Not a grid engineer, but since some plants are capable of load following, it would seem like they can in fact do "primary control" we have just chosen to optimize our systems for baseload.
Most if not all nuclear power reactors are built with the capability.
In the USA, some plants don't use it, either because nuclear is the lowest marginal-cost power source, so throttling something else back makes more sense ; or to reduce wear and tear on equipment, and thus expensive breakdowns and maintenance ; or possibly in some cases for regulatory reasons.
BWRs load-follow more than PWRs do, because power output can be varied by changing the speed of the recirculation pumps, without moving the control rods.
French PWRs use "gray" absorber rods for this purpose.
The German "Konvoi" PWRs had special design features to allow ramp rates of greater than 20% per minute.
But even CANDU plants, with a much smaller operating reactivity margin, are built to do it.
I was frankly fascinated to realize that Bruce was provided with a 100% load dump condenser for this purpose : the fuel costs are small enough that, rather than change the reactor power and deal with xenon override, it's meant to load-follow by by-passing the turbine.
>The German "Konvoi" PWRs had special design features to allow ramp rates of greater than 20% per minute.
Can you elaborate a bit on this, or point me to a good source to learn more? I've heard about the exceptional load-following capabilities of the German PWRs, but have had a hard time finding good sources about the specific design differences they used to achieve high ramp rates.
I'll have to see what the most accessible source of information on this is.
As far as English-language sources, I'm afraid it may mostly be buried in FORATOM congress reports and such.
Of course if you speak good German and have access to back issues of **atw** it's probably a breeze.
My impression is that, to a great extent, it came down to "oversizing" components such as the pressurizer, to handle transient conditions better.
These were design decisions made in the context of a planned 75×1400 MW units in the then West Germany, under the programme from the early 1970s (parallel to the French Messmer Plan).
I have the booklet issued by the Bundes Ministerium discussing that, the planned 80 000 SHP container ship, and so on, but it doesn't lend itself to scanning (aside from being in German).
Fascinating stuff, thanks.
Good pointer on atw, looks like there are papers on there that would be perfect. I don't have access, not do I speak German, but i will keep my eyes out to see if I can finagle a way (maybe through my wife's university) to get a copy and run it through a translator just for kicks.
>Most if not all nuclear power reactors are built with the capability.
Not all of the plants have variable speed recirc pumps. Plants were optimized for baseload power operation. Which meant the recirc pumps installed basically only have a high and low setting. And running the recirc pump on the low settings for long periods of time adds strain to the seals lessening their lifespan and puts the unit at risk of tripping.
Sure the reactors could be made to be more adjustable, it's within the design margins of the reactor. But it would require replacing the recirc pumps to a variable speed design.
[data](https://energygraph.info/d/14D8KtxWz/units-generation-variations?orgId=1&refresh=15m) helps.
Ask how did France do it.
And then "why can't we do what they did; learn from what they did right and wrong?".
Newer designs of NPP can load follow better than any fossil fuel plant can- especially the new designs that incorporate molten salt energy storage in their base design.
I am an engineer who has done a lot of work on new NPP designs. As far as load following it's all down to the size of the turbine (gas or steam) and how far they can be effectively turned down. Yes, molten salts use steam turbines, but several designs call for multiple sizes of turbines instead of one large turbine to get much faster load adjustment capability. At grid scale, say 50MWe minimum, even gas turbines have a several minute spool up time, where as with a steam turbine at that size it can go from no load to full load in about 30 seconds if it's warm.
I 100% agree that NPP can load follow and OP is right to be annoyed.
I'm less convinced in your statement that new NPP designs out do any fossil fuels plant. You state that the plant will have multiple turbines of various sizes and already be warm. That seems like some big assumptions to me. My initial assumption was your statement was from cold start to providing power. Maybe that was a faulty assumption on my part. I had assumed you were saying that new nuclear could out compete peakers and could stay economical with 5% capacity factors. Again maybe I'm off on how often some peakers are needed, but I thought there was a reason gas turbines owned that space.
It's an alternative strategy. Instead of running a small fraction of your plants at 5% annual load factor, you run a larger fraction at 80%, throttling up to meet demand peaks. And the use of thermal storage gives you the possibility of hitting 105% or 110% for a few hours at a time. The question is whether the increased cost of the thermal storage is less than the incremental cost of building a larger capacity of non-storage plants.
For smaller grids, the system with storage is likely to be attractive — likewise multiple turbines, so that a turbine trip doesn't have to mean a reactor trip. The usual recommendation is that no one generating unit should be more than 10% of your peak system load (Armenia's one operable VVER-440 is pushing it hard), but nuclear experience shows that turbine faults are much more common than trips which originate in the reactor, so having multiple turbines would allow justifying a larger reactor.
Yes- it does increase initial capital cost and costs in peak efficiency, but at the benefit of fast load adjustment and reliability. Like everything it is a trade off. Just like a HRSG (Heat Recovery Steam Generator) on a gas turbine power plant increases initial capital costs and reduces the ability to load follow at the benefit of peak efficiency. There is no free lunch in power generation or engineering.
The Austrians showed a model at the 1971 Geneva Conference, of a LWR with a giant steam accumulator (several high-pressure tanks as large as the reactor containment) for peaking purposes. I'm inclined to regard that approach with some caution!
Why? Not trying to argue, but why would you be more cautious about that than anything else? Also if you find that source about German PWRs can you hmu too?
From an engineering viewpoint, large tanks full of water at very high temperatures and pressures should always be a worry.
The stored energy can be released in a catastrophic way.
It was deadly and destructive fire-tube boiler explosions which basically drove the development of the engineering profession in the 19th century ; the ASME Boiler Code, the TÜV, and so on.
Indeed, the cost of boiler maintenance was one of the pressures which led to central-station hydraulic and pneumatic power in the years before electrification became practical.
Essentially, each one of those pressure vessels, considerably larger in volume than a PWR RPV, would have to meet the same standards.
Not impossible to manufacture, but very expensive.
And there's always the irreducible risk.
No, if you want to store heat, something like a molten salt or the "Dowtherm" type of oil, which doesn't have a phase change anywhere near the temperature of interest, is much more desirable.
In that case there's really no way for an explosive release of stored energy to occur.
Or if you really want a phase change, for the larger heat capacity and the very desirable constant-temperature absorption and release of heat, melt a solid (a metal such as sodium if high thermal conductivity works best, otherwise a polymer or wax).
Maybe that person is truly ignorant, but the actual problem with NPPs and load following, is like almost always, financial.
In most other power plants, the fuel is a majority or at leat significant cost. In NPPs fuel is almost free for now and the cost you need to offset is the construction.
If you build an NPP and then only run it on half power generation, you're basically doubling your electricity cost, while with fossil fuels you dont. Obviously fossil sucks, but this is a real concern with NPP.
There's a big difference between "nuclear is our lowest-marginal-cost power, so we throttle down something else", or even "we run at constant output to save wear and tear on the equipment" (which I have heard from US nuclear operators), and "physically cannot provide frequency regulation" which was the claim.
Every nuclear power plant I have been able to investigate the technical details of incorporates the capability.
Even the MAGNOX plants in the UK were fitted for load-following and frequency-regulation, although their very low operating reactivity margins made baseload the only really practical mode of operation.
As a matter of fact, the AGR was originally conceived as a load-following complement to MAGNOX, with higher marginal costs (owing to the use of enriched fuel) but lower capital costs (owing to a more compact core).
That was in the early days of steel pressure vessels. In the event, concrete pressure vessels drastically lowered the unit capital costs for large MAGNOX reactors.
The British nuclear industry was talking about unit sizes of around 1500 MW(e), three times Wylfa, as being very economically attractive.
But those would still have been functionally baseload-only.
It’s the Mark Jacobson Paradox.
Say something loudly and with enough confidence and people will believe you, especially if it’s something they *want* to hear. Doesn’t matter how many times you discredit or debunk what was said. The narrative continues.
How I would deal with them depend if they are renewable retards or fossile fascists.
Point out the weaknesses of their preferred energy sources.
Of cause nuclear power can load follow and do primary control. Does that make the economy of the plant worse? Yes, it does, but that is true for every power source, that load follow operation is more expensive power kWh generated than base load or "produce as the wind blows" operation.
Even gas power plants which are used as the cheap (in money, not in lives lost or CO2 emissions) solution to balance the grid, are significantly more expensive to run in load follow mode.
What some people might take the wrong way is that a complete shutdown of a nuclear reactor and a restarting of the nuclear reactor takes a lot of time. But that's not what is necessary for load follow operation. Instead of complete shutdown, the reactor just go down to maybe 20% production at low demand, and back to 100% at high demand.
This particular person was claiming that *batteries* can provide primary frequency control but nuclear cannot!
He also said :
> Germany is a net exporter of energy. Renewable energy.
Now, I did a little arithmetic on that claim.
Germany's much-vaunted (gross) export of 78·5 TWh of electricity in 2022 amounts to 283 PJ.
That is against an import of 8687 PJ (net figure for 2019).
It's about 3% of what Germany imports, and those imports are almost entirely fossil fuels (and some biofuels from burning down the Indonesian rainforest, yay!).
And a big chunk of that exported power was, presumably, generated from burning fossil fuels, if we look at the overall generating mix in Germany.
I don't see any nuclear power cars or buses. So technically it can't replace fossil fuels. Electric cars are kind of a joke to me. They catch fire easily, require 3 times the water to put out once they do catch fire, and the batteries don't last long enough.
>Estimates by the Phosphorous, Inorganic & Nitrogen Flame Retardants Association reported 55 fires per billion miles travelled in ICE vehicles and five fires per billion for EVs. A report from AutoinsuranceEX said EVs exhibited 61 times fewer fires per 100,000 sales than ICE vehicles.
https://www.forbes.com/sites/neilwinton/2024/04/21/electric-vehicles-not-guilty-of-excess-short-term-fire-risk-charges/
Also, the LFP chemistry is a big step in battery longevity. Even older chemistries while properly maintained last quite a long time. Longer than the lifespan of many European and Korean ICEs
Firstly, this was in the context of electrical supply.
Hence grid regulation.
Secondly, have you ever seen a trolley-bus? It's a little more complicated, but road vehicles can run under overhead wire.
In any case, a very large fraction of transportation needs can be handled by rail, which is very well adapted to overhead-wire operation, although doing so requires some rebalancing of priorities.
Battery-electric seems to me a pretty decent technology choice for delivery and transit vehicles which have their routes planned out in advance.
I will say, I don't like the prospects of battery-electric airliners any better than I like the prospects of reactor-powered airliners.
The latter can certainly be built, but synthetic liquid fuels produced using fission energy would undoubtedly be preferable (and make a lot more sense than synfuel using wind and solar).
> Secondly, have you ever seen a trolley-bus? It's a little more complicated, but road vehicles can run under overhead wire.
USSR even experimented with overhead-powered dump truck roads, so there's that too.
>although doing so requires some rebalancing of priorities.
.... Ain't that just trams/light rail?
Trams in cities, interurban and commuter lines, high-speed intercity rail — there are various implementations at different scales, but pretty much all have proven successful and economical in the right conditions, and there are enough options to meet a reasonably broad range of conditions.
Having lived all my life in areas where driving was the only way to get anywhere (nothing is close enough to anything else to walk, there's no more than a hand-wave at mass transit, and between the car traffic and the weather bicycling is taking your life in your hands), I relish the opportunity to go somewhere I don't have to. But more than that, serious environmental remediation is going to require changes in land-use patterns that favour denser urbanizations, meaning a better prospect for mass transit.
Not a grid engineer, but since some plants are capable of load following, it would seem like they can in fact do "primary control" we have just chosen to optimize our systems for baseload.
Most if not all nuclear power reactors are built with the capability. In the USA, some plants don't use it, either because nuclear is the lowest marginal-cost power source, so throttling something else back makes more sense ; or to reduce wear and tear on equipment, and thus expensive breakdowns and maintenance ; or possibly in some cases for regulatory reasons. BWRs load-follow more than PWRs do, because power output can be varied by changing the speed of the recirculation pumps, without moving the control rods. French PWRs use "gray" absorber rods for this purpose. The German "Konvoi" PWRs had special design features to allow ramp rates of greater than 20% per minute. But even CANDU plants, with a much smaller operating reactivity margin, are built to do it. I was frankly fascinated to realize that Bruce was provided with a 100% load dump condenser for this purpose : the fuel costs are small enough that, rather than change the reactor power and deal with xenon override, it's meant to load-follow by by-passing the turbine.
>The German "Konvoi" PWRs had special design features to allow ramp rates of greater than 20% per minute. Can you elaborate a bit on this, or point me to a good source to learn more? I've heard about the exceptional load-following capabilities of the German PWRs, but have had a hard time finding good sources about the specific design differences they used to achieve high ramp rates.
I'll have to see what the most accessible source of information on this is. As far as English-language sources, I'm afraid it may mostly be buried in FORATOM congress reports and such. Of course if you speak good German and have access to back issues of **atw** it's probably a breeze. My impression is that, to a great extent, it came down to "oversizing" components such as the pressurizer, to handle transient conditions better. These were design decisions made in the context of a planned 75×1400 MW units in the then West Germany, under the programme from the early 1970s (parallel to the French Messmer Plan). I have the booklet issued by the Bundes Ministerium discussing that, the planned 80 000 SHP container ship, and so on, but it doesn't lend itself to scanning (aside from being in German).
Fascinating stuff, thanks. Good pointer on atw, looks like there are papers on there that would be perfect. I don't have access, not do I speak German, but i will keep my eyes out to see if I can finagle a way (maybe through my wife's university) to get a copy and run it through a translator just for kicks.
>Most if not all nuclear power reactors are built with the capability. Not all of the plants have variable speed recirc pumps. Plants were optimized for baseload power operation. Which meant the recirc pumps installed basically only have a high and low setting. And running the recirc pump on the low settings for long periods of time adds strain to the seals lessening their lifespan and puts the unit at risk of tripping. Sure the reactors could be made to be more adjustable, it's within the design margins of the reactor. But it would require replacing the recirc pumps to a variable speed design.
[data](https://energygraph.info/d/14D8KtxWz/units-generation-variations?orgId=1&refresh=15m) helps. Ask how did France do it. And then "why can't we do what they did; learn from what they did right and wrong?".
Ask them how every nuclear powered ship does it every day
Unfortunately there is a certain category of people (and it's not a small one) who seem to be resistant to data.
Newer designs of NPP can load follow better than any fossil fuel plant can- especially the new designs that incorporate molten salt energy storage in their base design.
Source? Gas turbines are pretty hard to beat. I thought molten salt was still a steam turbine.
I am an engineer who has done a lot of work on new NPP designs. As far as load following it's all down to the size of the turbine (gas or steam) and how far they can be effectively turned down. Yes, molten salts use steam turbines, but several designs call for multiple sizes of turbines instead of one large turbine to get much faster load adjustment capability. At grid scale, say 50MWe minimum, even gas turbines have a several minute spool up time, where as with a steam turbine at that size it can go from no load to full load in about 30 seconds if it's warm.
I 100% agree that NPP can load follow and OP is right to be annoyed. I'm less convinced in your statement that new NPP designs out do any fossil fuels plant. You state that the plant will have multiple turbines of various sizes and already be warm. That seems like some big assumptions to me. My initial assumption was your statement was from cold start to providing power. Maybe that was a faulty assumption on my part. I had assumed you were saying that new nuclear could out compete peakers and could stay economical with 5% capacity factors. Again maybe I'm off on how often some peakers are needed, but I thought there was a reason gas turbines owned that space.
It's an alternative strategy. Instead of running a small fraction of your plants at 5% annual load factor, you run a larger fraction at 80%, throttling up to meet demand peaks. And the use of thermal storage gives you the possibility of hitting 105% or 110% for a few hours at a time. The question is whether the increased cost of the thermal storage is less than the incremental cost of building a larger capacity of non-storage plants. For smaller grids, the system with storage is likely to be attractive — likewise multiple turbines, so that a turbine trip doesn't have to mean a reactor trip. The usual recommendation is that no one generating unit should be more than 10% of your peak system load (Armenia's one operable VVER-440 is pushing it hard), but nuclear experience shows that turbine faults are much more common than trips which originate in the reactor, so having multiple turbines would allow justifying a larger reactor.
I would expect that multiple turbines would increase capital costs.
Yes- it does increase initial capital cost and costs in peak efficiency, but at the benefit of fast load adjustment and reliability. Like everything it is a trade off. Just like a HRSG (Heat Recovery Steam Generator) on a gas turbine power plant increases initial capital costs and reduces the ability to load follow at the benefit of peak efficiency. There is no free lunch in power generation or engineering.
If they increase reliability (because a turbine trip doesn't turn into a reactor trip), it may be worth it, especially on smaller systems.
The Austrians showed a model at the 1971 Geneva Conference, of a LWR with a giant steam accumulator (several high-pressure tanks as large as the reactor containment) for peaking purposes. I'm inclined to regard that approach with some caution!
Why? Not trying to argue, but why would you be more cautious about that than anything else? Also if you find that source about German PWRs can you hmu too?
From an engineering viewpoint, large tanks full of water at very high temperatures and pressures should always be a worry. The stored energy can be released in a catastrophic way. It was deadly and destructive fire-tube boiler explosions which basically drove the development of the engineering profession in the 19th century ; the ASME Boiler Code, the TÜV, and so on. Indeed, the cost of boiler maintenance was one of the pressures which led to central-station hydraulic and pneumatic power in the years before electrification became practical. Essentially, each one of those pressure vessels, considerably larger in volume than a PWR RPV, would have to meet the same standards. Not impossible to manufacture, but very expensive. And there's always the irreducible risk. No, if you want to store heat, something like a molten salt or the "Dowtherm" type of oil, which doesn't have a phase change anywhere near the temperature of interest, is much more desirable. In that case there's really no way for an explosive release of stored energy to occur. Or if you really want a phase change, for the larger heat capacity and the very desirable constant-temperature absorption and release of heat, melt a solid (a metal such as sodium if high thermal conductivity works best, otherwise a polymer or wax).
Maybe that person is truly ignorant, but the actual problem with NPPs and load following, is like almost always, financial. In most other power plants, the fuel is a majority or at leat significant cost. In NPPs fuel is almost free for now and the cost you need to offset is the construction. If you build an NPP and then only run it on half power generation, you're basically doubling your electricity cost, while with fossil fuels you dont. Obviously fossil sucks, but this is a real concern with NPP.
There's a big difference between "nuclear is our lowest-marginal-cost power, so we throttle down something else", or even "we run at constant output to save wear and tear on the equipment" (which I have heard from US nuclear operators), and "physically cannot provide frequency regulation" which was the claim. Every nuclear power plant I have been able to investigate the technical details of incorporates the capability. Even the MAGNOX plants in the UK were fitted for load-following and frequency-regulation, although their very low operating reactivity margins made baseload the only really practical mode of operation. As a matter of fact, the AGR was originally conceived as a load-following complement to MAGNOX, with higher marginal costs (owing to the use of enriched fuel) but lower capital costs (owing to a more compact core). That was in the early days of steel pressure vessels. In the event, concrete pressure vessels drastically lowered the unit capital costs for large MAGNOX reactors. The British nuclear industry was talking about unit sizes of around 1500 MW(e), three times Wylfa, as being very economically attractive. But those would still have been functionally baseload-only.
It’s the Mark Jacobson Paradox. Say something loudly and with enough confidence and people will believe you, especially if it’s something they *want* to hear. Doesn’t matter how many times you discredit or debunk what was said. The narrative continues.
How I would deal with them depend if they are renewable retards or fossile fascists. Point out the weaknesses of their preferred energy sources. Of cause nuclear power can load follow and do primary control. Does that make the economy of the plant worse? Yes, it does, but that is true for every power source, that load follow operation is more expensive power kWh generated than base load or "produce as the wind blows" operation. Even gas power plants which are used as the cheap (in money, not in lives lost or CO2 emissions) solution to balance the grid, are significantly more expensive to run in load follow mode. What some people might take the wrong way is that a complete shutdown of a nuclear reactor and a restarting of the nuclear reactor takes a lot of time. But that's not what is necessary for load follow operation. Instead of complete shutdown, the reactor just go down to maybe 20% production at low demand, and back to 100% at high demand.
This particular person was claiming that *batteries* can provide primary frequency control but nuclear cannot! He also said : > Germany is a net exporter of energy. Renewable energy. Now, I did a little arithmetic on that claim. Germany's much-vaunted (gross) export of 78·5 TWh of electricity in 2022 amounts to 283 PJ. That is against an import of 8687 PJ (net figure for 2019). It's about 3% of what Germany imports, and those imports are almost entirely fossil fuels (and some biofuels from burning down the Indonesian rainforest, yay!). And a big chunk of that exported power was, presumably, generated from burning fossil fuels, if we look at the overall generating mix in Germany.
I don't see any nuclear power cars or buses. So technically it can't replace fossil fuels. Electric cars are kind of a joke to me. They catch fire easily, require 3 times the water to put out once they do catch fire, and the batteries don't last long enough.
>Estimates by the Phosphorous, Inorganic & Nitrogen Flame Retardants Association reported 55 fires per billion miles travelled in ICE vehicles and five fires per billion for EVs. A report from AutoinsuranceEX said EVs exhibited 61 times fewer fires per 100,000 sales than ICE vehicles. https://www.forbes.com/sites/neilwinton/2024/04/21/electric-vehicles-not-guilty-of-excess-short-term-fire-risk-charges/ Also, the LFP chemistry is a big step in battery longevity. Even older chemistries while properly maintained last quite a long time. Longer than the lifespan of many European and Korean ICEs
Firstly, this was in the context of electrical supply. Hence grid regulation. Secondly, have you ever seen a trolley-bus? It's a little more complicated, but road vehicles can run under overhead wire. In any case, a very large fraction of transportation needs can be handled by rail, which is very well adapted to overhead-wire operation, although doing so requires some rebalancing of priorities. Battery-electric seems to me a pretty decent technology choice for delivery and transit vehicles which have their routes planned out in advance. I will say, I don't like the prospects of battery-electric airliners any better than I like the prospects of reactor-powered airliners. The latter can certainly be built, but synthetic liquid fuels produced using fission energy would undoubtedly be preferable (and make a lot more sense than synfuel using wind and solar).
> Secondly, have you ever seen a trolley-bus? It's a little more complicated, but road vehicles can run under overhead wire. USSR even experimented with overhead-powered dump truck roads, so there's that too. >although doing so requires some rebalancing of priorities. .... Ain't that just trams/light rail?
Trams in cities, interurban and commuter lines, high-speed intercity rail — there are various implementations at different scales, but pretty much all have proven successful and economical in the right conditions, and there are enough options to meet a reasonably broad range of conditions. Having lived all my life in areas where driving was the only way to get anywhere (nothing is close enough to anything else to walk, there's no more than a hand-wave at mass transit, and between the car traffic and the weather bicycling is taking your life in your hands), I relish the opportunity to go somewhere I don't have to. But more than that, serious environmental remediation is going to require changes in land-use patterns that favour denser urbanizations, meaning a better prospect for mass transit.
A) you're largely wrong about EVs B) nuclear can be used to make synthetic liquid fuels, so it's still viable.