only commercial SFRs.
So there's still hope for SFRs as Gen IV nukes. The French are working on a huge program called ASTRID to make a better SFR. The Koreans have KALIMER/PGSFR that's very far along in design. The US has TerraPower's Traveling Wave SFR, the Indians are turning a big one on now, China is operating a sodium-cooled test reactor (CEFR). The Russians are building another awesome SFR test reactor (MBIR, to replace BOR-60) and continue to operate and sell their BN-600/800, etc. series power plants.
So, at the risk of sounding foolish: what's the advantage of a fast reactor? If I'm remembering correctly, U-235 has a much better thermal than fast fission cross section.
As to the rest, I'm sure there are risks to pressurizers and natural circulation, but they seem a lot more comfortable than trying to avoid sodium leaks. Or is there so little corrosion in sodium systems that it works out pretty well?
I'm not an expert, but IIRC a fast neutron reactor can change power levels very rapidly. The rate of change for a thermal reactor needs to be much lower.
Not foolish. It's really quite non-intuitive. I'll try to break it down.
Physical realities of note:
1. The only fissile nuclide (ie one that readily splits) that existed on Earth in 1938 is the minority uranium isotope, U-235, at a concentration of 0.7% compared to U-238. More exist now (such as Pu239, U233), but we had to synthesize them.
2. U-235 is 1000s of times more likely to split if it is hit with a slow (aka "thermal") neutron than a fast one.
3. If the (very plentiful) U-238 nuclide absorbs a neutron, it converts a few neutrons into protons until it becomes Plutonium-239, now a fissile nuclide(!). Same can be said about Thorium-232 and fissile U-233.
4. Every fissile nuclide releases substantially more secondary neutrons per neutron absorbed if hit with a fast neutron instead of a slow one.
So the implications of these is as follows. To get a critical chain reaction working in the first place, Facts 1 and 2 necessitated the slowing-down of neutrons in an arrangement of natural (unenriched) uranium. This was originally done with very pure graphite in Chicago in a squash court by Enrico Fermi and co. in December, 1942. This led to natural-uranium fueled, thermal neutron plutonium-production reactors in Washington state using Fact 3 for the Manhattan Project. These reactors essentially converted diluted fissile material (natural uranium) into concentrated fissile material (chemically-separable Plutonium) for use in nuclear bombs.
With Plutonium and enriched uranium available in the 1950s, it was now possible to start a chain reaction without slowing the neutrons down (getting around Fact 2). It was thought that Uranium was exceedingly scarce worldwide (turned out to be not entirely true), so rapidly converting lots of U-238 into Pu-239 fuel was thought essential to scale nuclear as a power source. To do this (without burning quickly through all the world's U-235), you need lots and lots of excess neutrons. Enter Fact 4.
Facts 3 and 4 led to the development of fast breeder reactors, which can produce world-scale clean energy for thousands upon thousands of years using known resources. So really the sustainability of breeding is the key capability of fast reactors, and the roughly 100x improvement in safety (measured by core damage frequency) is a bonus. You can also burn nuclear waste if you do a fully-closed fuel cycle (because fast neutrons can split even non-fissile nuclides like Pu240, Np237, Am241), emitting only fission products that decay to stability in hundreds of years instead of hundreds of thousands of years.
Absolutely! In fact, I spent all of my first 18 years 9.5 miles from a PWR.
Nuclear reactors are currently saving lives, as we speak, by displacing air pollution deaths. By 2013, the world fleet of nukes had saved 1.8 million lives and displaced 65 billion tonnes CO2-eq [1]. Living near nukes is safe because you are more likely to be breathing clean air.
Yes. (1) because you ask that question, it means land is going to be cheap. (2) my lifetime radiation dose will be lower then if I live anywhere near a coal plant. (3) my respiratory health will be a lot better then if I live anywhere near a coal train line.
(4) you could also argue I'm just saying this because asked - but I live in Sydney with a primary science degree. One of the places I really wanted to work was the Lucas Heights Research Reactor.
I'm sorry that I'm off-topic, but let's have a cultural minute here: while you're there, I've never succeded to locate the industries when I lived in Sydney. Does Australia get much of its energy from nuclear? Where are the plants located in NSW? Do you also have some petroleum industries like refineries? I've never seen refinery-type landscape (kilometers of stack chimneys). Do you have industrial landscapes in Australia, like we have in Europe with kilometers of factories, low-income workers, areas which are monitored for huge industrial risks? My question is as much about the geography of NSW as about the industrial sector of Australia.
Australia get's literally none of it's energy from nuclear - the Lucas Height's reactor is a research reactor (60% enriched uranium core) which manufactures medical isotopes for our part of Asia and supports research.
We have some of everything, but I can't think of anywhere where I'd say we have long industrial landscapes. NSW is quite agrarian, a fair bit of high tech industry, but you can still live in towns which run near coal transport lines (2um particulates are a big health concern for residents from the dust). I live in Sydney near the center, so it's pretty much all commerce.
I believe UPower reactors (no renamed to Oklo after the spontaneous chain reactions that occurred in Africa 2 billion years ago) are even smaller. My guess from the rename is that they want to make shippable modules that are entirely self-contained, i.e. you just set it down and plug stuff in. Could be useful in very distributed markets. NuScale can ship lots of parts but you still have to build out a big site.
With current and foreseeable low cost of natural gas in the USA, nuclear tech will never be economically competitive. In addition, the nuclear industry asks the government to legislate liability caps.
Utility companies are making long-term capital expenditure bets in a uncertain political and economic environment. If they can get cheap gas and cheap gas turbines, why would they consider risky, expensive, unproven technologies?
> McGough says the company envisions the modules also could be used in other ways. For example, he says, they could be installed near wind turbines as backup when the wind isn't blowing. Or they could be used by the military to power bases that need electricity even if the grid goes down. About a dozen clients in the U.S. and abroad are looking at the technology, he says.
I have seen this company slowly mature over my past 6 years living in Corvallis, Oregon (original location for NuScale). I was excited when I first saw the design and started to look at employment opportunities at the company. At the time, they only were looking for experienced engineers (15+ years) with knowledge of the Nuclear Regulation Commission (NRC).
Even after 6 years, they just now have submitted the application to NRC. It is depressing how much Nuclear has been over-regulated.
A single accident can kill thousands, cause cancer for several hundred thousands more, cost billions of dollars in clean up usually tax payers pay for, nuclear plants have no concept of proper disposing and dismantling a reactor, have byproducts with unacceptable half lives, are potential targets for terror threats, use other harmful chemicals (people like to ignore) etc. etc. etc.
The long time horizon to recover from any disaster is scary. Chernobyl (clearly inadequate safety planning) aside, is there any reason to believe that a Fukushima-type disaster would not be possible (or inevitable)?
Meanwhile, any kid can go buy a gallon of petrochemicals without any kind of license and contribute to one of the most deadly and dangerous problems our species has ever faced.
There are lots of small and medium sized reactor schemes.[1] As of 2014, there were four from the US alone, and 36 worldwide. Nuscale is covered starting at page 80 of that study.
NuScale wants to operate their reactor modules in a water pool, with all the reactors at a site sharing the same pool. If anything goes seriously wrong with one unit, the pool gets contaminated. Then all the units, and the spent fuel pool, are inaccessible, and repair becomes a huge problem.
The only reason NuScale is supposed to be cheaper is optimistic safety assumptions. "The NuScale Emergency Planning Zone (EPZ) is expected to
be as near as the site boundary rather than the current 10 miles required by large traditional plants in the U.S." - IAEA. NuScale's design focuses on emergency core cooling, with their water pool approach. But other things can go wrong. Such as leaks. There's a long history of nuclear reactor leaks.
Installing partitions in the pool to isolate each reactor should be a very minor expense. They need not even be self-supporting, just watertight enough to prevent mixing.
Builing a larger or more partitioned pool shouldnt even enter into the cost equation imho. Water and concrete are rather cheap given the context.
Compare the Babcock and Wilcox (now BWXT) design in the same document. They have a full large containment building around each reactor.
If you have a full, large containment structure, serious reactor troubles at the meltdown level are expensive, like Three Mile Island, but not disasters, like Fukushima. At Fukushima, the containment on the plant was a small vessel around the reactor vessel, like NuScale, and it wasn't able to contain the meltdown.
NuScale's design assumes there will never be a meltdown.
Stop looking at nuclear.
(Maybe read up on the nuclear disasters so far and think about that when they install a nuclear power plant in your neighborhood...)
The renewables vs. fossil vs. nuclear issues have been debated extensively over the decades.
There are two game changers today: fracking and lower-cost solar.
Fracking has totally changed the equation. Natural gas has blown away oil and coal in power generation, and solar (when combined with the federal tax incentive) is finally becoming competitive with traditional utilities.
Nuclear is appealing for various reasons, mainly the avoidance of combustion and carbon release, and also the technology has advanced greatly since its heyday in the '70s. Pebble reactors, micro reactors, better waste processing are compelling reasons to consider a renewed push into nuclear.
But as more residences and commercial buildings adopt solar, and fracked gas (plus vast new gas field discoveries in the Mediterranean and elsewhere) continues to be extremely available and competitive, nuclear looks increasingly like an also-ran.
Still, nuclear has a great future in orbital and interplanetary spacecraft, where miniaturization and reliability are paramount, and safety and affordability are secondary (just locate the nuclear plant at the tail end of the ship behind a few feet of shielding).
Also, we have a pretty good idea how far we can practically, economically, push things like solar/wind, IF storage is worked out. The processes of converting photons and wind into electron potential are well understood - it's just math. But, with storage - renewable power is still never going to be "free-ish". More cost-effective than burning hydrocarbons, maybe, but cheaper is not "free".
What if we could bootstrap our way to free-ish? To do so, we'd have to develop the technology further than it has been developed so far today - and that's an evolutionary process. It would take decades of sustained R&D. But, the carrot is huge -- one benefit would be that we'd never have to worry about fresh water - anywhere - ever again. Nuclear, then nuclear++, then nuclear+++ offers us this hope, to a degree that renewables do not.
Nuclear reactors are extremely safe and disasters are very unlikely. Obviously Fukushima and Chernobyl come to mind but so do famous plane crashes. This doesn't mean planes aren't incredibly safe. Net, nukes have saved 1.8 million lives by displacing air pollution deaths.
Nuclear is very small footprint. There is 2 million times the energy in a handful of nuclear fuel than in a handful of fossil fuel. If you got all of your primary energy from nukes (electricity, heat, transportation) as an average american for 80 years, you would require 1.5 soda cans of fuel and generate 1.5 soda cans of waste.
Comparing that to fossil fuels is a non-argument, nuclear is a clear winner. Comparing to renewables is less straightforward, but consider all the manufacturing and process to build out the facilities to harvest all that unbelievable magnitude of wind and solar. Magnets in turbines and semiconductor additives in solar PV have to come from somewhere, and currently scaling to world-scale is nearly infeasible. Once thin-film solar can be done without rare-earths it might become doable, but will still have a huge huge footprint. Now start asking about energy storage. Imagine a northeastern US winter on one of those icy and cloudy cold nights. Now imagine that lasts a week or two. The storage and/or long-distance transmission is unimaginable. In these conditions, nuclear chugs along beautifully, 24 hours a day, rain or shine.
In desert sun with no nearby cooling water, solar kicks ass whereas nuclear is challenged.
Renewables and nuclear are both essential to responsibly power human civilization.
I think the problem is the historical fact that cost of negative externalities of nuclear projects don't get built into these projects are borne by tax payers and people with significantly disrupted lives in very short durations. The two big meltdowns Fukushima and Chernobyl have left large areas necessarily depopulated and certainly have raised cancer risks. No one seems to have a realistic end of life plan for nuclear sites and the next generation inherits the problem.
If we mandate nuclear plants buy enough insurance cover to deal with Fukushima/ Chernobyl type disasters, they would likely be completely uncompetitive with other power sources.
The Wikipedia article[1] on thorium reactors lists the following disadvantages (quoted from the article):
- Breeding in a thermal neutron spectrum is slow and requires extensive reprocessing. The feasibility of reprocessing is still open.
- Significant and expensive testing, analysis and licensing work is first required, requiring business and government support. According to a 2012 report by the Bulletin of the Atomic Scientists, about using thorium fuel with existing water-cooled reactors, it would "require too great an investment and provide no clear payoff," noting that "from the utilities’ point of view, the only legitimate driver capable of motivating pursuit of thorium is economics."
- There is a higher cost of fuel fabrication and reprocessing than in plants using traditional solid fuel rods.
- Thorium, when being irradiated for use in reactors, will make uranium-232, which is very dangerous due to the gamma rays it emits. This irradiation process may be altered slightly by removing protactinium-233. The irradiation would then make uranium-233 in lieu of uranium-232, which can be used in nuclear weapons to make thorium into a dual purpose fuel.
/end quote
I do wonder whether some of these issues are significantly different from the problems of uranium fission reactors. The benefits of thorium are huge: can't be used to produce nuclear bomb material; easier to prevent meltdowns; enrichment of fuel not needed.
"NuScale is already partnering with a consortium of Utah utilities to build a 12-module power plant on land in Idaho owned by the U.S. Department of Energy." -- I wonder if they would run all the wires over the border to a giant data center right there on some DoD owned land. :-) [1]
The TRIGA reactors are similar [2] although much smaller. I'm surprised they would share a pool though I'd think having them in separate pools would provide both better encapsulation if something was to go wrong and easier maintenance and disposal.
[1] Actually the NSA's data center is south of the Great Salt Lake so it would be a fairly long run of wires for that.
I'm pessimistic that this proposal will go very far in the face of sustained opposition by groups like Greenpeace or Sierra Club. Another tragic remainder of the harm caused by undereducated misdirected environmental activism.
You all have heard that we can harness energy from the light of the sun and convert it into electricity[1] with the risk of contaminating the environment which sustains us[2] coming only from the production of the tools to harness that energy from light, right?
Aside from the context of space travel beyond where collecting this underutilized resource, "Light From Stars" is viable, why is this even a conversation?
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[ 2.8 ms ] story [ 171 ms ] threadYes, but I'm not sure that was an overwhelmingly positive example supporting increased use of widespread reactors:
https://en.wikipedia.org/wiki/McMurdo_Station#Nuclear_power_...
As a result of continuing safety issues (hairline cracks in the reactor and water leaks), the U.S. Navy Nuclear Power Program decommissioned the plant in 1972.
Or course, one would hope that more modern design would be safer.
The S6G reactor in Los Angeles class submarines outputs 150 megawatts and is 33 feet in diameter and 42 feet long (~144,000 cubic feet).
So, corrected:
For comparison, the reactor described here outputs 50 megawatts, and is 15 feet in diameter and 76 feet long (~13,500 cubic feet).
The S6G reactor in Los Angeles class submarines outputs 150 megawatts and is 33 feet in diameter and 42 feet long (~35,000 cubic feet).
[1] https://www.youtube.com/watch?v=1Ujx_pND9wg
> But one company thinks that by going smaller, they could actually make nuclear power more affordable.
And later in the article:
> The company believes that 570-MW project can be completed for less than $3 billion. By comparison, a new 1,150-MW reactor at Watts Bar in Tennessee cost around $4.7 billion and began operation in 2016 after years of delays.
Based on those numbers, the construction cost of the modular reactor system is almost 30% more expensive per MW. Are they anticipating the operational costs to be lower, thus saving money in the long run? But the article claims they're trying to save on the construction costs:
> Companies such as NuScale hope to offset the higher costs by saving on the cost of construction
Which isn't true, based on the numbers the article quotes.
On a related note, I wonder if refueling these modular would be more difficult/costly because of their smaller size and the submersion design?
Maybe, but I would have thought that would have either factored that into the quoted cost estimates, or that they would have said something like "and similar future plants would cost X". (where X is lower).
I don't think that explains it, based on the article. Each individual module produces 50 MW, so a 570 MW plant would already involve 11+ individual modules/reactors. So presumably the modularization effect is already taken into consideration for the cost estimate of the 570 MW plant.
If you are a special case (US military base, remote area) and you only want 1 or 2 NuScale modules, and therefore is cheaper.
As a nuclear industry person, I wish NuScale very well. I just don't think they're targeting world-scale energy.
The name of the game in nuclear innovation is to bring down costs while improving safety and minimizing proliferation and waste. Costs are dominated by construction (fuel costs are <10% of a nuclear venture because nuclear fuel is so energy-dense) so ideas like modularization and standardization are intriguing. Many nukes are built by assembling lots of pre-fab modules to try to take advantage of this. But sometimes the modules show up and don't fit together, costing more and causing long delays. So it will take a while for modular construction to be really figured out enough to make a big impact.
For what it's worth, from my view one of the most exciting ideas is to build big nukes on big ships. Sounds crazy but hear me out. You construct in a shipyard which is very controlled and standardized so you can pump them out rapidly and cheaply with high QA. You park them 10km offshore of your customer and run underground cables so there are zero people in your exclusion zone for worst-case accidents. If something goes wrong, you're in the water so you can't run out of cooling and the protective fission product barriers always stay intact. You even design to let it sink, stay intact, and have a pre-planned recovery operation worked out. If you have a fleet of 20 customers, you can have one extra plant that relieves another to go home for maintenance and refueling, allowing very high capacity factors. Russians and Chinese are building nukes on ships already (mostly to power oil rigs and remote areas), and we know the navy nukes work great. Could be fun.
This clearly isn't an everyday occurrence.
[1] https://en.wikipedia.org/wiki/Prelude_FLNG
Another new concern of offshore nuclear is the physical protection. Can some terrorist in a mini-sub get near it and sink it? With high frequency sonar and whatnot this should be doable. It's probably harder to get to a big ship than to a land-based plant. And again the worst case would be the sink and recover plan.
That said, SMRs are an incredibly exciting innovation in nuclear energy production. Until now, you've had to build at a large scale. Nothing else made sense economically, and most of the regulatory process presupposes such a scale, but it also limited the markets where you could build to larger ones. More flexible scaling (using multiple, smaller reactors to mix and match what fits an area's forecasted demand in the future) and a lower initial cost can make nuclear a more appealing option for more regions.
Despite the higher cost per MW, SMRs are a lot more flexible compared to traditional nuclear power plants where--by definition--you have to build at a very large scale. SMRs can make nuclear a more appealing energy source for regions with lower electricity demand. And the initial costs are significantly lower even without better economies of scale. They might not be as efficient, but that's not the only factor involved in cost analyses. Remote areas, where traditional nuclear plants are way too large and transportation infrastructure necessary for other conventional energy alternatives isn't sufficient, are particularly appealing use cases.
As for refueling, that depends on the reactor design. Various SMRs designs have refueling cycles of around ~1-10 years[0] (most are somewhere in the middle), and some of the small ones like Gen4's LMR are sealed with no on-site access.[1] It's shipped back to the factory for refueling. And while that sounds like a pain in the ass, it's much less of one than having to deal with storing spent fuel on-site. Those implications will also likely result in some major regulatory changes for SMR plants.
0. http://forumonenergy.com/2015/03/17/types-of-smrs/
1. http://www.hyperionpowergeneration.com/product.html
This thing fits on the back of a semi truck, and is supposed to be 50 megawatts capable.
The Hooper solar power plant in Colorado's San Luis valley is also 50 megawatt, and spans 320 acres.
Edit: Well, apples to apples for actual "energy density" vs photo voltaic cells. Not making a statement about which is better either...just an interesting comparison.
Here they do say ~90 acres for 1 GW (I read 0.14 sq mi in the thumbnail, the video doesn't load), so still vastly less area than solar:
http://www.nuscalepower.com/why-smr/environmental-footprint
They probably don't scale down well though (like if some of the area is setback).
https://carboncounter.wordpress.com/2015/07/13/a-book-recomm...
As long as we only consider nameplate capacity and ignore capacity factor of course, which greatly favours solar as it has a much lower capacity factor than nuclear. If you factor that in the difference grows by ~4x (PV in dry southern US states has a capacity factor of ~20%, US nuclear plants are around 90%).
Note: I'm not a nuke supporter just a curious guy.
[1]: http://www.pbs.org/wgbh/nova/tech/the-nuclear-option.html [2]: http://www.pbs.org/video/2365930275/
When an nucleus fissions, not all the heat comes out at once. Roughly 7% of the energy comes out later, distributed in time as a decaying exponential [1]. The really key safety challenge of nuclear is cooling that after the chain reaction is stopped (because 7% of 3 billion Watts is 210,000,000 Watts). So if the power goes out (like in Fukushima), traditional plants rely on active cooling systems like diesel generators, fuel cells, steam turbines, etc. to run pumps that cool the fuel, preventing the fission products from emerging.
There are some nuclear reactors that can handle the decay heat without active cooling systems. They're mostly low-pressure/exotic coolant systems, including liquid sodium metal, molten salt (FLiBe, NaCl, etc.), molten lead, etc. These can just naturally circulate and dump heat thorough ambient heat exchangers outside. And some gas-cooled Pebble Bed reactors can do it too because their fuel can get hot enough to just conduct it out.
Worldwide, we have by far the most experience with sodium-cooled fast reactors (400 reactor-years). As pointed out in NOVA, two weeks before Chernobyl, the small sodium-cooled EBR-II in Idaho demonstrated station blackout conditions without scram and it just shut itself down and cooled itself.
But sodium metal has a problem. It is quite reactive with air and water, so dealing with it can be an operational challenge. We know how to deal with sodium leaks in sodium-water steam generators (arguably the most "exciting" component in a SFR) and sodium fires, but they can still be expensive. The French SuperPhenix SFR suffered a series of political and weather-related challenges that ended up giving it a terrible operational record. The Japanese SFR Monju has a bad history too with some 10 year outages and whatnot. But EBR-II and FFTF in the US operated fantastically until Bill Clinton finished shutting down their funding following the long slowdown of nuclear research that came after the failed and super-expensive Clinch River Breeder Reactor Project, and the Russians now have the best and only commercial SFRs.
So there's still hope for SFRs as Gen IV nukes. The French are working on a huge program called ASTRID to make a better SFR. The Koreans have KALIMER/PGSFR that's very far along in design. The US has TerraPower's Traveling Wave SFR, the Indians are turning a big one on now, China is operating a sodium-cooled test reactor (CEFR). The Russians are building another awesome SFR test reactor (MBIR, to replace BOR-60) and continue to operate and sell their BN-600/800, etc. series power plants.
[1] https://whatisnuclear.com/physics/decay_heat.html
As to the rest, I'm sure there are risks to pressurizers and natural circulation, but they seem a lot more comfortable than trying to avoid sodium leaks. Or is there so little corrosion in sodium systems that it works out pretty well?
Physical realities of note:
1. The only fissile nuclide (ie one that readily splits) that existed on Earth in 1938 is the minority uranium isotope, U-235, at a concentration of 0.7% compared to U-238. More exist now (such as Pu239, U233), but we had to synthesize them.
2. U-235 is 1000s of times more likely to split if it is hit with a slow (aka "thermal") neutron than a fast one.
3. If the (very plentiful) U-238 nuclide absorbs a neutron, it converts a few neutrons into protons until it becomes Plutonium-239, now a fissile nuclide(!). Same can be said about Thorium-232 and fissile U-233.
4. Every fissile nuclide releases substantially more secondary neutrons per neutron absorbed if hit with a fast neutron instead of a slow one.
So the implications of these is as follows. To get a critical chain reaction working in the first place, Facts 1 and 2 necessitated the slowing-down of neutrons in an arrangement of natural (unenriched) uranium. This was originally done with very pure graphite in Chicago in a squash court by Enrico Fermi and co. in December, 1942. This led to natural-uranium fueled, thermal neutron plutonium-production reactors in Washington state using Fact 3 for the Manhattan Project. These reactors essentially converted diluted fissile material (natural uranium) into concentrated fissile material (chemically-separable Plutonium) for use in nuclear bombs.
With Plutonium and enriched uranium available in the 1950s, it was now possible to start a chain reaction without slowing the neutrons down (getting around Fact 2). It was thought that Uranium was exceedingly scarce worldwide (turned out to be not entirely true), so rapidly converting lots of U-238 into Pu-239 fuel was thought essential to scale nuclear as a power source. To do this (without burning quickly through all the world's U-235), you need lots and lots of excess neutrons. Enter Fact 4.
Facts 3 and 4 led to the development of fast breeder reactors, which can produce world-scale clean energy for thousands upon thousands of years using known resources. So really the sustainability of breeding is the key capability of fast reactors, and the roughly 100x improvement in safety (measured by core damage frequency) is a bonus. You can also burn nuclear waste if you do a fully-closed fuel cycle (because fast neutrons can split even non-fissile nuclides like Pu240, Np237, Am241), emitting only fission products that decay to stability in hundreds of years instead of hundreds of thousands of years.
Nuclear reactors are currently saving lives, as we speak, by displacing air pollution deaths. By 2013, the world fleet of nukes had saved 1.8 million lives and displaced 65 billion tonnes CO2-eq [1]. Living near nukes is safe because you are more likely to be breathing clean air.
[1] http://cen.acs.org/articles/91/web/2013/04/Nuclear-Power-Pre...
(4) you could also argue I'm just saying this because asked - but I live in Sydney with a primary science degree. One of the places I really wanted to work was the Lucas Heights Research Reactor.
We have some of everything, but I can't think of anywhere where I'd say we have long industrial landscapes. NSW is quite agrarian, a fair bit of high tech industry, but you can still live in towns which run near coal transport lines (2um particulates are a big health concern for residents from the dust). I live in Sydney near the center, so it's pretty much all commerce.
The power generated by the reactor isn't the important part, the technology is. They've fixed a lot since Chernobyl.
Utility companies are making long-term capital expenditure bets in a uncertain political and economic environment. If they can get cheap gas and cheap gas turbines, why would they consider risky, expensive, unproven technologies?
There is a cheaper, safer and abundant alternative. Solar energy. Just do it already.
Even after 6 years, they just now have submitted the application to NRC. It is depressing how much Nuclear has been over-regulated.
Even Fukushima didn't kill anyone, just some contamination that will cause some statistical level of cancer increase.
NuScale wants to operate their reactor modules in a water pool, with all the reactors at a site sharing the same pool. If anything goes seriously wrong with one unit, the pool gets contaminated. Then all the units, and the spent fuel pool, are inaccessible, and repair becomes a huge problem.
The only reason NuScale is supposed to be cheaper is optimistic safety assumptions. "The NuScale Emergency Planning Zone (EPZ) is expected to be as near as the site boundary rather than the current 10 miles required by large traditional plants in the U.S." - IAEA. NuScale's design focuses on emergency core cooling, with their water pool approach. But other things can go wrong. Such as leaks. There's a long history of nuclear reactor leaks.
[1] https://www.iaea.org/NuclearPower/Downloadable/SMR/files/IAE...
Builing a larger or more partitioned pool shouldnt even enter into the cost equation imho. Water and concrete are rather cheap given the context.
If you have a full, large containment structure, serious reactor troubles at the meltdown level are expensive, like Three Mile Island, but not disasters, like Fukushima. At Fukushima, the containment on the plant was a small vessel around the reactor vessel, like NuScale, and it wasn't able to contain the meltdown. NuScale's design assumes there will never be a meltdown.
More likely you share a common cooling system between reactors. And maybe containment?
Also, again, why bother?
https://www.greentechmedia.com/articles/read/how-much-renewa...
Vote this down all you like, it doesn't change the facts.
There are two game changers today: fracking and lower-cost solar.
Fracking has totally changed the equation. Natural gas has blown away oil and coal in power generation, and solar (when combined with the federal tax incentive) is finally becoming competitive with traditional utilities.
Nuclear is appealing for various reasons, mainly the avoidance of combustion and carbon release, and also the technology has advanced greatly since its heyday in the '70s. Pebble reactors, micro reactors, better waste processing are compelling reasons to consider a renewed push into nuclear.
But as more residences and commercial buildings adopt solar, and fracked gas (plus vast new gas field discoveries in the Mediterranean and elsewhere) continues to be extremely available and competitive, nuclear looks increasingly like an also-ran.
Still, nuclear has a great future in orbital and interplanetary spacecraft, where miniaturization and reliability are paramount, and safety and affordability are secondary (just locate the nuclear plant at the tail end of the ship behind a few feet of shielding).
What if we could bootstrap our way to free-ish? To do so, we'd have to develop the technology further than it has been developed so far today - and that's an evolutionary process. It would take decades of sustained R&D. But, the carrot is huge -- one benefit would be that we'd never have to worry about fresh water - anywhere - ever again. Nuclear, then nuclear++, then nuclear+++ offers us this hope, to a degree that renewables do not.
Nuclear is very small footprint. There is 2 million times the energy in a handful of nuclear fuel than in a handful of fossil fuel. If you got all of your primary energy from nukes (electricity, heat, transportation) as an average american for 80 years, you would require 1.5 soda cans of fuel and generate 1.5 soda cans of waste.
Comparing that to fossil fuels is a non-argument, nuclear is a clear winner. Comparing to renewables is less straightforward, but consider all the manufacturing and process to build out the facilities to harvest all that unbelievable magnitude of wind and solar. Magnets in turbines and semiconductor additives in solar PV have to come from somewhere, and currently scaling to world-scale is nearly infeasible. Once thin-film solar can be done without rare-earths it might become doable, but will still have a huge huge footprint. Now start asking about energy storage. Imagine a northeastern US winter on one of those icy and cloudy cold nights. Now imagine that lasts a week or two. The storage and/or long-distance transmission is unimaginable. In these conditions, nuclear chugs along beautifully, 24 hours a day, rain or shine.
In desert sun with no nearby cooling water, solar kicks ass whereas nuclear is challenged.
Renewables and nuclear are both essential to responsibly power human civilization.
If we mandate nuclear plants buy enough insurance cover to deal with Fukushima/ Chernobyl type disasters, they would likely be completely uncompetitive with other power sources.
- Breeding in a thermal neutron spectrum is slow and requires extensive reprocessing. The feasibility of reprocessing is still open.
- Significant and expensive testing, analysis and licensing work is first required, requiring business and government support. According to a 2012 report by the Bulletin of the Atomic Scientists, about using thorium fuel with existing water-cooled reactors, it would "require too great an investment and provide no clear payoff," noting that "from the utilities’ point of view, the only legitimate driver capable of motivating pursuit of thorium is economics."
- There is a higher cost of fuel fabrication and reprocessing than in plants using traditional solid fuel rods.
- Thorium, when being irradiated for use in reactors, will make uranium-232, which is very dangerous due to the gamma rays it emits. This irradiation process may be altered slightly by removing protactinium-233. The irradiation would then make uranium-233 in lieu of uranium-232, which can be used in nuclear weapons to make thorium into a dual purpose fuel.
/end quote
I do wonder whether some of these issues are significantly different from the problems of uranium fission reactors. The benefits of thorium are huge: can't be used to produce nuclear bomb material; easier to prevent meltdowns; enrichment of fuel not needed.
[1] https://en.wikipedia.org/wiki/Thorium-based_nuclear_power#Po...
R&D, construction, permitting and regulatory?
It's hard to understand why it can't be done less expensively without big safety compromises.
$500M on R&D $3000M on construction $1500M on permitting and regulatory
Construction delays and supply chain issues have been known to bring construction costs way up.
The TRIGA reactors are similar [2] although much smaller. I'm surprised they would share a pool though I'd think having them in separate pools would provide both better encapsulation if something was to go wrong and easier maintenance and disposal.
[1] Actually the NSA's data center is south of the Great Salt Lake so it would be a fairly long run of wires for that.
[2] http://www.ga.com/triga
Aside from the context of space travel beyond where collecting this underutilized resource, "Light From Stars" is viable, why is this even a conversation?
[1] https://en.wikipedia.org/wiki/Solar_power
[2] https://en.wikipedia.org/wiki/Lists_of_nuclear_disasters_and...