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#26 2018-01-21 11:29:25

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

I do think that the combination approach is the biggest of redundancy approach that we can have, but what are the balance sheet numbers for being in a rationing mode if 1 fails?
It appears that Nasa is sizing these for current payload capability, so if the Mars Dragon retropopulsion was tried that opens up a near manned capable mission with what we already have.

louis wrote:

Sounds to me like you have confused the Kilopower and Megapower projects. The 2MW project is stated to be designed to weigh 35-45 tonnes.

https://github.com/briligg/moonwards/wi … r-(KRUSTY)

Can't see a 1MW plant ever getting down to under half a tonne. 

You accept the need for a back up nuclear reactor?  So that's doubling your tonnage.

Is it safe to send these two large nuclear plants with no shielding to Mars, where they will then be handled by the pioneers? 

What's powering your Rover?  How do you dig a 20 metre hole?

What happens to all the waste heat from such a large plant?

They haven't even produced a Kilopower 10Kwe unit yet only smaller proof of concept plants.

My energy system proposals fully take account of the need to provide reliable power. The system is overdesigned at about 140% of normal insolation power capacity.

Quaoar wrote:
louis wrote:

The new list in post #11 equates to about 1MW across the surface mission,using flexible lightweight PV panelling at about 0.5 kg per sq metre. A 1MW nuclear power solution would probably mass in the 150 tonnes range but it's difficult to say as no one has yet explained how and where it will be set up, and the amount of shielding if any to be used.

Los Alamos one-megawatt-heat-pipe nuclear reactor has a weight of only 493 kg, and it's very sturdy and reliable having very few moving parts.
You can dig a 20-meter-deep hole 500 m far from the landing site, tow the reactor there with the rover and do the start-up when you are back.
Producing 1100 tons of propellant is not a piece of cake and you need a robust power source able to work continuously day and night. Take in mind that martian sand-storms cannot topple a lander like in the movie "The Martian", but they can last for a month obscuring the sun, drastically reducing the power supply to your life support and the ISPP-device. That's why you need one nuclear reactor, or rather two of them - one working and one for back-up - for your first mission.

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#27 2018-06-17 07:59:23

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

bump as we are wanting to make sure after the dust storm that first mission to Mars does not end in that rovers fate....

kbd512 wrote:

If the experiments done by Lockheed-Martin scales linearly, then solar power alone, without batteries, is more than sufficient for LOX/LCH4 and LOX/LH2.  Forget about using megawatts of power at night.  It's not necessary or desirable from a mass standpoint.  Take more food and water.  You'll need that to survive.  You don't need megawatts of power when using modern electronics and life support equipment.

Keep the habitat powered by its own dedicated solar array and batteries that don't out-gas or explode.  This fanciful idea that you don't have to monitor the electrical power systems, so long as you're not using nuclear, is pure unadulterated BS.  There is no such thing as a megawatt class power system that doesn't require monitoring.  Anyone who thinks otherwise is blissfully unaware of what can and will go wrong, no matter where the power is coming from.

Keep the reactor in standby mode, where it's warmed up and can ramp up to full power in minutes, just in case someone does something unbelievably stupid with the batteries that power the life support equipment.  At 1kW or less of thermal power, the reactor is ready to operate when required, but not in a condition where losing all of the coolant loops could present any sort of thermal power rejection problem.  A reactor scram at that power level is almost like flipping a switch.  Fission stops in seconds.

Since I know all actual objections to using KiloPower have to do with safety and the potential for a melt-down, I'll post some of the documents that show the modeling and testing done to assure desired operation here:

Space Nuclear Reactor Engineering

KiloPower Project - KRUSTY Experiment Nuclear Design

KRUSTY Design and Modeling

If you think the people who design and build these things just have blind faith in anything, you'd be wrong.  Everything, and I do mean everything they can think of, gets tested.  They intentionally try to destroy the reactor just to see what will happen.  All models and assumptions are actually tested to ensure they agree with reality.  If they don't, then the engineers go back to the drawing board and re-test, as required.

When they tell you how much these things weigh, how big they'll be, how hot they get, and how much radiation they'll produce, they're not talking out their rear ends.  They create ANSYS models, which they then turn into manufactured hardware, and that's what gets tested.  ANSYS can tell you with high precision how much something will weigh when it's made from known materials.  KiloPower is metal blocks and tubes with a working fluid sealed into the tubes.  For a reactor this small, a 10% scale model can tell you with excellent fidelity what a slightly larger device will weigh, how much thermal power you get, and what the results of a thermal system failure will be.  The actual observed data agree very well with the model and that gives engineers confidence that the slightly dimensionally larger core model will behave in much the same way with small incremental increases in thermal output levels.

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#28 2019-07-05 21:31:36

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

From the link of Louis:
68747470733a2f2f6b36312e6b6e332e6e65742f746172696e67612f422f442f352f442f382f412f496e666f5f5365742f3639312e706e67

It shows the progression of how the reactor is to progress...

NASA concept for generating power in deep space a little KRUSTY

Kilopower Reactor Using Stirling TechnologY (KRUSTY)

Kilopower reactors to generate anywhere from one to ten kilowatts of electrical power,  a lightweight fission reactor

Its a piston drive system which means its going to need a radiator to remove the heat so as to keep the cycle going.

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#29 2019-07-06 05:03:36

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,380

Re: NASA and DOE to test kilopower nuclear reactor for space applications

100 watts output achieved so far? Hmm...They claim it's "lightweight" but don't give its mass. Looks fairly bulky to me.

NASA appear to be expending a lot of energy on this project, but progress seems to be at a snail's pace. That must reflect technological challenges...the more challenges, the more it sounds like something could go wrong.

I don't see this as a solution to providing energy for living on Mars. I see it more as perhaps something to be used in exploring the outer solar system.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#30 2019-07-06 08:51:55

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

Back filled 2 posts from the past into the topic and here is a bit more research on KRUSTY

Kilopower (full name is Kilopower Reactor Using Stirling Technology, or KRUSTY
https://en.wikipedia.org/wiki/Kilopower
https://www.nasa.gov/directorates/spacetech/kilopower
https://www.grc.nasa.gov/www/tmsb/stirling.html
https://www.nasa.gov/press-release/demo … ion-power/

https://www.energy.gov/nnsa/articles/kr … xploration

stmd_kilopower_1%5B1%5D.jpg?itok=IrHgrzcR

https://www.performance.gov/gearawards/KRUSTY-Team/

KRUSTY was designed to test a prototype fission thermal energy reactor coupled to a Stirling engine powered electric generator.
Throughout the experiment, the team simulated power reduction, failed engines and failed heat pipes, showing that the system could continue to operate and successfully handle multiple failures.

krusty-nasa-nuclear-reactor-space-orbit-moon-mars-habitat-explore.jpg?quality=75&strip=all&w=1100&h=618

https://www.lanl.gov/discover/news-rele … ission.php

Sounds like they are ready for the next step up in design power levels as a prototype unit....

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#31 2019-07-06 09:34:21

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

another image from the above link:

68747470733a2f2f7777772e6e6578746269676675747572652e636f6d2f77702d636f6e74656e742f75706c6f6164732f323031372f30372f34336461383366316635346632663737363533633036636534653565313864652d31303234783832302e706e67

With the stirling steps to go with how the heat is produced

68747470733a2f2f6b36302e6b6e332e6e65742f746172696e67612f442f352f422f442f432f422f496e666f5f5365742f4637342e706e67

Progression of mass to power output

The small size of the Kilopower unit and low power level benefit safety, transport, cost, testing, and demonstration. The small size also reduces complexity.

    800 W Stirling - Approx. 2.5 m long 400 kg or 2 W/kg
    1 kW Thermoelectric - Approx. 4 m long 600 kg or 1.7 W/kg
    3 kW Stirling - Approx. 5 m long 750 kg or 4 W/kg
    10 kW Stirling - Approx. 4 m tall 1800 kg or 5 W/kg

so heat to energy conversion via a stirling engine without melt down is the key to the inner working of the kilowatt reactor.

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#32 2019-07-06 09:41:10

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,686

Re: NASA and DOE to test kilopower nuclear reactor for space applications

For SpaceNut re #30 (and specifically the nnsa link) ...

The article at the nnsa link includes a section that explains how the uranium core is safely transported and then brought into service.

The core is subcritical in air (as shown in a picture) but when it is placed inside a neutron reflector, it goes into a (apparently modest) critical state, so that neutrons bounce back and forth in the volume, fissioning atoms at random. 

That is a very NICE piece of engineering! 

This work appears to show the way forward for fission power for homesteads on Mars, but far more importantly, for homesteads on Earth, in regions where this power would be both appreciated and welcomed, and defended from terrorists.

(th)

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#33 2019-07-06 10:01:14

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

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#34 2019-07-06 12:08:29

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

Nasa pegs the power requirements for a human mars mission at 40 -50 kw to be generated constantly for each hour.

The testing of Krusty in 2018:

The team exceeded their own expectations with a modified test unit that output greater than 4 kilowatts of power at an operating temperature of 800 degrees Celsius, with a power conversion efficiency of 35 percent.

ijetlydyg4ywsbmymzlh.jpg

lessons learned
https://arc.aiaa.org/doi/abs/10.2514/6.2018-4973

The use of this type of reactor replaces the typical RTG which is used quite often for missions that can not have solar.
http://large.stanford.edu/courses/2017/ … 219467.pdf

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#35 2019-07-06 12:27:36

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,380

Re: NASA and DOE to test kilopower nuclear reactor for space applications

Cuts out the middle man...the terrorist can just buy a few direct from a supplier and then use the radioactive material in a terrorist attack...

Er, no...this is not the solution to our energy needs!

tahanson43206 wrote:

For SpaceNut re #30 (and specifically the nnsa link) ...

The article at the nnsa link includes a section that explains how the uranium core is safely transported and then brought into service.

The core is subcritical in air (as shown in a picture) but when it is placed inside a neutron reflector, it goes into a (apparently modest) critical state, so that neutrons bounce back and forth in the volume, fissioning atoms at random. 

That is a very NICE piece of engineering! 

This work appears to show the way forward for fission power for homesteads on Mars, but far more importantly, for homesteads on Earth, in regions where this power would be both appreciated and welcomed, and defended from terrorists.

(th)


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#36 2019-07-06 12:41:05

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

nah just keep building large nuclear plants and send in a few cruise missles... or some other air attack weapon.

Normally this is not an issue for a nation that considers its self safe but that goes away when anachism sets in where no one cares about laws, rules of order ect....

This is not a problem for where we really want to use this....Moon or Mars and for the travels of the rest of our universe....

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#37 2019-07-06 17:30:11

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

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#38 2019-07-06 19:02:48

kbd512
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Registered: 2015-01-02
Posts: 3,128

Re: NASA and DOE to test kilopower nuclear reactor for space applications

We can always count on Louis to save us from those evil PhD-wielding nuclear physicist astronaut terrorists on Mars with his solar panel and battery ideology.  Kinda reminds me of those monks from Monty Python as they were walking around in circles and smacking themselves in the head with their books.  Louis could've just said, "I don't understand a damn thing about nuclear power and it scares me to death because it looks like black magic", and that would've been more than enough for me to cease all interaction with him on that point, since it no longer has anything to do with math / logic / basic reasoning.

Sadly, I've seen few more contorted views on something than what he's repeatedly expressed towards nuclear power.  Whenever basic math doesn't support his line of argumentation, we quickly veer off into bizarro world.  There are no Allah worshipers on Mars, and I sincerely doubt we have to worry about any of the faithful converting the various rocks / meteorites / buried glaciers found there to their religion through the mixing of terrorism with nuclear weapons.  Maybe he can't connect enough "dots" to recognize that all the HEU being used in KiloPower reactors could finally make its way off planet Earth, to be used for the peaceful purpose of establishing a second branch of human civilization on Mars, rather than being subject to potentially nefarious uses back here on Earth.  If those religious dimwits become educated and focused enough to establish their own space program that successfully lands a rocket on Mars, then we probably don't have to worry about them going to Mars to bring nuclear materials back to Earth, that we previously sent to Mars, just to terrorize their fellow humans into following their religion.

My personal favorite was the "China syndrome" Hollyweird mythology he brought up when we were last discussing KiloPower.  That was a real head scratcher.  Then again, I realize that I don't have the foggiest idea about what people who are utterly clueless about nuclear power worry about happening.  I guess with enough profound ignorance, you can make up absolutely anything in your head, no matter how divergent from reality.

Moving back on topic, to something approaching sanity and objective reality, the decay heat from a long-operating 10kWe KiloPower reactor is around 450Wt.  That's not nearly enough to begin to melt 50kg's of Uranium metal.  The 1kWe version is 45Wt from using 30kg's of HEU.  When launched, KiloPower has a whopping 2 Curies of radioactive material inventory onboard.  No, that's still not "nothing whatsoever", but so close to nothing as to be functionally indistinguishable.  If you slept with your favorite reactor during the trip to Mars, you'd still receive less radiation from the reactor you're sleeping with than you'd receive from flying across the Atlantic in an airliner.  That's just a result of that crazy little "math thing" that our anti-nuclear activists have never done before.  The standard MMRTG, of the kind that powers the only rover that's still moving around on Mars, has 60,000 Curies of radioactive material.  You'd get second degree thermal burns if you tried to bear hug a MMRTG.  For what little it's apparently worth, there's also little reason to sleep with a nuclear power device to keep warm when there are lots of other people making the same trip with you.  Presumably, blankets will also be provided, as they already are on ISS.

If you attempt to increase the power output by a mere 30Wt in 1 second, thermal power output will nosedive.  This means the output is self-regulating and that the reactor has to be gradually "warmed up" by slowly withdrawing its single Boron Carbide control rod.  It's intended to be turned on over the course of multiple hours and then left running at some percentage of rated output for many years thereafter.  It's possible to shut it down for maintenance of movement, but it takes hours to bring up to full power.  If you had a knife sharp enough to chop all of the high grade steel heat pipes off the reactor, power output would fall off a cliff in mere seconds.  The residual power from decay heat, even after years of continuous operation at high output, is woefully insufficient to melt 50 kilos of Uranium metal, never mind the hundreds of kilos of steels, Beryllium Oxide reflector material, and various radiation shielding materials affixed to the core.  It's not quite as fast as flipping a light switch, but pretty darned close.  Therefore, all of these "What if it melts down?" questions are moo points, like the opinions of cows.  Sorry, Joey, couldn't resist.

Bottom line, if you don't understand the technology then you can simply stay the hell away from it and let those who do understand it use their engineering talents to ensure that you have the heat and power you need to survive, whether the Sun is bright and shining or scarcely visible.  Mars is about as hostile an environment as any we have any hope of surviving, long-term, and we're going to need ALL of the tools in our tool belt to survive and thrive.  KiloPower is but one example of a "power tool" in our tool belt.  Much like chain saws and firearms, they only pose significant danger to those too cavalier and careless to be entrusted with the responsibility of operating them.

Thankfully, NASA has recognized the utility of durable and easily deployable power sources that reliably produce power for many years on end, which is exactly what KiloPower will do.  The "nattering nabobs of negativism" of this world are being ignored by NASA, precisely because they know so little and science has yet to provide practical alternatives.  In order to design any mission involving humans, you need to know how much power you can reliably get.  If you don't get that power, then people will die.  It really is that simple.

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#39 2019-07-07 02:08:31

Terraformer
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From: Lancashire
Registered: 2007-08-27
Posts: 3,180
Website

Re: NASA and DOE to test kilopower nuclear reactor for space applications

As far as terrorism goes, I'm more worried about some smart terrorist (rare, fortunately, but they do exist) figuring out how to build an airship mounted sun gun and weaponising solar power. *shudders* Along with them realising they can use a drone or balloon to deliver flechettes.


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#40 2019-07-07 07:17:56

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,380

Re: NASA and DOE to test kilopower nuclear reactor for space applications

I was responding to TA's claim that it would provide energy for "homesteads on Earth, in regions where this power would be both appreciated and welcomed, and defended from terrorists."  I was pointing out that making nuclear reactors available to ordinary members of the public to buy is a pretty obvious route by which terrorists would obtain radioactive material for "dirty" bombs. I never claimed there would be a terrorist threat on Mars.

Kilopower nuclear reactors might work on Mars. We don't know yet. Development seems to be awfully slow. Are we really OK with putting passengers together with KP reactors?  I'd have my doubts. And there seems to be a complete lack of transparency about mass and safety measures.

We already have PV that we know works on Mars. Tie it into methane and oxygen generation (which Space X plan to do anyway in order to produce the fuel and propellant for a return flight) and you then have a complete energy solution.

We've yet to see proper comparisons betweeen KP and PV based solutions. KP could never be a complete solution in and of itself - at least previous discussions have led to that conclusion...there will be a PV element.

I have stated previously that nuclear power might have some role to play on Mars. It makes more sense there than on Earth, because with a very low population density and in the absence of huge areas of agricultural land the effects of a nuclear accident would be far less dangerous and humans would already be living in habitats well protected from radiation. Clearly, nuclear power might be important in terraformation, since you could use it to add heat to the planet. But again, I think other more cost effective solutions like solar mirror satellite are likely to be adopted.




kbd512 wrote:

We can always count on Louis to save us from those evil PhD-wielding nuclear physicist astronaut terrorists on Mars with his solar panel and battery ideology.  Kinda reminds me of those monks from Monty Python as they were walking around in circles and smacking themselves in the head with their books.  Louis could've just said, "I don't understand a damn thing about nuclear power and it scares me to death because it looks like black magic", and that would've been more than enough for me to cease all interaction with him on that point, since it no longer has anything to do with math / logic / basic reasoning.

Sadly, I've seen few more contorted views on something than what he's repeatedly expressed towards nuclear power.  Whenever basic math doesn't support his line of argumentation, we quickly veer off into bizarro world.  There are no Allah worshipers on Mars, and I sincerely doubt we have to worry about any of the faithful converting the various rocks / meteorites / buried glaciers found there to their religion through the mixing of terrorism with nuclear weapons.  Maybe he can't connect enough "dots" to recognize that all the HEU being used in KiloPower reactors could finally make its way off planet Earth, to be used for the peaceful purpose of establishing a second branch of human civilization on Mars, rather than being subject to potentially nefarious uses back here on Earth.  If those religious dimwits become educated and focused enough to establish their own space program that successfully lands a rocket on Mars, then we probably don't have to worry about them going to Mars to bring nuclear materials back to Earth, that we previously sent to Mars, just to terrorize their fellow humans into following their religion.

My personal favorite was the "China syndrome" Hollyweird mythology he brought up when we were last discussing KiloPower.  That was a real head scratcher.  Then again, I realize that I don't have the foggiest idea about what people who are utterly clueless about nuclear power worry about happening.  I guess with enough profound ignorance, you can make up absolutely anything in your head, no matter how divergent from reality.

Moving back on topic, to something approaching sanity and objective reality, the decay heat from a long-operating 10kWe KiloPower reactor is around 450Wt.  That's not nearly enough to begin to melt 50kg's of Uranium metal.  The 1kWe version is 45Wt from using 30kg's of HEU.  When launched, KiloPower has a whopping 2 Curies of radioactive material inventory onboard.  No, that's still not "nothing whatsoever", but so close to nothing as to be functionally indistinguishable.  If you slept with your favorite reactor during the trip to Mars, you'd still receive less radiation from the reactor you're sleeping with than you'd receive from flying across the Atlantic in an airliner.  That's just a result of that crazy little "math thing" that our anti-nuclear activists have never done before.  The standard MMRTG, of the kind that powers the only rover that's still moving around on Mars, has 60,000 Curies of radioactive material.  You'd get second degree thermal burns if you tried to bear hug a MMRTG.  For what little it's apparently worth, there's also little reason to sleep with a nuclear power device to keep warm when there are lots of other people making the same trip with you.  Presumably, blankets will also be provided, as they already are on ISS.

If you attempt to increase the power output by a mere 30Wt in 1 second, thermal power output will nosedive.  This means the output is self-regulating and that the reactor has to be gradually "warmed up" by slowly withdrawing its single Boron Carbide control rod.  It's intended to be turned on over the course of multiple hours and then left running at some percentage of rated output for many years thereafter.  It's possible to shut it down for maintenance of movement, but it takes hours to bring up to full power.  If you had a knife sharp enough to chop all of the high grade steel heat pipes off the reactor, power output would fall off a cliff in mere seconds.  The residual power from decay heat, even after years of continuous operation at high output, is woefully insufficient to melt 50 kilos of Uranium metal, never mind the hundreds of kilos of steels, Beryllium Oxide reflector material, and various radiation shielding materials affixed to the core.  It's not quite as fast as flipping a light switch, but pretty darned close.  Therefore, all of these "What if it melts down?" questions are moo points, like the opinions of cows.  Sorry, Joey, couldn't resist.

Bottom line, if you don't understand the technology then you can simply stay the hell away from it and let those who do understand it use their engineering talents to ensure that you have the heat and power you need to survive, whether the Sun is bright and shining or scarcely visible.  Mars is about as hostile an environment as any we have any hope of surviving, long-term, and we're going to need ALL of the tools in our tool belt to survive and thrive.  KiloPower is but one example of a "power tool" in our tool belt.  Much like chain saws and firearms, they only pose significant danger to those too cavalier and careless to be entrusted with the responsibility of operating them.

Thankfully, NASA has recognized the utility of durable and easily deployable power sources that reliably produce power for many years on end, which is exactly what KiloPower will do.  The "nattering nabobs of negativism" of this world are being ignored by NASA, precisely because they know so little and science has yet to provide practical alternatives.  In order to design any mission involving humans, you need to know how much power you can reliably get.  If you don't get that power, then people will die.  It really is that simple.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#41 2019-07-07 14:53:01

kbd512
Moderator
Registered: 2015-01-02
Posts: 3,128

Re: NASA and DOE to test kilopower nuclear reactor for space applications

Louis,

Joe Blow or Jane Blow down the street won't be getting his or her hands on a nuclear reactor loaded with HEU.  Reality check, please.  NASA is talking about giving these devices to companies like SpaceX and Boeing.  They're offering it precisely because they want their missions to succeed and are willing to put the full resources of the US government behind such efforts.  They're not going to hand them out like candy to anyone who wants one.  That's not how distribution of government resources to private entities works, especially as it pertains to nuclear materials and technology.

Rather than complaining about the pace of development, which doesn't proceed according to anybody's time table, I think it's better to focus on how reliable and repeatable we can make the results have been.  Orbital ATK's MegaFlex has yet to be demonstrated in space and it's been in development longer than the KiloPower concept even existed.  Thus far, KiloPower development has not encountered any show-stopper issues and has demonstrated every claim that the designers made.  All tests have yielded positive results.  Similarly, MegaFlex's protracted development has also proceeded smoothly.  I'd rather that exhaustive testing was performed on both systems, rather than sending them to space before they were ready for prime time.

PV power alone couldn't keep a rover alive using less power than an incandescent light bulb consumes, so I question the merit of anyone claiming that PV and batteries will provide power for everything.  If total power provisioning mass didn't matter at all, which is certainly not even close to reality here, then maybe that could work.  I don't recall anyone here claiming that a nuclear power source should be used for everything.  In fact, I believe my exact comments on the matter were "take everything" or "all of the above approach" or something to that effect.  That means we use every properly tested power provisioning technology that science can provide.  Nuclear power is an important part of what science can provide.

PV and batteries are great when they work and the environment is amenable to their use, which would be why we've spent so much time and money on those two technologies.  Unfortunately, the surface of Mars is an exceptionally hostile environment.  Given proper design, nuclear power works 24/7/365, no matter the local weather.  That said, neither is a suitable replacement for the other.  Solar arrays don't work at night and the types of stupidly simple fission reactor designs suitable for use in space don't have the power density to provide enough peak output.  The batteries used in space remain incredibly heavy for the energy density provided, so providing hundreds of kilowatts to megawatts of storage capacity in the form of space-rated battery modules is an absurd waste of available payload capacity.  Production beats storage pretty much every single time.  However, combining PV with batteries and nuclear fission provides astronauts and experiments and ISRU technologies with a complete power provisioning solution.

The KiloPower fission reactor design has no sophisticated control electronics.  It doesn't contain a single microchip or transistor anywhere in the design.  Nothing more sophisticated than electric servos and batteries is included as part of the control package.  The designers were adamant about that point.  It contains a single control servo for the single control rod, a pair of D-cell batteries to operate the control rod, and has 4 Stirling engines / electric generators connected to it.  That's it.  It's turned on remotely using a control cable to operate the servo.  The batteries are merely a backup power solution for operating the control rod.  It has no sophisticated monitoring software or electronics because the self-regulating design doesn't require any.  All those months of testing were done to ensure that the reactor operated without the need for 24/7 monitoring.  The only monitoring to be done by the crew is to ensure radiation levels are within permissible exposure limits.  The designers have also stated that the shielding is sufficient that someone can walk right up to an operating reactor for minor repairs, for brief periods of time.

Regarding cost-effectiveness, there is little comparison between nuclear of the variety under consideration and PV since the nuclear materials are simply sitting in a bunker in the desert.  The PV panels, of the kind developed by Orbital ATK for use on Mars, costs upwards of $1M/kWe of output.  Those are just the fabrication costs for the hand-built arrays.  That has nothing to do with systems integration or shipping.  The entire KiloPower development program, up to this point, has cost a whopping $20M.  That has primarily purchased the services of our government's nuclear engineers and the use of the facilities for design work and experiments.  Completion of development with an actual deep space test is expected to cost about $200M, nearly all of which is related to the launch cost of purchasing launch services from SpaceX or ULA.

The UltraFlex arrays on Mars InSight set a record for power generation on Mars, generating 4,588Wh during 1 Sol, or 2,294Wh per array on what was obviously a very clear day.  Each array is 2.2m wide.  In order to produce the same amount of power as a single 10kWe KiloPower reactor in a day, we need 105 of those arrays set outside on the ground.  Laid end-to-end, they'd be 231m long.  That's almost 253 square yards of solar panels, or 2.5 football fields long.  We don't have to lay them end-to-end in a neat row, and probably wouldn't for all practical purposes, but it accurately illustrates the point.  NASA wants to send 5 KiloPower reactors to Mars for a mission.  That can provide up to 1.2MWh of power per day.  Now we're talking about a solar array that's 1,155m / 1,263 yards long, or 12 football fields in length to provide equivalent power on the clearest day.  At some point, reality has to set in and you have to admit that you have a complex problem to solve, no matter what solution you choose.  Anybody who thinks it's going to be easier to deploy those arrays than it would be to deploy a handful of small reactors is living in fantasy land.  Should we take lots of PV anyway?  Sure, but we need to figure out how to deploy it first.

Each ISS ORU battery pack weighs 520lbs and stores 14,874Wh of electricity using GS Yuasa LSE134 3.7V / 134Ah cells.  There are 30 cells per pack.  We would need 81 of these ORU's to store 1.2MWh, if we completely drained them, which would drastically shorten the cell life.  The cells would weigh 42,120lbs.  The 5 KiloPower reactors would weigh 19,800lbs (1,800kg each).  With the weight saved over the batteries, we could include extra 10 tons of solar power.  That solution would vastly outstrip the power provisioning capabilities of the PV and battery only solution.  I estimate that we could get ~761kWh per day, on a clear summer day, from the 10t solar array.  That's nearly 2MWh of power per day, with 1.2MWh of 24/7 power.  If we ran the reactors at 75% of rated output, we sill get 900kWh.  It's highly improbable that we couldn't at least sustain life support with that much power.  NASA says they only need the output from a single 10kWe KiloPower to provide life support for six crew members.  The rest of the power is for propellant production... whenever some gets that to work.

Nobody, meaning not NASA nor SpaceX nor anybody else, has developed a functional LOX/LCH4 plant for Mars at the scale required for practical propellant production.  A Sabatier reactor lab experiment doesn't come close to qualifying.  That's why there haven't been any patent applications for the technology.  It simply doesn't exist... yet.  We should probably discuss this as well, right after we have a working laboratory scale system demonstration of a complete propellant plant that takes ice loaded with highly corrosive salts and sediment and converts it into LCH4.  That requires 24/7/365 automated drilling / water extraction / chemical refinery operation, with little to no monitoring and labor.  If you think a nuclear reactor is too dangerous or unreliable to simply drop on the ground and connect to your spacecraft, well, just wait till you see a drilling rig in operation.

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#42 2019-07-07 15:02:44

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

We have done the calculations before in other topics for Solar and Louis does not believe them or has his own idea of them. That said what else is there for testing other than to scale up its design to forfill the power requirements that we do want 24/7 on mars.

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#43 2019-07-07 15:51:25

kbd512
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Registered: 2015-01-02
Posts: 3,128

Re: NASA and DOE to test kilopower nuclear reactor for space applications

SpaceNut,

What science and engineering can actually deliver is not predicated on the belief system of Louis, nor my own belief system, nor that of anyone else.  As near as I can tell, I have provided reasonably accurate depictions of what practical power provisioning systems will look like, mass and size-wise, using current and/or near-term technologies.  None of those technologies will be as light as we'd like them to be, nor as cheap, nor as easy to use.  If someone doesn't like that, then they should get busy designing a better solution.  I tend to just follow the work of the experts in this area and wait for them to hand down the solution from on high.

It's not the PV that makes the PV and battery only solution impractical.  It's really just the batteries.  It's the same problem we're having with electric vehicles.  When all the packaging and cooling for the batteries is included, we have mid-sized sedans that weigh as much as light duty trucks.  Lighter and stronger structural materials could alleviate some of that problem, but only to a point.  This is problematic for land vehicles, nearly impractical for any sort of passenger aircraft, and well nigh unto impossible as a practical solution that has to function reliably for many years in the hostile Martian surface environment.  In simple terms, the complete solution remains impractical using known technology.  I'm not happy at all about that, but it's still true.  I wish we had batteries that were functional replacements for liquid hydrocarbon fuels, but we're still an order of magnitude off that target and we don't even know what "right" looks like.

I think if we had thin film PV for daylight power, fission reactors for night power, CH4 fuel cells for backup / vehicle power, and better Lithium-ion or Lithium-whatever (something in the 1kW/kg range) for emergency power, then we'd be where we need to be to do a surface mission and assure that we always have power.  That's a non-negtioable mission requirement.

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#44 2019-07-07 17:04:07

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,380

Re: NASA and DOE to test kilopower nuclear reactor for space applications

No one has been able to give any proven figures for KP mass. We don't know if it has to have shielding. We do know you'll need at least one back up for a Mars mission - you couldn't stake the whole mission on one KP being guaranteed to work.

Mass figures for current space-proved PV are well established. 

I find it puzzling that KP development is taking so long. This project began back in 2012. That's seven years already and no one seems to be suggesting it will be safe and ready for use with humans any time soon.

We know how to do 24/7 energy generation on Mars through a combination of methane/oxygen supply and storage and PV.

SpaceNut wrote:

We have done the calculations before in other topics for Solar and Louis does not believe them or has his own idea of them. That said what else is there for testing other than to scale up its design to forfill the power requirements that we do want 24/7 on mars.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#45 2019-07-07 18:01:39

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

Figure_7_Natural%20and%20Manmade%20Exposures%20to%20Radiation_%20LL.png?itok=BiuwzvXk

https://www.nasa.gov/directorates/spacetech/kilopower

The project will remain a part of the Game Changing Development (GCD) program, with the goal of transitioning to the Technology Demonstration Mission program in Fiscal Year 2020.

https://www.nasa.gov/sites/default/file … 180111.pdf

1 pound of uranium fuel can produce as much energy as about 3 million pounds of burnable coal.

10kw at 1500kg

unit comes with its own shielding

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#46 2019-07-07 18:51:07

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,380

Re: NASA and DOE to test kilopower nuclear reactor for space applications

You're being v. naive. Why do you think they don't give the total mass figure for a human mission?


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#47 2019-07-07 19:16:08

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,380

Re: NASA and DOE to test kilopower nuclear reactor for space applications

Well you must be a great prognosticator kbd since this development programme is not yet complete and we all know the hard decisions are always postponed to the final stages in a project.

You are being obsessive about PV and chemical batteries. I advocate PV plus methane/oxygen supply/storage (methane powered generator).

With a 500 ton mission as proposed by Space X, you can arrive at Mars with a rich energy source to power your settlement even through the worst dust storm.  So, on a worst case scenario (a major dust storm), you power the settlement maybe 60% from the methane and oxygen you brought with you and 35% from your PV system plus maybe 5% from batteries powered up by PV fins during your flight to Mars. The worst ever dust storm lasted 9 months but there was never more than 80% reduction in insolation and that is only for a few sols.



kbd512 wrote:

SpaceNut,

What science and engineering can actually deliver is not predicated on the belief system of Louis, nor my own belief system, nor that of anyone else.  As near as I can tell, I have provided reasonably accurate depictions of what practical power provisioning systems will look like, mass and size-wise, using current and/or near-term technologies.  None of those technologies will be as light as we'd like them to be, nor as cheap, nor as easy to use.  If someone doesn't like that, then they should get busy designing a better solution.  I tend to just follow the work of the experts in this area and wait for them to hand down the solution from on high.

It's not the PV that makes the PV and battery only solution impractical.  It's really just the batteries.  It's the same problem we're having with electric vehicles.  When all the packaging and cooling for the batteries is included, we have mid-sized sedans that weigh as much as light duty trucks.  Lighter and stronger structural materials could alleviate some of that problem, but only to a point.  This is problematic for land vehicles, nearly impractical for any sort of passenger aircraft, and well nigh unto impossible as a practical solution that has to function reliably for many years in the hostile Martian surface environment.  In simple terms, the complete solution remains impractical using known technology.  I'm not happy at all about that, but it's still true.  I wish we had batteries that were functional replacements for liquid hydrocarbon fuels, but we're still an order of magnitude off that target and we don't even know what "right" looks like.

I think if we had thin film PV for daylight power, fission reactors for night power, CH4 fuel cells for backup / vehicle power, and better Lithium-ion or Lithium-whatever (something in the 1kW/kg range) for emergency power, then we'd be where we need to be to do a surface mission and assure that we always have power.  That's a non-negtioable mission requirement.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#48 2019-07-07 20:31:31

kbd512
Moderator
Registered: 2015-01-02
Posts: 3,128

Re: NASA and DOE to test kilopower nuclear reactor for space applications

Louis,

I hate to break this to you, but ANSYS models of mass and volume, especially for metals with known masses and thermal properties, are NOT "theories" about how much something will weigh, nor how much cooling capacity a specific Aluminum alloy radiator panel can provide.  If ANSYS couldn't tell you how much something weighed, there'd be no way to use it to design jet engines and airliners.  KiloPower is almost entirely blocks and tubes of different types of metals.  The only ceramic metal in the entire assembly is the Beryllium Oxide reflector cylinder.  The mechanical properties of that material, to include mass and thermal properties, have been known for decades.

The nuclear engineers at the Nevada National Security Site (NNSS) have built and tested a 10% scale model (1kWe) and that is sufficient for determining how such a tiny reactor would behave.  They've tested it in a vacuum chamber with thermal environments matching those found in space.  The 1kWe HEU / Molybdenum alloy core is 4.5" D x 9.5" L and weighs 28.4kg.  The 10kWe HEU / Molybdenum alloy core is 6" D x 11" L and weighs 43.7kg.  The 1kWe core, less radiators and shielding, weighed 134kg.  The 10kWe core, less radiators and shielding, will weigh 226kg.  The 1kWe to 10kWe Stirling generators are COTS products that were used in testing and have known masses.

The actual 10kWe KiloPower reactor can weigh anywhere between 1,068kg and 1,484kg, dependent upon how much shielding mass is added.  The nuclear engineers sold the reactor weight to NASA based upon the heavy shielding configuration, not the light shielding configuration.

KILOPOWER REACTORS FOR POTENTIAL SPACE EXPLORATION MISSIONS - David I. Poston, Marc Gibson, Patrick McClure - Los Alamos National Laboratory

White Paper - Comparison of LEU and HEU Fuel for the Kilopower Reactor

DESIGN OF THE KRUSTY REACTOR

Kilopower Reactor Using Stirling TechnologY (KRUSTY) Nuclear Ground Test Results and Lessons Learned

The heat pipe system:

Titanium-Water Heat Pipe Radiators for Kilopower System Cooling Applications

This is what one of the Stirling engines looks like:

Qnergy Stirling Engine

I can't recall if Qnergy or Sunpower (now part of Qinetiq?) won the contract, though.

A blog discussing the upside and downside of different KiloPower reactor configurations:

KRUSTY: We Have Fission! Kilopower part III

A decent resource for understanding the various nuclear power systems under consideration:

American Space Nuclear Electric Systems

David Poston very helpfully included his phone number and E-mail address so you can contact him if you're concerned about the shielding.  I assure you that nobody is trying to hide anything from you.

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#49 2019-07-07 20:53:13

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,490

Re: NASA and DOE to test kilopower nuclear reactor for space applications

The kilowatt reactor or its rocket exploded on the launch pad, the uranium 235 in the core would expose people one kilometer away to radiation levels no more than natural background levels. Distance from a full open amount of material....

pg 10 gives the shielding layout
https://www.nasa.gov/sites/default/file … 011618.pdf

https://ntrs.nasa.gov/archive/nasa/casi … 002010.pdf

https://ntrs.nasa.gov/archive/nasa/casi … 011723.pdf

The baseline JEO spacecraft included five Multi-Mission Radioisotope Thermoelectric Generators (MMRTGs) with a total mass of about 240 kg providing about 500 W while using 20 kg of Pu-238.

The REP version uses nine large (550 W) Advanced Stirling Radioisotope Generators (ASRGs) providing a net power of about 4 kWe with 27 kg of Pu-238.

A test configuration of a Kilopower concept using the smaller core and eight ASCs to produce 800 W of electric power. The overall system is approximately 2.5 m long and weighs about 400 kg (2 W/kg).

Also you did see the forklift used to stack the parts well it has a weight limit for what it can lift....google it....

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#50 2019-07-07 21:01:45

kbd512
Moderator
Registered: 2015-01-02
Posts: 3,128

Re: NASA and DOE to test kilopower nuclear reactor for space applications

Louis,

Speaking of prognostication, you still haven't told me how you're going to obtain the 1,100t of propellants to leave the planet, nor how much any of that equipment will weigh.  If it's a one-way trip, then it's gonna be awfully expensive.

If you run out of Methane or the Methane isn't available, then what?

Ever wonder how long that CH4 would last with a 75% efficient fuel cell?

55.6MJ/kg = 15.44kWh/kg

Let's say we arrive with 450t of LOX/LCH4 to play with.  That's 150t of LCH4 and 300t of LOX (stoichiometric O/F ratio).

11,580Wh (75% of the theoretical maximum energy stored in each kg of CH4) * 150,000kg = 1.737GWh

That's 1,447.5 days of power, which is almost 4 years worth of power provided by 5 KiloPower reactors.  But wait...  We seem to be forgetting a few important things.  We only have 50t of useful payload left for absolutely everything else we need to survive, to include water, food, and some way to make propellants to come home or equipment to grow crops since we're never leaving the planet without the propellant.  Seems like a mighty fine waste of payload capacity to me, but YMMV.

To actually come home, we need more than twice as much propellant as we started with if we took 450t worth of it to Mars.  Something tells me we need a more mass efficient energy provisioning solution.  I already know you'll come here and make the case for why we don't.  We have plenty of mass to play with, we can just dump it into batteries and solar panels without consequence, nor any clue about how to get home, etc.

Energy production beats energy storage every day of the week, both here on Earth and on Mars.

GW told you what the mathematically computed minimum energy requirements would be and it's more continuous power than we've ever generated in space by more than an order of magnitude.  In point of fact, our 450t of Methalox won't even last 4 years if we use it for drilling operations.

Here's another bit of prognostication, though.  You can't run a drilling and extraction operation with an 80% fluctuation in available power and burning the fuel you need to get home for drilling operations only pays off if you hit water.  You either have power on tap to get work done or work stops.  Ask me how I know this.

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