Uranium/Plutonium hot to the touch?

  • Context: Undergrad 
  • Thread starter Thread starter jmatejka
  • Start date Start date
  • Tags Tags
    Hot
Click For Summary

Discussion Overview

The discussion revolves around the thermal properties of uranium and plutonium, specifically whether these materials are hot to the touch due to their radioactive decay or if other factors contribute to any observed heat. Participants explore various scenarios, including historical incidents and applications of these materials in technology.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants speculate that the heat observed in certain radioactive materials may not originate from uranium or plutonium themselves, but rather from other irradiated metals or elements nearby.
  • One participant notes that plutonium-238 is a powerful alpha emitter and can generate heat, suggesting that large enough pieces could melt snow.
  • Another participant recalls that plutonium used in the Manhattan Project felt slightly warm but was manageable to handle, indicating that it may not be excessively hot.
  • There is mention of a historical incident involving warm barrels found in Georgia, which were likely sources from a seed irradiation facility, indicating that not all warm materials are plutonium or uranium.
  • Some participants discuss the use of plutonium in radioisotope thermoelectric generators (RTGs) for spacecraft, noting that these devices can generate heat and electricity over long periods.
  • One participant shares an anecdote about handling depleted uranium (U-238), which was not warm to the touch, highlighting its low activity due to its long half-life.
  • There are references to the loss of plutonium from the Apollo 13 mission and discussions about the implications of RTGs in remote facilities, including potential hazards if they are not maintained properly.

Areas of Agreement / Disagreement

Participants express a range of views on the thermal properties of uranium and plutonium, with no consensus reached on whether these materials are inherently hot to the touch or if other factors contribute to any observed warmth. The discussion remains unresolved regarding the specifics of the historical incidents mentioned.

Contextual Notes

Some claims about the thermal properties of uranium and plutonium depend on the definitions of "hot" and the context of their use. The discussion includes references to specific historical events and technical applications, which may not be universally applicable.

jmatejka
Messages
126
Reaction score
1
(Hot here refers to temperature, NOT the obvious radioactivity),Yes, perhaps a silly question, but maybe not.

I can't remember where I read about Russian children finding "radioactive" metal in a forest that had melted the snow around it.

Perhaps they found metal that had been neutron bombarded, and the decay made this metal hot?

Maybe the more enriched the Uranium or Plutonium the cooler, maybe "other" metals/elements absorb the decay and convert to heat?(actual Urainium/Plutonium not hot to the touch?)

All speculation by me, any answers? Thanks, John
 
Science news on Phys.org
Pu is used as a heat source in generators for spacecraft , it's a bit expensive to have lying around in the coutryside but you never know.
Pu238 is the most powerfull, it's a 5Mev alpha emitter with a half life around 85years.
So around 6x10^11 decays/second/g * 1.6x10^-11J gives a power of 0.5W/g, they would have to be reasonably big
lumps to melt snow.
 
mgb_phys said:
Pu is used as a heat source in generators for spacecraft , it's a bit expensive to have lying around in the coutryside but you never know.
Pu238 is the most powerfull, it's a 5Mev alpha emitter with a half life around 85years.
So around 6x10^11 decays/second/g * 1.6x10^-11J gives a power of 0.5W/g, they would have to be reasonably big
lumps to melt snow.

I'm sure (from memory) it was'nt plutonium or uranium the kids found, it was another metal that had been irradiated. This article is what made me think, is it the uranium/plutonium that is hot, or is it the other metals/elements around it, getting hot. Thanks
 
Radioactive decay produces heat. This does not simply go linearly with the mass, but with plutonium and uranium you will have fission effects. The temperature increases massively the closer you come to the critical mass.
 
According to one of my books about the Manhattan project the plutonium for Trinity (the first bomb they tested) felt slightly warm when they touched it, but it wasn't hot so they could easily handle it when they assembled the bomb (I am not even sure they wore gloves, although considering hos toxic Pu is I hope so).

Hence, if you leave a large piece of Pu in the snow it might very well melt some of it.

Btw, isn't this what is suppose to have happened to the Pu in the bomb that was "lost" on Greenland? As far as I remember they found some of it but the Pu was gone, presumably because it had simply melted through the ice and then sunk into the sea underneath.
 
f95toli said:
Btw, isn't this what is suppose to have happened to the Pu in the bomb that was "lost" on Greenland? As far as I remember they found some of it but the Pu was gone, presumably because it had simply melted through the ice and then sunk into the sea underneath.

The burning jet fuel probably had more of an effect on the snow.
 
jmatejka said:
I'm sure (from memory) it was'nt plutonium or uranium the kids found, it was another metal that had been irradiated. This article is what made me think, is it the uranium/plutonium that is hot, or is it the other metals/elements around it, getting hot. Thanks
I don't remember any such incident, there was a case in Georgia (IIRC) where a group of hunters camped on a bunch of warm barrels they found in the woods. They were sources from a seed irradiation facility, so were probably Co or Sr.

In a RTG the plutonium gets hot and the heat generates electricity. Ultimately the heat transfers to the cooling vanes on the outside of the package. You can think of the Pu source as just an electric heater with a battery that lasts 100s of years.

The Russians do (or did) use a lot of them to power unmanned installations in the arctic - weather stations, radio beacons etc (there isn't a lot of sunlight for solar power), so they might have lost a few.
 
Great info! Thanks
 
The Russians used RTG's to power remote facilities such as lighthouses. During the fall of the Soviet Union, many of these RTG's went into disrepair or were stolen. I believe they contained Sr-90. Such a device would be hot to the touch, and very dangerous.
 
  • #10
Many years ago I worked at a govt facility that had a door propped open with a piece of D38 (U238) in a plastic bag. It was not warm to the touch.
 
  • #11
Bob S said:
a piece of D38 (U238) in a plastic bag. It was not warm to the touch.
U238's half life is about the age of the Earth so the activity is very low.
 
  • #12
As mentioned here, Plutonium "buttons" are used along with thermal couples to generate electicity for satellites intended to go long distances (away from Sun). The power source (is (or at least the buttons) are designed to withstand re-entry in case of a launch failure. The buttons also capture a significant part of the radiation coverting it to heat, but I doubt they are safe to handle long term. The only USA plutonium + thermal-couple generator I recall that was lost on earth, is the one from the lunar module from Apollo 13, it's at the bottom of some ocean, probably still generating potential power.

U238 is fairly stable. Depleted Uranium was used as ballast in Formula 1 race cars until it was banned for cost (not hazard) reasons.
 
  • #13
Jeff Reid said:
The only USA plutonium + thermal-couple generator I recall that was lost on earth, is the one from the lunar module from Apollo 13, it's at the bottom of some ocean, probably still generating potential power.
I don't think the lunar module made it back to Earth intact. It would have complete burned up on reentry.

AM
 
  • #14
Jeff Reid said:
The only USA plutonium + thermal-couple generator I recall that was lost on earth, is the one from the lunar module from Apollo 13, it's at the bottom of some ocean, probably still generating potential power.

They had an RTG? I though the LEM was powered by fuel cells. Or was this for an experiment?
 
  • #15
Didn't a Russian satellite powered by an RTG recently crash in Canada? I seem to remember the Canadian government making a fuss about Russia paying for the cleanup or something.
 
  • #16
Jeff Reid said:
The only USA plutonium + thermal-couple generator I recall that was lost on earth, is the one from the lunar module from Apollo 13, it's at the bottom of some ocean, probably still generating potential power.

Andrew Mason said:
I don't think the lunar module made it back to Earth intact. It would have complete burned up on reentry.
"Because this mission was aborted, its RTG now rests in the South Pacific ocean, in the vicinity of the Tonga Trench."

Wiki RTG .htm

Vanadium 50 said:
They had an RTG? I though the LEM was powered by fuel cells.
Since the lunar module was never planned to be returning to Earth, it had an RTG on board, apparently for an experiement intended to be left on the moon. I didn't mean to imply that the LEM was powered by that RTG, just that it had one on board. Read the article from the Wiki link above for more info, plus the link to Appollo 13.
 
Last edited:

Similar threads

Water and Uranium-235 Reactivity in W88 Secondary: Safety Concerns Explained
  • · Replies 15 ·
Replies
15
Views
6K
Who had the means and motive to use Polonium-210 as a weapon?
  • · Replies 17 ·
Replies
17
Views
9K
Writing: Read Only What Does Great Lakes Earth Look Like from Space?
  • · Replies 1 ·
Replies
1
Views
4K
Mathematica This Week's Finds in Mathematical Physics (Week 241)
  • · Replies 8 ·
Replies
8
Views
5K
Mathematica This Week's Finds in Mathematical Physics (Week 242)
  • · Replies 1 ·
Replies
1
Views
4K