OOPS

Loren Pechtel wrote:The center of the sun is about 150 g/cm^3. The most logical material for an h-bomb is lithium deuteride at .83g/cm^3. Thus it's 180x compression to the density of the sun. That yields a temperature of about 54k K--nowhere near hot enough. (Even worse for reactors--the fuel is 1/10th the density so you need 10x the compression--but it's 15x colder, so the end result is an even lower temperature.) They're using gravity for the compression and something else for the heat.

Temperature doesn't really matter if you compress the matter so much that the nuclei do interact despite their EM repulsion. Heat in a star's core is not a cause of fusion, it's an effect. Sure, once it's there, heat causes more fusion to happen, positively feeding the cycle back, but at the same time causes nucleai to traval further, reducing density and thus negatively feeding back.

ThinksMarkedly wrote:

Loren Pechtel wrote:The center of the sun is about 150 g/cm^3. The most logical material for an h-bomb is lithium deuteride at .83g/cm^3. Thus it's 180x compression to the density of the sun. That yields a temperature of about 54k K--nowhere near hot enough. (Even worse for reactors--the fuel is 1/10th the density so you need 10x the compression--but it's 15x colder, so the end result is an even lower temperature.) They're using gravity for the compression and something else for the heat.

Temperature doesn't really matter if you compress the matter so much that the nuclei do interact despite their EM repulsion. Heat in a star's core is not a cause of fusion, it's an effect. Sure, once it's there, heat causes more fusion to happen, positively feeding the cycle back, but at the same time causes nucleai to traval further, reducing density and thus negatively feeding back.

That's going to require incredibly more force.

Loren Pechtel wrote:The center of the sun is about 150 g/cm^3. The most logical material for an h-bomb is lithium deuteride at .83g/cm^3. Thus it's 180x compression to the density of the sun. That yields a temperature of about 54k K--nowhere near hot enough. (Even worse for reactors--the fuel is 1/10th the density so you need 10x the compression--but it's 15x colder, so the end result is an even lower temperature.) They're using gravity for the compression and something else for the heat.

ThinksMarkedly wrote:Temperature doesn't really matter if you compress the matter so much that the nuclei do interact despite their EM repulsion. Heat in a star's core is not a cause of fusion, it's an effect. Sure, once it's there, heat causes more fusion to happen, positively feeding the cycle back, but at the same time causes nucleai to traval further, reducing density and thus negatively feeding back.

Loren Pechtel wrote:That's going to require incredibly more force.

That is clearly not a problem in the Honorverse: consider the enormous amount of energy needed to create a wedge.

tlb wrote:

Loren Pechtel wrote:That's going to require incredibly more force.

That is clearly not a problem in the Honorverse: consider the enormous amount of energy needed to create a wedge.

That's what I was thinking. Under normal circumstances, using gravity to create fusion is going to require vast amount more energy than you get out of the fusion, unless you have so much mass helping you with that gravity. In that case, no amount of stealth is going to help you hide that mini-sun you're carrying in the belly of your ship.

We don't understand energy when hyperspace and the alpha wall are concerned in the Honorverse. Ships seem to get free energy from somewhere, and yet they still need fusion reactors with prodigious amounts of mass to sustain them for 6 months. So tlb's remark is valid.

Maybe they can harness hyperspace energy but only for gravitation, but to transform that energy into some other kind of useable energy requires the reactors. I just don't know why you'd use fusion for that: if you have a force capable of moving stuff, move some charged particles in a magnetic field.

Jonathan_S wrote:

cthia wrote:I like your logic, but it brings us right back to the suddenness of the explosions. Containment failure is usually an inexorable march towards destrucion, not a sudden jump. But the nature of the explosions does denote reactor involvement.

Normally - when you're trying to resist the containment failure. But the ship fusion reactors use gravitically/electromagnetically compressed (GRAVMAK) plasma; and if you can simply turn those off you'd instantly lose containment and with no gravity well or EM field restraining the plasma it'd instantly and catastrophically explode out through the physical shell of the reactor.

So if you wanted to build in the ability to scuttle via reactors it'd be perfectly doable to design the reactors to support that.

OTOH it's also conceivable that they'd instead be designed to make it as hard as possible to for them to ever fail - even under deliberate action (possibly even to the extent where they can do what Chernobyl failed to; safely balance power reduction with safe containment -- powering the safety systems using only the remaining reactor power all the down way to cold metal)

And we simply don't know which way the Haven reactors were designed.

I didn't remember that ships' reactors use gravity - in the manner that they do. Recall that I was once invited to visit several nuclear power plants. Presently, they are designed to resist a complete failure of all systems for some significant amount of time far beyond "instant" destruction.*

For instance, the control rods use magnetism to keep them suspended above the reactor, and to lower them when needed. A complete failure of that system automatically uses gravity to drop all control rods. That is the meaning of fail-safe. If a system fails, it is still safe, for a reasonable amount of time.

Since Honorverse reactors are quite different in design and scope, I don't know how fail-safe would be implemented. Or, if a certain amount of time would be available to eject the reactor. Since Honorverse reactors are operated under battle conditions, I'd expect a design that would consider a complete failure of all systems. A design that would allow them to keep the notion of "fail-safe," and would also allow some time to eject. Certainly more than just instantly. How? Beats me. It would also be ironic if Honorverse reactors would incorporate a system (self-destruct) that circumvents the notion of "fail-safe."

Thanks for jump starting my memory.

* They are designed to resist a complete failure of all systems simultaneously. Believe me, we asked. When you are standing inside one of these things, you feel it's enormous power. It's like a heart beat. It beckons you to consider your own mortality and how safe you are by being there. Frightened visitors want to know and ask questions. Was I frightened being inside one of these things? Hell yea, every single time. My fright actually began the morning of each visit. Anxiety several days before that.

Late edit: link repaired.

I hesitate to point this out, but please consider the history.
Twenty years ago an extremely bright and talented author wrote a SiFi book hoping it would sell. It did, so he wrote a sequel, then another, and a massive series came into being, that we have all enjoyed. It had by then locked into place a number of immutable rules and tenets.
Twenty years later hundreds of highly intelligent people (some with heavy duty physics quals) argue the toss about every small detail. That it has a few inconsistencies as it does, is a testament to RFC's genius.
Two alternative ways of looking at this, are to imagine how an ancient Roman from 0 AD would view our science and engineering, and the other is to consider alternative histories or universes where rules are subtly different.

Daryl wrote:I hesitate to point this out, but please consider the history.
Twenty years ago an extremely bright and talented author wrote a SiFi book hoping it would sell. It did, so he wrote a sequel, then another, and a massive series came into being, that we have all enjoyed. It had by then locked into place a number of immutable rules and tenets.
Twenty years later hundreds of highly intelligent people (some with heavy duty physics quals) argue the toss about every small detail. That it has a few inconsistencies as it does, is a testament to RFC's genius.
Two alternative ways of looking at this, are to imagine how an ancient Roman from 0 AD would view our science and engineering, and the other is to consider alternative histories or universes where rules are subtly different.

Mind you, I imagine that ancient Roman would be less than impressed with our concrete.

And it's not just that intelligent people stick fingers through any holes; it's that real science has stepped forwards quite a bit since OBS was written. Hubble, Kepler. LHC, LIGO. All and more have added to our knowledge of physics. The most awkward moment was probably in 2017, when the speed of gravity was confirmed as approximately c and not 64c. Oh well.

munroburton wrote: The most awkward moment was probably in 2017, when the speed of gravity was confirmed as approximately c and not 64c. Oh well.

That may be true in normal space; but what about on the Alpha wall?

PS. I think that it was mentioned in SVW that some smaller ships had a way to eject the fusion reactor, but Honor's ship did not. That made replacing the unit much more difficult.

tlb wrote:

munroburton wrote:
PS. I think that it was mentioned in SVW that some smaller ships had a way to eject the fusion reactor, but Honor's ship did not. That made replacing the unit much more difficult.

Heck at Basilisk the CL Fearless did eject a fusion reactor

On Basilisk Station wrote:She couldn't hear the alarm in Fusion One's vacuum, but she could see the numbers flashing blood-red on the panel. The mag bottle was going, counting down with lightning speed, and there was no longer time to kill the plasma flow.
She rolled across the deck, trying not to think, knowing what she had to do, and drove her hand toward the scarlet bulkhead switch.
[snip]
The emergency jettisoning charges hurled the entire side of Fusion One out into space a microsecond before the ejection charges blew the reactor after it. There had to be a delay, be it ever so tiny, lest a faltering mag bottle be smashed against an intact bulkhead and liberate its plasma inside the ship. But small as that delay was, it was almost too long.
Dominica Santos, Allen Manning, and Angela Earnhardt died instantly. The dying containment field failed completely just as the reactor housing blew through the opening, and the terrible fury of a star's heart erupted back into the compartment as well as out. Fusion One vanished, along with seven hundred square meters of Fearless's outer hull, Missile Two, Laser Three, Point Defense One, Rad Shield One, all of her forward fire control sensors, and her forward port sidewall generators, and forty-two of Fearless's surviving crewmen died with them. A streamer of pure energy gushed out of the dreadful wound, and the light cruiser heaved bodily up to starboard in maddened response.

But yes, it was mentioned in SVW that larger ships, like HMS Nike, didn't have ejectable fusion reactors

Short Victorious War wrote:"If Nike were a smaller ship, we could disable the charges and take out the emergency panel, but that won't work here."
Honor nodded in understanding. As in most merchantmen, fusion rooms in destroyers and light cruisers—and some smaller heavy cruisers—were designed with blow-out bulkheads to permit them to jettison malfunctioning reactors as an emergency last resort. But larger warships couldn't do that, unless their designers deliberately made their power plants more vulnerable than they had to. Nike was a kilometer and a half long, with a maximum beam of over two hundred meters, and her fusion plants were buried along the central axis of her hull. That protected them from enemy fire, but it also meant she simply had to hope the failsafes worked in the face of battle damage which did get through to them . . . and that there was no easy access to them from outside.

So being deeply buried behind multiple layers of armor makes their fusion reactors less likely to be damaged. But if they are damaged then you have only the emergency shutdown mechanisms to save you.

Sorry, been gone for a bit.

ThinksMarkedly wrote:The big difference between an anti-matter annihilation event and a fusion bottle letting go is that anti-matter doesn't stop being anti-matter after a while in vacuum, but hot plasma cools down. Anti-matter reactions are self-sustaining while fusion are self-extinguishing. Regardless of how you drop the anti-matter containment, the anti-matter will eventually meet matter and annihilate. The majority of the ship isn't blown up by annihilation, but by the high-energy photons that the first annihilations create. Whereas in fusion, with the temperature of the plasma dropping, fusion stops and all you have left is high-energy hydrogen, helium, lithium, etc. that make a lot of damage as it expands.

In a controlled scuttling event, it's possible the reactors are fed an overwhelming amount of plasma to turn the reaction up, just short of melt-down, so there's enough plasma mass and it's hot enough to vaporise the rest of the ship when containment does go down.

BTW, given that the Honorverse is based on gravitational technology, it's possible that their fusion is enabled by gravitation, not temperature. That might make for much safer reactors. But then we might not have the big booms of containment failure.

I think we can safely ignore the power drop-off from the distance around the reactor for intra-ship purposes. Regardless of how such power levels are achieved, we know from canon that a single fusion plant blowing can vaporize armor off the unshielded hull of ship hundreds of kilometers away (PNS Atilla and PNS Farnese in EoH), and that was under typical operating regimes and not a deliberate overload. Of course, we see something similar from the ejected core from Fearless in OBS as well, but that's a smaller plant and IIRC a sidewall is involved.

Theemile wrote:But, externally, you would see much the same from the missile wedges firing up. If all the missiles in the tubes suddenly fired up their wedges, all the ship's reactors would lose containment instaneously.

Besides, Shannon already saw this happen once. Her mind probably worked on a way to do it remotely for the intervening years. And she has access to the TAC updates going to the Missiles.

We can reasonably put the wedge theory to bed, I think, by the fact that Harkness had to physically access the pinnace to sabotage it. He had weeks worth of planning and sabotage time to work with and couldn't do it. Or at least didn't, despite the fact that assuring the destruction of the ship should have been an even higher priority than getting off of it due to all the classified information he'd given as bait (and killing Ransom was a goal in itself, of course). It seems to be a case where a physical interlock performed as designed.

Also, the explosion from the wedge destruction was described differently from more common reactor explosions, since a reactor explosion is an internal explosion rupturing an armored hull whereas the wedge destruction was simply the explosion lighting up a hull that was already flying to pieces. But who knows how far away an observer would need to be to see such a difference in the explosion.

munroburton wrote:

tlb wrote:Or just "drop sidewalls and fire"?

Upon further reflection, I don't think there would've been any sidewalls to interpose. Superdreadnoughts don't line up side-by-side - they go nose-to-tail, vertically stacked. The StateSec broadsides would've been pointed towards Giscard/Tourville's flagships.

Those would've all been spinal shots. Straight through the targets' longest axis, stem to stern.

The problem with that theory is that SDs, particularly the hammerheads, are designed and armored to resist fire of exactly that type. Enough grazer fire could do it eventually, but probably not the first salvo. Even from another SD's full chase armament, that's not going to be enough. And since they're all shooting each other in the hammerheads, the first salvo is going to wreck enough that there isn't going to be much of a second salvo.