NASA successfully tests portable nuclear reactor for crewed missions to Mars

[Shawn Knight]

Setting up a colony on Mars will undoubtedly go down as one of humanity’s greatest achievements. Realizing that goal, however, presents a unique set of challenges.

Getting humans to our nearby celestial neighbor will be a tough task in its own right but once they get there, how will astronauts sustain life and possibly get back home? It’s a question experts have been working to answer for years and on Wednesday, we got one step closer to a viable solution.

NASA and the Department of Energy’s National Nuclear Security Administration (NNSA) have successfully demonstrated a miniature nuclear reactor power system that could one day be used in long-duration missions to the Moon, Mars and beyond.

Dubbed Kilopower, the small, lightweight fission system is able to provide up to 10 kilowatts of electrical power continuously for a minimum of 10 years. Pair a few units together and you’ve suddenly got enough power to establish an outpost, NASA says.

The prototype uses a solid, cast uranium-235 reactor core which is roughly the size of a paper towel roll. Reactor heat is transferred via passive sodium heat pipes to high-efficiency Stirling engines which convert the heat to electricity.

David Poston, the chief reactor designer at NNSA’s Los Alamos National Laboratory, said they threw everything they could at the reactor during testing and it passed with flying colors.

NASA said the project will remain a part of the Space Technology Mission Directorate’s Game Changing Development program with the goal of transitioning to the Technology Demonstration Mission program in fiscal year 2020.

Permalink to story.

https://www.techspot.com/news/74436-nasa-successfully-tests-portable-nuclear-reactor-crewed-missions.html

 

[GeforcerFX]

Nice, but we need 200+kilowatts to really sustain a decent sized group. But it's progress, mars has wind as well so wind power is another option there, and solar during the day. Batteries would be a pain in the butt though, metal based wouldn't be very feasible for that distance of travel.

 

[Uncle Al]

And to boot Thorium reactors are cooler operating temperatures, longer lasting and we have an abundance of it at the Paducah KY plant. Sounds like the same old political game playing that got us into uranium reactors decades ago. Besides, 10 years isn't so long on another planet .... how on earth will they refuel it and what to do with the waste? Start another Superfund project on another planet! Sheeeezzzzeeeeee

 

[Fluffybunny68]

And to boot Thorium reactors are cooler operating temperatures, longer lasting and we have an abundance of it at the Paducah KY plant. Sounds like the same old political game playing that got us into uranium reactors decades ago. Besides, 10 years isn't so long on another planet .... how on earth will they refuel it and what to do with the waste? Start another Superfund project on another planet! Sheeeezzzzeeeeee

You mean how on mars will you refuel it.

 

[GeforcerFX]

And to boot Thorium reactors are cooler operating temperatures, longer lasting and we have an abundance of it at the Paducah KY plant. Sounds like the same old political game playing that got us into uranium reactors decades ago. Besides, 10 years isn't so long on another planet .... how on earth will they refuel it and what to do with the waste? Start another Superfund project on another planet! Sheeeezzzzeeeeee

well if they brought it there by rocket, I'm sure they can find some way to dispose of the core.... I was surprised it was still a uranium reactor as well, guess they are starting with familiar ground first.

 

[wiyosaya]

And to boot Thorium reactors are cooler operating temperatures, longer lasting and we have an abundance of it at the Paducah KY plant. Sounds like the same old political game playing that got us into uranium reactors decades ago. Besides, 10 years isn't so long on another planet .... how on earth will they refuel it and what to do with the waste? Start another Superfund project on another planet! Sheeeezzzzeeeeee

The article says that it uses solid sodium heat pipes to cool the core and transfer the energy to sterling engines. This is far from a Fukushima, Chernobyl, or Three Mile Island type plant.

Higher temperatures mean higher thermal efficiency by the Carnot equation:

1 - (Tout/Tin)

I would put odds on the fact that the people who designed this are among the best and most knowledgeable nuclear engineers in the world and know full well the hazards of U235 based reactors. The article says that the heat then drives a highly efficient Sterling Engine. From Wikipedia:

A Stirling engine is a heat engine that operates by cyclic compression and expansion of air or other gas (the working fluid) at different temperatures, such that there is a net conversion of heat energy to mechanical work. More specifically, the Stirling engine is a closed-cycle regenerative heat engine with a permanently gaseous working fluid. Closed-cycle, in this context, means a thermodynamic system in which the working fluid is permanently contained within the system, and regenerative describes the use of a specific type of internal heat exchanger and thermal store, known as the regenerator. Strictly speaking, the inclusion of the regenerator is what differentiates a Stirling engine from other closed cycle hot air engines.

https://en.wikipedia.org/wiki/Stirling_engine

My bet is that they considered the possibility of using Thorium, however, U235 was better due to the requirements with respect to the environments where it might be used. The article also says that the team threw everything they could at it and it withstood the tests. That is not to say that they could not have missed something, but it sounds like they did everything they thought of to make it fail and it refused to do so.

The problem with U235 reactors so far is that they are subject to loss of coolant - in most cases - liquid water. With a solid sodium heat pipe coolant system, loss of coolant sounds like it is far less likely to occur.

If the coolant were water, I would also be saying WTF, but this sounds, to me anyway, like it might be as far beyond liquid cooled U235 reactors as ion propulsion is beyond chemical rocket engines.

 

[Skjorn]

how on earth will they refuel it

probably how they normally do on Earth

 

[corvard]

Nice, but we need 200+kilowatts to really sustain a decent sized group. But it's progress, mars has wind as well so wind power is another option there, and solar during the day. Batteries would be a pain in the butt though, metal based wouldn't be very feasible for that distance of travel.

Wind power on Mars is not an option, because martian air is too thin.

 

[VitalyT]

You mean how on mars will you refuel it.

It is designed to operate continuously for 10 years, once fully loaded, and then to be scrapped.

So no refueling.

 

[andrewdoyle88]

What is this, a reactor for ANTS?! The reactor has to be at least... three times bigger than this!

 

[frostyshield]

"David Poston, the chief reactor designer at NNSA’s Los Alamos National Laboratory, said they threw everything they could at the reactor during testing and it passed with flying colors."

Bet they didn't throw a fridge at it tho did they...

 

[Bubbajim]

I love the naming conventions of physicists.

"We've got this thing like a star but it pulses", "Let's call it a Pulsar!"
"Ok, this theory suggests these weird holes that even light can't escape", "that's a Black hole!"
"We're setting up a department to look at developing quite radical technological advancements", "well, that's the Game Changing Development Program!"

 

[UncleSharkey]

1.21 gigawatts? 1.21 GIGAWATTS!? Great Scott! Oh never mind it's only 10 kilowatts.

 

[GreenNova343]

Nice, but we need 200+kilowatts to really sustain a decent sized group. But it's progress, mars has wind as well so wind power is another option there, and solar during the day. Batteries would be a pain in the butt though, metal based wouldn't be very feasible for that distance of travel.

Per their fact sheet (https://www.nasa.gov/sites/default/files/atoms/files/ns_kilopower_fs_180111.pdf) NASA is expecting to need only 40kWe for the initial outpost, which means maybe 6-8 of these (4 online, 2-4 backups) to start with. Even with that many though, the question is how much solar paneling and/or windmills will you need to generate the same amount?

Plus, with these being the initial models, larger facilities might just need additional units, or they might be able to scale them up. If a core the size of a paper towel roll can provide 10kWe, I wonder how much a core the size of a welder's acetylene tank -- or better yet, a core the size of your typical household outside propane tank -- would be able to provide?

 

[mbrowne5061]

And to boot Thorium reactors are cooler operating temperatures, longer lasting and we have an abundance of it at the Paducah KY plant. Sounds like the same old political game playing that got us into uranium reactors decades ago. Besides, 10 years isn't so long on another planet .... how on earth will they refuel it and what to do with the waste? Start another Superfund project on another planet! Sheeeezzzzeeeeee

The inverse square law makes solar panels not viable for large scale power production, and Mar's thin atmosphere cripples the amount of force that any design of wind turbine can capture. You will need a lot of power on the surface of Mars to sustain life, so a nuke of some kind will be necessary.

10 years refers to the minimum run-time. My bet is that its the sodium wearing out the sterling engine that limits its life span. 10 years is already a super long time for any mechanical system to operate non-stop. As for its danger, by using molten sodium instead of supercritical water, the system can operate passively, without any human interaction. Commercial nuclear here on Earth are all Mrk-I or Mrk-II Uranium designs, which use supercritical water and require active cooling and active pressurization to maintain operations. If cooling or pressurization fails, the water exits its supercritical state via a gas-state, expanding and eventually bursts the pipes designed to contain them. Once the water is gone, the fuel is too hot (needs to be hot, to maintain the water in its supercritical state - can't use cooler fuel), and begins to melt through everything - sinking towards the earth's core as it goes. Hence, "meltdown".

This "Kilopower" reactor would fall under a Mrk-III or Mrk-IV Uranium design, and cannot "meltdown" unless the cooling system itself is pierced from the outside at a point lower than the fuel itself. The fuel cannot get hot enough to vaporize sodium (even 100% pure Uranium isn't hot enough to do that), so the working fluid (sodium) doesn't need any active cooling to stay operational. Even then, if you mix the fuel with right doping agents, in the right way, you might even get it cool enough that even without the sodium in the system, there is no meltdown - you just don't generate power. It sounds like this is a mashup of a Mrk-I or Mrk-II Thorium design, and a Mrk-III Uranium design.

 

[wiyosaya]

What is this, a reactor for ANTS?! The reactor has to be at least... three times bigger than this!

1.21 gigawatts? 1.21 GIGAWATTS!? Great Scott! Oh never mind it's only 10 kilowatts.

Per their fact sheet (https://www.nasa.gov/sites/default/files/atoms/files/ns_kilopower_fs_180111.pdf) NASA is expecting to need only 40kWe for the initial outpost, which means maybe 6-8 of these (4 online, 2-4 backups) to start with. Even with that many though, the question is how much solar paneling and/or windmills will you need to generate the same amount?

Plus, with these being the initial models, larger facilities might just need additional units, or they might be able to scale them up. If a core the size of a paper towel roll can provide 10kWe, I wonder how much a core the size of a welder's acetylene tank -- or better yet, a core the size of your typical household outside propane tank -- would be able to provide?

I would expect that this is sized for several goals:
1. Big enough to provide practical power.
2. Small enough to be relatively easily moved by astronauts on the moon or a planet.
3. Small enough to fit onto the spacecraft that will bring it to where ever it is needed.

As I see it, the last item is perhaps the most important because if you cannot fit it on a rocket, well, need I say more?

 

[wiyosaya]

The inverse square law makes solar panels not viable for large scale power production, and Mar's thin atmosphere cripples the amount of force that any design of wind turbine can capture. You will need a lot of power on the surface of Mars to sustain life, so a nuke of some kind will be necessary.

10 years refers to the minimum run-time. My bet is that its the sodium wearing out the sterling engine that limits its life span. 10 years is already a super long time for any mechanical system to operate non-stop. As for its danger, by using molten sodium instead of supercritical water, the system can operate passively, without any human interaction. Commercial nuclear here on Earth are all Mrk-I or Mrk-II Uranium designs, which use supercritical water and require active cooling and active pressurization to maintain operations. If cooling or pressurization fails, the water exits its supercritical state via a gas-state, expanding and eventually bursts the pipes designed to contain them. Once the water is gone, the fuel is too hot (needs to be hot, to maintain the water in its supercritical state - can't use cooler fuel), and begins to melt through everything - sinking towards the earth's core as it goes. Hence, "meltdown".

This "Kilopower" reactor would fall under a Mrk-III or Mrk-IV Uranium design, and cannot "meltdown" unless the cooling system itself is pierced from the outside at a point lower than the fuel itself. The fuel cannot get hot enough to vaporize sodium (even 100% pure Uranium isn't hot enough to do that), so the working fluid (sodium) doesn't need any active cooling to stay operational. Even then, if you mix the fuel with right doping agents, in the right way, you might even get it cool enough that even without the sodium in the system, there is no meltdown - you just don't generate power. It sounds like this is a mashup of a Mrk-I or Mrk-II Thorium design, and a Mrk-III Uranium design.

The breath of fresh air to the conversation.

In a standard fission power plant, the super-critical water loop provides heat to the steam loop to convert water to steam and drive steam turbines in the plant. There is no mixture of super-critical water, which is contaminated with radiation, with the water used to produce the steam. Only the heat is transferred and this also prevents the water used for steam from getting contaminated with radiation.

In Kilopower, I would also expect that the sodium loop is separate from the heat exchanger on the sterling engine and that the heat from the sodium loop is used to provide heat only to the sterling engine. I am not saying that the sterling engine will not suffer from mechanical wear, however, to me, anyway, it makes more sense to keep the loops separate except for the fact that the one provides heat to the other.

 

[GeforcerFX]

Wind power on Mars is not an option, because martian air is too thin.

Correct, I thought it was still kPA, low, but at least in the same realm as earth. I wonder if dust storms could be used to push the blades instead? They would have more mass than the atmosphere, would be a different looking type of blade for sure.

 

[wiyosaya]

On watching the video, once again I see where Musk's plan is folly. One of the prime uses of this is to produce hydrogen and oxygen that will be used as fuel to return astronauts to Earth. Musk has no plan for return.

Correct, I thought it was still kPA, low, but at least in the same realm as earth. I wonder if dust storms could be used to push the blades instead? They would have more mass than the atmosphere, would be a different looking type of blade for sure.

Those blades would be a challenging design.

 

[corvard]

On watching the video, once again I see where Musk's plan is folly. One of the prime uses of this is to produce hydrogen and oxygen that will be used as fuel to return astronauts to Earth. Musk has no plan for return.


Those blades would be a challenging design.

As far as I could understand musk he says that he's making road to mars, he ain't planning to reach mars.

 

[GeforcerFX]

Those blades would be a challenging design.

Yeah I got the image of like old school water wheels, like from the back of boats, tons of surface area to catch as much material as possible. Nuclear or sometime type of oxygen burner system ( pulling oxygen down from the atmosphere) to create energy would be the best solution.

 

[CrazyDave]

Out of curiosity, if this was on a rockets payload and the rocket goes boom on the launchpad, or part way up to orbit (As so happens every now and then), would this not possibly send pieces of uranium over a large area?

 

[GreenNova343]

I would hate to have to depend on dust & sand hitting the blades. It might be more akin to water turbine blade designs, but I would be worried about damage to the blades & ease of replacement/repair...

 

[GeforcerFX]

Out of curiosity, if this was on a rockets payload and the rocket goes boom on the launchpad, or part way up to orbit (As so happens every now and then), would this not possibly send pieces of uranium over a large area?

We have launched nuclear reactors before, both the voyagers were powered by a nuclear reactors that ran off plutonium 238. There is always going to be a risk, but these are relatively small reactors, not a lot of uranium and the uranium may not actually separate in the explosion (dense stuff) so nothing really spreads.

 

[TheBigT42]

Can I get one for my electric car?