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How the Curiosity Rover's Nuclear Battery Works

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Re: How the Curiosity Rover's Nuclear Battery Works

#61

Post by grecy »

bennysaurus wrote: post #59
brudgers wrote: post #40

Earlier quoted context omitted.

My understanding of the problem is that nuclear sources tend to be nasty stuff and not the sort of thing that one really wants lay people responsible for discarding.

I think the OP is looking at using their stove as the heat source, not a nuclear battery. On that note, the idea you're talking about was actually considered for a little while for public use until the dangers were found to outweigh the benefits.

Right now I'm thinking about a stove, but this nuclear battery has me thinking.

I am wondering if it would be possible to buy or build such a nuclear battery.

Re: How the Curiosity Rover's Nuclear Battery Works

#62

Post by bigiain »

sehugg wrote: post #8
sp332 wrote: post #6

How much power does the device generate? How much will it generate in 14 years when it is "expended"? Edit: Initially 2 kW of thermal power and 125W of electrical power, falling by only 20% after 14 years. https://en.wikipedia.org/wiki/MMRTG#Design_and_specification...

According to Wikipedia, 125 watts when it was launched, down to about 100 watts in 14 years. The JPL guys claim that the RTG is really just a trickle charger for the batteries that actually handle the load -- which likely has transients that the thermocouple in the RTG couldn't handle. I don't know the lifetime of the lithium-ion battery pack but I'm guessing it'll degrade way before the RTG power decreases below the…

There's a LiPo technology called "thin film lithium" which is claimed good for 10,000 cycles - assuming one charge/discharge cycle per day (and incorrectly using earth-days for simplicity), that'd give you ~27 years lifetime from the battery. (I wonder if this'll end up with the same "over engineered" reliability that let the Spirit rover last over 6 years when intended for a 90 day mission?)

Re: How the Curiosity Rover's Nuclear Battery Works

#63

Post by bennysaurus »

grecy wrote: post #61
bennysaurus wrote: post #59

Earlier quoted context omitted.

I think the OP is looking at using their stove as the heat source, not a nuclear battery. On that note, the idea you're talking about was actually considered for a little while for public use until the dangers were found to outweigh the benefits.

Right now I'm thinking about a stove, but this nuclear battery has me thinking. I am wondering if it would be possible to buy or build such a nuclear battery.

Certainly to build one the theory behind it wouldn't be tough, it'd operate on the same principles as the stove setup. To buy though? There's a story of a boy scout who did something similar as part of a personal experiment in the 90's. (Before getting raided out of fear by the FBI) Will have to find that story again.

In almost every country the materials required are tightly regulated and getting permission even in a lab environment is tough work. If you can work out the legalities and safety, I'd be interested too!

Re: How the Curiosity Rover's Nuclear Battery Works

#64

Post by bigiain »

ilamont wrote: post #37

What are the safety implications of launching 10 pounds of plutonium-238 on a rocket that could malfunction or explode before gaining escape velocity? The article says the plutonium would not explode, but what about plutonium particles or radiation entering the atmosphere and ocean?

You know coal typically contains 1-4ppm of both Uranium and Thorium, right? http://pubs.usgs.gov/fs/1997/fs163-97/FS-163-97.html

And that the US burns around 1 billion tons of coal a year? https://en.wikipedia.org/wiki/Coal

So coal fired powerstations send something like a few thousand tons of Uranium and Thorium into the environment every year (he said, blithely simplifying ppm into "proportion by weight").

Still worried about 10lbs of Plutonium?

Re: How the Curiosity Rover's Nuclear Battery Works

#67

Post by joshAg »

ktizo wrote: post #65

So, when can I get a nuclear car? And what's the insurance gonna cost?

when we start building "breeder" reactors again. Plutonium is a byproduct of the breeder reactors when they create the type of uranium that can be used for nuclear bombs (this is one of the reasons that breeder reactors aren't popular). I was talking with one of the scientists at Ames last night, and apparently this is pretty much the last of NASA supply, since the US has significantly cut down on their production of weaponizeable uranium.

Re: How the Curiosity Rover's Nuclear Battery Works

#68

Post by [deleted] »

bigiain wrote: post #64
ilamont wrote: post #37

What are the safety implications of launching 10 pounds of plutonium-238 on a rocket that could malfunction or explode before gaining escape velocity? The article says the plutonium would not explode, but what about plutonium particles or radiation entering the atmosphere and ocean?

You know coal typically contains 1-4ppm of both Uranium and Thorium, right? http://pubs.usgs.gov/fs/1997/fs163-97/FS-163-97.html And that the US burns around 1 billion tons of coal a year? https://en.wikipedia.org/wiki/Coal So coal fired powerstations send something like a few thousand tons of Uranium and Thorium into the environment every year (he said, blithely simplifying ppm into "proportion by weight"). Still wo…

[deleted]

Re: How the Curiosity Rover's Nuclear Battery Works

#69

Post by DeepDuh »

Wingman4l7 wrote: post #66

Calling it a "battery" is disingenuous. An RTG doesn't fit the typical definition of a battery -- it doesn't store electrical energy. A better name would be "power supply".

Well it does - it stores nuclear binding energy that's unstable enough to be extracted and stable enough to last for x years. It's a nuclear battery just like convential ones are chemical batteries.

Re: How the Curiosity Rover's Nuclear Battery Works

#70

Post by excuse-me »

uvdiv wrote: post #22
adrr wrote: post #18

Earlier quoted context omitted.

There's Pu238 in our nuclear fuel rods, we aren't allowed to reprocess spent fuel to extract it.

That's worthless because it's contaminated with other isotopes of plutonium. Pure Pu-238 is made by irradiating Np-237, which comes from spent fuel but is already separated in very large amounts in the US. I think the main setback is funding.

It's useless in a fissile device, perfectly usable as a nuclear battery. Waste Pu238 it's a bit dirty if it explodes because of all the other stuff that's mixed in with it - but it's only Florida.
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