11 posts in this topic

Posted

To the stars: After a 25 year hiatus, NASA restarts plutonium production

Radioisotope_thermoelectric_generator_plutonium_pellet-640x503.jpg

After a quarter-century hiatus, the United States has begun producing plutonium-238 once more. The decision was made to ensure that future NASA projects would have access to the valuable fuel. As US stocks dwindled, NASA began buying plutonium-238 from Russia, but that agreement came to an end in 2010. When most people think of plutonium, they think of nuclear weapons

Share this post


Link to post
Share on other sites

Posted

It's about f'ing time!!

You can make RTG's from other materials, but there nowhere near as effective. There's a big one powering the Curiosity rover and many deep space probes that are too far out for solar to be practical.

Share this post


Link to post
Share on other sites

Posted

hmm i wonder if they could use this to power VASIMR

Share this post


Link to post
Share on other sites

Posted

So now maybe we can stop bumming the stuff from other countries.

Share this post


Link to post
Share on other sites

Posted

what picture is that, why its red ?

Share this post


Link to post
Share on other sites

Posted

hmm i wonder if they could use this to power VASIMR

Radioisotope Thermoelectric Generators (RTG's) produce a few hundred to a couple thousand watts. VASIMR needs hundreds of thousands to millions of watts.

what picture is that, why its red ?

The plutonium oxide pellet above is red hot because of the heat of radioactive decay. Left in open air if wouldn't be that hot. Pics like that are done by putting the pellet in a graphite container, which causes it to get hotter, then removing it to snap the image. Its natural color is a yellowish to olive green.

Share this post


Link to post
Share on other sites

Posted

The plutonium oxide pellet above is red hot because of the heat of radioactive decay. Left in open air if wouldn't be that hot. Pics like that are done by putting the pellet in a graphite container, which causes it to get hotter, then removing it to snap the image. Its natural color is a yellowish to olive green.

Interesting info, Doc. Thanks. What happens if it's left in the graphite container?

Share this post


Link to post
Share on other sites

Posted

It stays red hot, the graphite acting as an insulator, and in an RTG the heat from Pu238 decay causes a surrounding thermocouple array to produce electricity. No or few moving parts, high reliability, and it has a half-life of 87.74 years.

In terms of radiation safety, Pu238 is an alpha emitter (high speed helium nuclei) which can be stopped cold by just a metallic casing, so minimal shielding is required. Impurities may add a slight beta (electrons) or gamma output, but they too can be effectively shielded. 2.5mm of lead is enough, and the casing is often its equivalent. Still best used in un-manned applications though.

Note that the yellowish to olive green color is for a plutonium oxide. Pure plutonium looks a lot like nickel or silver, but its brittle and it's not a good conductor.

Share this post


Link to post
Share on other sites

Posted

When people are talking about radiation I never have any idea what people are talking about, and yet, I still find it incredibly interesting.

Share this post


Link to post
Share on other sites

Posted

Ah - radiation. The oogie-boogie-man. The basics aren't that hard.

Matter is made of particles, mostly electrons (- charge), protons (+ charge), and neutrons (no charge), plus several dozens of others with similar charges. There is also electromagnetic radiation, which can be anything from radio waves, infrared, visible and ultraviolet light, to x-rays and gamma rays.

When we talk of "radiation" in the usual sense we're typically talking about high speed helium nuclei (alpha particles), electrons (beta particles), neutrons, x-rays and gamma rays.

The one thing these all share is that they can ionize atoms, meaning they can knock electrons out of ordinary atoms leaving them with a net + charge, which changes how it interacts with other atoms. If too many of these ionized atoms are in a living things DNA it cause problems; mutations, cancer or other health issues.

We run this risk even without nuclear power & such because of radiation sources in nature. Fly a plane, travel in space, go in most basements or underground, or even eat food grown in the Earth and you consume or are exposed to radiation sources. To a degree they even contribute to evolution by causing mutations. Radiation even streams through the atmosphere from deep space and the sun.

Mitigating this, cells have DNA repair mechanisms which help considerably, and there are medical teeatments in development that can be administered to help with many acute radiation sickness issues. Lots of work to do though.

2 people like this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0

  • Recently Browsing   0 members

    No registered users viewing this page.