Remove "radioactive exhaust" from the part description of the LV-N

[Kasuha]

Could you please name your source? All i see every time is that the propellant passes in-between the fuel rods. If that wouldn't be the case than there wouldn't be the problems with pressure differences or corrosion of the fuel rods.

For instance this article mentions that "One big problem was that all that super-heated hydrogen corroded the fuel cladding, causing the thing to leak radioactive uranium."

In order to corrode the cladding, some must have been in place first.

And regarding the volume of mentioned leaks, official reports supposedly qualify it as "negligible" although I have not found any actual numbers.

[lajoswinkler]

Huh, I made a mistake.

NERVA does give off radiation. It gives plenty of it. Neutron flux around it is enormous, as well as gamma rays.

What it does not give are copious amounts of radioactive exhaust, which is a totally different thing.

It does give off small amounts of tritium which is made by irradiating hydrogen (NERVA reaction medium) with neutrons.

Therefore LV-N engine would be a great radiation hazard, but a small, insignificant radiological hazard.

[r4pt0r]

Huh, I made a mistake.

NERVA does give off radiation. It gives plenty of it. Neutron flux around it is enormous, as well as gamma rays.

What it does not give are copious amounts of radioactive exhaust, which is a totally different thing.

It does give off small amounts of tritium which is made by irradiating hydrogen (NERVA reaction medium) with neutrons.

Therefore LV-N engine would be a great radiation hazard, but a small, insignificant radiological hazard.

so while its running its bad, but once its off there is no lingering damage?

[Sirrobert]

so while its running its bad, but once its off there is no lingering damage?

I'm pritty sure you can't just turn off a nuclear reactor.

What he meant is that it DOES give up radiatION, but no radioactive MATERIAL.

So it's completely safe to fire in the atmsophere, because the only thing you can irradiate there is air

[vger]

The "radioactive exhaust" bit in the LV-N part description is misleading; solid-core NTRs working properly do not emit radioactive material.

Or... make the rocket vent 'glowing green' gas. This is a Kerbal engine after all.

[CaptRobau]

Guys, if you want the incorrect information removed early, go into the part.cfg of the NTR and take the info out, put what you want in.

I think the point is less that they want it changed for themselves, but rather that they want it changed for everyone to prevent people getting a wrong idea of how NTRs work both in-game as well as in real-life.

[Red Iron Crown]

Having the LV-N run on liquid fuel only would greatly simplify spaceplane design, as they wouldn't need oxidizer at all if a nuke is used for out-of-atmosphere maneuvers.

[Brotoro]

Well, on the one hand it seems like a very minor thing, but then again there's no real reason for it to be incorrect and this would be a very simple change. Maybe just change it to something like "Don't let the trefoil and radioactive core fool you, this engine doesn't give off any radiation (usually)."

This description is also inaccurate. Even though NERVA engine exhaust is not very radioactive, the engine emits lots of neutrons and gamma rays when in operation.

I would suggest: "Despite the big scary trefoil painted onto the side of this engine, the exhaust of the the LV-N Nuclear Rocket Motor is hardly radioactive at all--but you do NOT want to hug it when it's operating."

[lajoswinkler]

so while its running its bad, but once its off there is no lingering damage?

After you turn it off, there is still spontaneous fission of the daugher nuclei, and they're furiously radioactive. Incredible, astounding, awesome levels of gamma and beta rays are given off, and lots of heat is produced. It drops at an exponential rate.

That's why power plants need to cool their cores after shut down for several days before the spent rods can be transferred into the cooling pool.

This is how the fuel bundles look after the initial cooling, during the transport to the pool... Now you can only imagine the intensity of the glow in a working reactor, in which both uranium and its daughter products decay like mad. (pressurized water reactor, of course - Cherenkov glow requires a medium)

[frizzank]

Im in favor of making it a liquid only rocket engine. This would make it more unique and much more useable.

[NERVAfan]

I think the point is less that they want it changed for themselves, but rather that they want it changed for everyone to prevent people getting a wrong idea of how NTRs work both in-game as well as in real-life.

Exactly. Nuclear space technology (heck, nuclear technology period) gets too much bad press as is.

[r4pt0r]

there seems to be disagreement on whether it is or isnt dangerous

whats the truth?

[m4v]

I really want some reputable source that says that the exhaust is not radioactive, I'm no nuclear scientist but it works as an open cycle system, is hard to take that claim just at face value. Kasuha linked an article that writes that the NERVA tests had "negligible" radiation exhaust, what is "negligible"? even if is low it does imply that the exhaust is radioactive at some level, which isn't what OP and others are claiming.

Even so posters above already established that the NERVA itself IS a radioactive hazard, whatever the description says, if the exhaust is radioactive or not, is just nitpicking.

Edited April 23, 2014 by m4v

[Red Iron Crown]

there seems to be disagreement on whether it is or isnt dangerous

whats the truth?

The reactor itself is mostly unshielded, and does emit radiation when active (and for a time after activity). The exhaust is not particularly radioactive or more dangerous than chemical rocket exhaust.

[NERVAfan]

Even so posters above already established that the NERVA itself IS a radioactive hazard, whatever the description says, if the exhaust is radioactive or not, is just nitpicking.

No, it's a huge difference -- it doesn't produce radioactive pollution. The reactor itself is radioactive while (and for a while after) it is running, but using a NERVA in the atmosphere doesn't release radioactive materials into the atmosphere (if it's working right).

[m4v]

No, it's a huge difference -- it doesn't produce radioactive pollution. The reactor itself is radioactive while (and for a while after) it is running, but using a NERVA in the atmosphere doesn't release radioactive materials into the atmosphere (if it's working right).

Things work right only on paper, in real life things work within acceptable limits of tolerance, that is to say, that there's radioactive exhaust but "negligible", and that's different than saying that is nonexistent. You only have to find a reputable source stating that the exhaust is not radioactive and that it remains that way during the lifetime of the rocket, otherwise all I see here is people on internet asking to accept their claim at face value.

[Stargate525]

Things work right only on paper, in real life things work within acceptable limits of tolerance, that is to say, that there's radioactive exhaust but "negligible", and that's different than saying that is nonexistent. You only have to find a reputable source stating that the exhaust is not radioactive and that it remains that way during the lifetime of the rocket, otherwise all I see here is people on internet asking to accept their claim at face value.

'negligible' in terms of radiation typically means 'so small as we're not going to bother with the math on it.' You're probably talking about levels akin to an X-ray, eating a banana, or a few hours in the sun.

[m4v]

'negligible' in terms of radiation typically means 'so small as we're not going to bother with the math on it.' You're probably talking about levels akin to an X-ray, eating a banana, or a few hours in the sun.

That's your assumption, negligible is a relative term and needs context or data for it to be meaningful, the NERVA tests were made during the time that nations made regular atmospheric nuclear tests, that time negligible could mean not as bad as nuclear fallout.

[TheCanadianVendingMachine]

Whats the point? It's a game. Not like it is something that is important, do it yourself if it annoys you...

[Bilfr3d]

I agree with TheCanadianVendingMachine. If you don't like it, remove it from the description.

[pizzaoverhead]

Whats the point? It's a game. Not like it is something that is important, do it yourself if it annoys you...

I agree with TheCanadianVendingMachine. If you don't like it, remove it from the description.

It's not that they don't like the description, it's that they don't like the effect that it will have on people who only learned of the existence of nuclear thermal reactors through KSP. Changing their personal part.cfg has no effect on this.

[MarvinKitFox]

Based on ISP and appearance, the LV-N is a Nerva-type. I.e. solid core.

Radiation released in the exhaust: almost indetectable. Very far below health concerns.

Radiation released from engine before first ignition: Virtually zero

Radiation released from a shut-down but used engine: Significant, but not too bad. Shieldable/avoidable with easy measures.

Radiation released from engine while running full throttle: Neutron flux from Hell, gamma flux from same. Not shieldable in general, is avoidable by interposing distance + fuel tank, etc. Nasty, but *can* be used safely if you plan well.

Radiation released in event of crash or mishandling: Oh Sh....! Get me outta here. Not just out of the neighborhood, get me to another SOI!

.

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In real life, I would be very nervous about any use of a Nerva-type engine within the Moon's orbit. And even severely cautious about launching a fully inerted engine from Earth, for assembly out there.

Its like a nuclear power plant. When working fine, it is very safe. But when it goes boom, it is a very very Very *very* bad day.

Of course, a launch mishap with a jebediah-class SuperDreadNaught (230 orange tanks) is a very very bad day in any case.

[lajoswinkler]

there seems to be disagreement on whether it is or isnt dangerous

whats the truth?

A nuclear reactor during active fission of its fuel will emit a crapload of neutrons which stick to the nuclei of other elements in the vicinity. The heavier the nucleus is, the more chance there is it will grab the neutron and turn into an unstable isotope. If you put some ordinary solution of sodium phosphate into a working reactor, phosphorus will turn into its unstable radioisotope, and you can use that solution in medical purposes.

Hydrogen requires two neutron captures, and its nuclei is the smallest (1 proton), so chances for turning into tritium are very small. Therefore only a tiny fragment of the initial hydrogen will become radioactive.

NERVA engine would be an incredible radiation hazard to be close to while it's working (neutrons, gamma rays, beta rays), and it would stay like that for a long time after shutdown, except there'd be no neutrons, only gamma and hard beta rays, as the fission products decay spontaneously.

So, yes. NERVA is dangerous to be around.

I really want some reputable source that says that the exhaust is not radioactive, I'm no nuclear scientist but it works as an open cycle system, is hard to take that claim just at face value. Kasuha linked an article that writes that the NERVA tests had "negligible" radiation exhaust, what is "negligible"? even if is low it does imply that the exhaust is radioactive at some level, which isn't what OP and others are claiming.

Even so posters above already established that the NERVA itself IS a radioactive hazard, whatever the description says, if the exhaust is radioactive or not, is just nitpicking.

It could be calculated how much of the exhaust turns to tritium, but it requires the knowledge of how a particular engine system is built.

NERVA is not for launching, it's for tugging in space. Dumping traces of tritium in space? Who cares?

[Seret]

Besides the exhaust high neutron flux will induce radioactivity in everything nearby, such as the structure of the engine.

[m4v]

NERVA is not for launching, it's for tugging in space. Dumping traces of tritium in space? Who cares?

Is not that I care, we are arguing about changing the engine description because people think it hurts the "public image" of a NERVA type rocket. Meanwhile KSP doesn't portray ANY of the negative and hazardous effects of the rocket, if NASA saw the stuff we do with NERVA rockets, they would be horrified.

Edited April 23, 2014 by m4v