Idea: X-Ray reflection

[KitemanSA]

Rider thesis didn't have any experimental data, as such it is just speculations.

That's beyond something that I think you should get away with!

But it is right up there with what you say all the time wrt Polywell! Goose, gander, sause? Ring a bell?

[chrismb]

Rider thesis didn't have any experimental data, as such it is just speculations.

That's beyond something that I think you should get away with!

But it is right up there with what you say all the time wrt Polywell! Goose, gander, sause? Ring a bell?

No ringing this end. Please explain/examples.

[chrismb]

Of course if we are discussing about the possibility of working of a Polywell and you remove the mechanism that is at the base of the creation of the well, is normal that you can demonstrate by math that there is no way it can work.

I've no problem with you raising this as a question. You are alluding to a flawed theory, rather than siting Rider as having engaged in speculation, though. I think we are agreed?!

[D Tibbets]

.....

the magrids would handle the x-ray heat in a similar manner, though a layer of dense metal like tungsten or depleted uranium (for P-B11) might be used so less thickness is needed.

That would be hilarious.

Greenpeace: So, even though these are technically "nuclear", they don't have any uranium in them, right?
EMC2: Uh...

Why, please educate me.
A dense metal will better block X-rays per unit of thickness than a light metal. This would be useful in trying to reduce the standoff distance between the magnet windings and the outer casing of the magrids. This is important for maximizing the magnetic field strength outside the magrid casing. . This is a distance/ volume consideration. Weight is a different issue depending on application. You would probably not want to use depleted uranium (enclosed in a refractory metal) with D-T, D-D or even D-He3 fuels due to the neutrons. But P-B 11 is different. If it took 1 day for a D-D fusing Polywell to transmute U238 into Pu239 quantities that might be a proliferation risk, then it would take a P-B11 Polywell ~ 30,000,000 days to do the same thing. That would be ~ 100,000 years. A little longer than the service life of the reactor

Actually, after thinking about it, the time to accumulate the plutonium would probably be ~ twice this time, as the half life is ~ 120,000 years.

Dan Tibbets

[KitemanSA]

That's beyond something that I think you should get away with!

But it is right up there with what you say all the time wrt Polywell! Goose, gander, sause? Ring a bell?

No ringing this end. Please explain/examples.

My bullshyte-o-meter is going haywire!......

Even when you GET data (limited as it was) you go beyond "speculative" to "bullsyte". Perhaps your proclaimation is "beyond something that I think you should get away with".

[chrismb]

What data? Be specific, man!

[KitemanSA]

What data? Be specific, man!

Buffalo muffins. You got the data as well as I did. You can dig it up again. You asked for an example of your "something beyond" and I gave it. That is all the research I wish to do for you.

[chrismb]

?!?!?

Mystical and obfuscating....

The only polywell data I recall having ever discussed here is 'we got 3 counts on a neutron detector' - because that's the only 'data' [term used very generously] I've seen released.

I guess it is par for the course here that people don't like actually pulling out real data to discuss, because in doing so the utterly miserable attempts at analysis that have dogged polywell in its 30 years of research get put into sharp relief.

Hide what you want to talk about, if you like. Surely you must get the feeling polywell is a whole, overcooked, dead duck now? No point blaming me for it.

[93143]

My point is still that I doubt that you can get to high enough temperatures with a cooling system integrated into the vacuum vessel.
The lower the temperature of cooling fluid the lower the conversion efficiency. Can we really consider that the cooling of the vacuum vessel will be done by extracting steam or any other working fluid at 600C?
As you reduce temperature your conversion efficiency drops quite fast.

The SC Brayton cycle was supposed to get the quoted high efficiencies with a ~300°C hot-side temperature, not a 600°C one. That's completely reasonable IMO.

Also, this is another illustration of how the comparison to the launch vehicle reactor is pertinent - the waste heat has to come off that thing at a much higher temperature, perhaps as high as 1500°C, to get a decent Isp.

I used EMC2's number. IIRC they're the ones that predicted 5%.

No doubt, but it does not occur to me that they have been validate by any result to date, so also a 1% or a 40% can be a good guess for what we know.

Stay on topic. We've been discussing x-ray recovery. If x-ray recovery is necessary, the bremsstrahlung fraction will be large, significantly larger even than the 5% estimate from EMC2. Therefore, if it can be demonstrated that cooling is necessary at 5% to prevent reactor damage, it follows that cooling will be necessary for the same reason in any scenario in which x-ray power recovery is necessary.

You may dispute the choice of radiation shield design assumptions that went into the analysis, but the bremsstrahlung fraction chosen was most definitely below the low end of the relevant range; your objection to it is therefore invalid.

I was objecting your assumption of "80% efficient direct conversion, counting brem losses", I never objected on the cooling system.

You'd have to reduce losses by a couple orders of magnitude to significantly change my conclusion. Do you really think a total thermal fraction of less than half a percent is plausible?

Space shuttle engines are working perfectly fine with their regenerative cooling, and I see no reasons why polywell should be different.

That's because the SSMEs don't leak much heat, and their regenerative cooling catches most of what they do leak. (In fact, I wouldn't be surprised if a running SSME had a net cooling effect on the Orbiter's structure, considering how cold the coolant is.) A bank of 3 SSMEs produces four times the power (chemical->thermal) of the reactor I posited; if they were leaking 400 MW or even 40 MW into the structure of the Shuttle, it wouldn't make it anywhere near orbit before disintegrating.

...

It strikes me that you don't seem to have much engineering understanding of this stuff. The role of insulation in controlling heat flux, for instance. The role of coolant flow rate in controlling peak temperature. That sort of thing.

Even better, a polywell based rocket to lift goods in space might even be only thermal with no direct conversion at all.

You'd get an awful Isp without a ridiculously high peak temperature. NERVA-type nuclear thermal is a lot lighter than Polywell per GW and has peak temperatures in the range of 2000-2800°C, but it still isn't anywhere near good enough for ground launch.

Rocket application is a different engineering issue than recover of heat with the aim of converting it back to electricity in an efficient way.
I really do not see how the two could be mixed in the discussion as you are trying to do.

It's very simple. In the rocket application you need to recover waste heat with extremely high efficiency, otherwise your launcher will disintegrate. So if we can do that, we can recover waste heat in a ground-based power plant with similar efficiency. Therefore your pessimism regarding the latter is inconsistent with your optimism regarding the former.

On top of that, to get a high vacuum Isp out of a Polywell-powered launch vehicle, the peak temperature of the waste heat recovery has to be extremely high. Therefore your pessimism regarding the peak temperature achievable in a ground-based power plant is also inconsistent with your optimism regarding LV application.

Taking into account that a large fraction of the flight path is in vacuum...

This, IMHO, is yet another issue, much different of what we have been discussing for now.

Not at all. It's simply a reminder that when designing a launch vehicle, your options for passive, non-regenerative cooling are limited.

[93143]

The only polywell data I recall having ever discussed here is 'we got 3 counts on a neutron detector' - because that's the only 'data' [term used very generously] I've seen released.

Haven't you read the leaked WB-6 report?

Or do you not consider it "data", since it was never officially released?

[KitemanSA]

?!?!?

Mystical and obfuscating....

Your demeaning pontifications are not limited to Polywell. Indeed the "bullshyte" comment was re Rossi's machine. You have no compuntion against demeaning others when they dare label something as speculative, but feel no problem with implying, even saying, something is a scam. Goose, Gander?

[chrismb]

I've laid out perfectly reasonable statements for those looking to weight up whether or not Rossi's scheme is a scam (and polywell similarly). I've not said outright that it is, only that I see little that colours it as a bona-fide scheme.

These statements constitute nether a speculation nor a theory. Therefore, I have no reason, cause nor need to defend anything I have said against your personal attack on me, in this regard.

You seem to have trouble with this 'sceptic/debunker' business, don't you? Rossi has pooped up on the scene to 'show' his thing off. Well, here's the beans; if you don't want people to question what you are doing, don't bother to show 'em anything!

Make a public demo? Fine, then be prepared for public comment.

It's not for the debunker to prove anything at all. It is for the debunker to show the flaws in the other person's scheme. It is all one-sided, with the person who wants to show off their new 'thing' having to do AAALLLLLLLL the work, and the debunker is at liberty to lobs questions at them.

I've always identified very specific issues as to why these schemes are questionable, and the slanging matches only get going when folks like yourself get all hot and bothered about someone trying to drill down into the detail and feel that it is fair game for you to throw verbal rotten tomatoes at me because I dared ask a few questions.

Get it? I am in the role of sceptic/debunker. I do not need to prove a damned thing. Those who use public money or make public announcements/demonstrations are the ones that have to prove the things that I show are in need of proving.

[Giorgio]

The SC Brayton cycle was supposed to get the quoted high efficiencies with a ~300°C hot-side temperature, not a 600°C one. That's completely reasonable IMO.

True, SC-CO2 cycle can work at 300C, yet efficiency does not go much over 40%.
Add losses from capturing the whole x-Ray fraction and you do not end much far away from my projected claim.
Even so, let's say we want to find a good mediation point and say that maximum conversion efficiency we can get is 45%.
Should we also remember that bremsstrahlung losses have to be made up completely by injected electrons?
so, as you increase bremsstrahlung, also the e-Guns will need to become bigger and consume more power. Power that you are generating with (even) 45% efficiency.

Thermal conversion efficiency does not make much difference if the X-Ray fraction is much higher than a low value (which was the assumption of this thread), no?

Also, this is another illustration of how the comparison to the launch vehicle reactor is pertinent - the waste heat has to come off that thing at a much higher temperature, perhaps as high as 1500°C, to get a decent Isp.

How can this be pertinent?
This thread assumes an high fraction of power as X-Ray that needs to be collected, converted and replenished (in energy terms) by the e-guns.
The other thread assumes polywell to work with little to no bremsstrahlung.
You keep mixing different threads, different applications different assumptions.
If (as improbable example) bremsstrahlung are near to zero you can even manage them at air frame level.

That's because the SSMEs don't leak much heat, and their regenerative cooling catches most of what they do leak. (In fact, I wouldn't be surprised if a running SSME had a net cooling effect on the Orbiter's structure, considering how cold the coolant is.) A bank of 3 SSMEs produces four times the power (chemical->thermal) of the reactor I posited; if they were leaking 400 MW or even 40 MW into the structure of the Shuttle, it wouldn't make it anywhere near orbit before disintegrating.

As above, fix the discussion and the discussion terms.
Is it about feasibility of a Polywell power plant machine with a high bremsstrahlung rate or feasibility of a polywell rocket with high bremsstrahlung rate?

It strikes me that you don't seem to have much engineering understanding of this stuff. The role of insulation in controlling heat flux, for instance. The role of coolant flow rate in controlling peak temperature. That sort of thing.

Great news. I guess this means that I will have to drop the Pixie Dust formula on the design of our next heat exchanger and use a coolant flow control instead.
I wonder how all the ones we have already designed and installed are working thought....

Even better, a polywell based rocket to lift goods in space might even be only thermal with no direct conversion at all.

You'd get an awful Isp without a ridiculously high peak temperature. NERVA-type nuclear thermal is a lot lighter than Polywell per GW and has peak temperatures in the range of 2000-2800°C, but it still isn't anywhere near good enough for ground launch.

If you think a conventional rocket I do agree, but for an hybrid spaceplane it might be feasible.
Someone made some calculations a couple of years ago, I will look back for them.

Not at all. It's simply a reminder that when designing a launch vehicle, your options for passive, non-regenerative cooling are limited.

But your options to have different engines for different applications are not limited.
No one forbids you to have an all electric converter for space apps and an all thermal solution for liftoff with an hybrid spaceplane solution.
This also replies to the other parts I did not quote to make it short.

Stay on topic. We've been discussing x-ray recovery. If x-ray recovery is necessary, the bremsstrahlung fraction will be large, significantly larger even than the 5% estimate from EMC2. Therefore, if it can be demonstrated that cooling is necessary at 5% to prevent reactor damage, it follows that cooling will be necessary for the same reason in any scenario in which x-ray power recovery is necessary.

I would love to stay on topic, and I do not feel that I am the one drifting it around.
Anyhow, I am ready to drop any other topic and just stay on this thread topic:
The need of recovery of a high bremsstrahlung fraction can render the reactor useless as a power generator?

I have not yet understood your point of view on this issue.

[93143]

True, SC-CO2 cycle can work at 300C, yet efficiency does not go much over 40%.
Add losses from capturing the whole x-Ray fraction and you do not end much far away from my projected claim.

That, and only that, is what I've been disputing. You seemed to be claiming that almost half of the waste heat would be lost to the surroundings rather than being captured by the cooling system. I think this is unjustified pessimism, particularly given the effort that would go into this segment of the design if it turned out high-efficiency x-ray capture was critical to close the power balance.

Everything else you've said about efficiency and power recirculation is true, but irrelevant to this point.

Keep in mind that while x-ray shielding requires thick walls, x-ray heating is basically a first-wall problem; you don't have to worry about significant power being dissipated in blocks of concrete several feet away from the vacuum vessel. Almost all the x-ray power comes out in the vacuum vessel wall itself, or in the equipment within it, and after that it's a straightforward matter of heat collection.

Also, this is another illustration of how the comparison to the launch vehicle reactor is pertinent - the waste heat has to come off that thing at a much higher temperature, perhaps as high as 1500°C, to get a decent Isp.

How can this be pertinent?
This thread assumes an high fraction of power as X-Ray that needs to be collected, converted and replenished (in energy terms) by the e-guns.
The other thread assumes polywell to work with little to no bremsstrahlung.
You keep mixing different threads, different applications different assumptions.
If (as improbable example) bremsstrahlung are near to zero you can even manage them at air frame level.

The reason the coolant peak temperature matters should be obvious, considering that you've been claiming it can't be very high. If you can't get 900 K on the ground, you certainly can't get 1800 K in a launch vehicle. A Polywell is a Polywell; there's no new physics that steps in to save you when you put one in a rocket.

As for the differing assumptions re: Bremsstrahlung fraction...

It doesn't matter what the bremsstrahlung fraction is for a launch vehicle reactor - there are other sources of waste heat (the direct conversion system, for example, cannot possibly be 100% efficient), and the power level is so high that even 5-10% percent waste heat, captured at 90% efficiency, is far too much. No one, not even the proponents, is claiming the waste heat level could be much lower than that, and it is likely to be higher, so the only option is to have near-perfect active cooling.

My point in bringing up the rocket example is that it is inconsistent for you to hold both (a) that launch vehicle application of Polywell will happen quickly and be relatively easy (assuming reasonably low bremsstrahlung fraction), and (b) that if bremsstrahlung fraction is high, close to half the thermal output of the reactor will be lost as leakage, not even caught by the cooling system.

Do remember that Polywell scaling means that a 5 GWf reactor will not be vastly larger than a 100 MWf reactor. In the 100 MWf case, a direct conversion efficiency of 75%, an electron/ion loss power of 20 MW, and a bremsstrahlung fraction of 1.74 (the thermal scenario) results in 219 MW of heat that needs to be dissipated. (It also requires ~54% thermal conversion efficiency in order to break even, but that's beside the point.) In the 5 GWf case, a direct conversion efficiency of 95% and zero bremsstrahlung or electron/ion wall losses results in 250 MW of heat, over at most triple the surface area, likely much smaller. With 85% DC efficiency in both cases (actually, due to beam spreading, the higher-power reactor will likely be worse than the low-power one, especially since it has to be compact), neglecting electron/ion wall losses, we have 189 MW in the 100 MWf case and 750 MW in the 5 GWf case.

In other words, under reasonable assumptions, it looks like the launch vehicle reactor (with low bremsstrahlung) would have a higher thermal power flux than the ground reactor (with high bremsstrahlung). So why is it so hard to cool the ground reactor, and so easy to cool the LV core?

As above, fix the discussion and the discussion terms.
Is it about feasibility of a Polywell power plant machine with a high bremsstrahlung rate or feasibility of a polywell rocket with high bremsstrahlung rate?

The original discussion was about the achievable efficiency of collection of x-ray energy as useful heat, that could then be fed through whatever thermal conversion system you like. I said it would likely be pretty high; you disagreed.

I then pointed out that you were very optimistic about the launch vehicle application working, and that this was logically inconsistent with your pessimism regarding heat recovery fraction because a launch vehicle reactor would need near-perfect heat recovery regardless of what the bremsstrahlung fraction was.

It's sort of a separate line of argument, in which I claim that you have made contradictory assertions without realizing the contradiction. Basically, I assert that you must pick one or the other; you cannot continue to claim simultaneously that LV application is easy and that high-efficiency waste heat recovery (by which, at the beginning of the argument, we both meant % of heat collected, not % of heat turned back into electricity) is impossible or prohibitively difficult.

As for myself, I believe neither.

It strikes me that you don't seem to have much engineering understanding of this stuff. The role of insulation in controlling heat flux, for instance. The role of coolant flow rate in controlling peak temperature. That sort of thing.

Great news. I guess this means that I will have to drop the Pixie Dust formula on the design of our next heat exchanger and use a coolant flow control instead.
I wonder how all the ones we have already designed and installed are working thought....:roll:

I said "seem". Your comments to date do not give me the impression that you are actually an engineer. Are you?

And do you have any idea what a multi-megawatt uncontrolled heat leak would look like on a machine with only half a dozen or so square metres of uncooled surface area? It would be glowing pretty brightly...

Even better, a polywell based rocket to lift goods in space might even be only thermal with no direct conversion at all.

You'd get an awful Isp without a ridiculously high peak temperature. NERVA-type nuclear thermal is a lot lighter than Polywell per GW and has peak temperatures in the range of 2000-2800°C, but it still isn't anywhere near good enough for ground launch.

If you think a conventional rocket I do agree, but for an hybrid spaceplane it might be feasible.
Someone made some calculations a couple of years ago, I will look back for them.

Okay. While you're at it, please remember that the stagnation temperature of high-altitude air reaches 600 K at about Mach 3, and 1800 K not much past Mach 6 (so you can't plausibly heat it directly for most of the way to orbit), and that the amount of energy required to get liquid hydrogen up to 1800 K (do you believe the cooling loop can hit that temperature? Bussard said so, but I'm not so sure) is about a quarter of the energy released by its combustion. In other words, the fusion reactor only adds about 25% more energy on top of what you'd get by deleting the reactor entirely and dumping the hydrogen straight into the airstream. What you're describing is sort of like an RBCC engine with a very fuel-rich rocket section, but far heavier due to the mass of the fusion reactor. You'd be better off with straight chemical.

Not to mention that to get to orbit, a significant fraction of the launch will have to be in vacuum, where an 1800 K hydrogen temperature gets you an Isp of about 725 seconds (63,000 lbf per GW), which is pretty miserable for such an appallingly heavy machine. Restrict the temperature to 600 K (the hot-side temperature we were discussing for the SC Brayton cycle) and you get worse Isp than a hydrolox chemical rocket, but with much larger/heavier tankage.

Not at all. It's simply a reminder that when designing a launch vehicle, your options for passive, non-regenerative cooling are limited.

But your options to have different engines for different applications are not limited.

Apparently you didn't follow the line of thought I was trying to head off. Never mind.

Anyhow, I am ready to drop any other topic and just stay on this thread topic:
The need of recovery of a high bremsstrahlung fraction can render the reactor useless as a power generator?

I have not yet understood your point of view on this issue.

I haven't given you my point of view on this issue. The discussion started with you asserting that x-ray recovery would take a significant hit from uncollected heat loss. I countered with an assertion that heat collection would likely be efficient enough that it wouldn't have a major impact on the power recovery efficiency, and I backed up my view with explanation. That is what we've been fighting about, though you seem to have forgotten this. Bringing other factors into the discussion, while it may be technically 'on topic' wrt the thread title, muddies the waters regarding the specific sub-thread we're engaged in here.

[Giorgio]

True, SC-CO2 cycle can work at 300C, yet efficiency does not go much over 40%.
Add losses from capturing the whole x-Ray fraction and you do not end much far away from my projected claim.

That, and only that, is what I've been disputing. You seemed to be claiming that almost half of the waste heat would be lost to the surroundings rather than being captured by the cooling system. I think this is unjustified pessimism, particularly given the effort that would go into this segment of the design if it turned out high-efficiency x-ray capture was critical to close the power balance.

If that was your doubt you should have asked the question in a direct way, like you did now.

It is clear (and I even specified) that the efficiency number I gave was referred to the final electricity production. After all that was what we were talking about.
That includes losses of uncollected heat, efficiencies of heat exchangers and heat to electricity conversion system including systems and ancillaries.

My personal assumption was to use a standard superheat steam conversion. Multiply all the subsystem efficiency factors among them and the final efficiency is not far away from what I stated.
If we add a SC-CO2 low heat step as you suggested than the situation clearly gets better as you can use lower heat fluid from some of the low thermal cooling loops, yet final efficiency is not going to be over 45%, and I am being really optimistic.

I think this is unjustified pessimism, particularly given the effort that would go into this segment of the design if it turned out high-efficiency x-ray capture was critical to close the power balance.
Everything else you've said about efficiency and power recirculation is true, but irrelevant to this point.

I do am pessimist, and I stated this clearly in a previous post. After spending few years designing heat exchange systems pessimism becomes a part of the way you must think if you want to meet the design specifications.

Almost all the x-ray power comes out in the vacuum vessel wall itself, or in the equipment within it, and after that it's a straightforward matter of heat collection.

There is not such a think as "a straightforward matter of heat collection". There can be straightforward heat dissipation, but efficient heat collection is hard. Even in a boilers where we have 100 years experience is hard.
I'll make you a very basic example. Sometimes we are obliged to place sub cooling circuits on specific locations of the heat exchanger just to limit peak heat concentrations or thermal stress on the metal or the sensor. That is lost heat and a reduction of exchanger efficiency. And this is but one of tens of issues you can and will face.

In other words, under reasonable assumptions, it looks like the launch vehicle reactor (with low bremsstrahlung) would have a higher thermal power flux than the ground reactor (with high bremsstrahlung). So why is it so hard to cool the ground reactor, and so easy to cool the LV core?

You are stating is hard. I am stating is inefficient.
Did it occur to you that a ground reactor must be made efficient as we need to get a profit out of it while a rocket application can also be inherently inefficient?
In a rocket application the main aim is to cool it down and we have quite a big experience in the use of regenerative cooling to do so.
Geometry will be quite an issue, but the low starting temperature of the working fluids and the fact that we do not need to recover the fluid used for cooling will be a good benefit.
You can't do that in a ground reactor if you want to make it profitable.

It's sort of a separate line of argument, in which I claim that you have made contradictory assertions without realizing the contradiction. Basically, I assert that you must pick one or the other;

Basically I cannot agree, because this is an IF-->THAN type of discussion. If you change the IF you can have a different THAN.
Until some real data will limit the IF options we can make all the assumptions we want, IMHO.

(by which, at the beginning of the argument, we both meant % of heat collected, not % of heat turned back into electricity)

Maybe you meant "% of heat collected", but I never did.
I'll quote my reply to Dan Tibbets:

I'm not sure what Giorgio means by global efficiency. But, most reactors will need active cooling with heat collection, which is used to generate electricity at perhaps 25-35% efficiency, depending on various issues.

I mean efficiency of absorption of X-ray into heat and transformation of this heat into electricity.

If you had any doubt about what I was meaning you should have asked to me and not give it for granted.
And as a side note, among engineers if you talk about recovered heat you talk about it in thermal power units, not percentages.

I said "seem". Your comments to date do not give me the impression that you are actually an engineer. Are you?

I am, are you? Did you ever design heat exchange systems? I do.

If you think a conventional rocket I do agree, but for an hybrid spaceplane it might be feasible.
Someone made some calculations a couple of years ago, I will look back for them.

Okay. While you're at it, please remember that the stagnation temperature of high-altitude air reaches 600 K at about Mach 3, and 1800 K not much past Mach 6 (so you can't plausibly heat it directly for most of the way to orbit), and that the amount of energy required to get liquid hydrogen up to 1800 K (do you believe the cooling loop can hit that temperature? Bussard said so, but I'm not so sure) is about a quarter of the energy released by its combustion. In other words, the fusion reactor only adds about 25% more energy on top of what you'd get by deleting the reactor entirely and dumping the hydrogen straight into the airstream. What you're describing is sort of like an RBCC engine with a very fuel-rich rocket section, but far heavier due to the mass of the fusion reactor. You'd be better off with straight chemical.

I said feasible, I never say easy.
If you want to discuss about it than open a new thread with your assumptions and we can talk about it.

Anyhow, I am ready to drop any other topic and just stay on this thread topic:
The need of recovery of a high bremsstrahlung fraction can render the reactor useless as a power generator?
I have not yet understood your point of view on this issue.

I haven't given you my point of view on this issue. The discussion started with you asserting that x-ray recovery would take a significant hit from uncollected heat loss. I countered with an assertion that heat collection would likely be efficient enough that it wouldn't have a major impact on the power recovery efficiency, and I backed up my view with explanation.
That is what we've been fighting about, though you seem to have forgotten this

Again I feel you did not understand my very basic position.
Uncollected heat loss is not equivalent to not cooling same parts of the reactor. It means not being able to bring the heat you intercept to the recovering system (i.e. to the power generation unit) in a recoverable way. This can happen for a plethora of reasons, from the heat simply being irradiated to the surrounding area up to a local cooling loop that does not generate a fluid with enough heat to include it into the power loop.