Hydrogen leak!

[Carlobrand]

We're going to begin with an assumption. Your ship hull is resistant to small penetrations. Think of it as a double-walled hull sandwiching a gel that extrudes and solidifies on exposure to vacuum, or some such. The hydrogen tankage is surrounded by a similar set-up, for obvious reasons. To penetrate and leave a hole requires something large - as for example a laser or a 30 kg. missile warhead.

Now, something big penetrates your fuel tank, punching through your hull and penetrating the other side of the tank to punch a hull into an adjoining compartment. Say a fist-sized hole. Hatches are quickly sealed, confining any effect to an area defined by internal bulkheads. Hydrogen is flooding into the compartment.

First scenario: you've been hit while fully pressurised. Liquid hydrogen is jetting in and vaporizing. Someone is trapped in the affected compartment. Will he die of cryogenic injury first, or suffocation? If a spark occurs, and assuming the mix is just right - or just wrong, from the viewpoint of the ship's crew - how violent will the resulting explosion be?

Second scenario: this is a combat event, you've depressurized to minimize potential combat damage prior to the event. A tank with 10 dTons of liquid hydrogen is venting both into space and into the compartment. A crewman is trapped but in protective gear. Does he suffer cryogenic injury, or will the suit provide sufficient insulation to prevent injury? At some point, the tank load will escape to space and the hydrogen in the compartment will reverse and vent back into the tank and then to space, leaving the compartment again in vacuum, but how quickly? Does the trapped crewman need to worry about being in an insidious atmosphere, or will it clear to vacuum quickly enough to protect him?

 

[Magnus von Thornwood]

Not a real scientist or mathematician.

However, I am a Referee and I do of course have a few thoughts. Some are even good ones.

Scenario One: I would go with suffocation first, then you get very cold. Which is good actually as here on good old TL-8 Terra we are finding that chilling down a trauma patients actually can improve survival rates, so by TL-A+ this should help your crewmates get your dead flesh alive again.

As for the explosion, which does more damage to the crew member, it will be quick, violent and probably contained in the compartment. From what I have seen of hydrogen explosions they are very, very fast and not as damaging to the container as say gasoline is.

Scenario Two: if the crew member is in a standard vaccsuit, prolonged exposure might start to damage the suit and then the spacer. (Okay, probably not, but it would go in a movie and we would all yell at the screen "BUT IT'S A FANARKING SPACESUIT, IT WORKS IN LIKE 5 KELVIN YOU IDIOTS!" and then wander into a tangent about how actually they also work in extreme heat...uhhh, yeah ) In truth it is only the insidious part that is a problem, L-Hydo while being extremely cold is still sort of warm compared to deep space vacuum.

Now, does it stay long enough to seep into the suit? Good question. How much does the crew sophont function on training at that point and they plug the hole without thinking about the insidious atmo being contained with them? Assuming a properly trained crew when the various alerts start scream/flash/overriding comms warning them of the presence of hydrogen in the compartment, they will allow the vacuum to clear the chamber and then patch the hole. By properly trained I mean Navy, Marine or Scout. Merchants could go either way, if they have Engineering or some Line skill then they probably do it right. Steward or Broker, "So, do you have VaccSuit on that character sheet?" becomes my response then maybe a juicy difficulty roll. Maybe an Army sophont, but there had better be a tale of daring do while be transported somewhere to fight.

And again I say, I may be totally off and Aramis will come in here and make me look like a science moron. Luckily this isn't my table so none of my players will know when I do it to them. :devil:

 

[Dragoner]

Fuel tank hits would be child's play compared to power plant hits. :devil:

 

[far-trader]

Nah, your powerplant getting hit is nothing

It won't go China Syndrome or Runaway Reaction on you. It won't blow up. It just quits giving you power. Even a resulting fuel leak will be minor as valves automatically shut down.

What you want to look out for is your jump drive being hit when it's charging up, like when you're desperately trying to escape by jumping out. Those capacitors blow and you are a guaranteed a total sensor kill of any ships in the area... as you go off like a small nova!

 

[Dragoner]

A damaged fusion reactor? Nah, that wouldn't flood the interior of a ship with a major dose of radiation.

 

[far-trader]

A damaged fusion reactor? Nah, that wouldn't flood the interior of a ship with a major dose of radiation.

Nope, it wouldn't

http://en.wikipedia.org/wiki/Fusion_power#Accident_potential

Yes, it's wiki, but I've seen similar elsewhere, this was just the first hit on googling for background.

 

[Icosahedron]

First scenario: you've been hit while fully pressurised. Liquid hydrogen is jetting in and vaporizing. Someone is trapped in the affected compartment. Will he die of cryogenic injury first, or suffocation? If a spark occurs, and assuming the mix is just right - or just wrong, from the viewpoint of the ship's crew - how violent will the resulting explosion be?

If he's in the path of the jet, he'll probably get a major dose of brittle-body syndrome, otherwise, I'd say he'd suffocate before the cooling atmosphere killed him. The chances of a spark occurring at exactly the right moment and no other are pretty slim, so your explosion will probably not have maximal effect. It may be just a major flashover rather than a full-blown explosion. However, if an explosion occurs, just google some pics of gas-main explosions to see the effects.

Second scenario: this is a combat event, you've depressurized to minimize potential combat damage prior to the event. A tank with 10 dTons of liquid hydrogen is venting both into space and into the compartment. A crewman is trapped but in protective gear. Does he suffer cryogenic injury, or will the suit provide sufficient insulation to prevent injury? At some point, the tank load will escape to space and the hydrogen in the compartment will reverse and vent back into the tank and then to space, leaving the compartment again in vacuum, but how quickly? Does the trapped crewman need to worry about being in an insidious atmosphere, or will it clear to vacuum quickly enough to protect him?

The suit is designed to protect against cold. How quickly? Piece of string. You could figure it out given the hole size and the volume of the compartment, but it's not the sort of calculation I'd like to do. Depends on the final pressure developed in the compartment anyway. Too many variables.

I'd guess a typical stateroom would empty from 1 bar through a fist hole to vacuum in a few minutes - but it's only a guess. Imagine the compartment as a water tank emptying - it'll get you in the right ball-park.

I imagine a suit would provide protection from insidiousness for that long.

Nope, it wouldn't

Especially not if your reactor is a pellet-fed inertial confinement type.

 

[Dragoner]

Nope, it wouldn't

http://en.wikipedia.org/wiki/Fusion_power#Accident_potential

Yes, it's wiki, but I've seen similar elsewhere, this was just the first hit on googling for background.

The wiki contradicts itself at the end; though I have heard different from engineers (from Neil Armstrong Hall) on the subject, that the radioactivity is issue with both reactors and drives.

 

[mike wightman]

Yeh - cos there's loads of real world fusion reactors and drives out there to compare

Look up the fusion reactions that are likely to be used in a Traveller grav-catalysed fusion reactor (the p-p chain that occurs in stars) and notice how many of the steps emit any sort of hard radiation? Your reactor will need shielding to protect against the gamma emissions and the positron annihilations that will occur, not to mention the odd stray neutrino or two (these are harmless by the way)

The reason I say grav-catalysed is because the only way I can see a fusion reactor being made small enough to fit in a vehicle or ship at the early fusion TLs is to use some sort of grav compression technology, at least until nuclear damper technology is perfected and strong force manipulation becomes possible.

As soon as any significant damage is done to your fusion reactor the reaction stops - the worst you'll get is a rapidly expanding (very small) very hot plasma. This could be dangerous in the engineering compartment, but the radiation is a non-issue providing your normal shielding is intact.

Now if the shielding is damaged while the reactor is running...

 

[BytePro]

To many open variables for any truly definitive answers (of real worth).

But some thoughts related to gaming it:

• A fist-sized hole can be plugged - with a fist, if nothing else!
• L-Hyd will vaporize and will move rapidly into compartment through even a small hole as the vaporization has a priming & siphoning effect.
• Direct exposure as mentioned will most likely result in death from shock (cardiac failure), before direct thermal or asphyxiation.
• The nature of death is actually probably irrelevant in-game, unless it is suspected of hiding a murder (Traveller NCIS).
• L-Hyd is vaporizing and will ignite at low mixing percentages with atmo (<5%), but not detonate till higher.
  - it would depend on when the mixture is ignited whether it just burns given the relief mechanisms inherent in the holes in stateroom and hull, or explodes.
• L-Hyd is not corrosive (no insidious atmo).
  - mixed with normal atmo may cause condensing, but nothing corrosive from that mixture either (unless other substances are involved).
• Immediate exposure should be a non-issue for Suits - but if significantly immersed for any period, will likely be unable to maintain internal heat and may suffer flexibility issues.

 

[BytePro]

Re: fusion reactors and radiation...

'Clean' fusion involves reactions that have no radioactive by-products of a long term or immediately harmful nature - but nuclear reactions involve radiation in the process (type, absorption, conversion determine net or operational and by-products being radioactive).

Exposure to ionizing radiation that would be an immediate concern is not at all a likely issue with any failure of fusion tech. (And anti-rad treatments would take care of those longer term health concerns.)

The immediate concerns are - electrocution (directly and from ionized air) and direct exposure to extreme heat or even plasma. Fuel leaks and resultant harm (even explosions) are probably the greater secondary concern - and such are likely mitigated by multiple redundant, and distanced, fail safes.

Loss of full power is probably the greatest effect impact. Especially if in combat or on a collision course with something... (time to outgas!)

 

[Dragoner]

Now if the shielding is damaged while the reactor is running...

That is exactly what a hit would be, a breach of containment. With the reactor likely at full output.

As propulsion engineers working at Armstrong, it is closer to their field of engineering than mine. Plus there are weaponized fusion reactions.

 

[Icosahedron]

[*]L-Hyd is not corrosive (no insidious atmo).
- mixed with normal atmo may cause condensing, but nothing corrosive from that mixture either (unless other substances are involved).
[*]Immediate exposure should be a non-issue for Suits - but if significantly immersed for any period, will likely be unable to maintain internal heat and may suffer flexibility issues.

The 'insidious' nature of Hydrogen is traditionally assumed to be it's small particle size, enabling it to pass through the suit fabric over time and hence cause suffocation, rather than any corrosive effect.

 

[Whipsnade]

That is exactly what a hit would be, a breach of containment. With the reactor likely at full output.

With containment gone, the reaction stops and, when the reaction stops, the radiation is gone. Not so with fission and far too many otherwise intelligent people seemingly cannot grok the difference.

Fusion is inherently different from fission, different "fuels", different containment, different byproducts, different ways to "extract" the energy, everything is different. Trust me, I'm a nuclear engineer.

Fusion uses nonradioactive elements in a somewhat radioactive process to produce energy with few, if any radioactive byproducts. Fission uses radioactive elements in a very radioactive process to produce energy with a great many radioactive byproducts.

Fusion reactions will eventually "contaminate" their containment vessels via particle bombardment but with nothing like speed or "virulence" fission reactions do.

As propulsion engineers working at Armstrong, it is closer to their field of engineering than mine.

Apples and oranges. Plasma streams used to provide thrust are something else entirely, especially if "fuel" is added to the stream to provide "heft".

Plus there are weaponized fusion reactions.

Again, apples and oranges. Among other issues, weaponized fusion reactions use fission triggers and thus have fission byproducts associated with them.

A containment breach in a Traveller fusion power plant will result in plasma and other damage due to heat transients. There will be no "fallout", no contamination, no Chernobyl or Daichiv or anything like you're assuming. There will be some gamma and neutron exposure, however and completely unlike fission, because those particles are being produced by the reaction and not the fuel, the end of the reaction means the end of their production. Yes, tritium will be produced and, yes, it emits a rather nasty alpha. That particle can be shielded by paper and dead skin. You'll literally need to inhale/swallow quite a bit of it for any danger to occur.

 

[BytePro]

Very well put Whipsnade!

The 'insidious' nature of Hydrogen is traditionally assumed to be it's small particle size, enabling it to pass through the suit fabric over time and hence cause suffocation, rather than any corrosive effect.

The situations as presented, that would be an extreme stretch, I think. Hydrogen is present molecularly and would be moving into a higher pressure suit with atmo, probably resulting in condensation at worst (which would further slow intrusion).

In a high pressure, pure gaseous atmo, molecular diffusion could certainly present a problem - particularly at joints, at least to the point of potentially being a fire hazard - given enough time. Suffocation probably not, at least in the time provided by a suit's power and air supplies (unless they are very long lasting - ala fusion and full reclaimer - in which case active removal of foreign gases would be credible).

 

[Whipsnade]

Very well put Whipsnade!

Thank you. I tried to make the points "accessible" without also "dumbing them down".

 

[BytePro]

Yeah - I sux at that. In work environs I hand off my writings to others and ask them to 'translate into human'.

[Spent over two hours yesterday trying to 'simplify' a few pages - best I got down to was a Flesch–Kincaid Grade Level of 11.7 ]

 

[Gray Pennell]

Fusion is inherently different from fission, different "fuels", different containment, different byproducts, different ways to "extract" the energy, everything is different. Trust me, I'm a nuclear engineer.

What do you think of Thorium LFTR?

 

[Enoki]

A variant is the fusion reactor on the ship has a partial containment failure. The ship is now being flooded with neutron radiation. Of course, no on can get to the controls and shut it down or restore the containment.....

 

[Whipsnade]

What do you think of Thorium LFTR?

It deserves further study seeing as there have been numerous advances since the late 60s.. I even believe the PRC is talking about a decades long research effort.

There are pros and cons of course. More fuel because it's a breeder, but that leads to proliferation issues. The fuel cycle is going to require lots of infrastructure too.

Of course, Daichi has most likely strangled the "Nuclear Renaissance" in it's cradle in all but totalitarian command economies.