Why aren't we using nuclear thermal rockets?

[Green Baron]

Here's data:

http://pluto.jhuapl.edu/Mission/Spacecraft/docs/NH-DEIS_Front.pdf

Risk assessment for the New Horizons mission defines the risk of releasing plutonium material (1% of the inventory, possible fatal consequences to humans from latent cancer 0.4 to 5.2) in the launch area in case of a launch failure as "unlikely" (1/100 to 1/10000), which is the highest of three categories (inlikely, very unlikely, extremely unlikely).

Only an uninformed person can assume that there is no risk connected with the launch of a modern RTG, and it is far higher than being hit from the ISS.

*hough*

 

Edit: but hey, this mission is fully worth the risk imo !

Edited December 20, 2018 by Green Baron

[DDE]

10 minutes ago, sh1pman said:

Only if you inhale/ingest it. And then it's metabolized and released by your body fairly quickly. I work with tritium a lot (well, used to work a lot, now using cheaper and safer alternative). If it's contained, even in plastic, it's harmless.

Same with refined uranium dioxide.

[tater]

The risk of being hit by ISS debris cannot be excluded. All risks are non-zero. They are none the less inconsequential. The US has had 3 RTGs hit Earth, 2 reentries, 1 launch failure. One (1964) burned up as designed.  50 years ago, another had a launch failure. It was collected, intact and reused. The last was supposed to land on the Moon (Apollo 13) and reentered with Aquarius. No radiation was ever detected (they looked).

The chances are non-zero, but I'm not even slightly concerned.

I'll continue to refer to people against space nuclear power as Luddites.

[kerbiloid]

Nuclear-challenged persons.

[Bill Phil]

RTGs have a few kilograms of radioactive material within them. Personally I’d be more worried about natural radiation sources than RTG failures. Radon has been found to be responsible for tens of thousands of deaths per year. A few kilograms of plutonium is a drop in a bucket in comparison. Heck, thousands of tonnes of radioactive material is released into the atmosphere by coal plants...

Is there risk? Of course. But there’s risk in everything. The question is whether or not the benefit is worth the risk.

[Green Baron]

Well, then, it is a shame, i continue referring to people playing down risks and ignoring data to the contrary as uninformed. I am certainly concerned, as i am to any risk i can see, though i cannot define most of them due to lack of knowledge. But i am in extremely good company here, if you know what i mean.

We all see what we want to see, eh ? :-)

--------------------

There is controversy over the Apollo 13 plutonium cask.

http://www.spacesafetymagazine.com/aerospace-engineering/nuclear-propulsion/will-anyone-recover-apollo-13s-plutonium/

Nobody looks or wants to see, that is, like so often, the problem. Funds.

---------------------

Nobody has been hit by parts of the ISS for now and probably nobody ever will, but people have been hit by debris from launch failures. The risk of such failure with nuclear release is much higher than being hit by debris from orbit because nothing falls up. It was in the range of 1/620 to 1/62,000 for the New Horizons mission in the launch area, as calculated by the Agency itself. That is a pretty good chance if you ask me.

 

 

8 minutes ago, Bill Phil said:

RTGs have a few kilograms of radioactive material within them. Personally I’d be more worried about natural radiation sources than RTG failures. Radon has been found to be responsible for tens of thousands of deaths per year. A few kilograms of plutonium is a drop in a bucket in comparison. Heck, thousands of tonnes of radioactive material is released into the atmosphere by coal plants...

Is there risk? Of course. But there’s risk in everything. The question is whether or not the benefit is worth the risk.

You have the numbers. Potentially 0.4 to 5.2 cases of latent cancer in the case of a launch failure in category "unlikely", more in the higher categories.

Edited December 20, 2018 by Green Baron

[tater]

Reactors (kilopower, etc) are required for BLEO human space exploration as I see it. There are tiny risks (as I said, all risks are non-zero), but they are not worth being concerned about as long as the engineers are concerned about it (and they 100% are, at least at NASA). No nukes, and we might as well stay home, because we're not going anywhere else without them.

[Green Baron]

We can go to Moon and Mars with solar. I mean, from an energy point of view alone, ignoring everything else. :-)

Edited December 20, 2018 by Green Baron

[tater]

2 minutes ago, Green Baron said:

It was in the range of 1/620 for the New Horizons mission in the launch area, as calculated by the Agency itself. That is a pretty good chance if you ask me.

Real data (not risk guesses) shows zero deaths or even injuries from any NASA space nuclear power so far. If you look at their safety estimates, the cancer deaths are listed as small fractions of a single person with cancer, and that's assuming the accident that released all the material happens in the first place.

The number of people killed by radiation at Fukishima was what, zero? (the one dead worker was killed by the tsunami, I think).

As I said, I'm entirely unconcerned, at least on the NASA end of things.

Just now, Green Baron said:

We can go to Moon and Mars with solar. I mean, from an energy point of view alone, ignoring everything else. :-)

Sorties, maybe (the Moon, yes, Mars requires nukes, IMO). Any bases require nukes both places.

 

[kerbiloid]

2 minutes ago, tater said:

The number of people killed by radiation at Fukishima was what, zero?

Reading about how they were cleaning the station and patching its walls, I doubt very much.

[tater]

BTW, modern NTP systems use low enriched uranium (20%), not the weapons grade stuff NERVA used. Way, way safer than 90%+ enriched U, or any Pu systems.

[Green Baron]

10 minutes ago, tater said:

Real data (not risk guesses) shows zero deaths or even injuries from any NASA space nuclear power so far. If you look at their safety estimates, the cancer deaths are listed as small fractions of a single person with cancer, and that's assuming the accident that released all the material happens in the first place.

Sure, it went well. Great. But there was no guarantee, that is the point !

Quote

The number of people killed by radiation at Fukishima was what, zero? (the one dead worker was killed by the tsunami, I think).

We'll never know, as there is little published data and cancer deaths are difficult to attribute. But up to 1400 (2016) cases may be related. We can believe what we want to. And keep the evacuation zone as big as necessary. But this wasn't about Fukushima ;-)

Quote

As I said, I'm entirely unconcerned, at least on the NASA end of things.

That is your right :-)

 

Edit: i will willingly advocate new nuclear powered missions to the solar system, no question. May point was: there is a risk connected to that technology, and it is higher than many think. We do not need it for now to power manned missions. By the time we may have better tech available. And, frankly, i was annoyed by you indirectly naming people like me "idiots". You cannot judge that, @tater.

 

Edited December 20, 2018 by Green Baron

[kerbiloid]

Working in light clothes inside the radioactive station, the wall patched with paper, a field of sunflowers?

Hundred(s) sound much closer to the truth, but we'll never know due to the specifics of their society.

[tater]

Nuclear is safer than solar right now per Watt generated (most panels are on rooftops, and people slip and fall, the mortality rate is near zero, but the power produced is very low, too). Both are so safe that saying nuclear is safer is almost meaningless, but they are both far, far safer than traditional power production. That includes all nuclear deaths. Nuclear is still way safer than any fossil fuels if you attribute all the Japanese tsunami deaths to nuclear, instead.

[Green Baron]

*lol*

Nuclear power generation is dangerous ! People die from bricks/screws/plastering/stucco falling off nuclear power plants !

Piffle.

 

Edited December 20, 2018 by Green Baron

[Brotoro]

1 hour ago, Green Baron said:

And, frankly, i was annoyed by you indirectly naming people like me "idiots". You cannot judge that, @tater.

 

I'm confused by what has your knickers in a twist. The only reference to "idiots" that I see that Tater made was referring to anyone who would build nuclear space systems withouts the necessary safeguards as idiots. Unless you are one of the Chinese designers he was potentially casting aspersions upon, I'm not sure why you are upset. 

[Green Baron]

You mean i overreacted ? Anyway, he repeated a similar statement with calling out "luddites" which is simply nonsense. I indeed prefer newer technologies for power generation and transportation, though i can't afford an electric car yet.

It is interesting, both sides tend to quit the path of reason in this discussion.

Anyway, nuclear contamination (in contrast to disaster) is not a non-issue. The risks are being assessed per mission (which i didn't know until today) and presented to the public, at least by the NASA. A modern RTG (like New Horizon's) does not bear the risk of disaster, but indeed of contamination with possible long term fatalities from cancer in the magnitude of 1/1000 to 1/10000. I admit, i thought the risk was actually lower.

Larger reactors of course impose a greater risk being heavier, containing more fuel, etc. The risk can be minimized through construction of course, but it will never be near zero. An impact of a Kosmos 954 type reactor in a densely inhabited area would surely have the potential for disaster, meaning a lot of potential fatalities and maybe uninhabitable ground for a time. I don't know, people who need >1000 deaths to name something a disaster will probably be "fine" ...

Edited December 20, 2018 by Green Baron

[Brotoro]

Overreacted? No, I think you read something that was NOT said. I would recommend going back and re-reading his post.

[Green Baron]

Just now, Brotoro said:

Overreacted? No, I think you read something that was NOT said. I would recommend going back and re-reading his post.

I edited my post. I think my impression was not incorrect.

[kerbiloid]

Going a little forward (though crawling behind KSPI-E), should we consider an antimatter-enforced fusion reactor as cleaner or vice versa.

On one hand, the annihilation itself is considered as giving neutral particles and leptons, so no radioactive waste. And in atomic amounts.
On another hand, what if we use antiatoms heavier than antihydrogen. Won't we get a whole spectre of random isotopes from partially annihilated cores?
Even if this is antihydrogen, won't its burst split the cores of the surrounding atoms of air, ground into same bunch of random isotopes.

Spoiler

2 hours ago, DDE said:

Nice fridge magnets, btw.

 

[Green Baron]

3 minutes ago, kerbiloid said:

Going a little forward (though crawling behind KSPI-E), should we consider an antimatter-enforced fusion reactor as cleaner or vice versa.

On one hand, the annihilation itself is considered as giving neutral particles and leptons, so no radioactive waste. And in atomic amounts.
On another hand, what if we use antiatoms heavier than antihydrogen. Won't we get a whole spectre of random isotopes from partially annihilated cores?
Even if this is antihydrogen, won't its burst split the cores of the surrounding atoms of air, ground into same bunch of random isotopes.

Fusion ? In two generations ? Which as just a little longer than Apollo is from us ... or not ?

Heat an inert gas to ludicrous ISP or spit out the fuel directly along the fieldlines ... theoretically fantastically maybe ...

[kerbiloid]

4 minutes ago, Green Baron said:

Fusion ? In two generations ? Which as just a little longer than Apollo is from us ... or not ?

No, but will the things get better or worse when the thermonukes will be annihilation-enforced. Or a pure annihilation engine exploded on the Earth.

Say, an antihydrogen hits an oxygen core in air.
There is obviously not enough antimatter to burn it all. So, we'll get 15 nucleons in some combination(s). Some of them radioactive, and their composition probably can widely vary.

Edited December 20, 2018 by kerbiloid

[Green Baron]

*looks at bottom of teapot*

I can't see us producing and storing antimatter in sufficient quantities, i only see fusion in a still nebulous future ...

Edited December 20, 2018 by Green Baron

[kerbiloid]

5 minutes ago, Green Baron said:

I can't see us producing and storing antimatter in sufficient quantities, i only see fusion in a still nebulous future ...

We never know how much horse manure will be produced by the end of century in London.

[wumpus]

2 hours ago, tater said:

The number of people killed by radiation at Fukishima was what, zero? (the one dead worker was killed by the tsunami, I think).

6 dead from non-radiation sources, several sailors on the USS Reagan received "severe radiation sickness" due to being downwind while bringing in supplies.

Three mile island was even less of an issue.  It certainly botched the reactor up enough, but was never a threat to the people outside the reactor.  I'd hate to think of the environmental damage the Fukishima tsunami would have done had they used coal and had open coal ash pits (the standard practice).  The tsunami would easily breach the pits and the floodwaters would have been full of coal ash.  I think this happened in North Carolina this September with hurricane Florance and the results aren't good.

To be honest, in the US nimbyism isn't needed to prevent any more nuclear reactors from being built.  The nuclear construction industry is so hopeless at being anywhere near budget that the beancounters would stab anyone trying to build such a thing to death long before a protest could be organized.  You can get a natural gas, solar, or wind power plant up at close enough to your expected costs and make money: don't ever expect that to happen in the US with nuclear power.