B How Dangerous is Plutonium in Real Life?

[DaveC426913]

All the best science comes from TV shows, right?

I just watched an ep of "Timeless", a new series about time traveling hijinks.

In this ep, they want back to the Nevada bomb tests of 1962 and stole a plutonium core of what looked like the Fat Man atomic bomb. They brazenly took the ~4 inch sphere "pit" out of its shielded case and carried it around - in nothing but their street clothes and lead-lined gloves. No one (even our intrepid 21st century travellers) seemed the least bit fazed.

How sick would they be after, say, a one minute exposure at a distance of 3 feet?

 

[fresh_42]

How sick would they be after, say, a one minute exposure at a distance of 3 feet?

Pu is also highly toxic. You won't even need the radiation to be killed.

 

[DaveC426913]

Well, they weren't eating it.

 

[anorlunda]

Pu spontaneously emits clumps of atoms from its surface. If you breathe them, they get stuck in your lungs that stay fixed in place, making a point source of radiation that bombards the nearest lung cells. Very dangerous for anyone in a room with exposed Pu.

I recall the word sinter (scinter?) for that process, but I can't find verification for that word.

My source was the book Making of the Atomic Bomb by Richard Rhodes.

 

[Vanadium 50]

I just watched an ep of "Timeless", a new series about time traveling hijinks.

Let me guess - our heroes number four: a history professor, a scientist, a soldier, and everyman. Exactly one of them is a hot babe, either the history professor (who, unlike a real history professor, is not an expert in one tiny subspecialty, but knows everything about everything) or everyman. Likewise, the scientist, in the proud tradition of The Professor on Gilligan's Island knows everything about everything scientific. At least one of the team is on it because, unbeknownst to everyone else, they want to rescue a loved one from a tragic death that has already happened in their timeline.

How close did I come?

How sick would they be after, say, a one minute exposure at a distance of 3 feet?

Not very. Pu-239 is an alpha source. Most alphas are stopped in the plutonium itself, and it is highly likely that the entire sphere is cladded with a think layer of some less reactive metal, and that will stop the alphas produced at the surface. My ballpark guess is a few sieverts per hour. Not small, but not something fatal in minutes.

Here's something else they got wrong - because everyone does. They probably made the pit about the size of a softball, and everyone is handling it as if it weighs a couple pounds (even in its suitcase). If it's the size of a softtball, it's closer to 50 pounds. Nobody acts as if it weighs that much.

 

[DaveC426913]

Let me guess - our heroes number four: a history professor, a scientist, a soldier, and everyman. Exactly one of them is a hot babe, either the history professor (who, unlike a real history professor, is not an expert in one tiny subspecialty, but knows everything about everything) or everyman. Likewise, the scientist, in the proud tradition of The Professor on Gilligan's Island knows everything about everything scientific. At least one of the team is on it because, unbeknownst to everyone else, they want to rescue a loved one from a tragic death that has already happened in their timeline.

How close did I come?

Preeeeeetty much nailed it.

• There's only three. The Historian, the Soldier and the Pilot.
• The Historian is the hot babe.
• None of them are scientists, not even the Pilot. He knows the machine but is otherwise the least skilled of the team (but the story is young yet).
• Pilot is also the token ethnic character, and the comedic relief.
• The Soldier lost a loved one and is indeed mooning about getting her back, between bouts of trying to shoot everything in sight.

 

[DaveC426913]

Pu spontaneously emits clumps of atoms from its surface. If you breathe them, they get stuck in your lungs that stay fixed in place, making a point source of radiation that bombards the nearest lung cells. Very dangerous for anyone in a room with exposed Pu.

Reading up a little on Pu cores, in this case a Christie Pit, it seems they were coated in a thin layer of nickel to prevent this.

As plutonium was found to corrode readily, the sphere was coated with nickel.

https://en.wikipedia.org/wiki/Fat_Man#Development

 

[DaveC426913]

Here's something else they got wrong - because everyone does. They probably made the pit about the size of a softball, and everyone is handling it as if it weighs a couple pounds (even in its suitcase). If it's the size of a softtball, it's closer to 50 pounds. Nobody acts as if it weighs that much.

I was doing a mental-back-of-napkin calc at the time (I guessed at Pu having a density on the order of 10g/cm³ - low by a factor of 2.), and came up with a ballpark 25 pounds.

They were carrying it like it was very heavy, but not 50 pounds heavy. (Imagine trying to wield a 50 pound bag of cement mix).

 

[Vanadium 50]

I guessed at Pu having a density on the order of 10g/cm3

That's about what lead is - most alloys are around 11. And that's what people think is heavy - close to as heavy as it gets. But gold, tungsten, uranium are all around 20.

 

[anorlunda]

Reading up a little on Pu cores, in this case a Christie Pit, it seems they were coated in a thin layer of nickel to prevent this.

https://en.wikipedia.org/wiki/Fat_Man#Development

Very interesting, I didn't know that. But Wikipedia says that the pits weren't generally used until 1960. This scenario is 1942.
https://en.wikipedia.org/wiki/Pit_(nuclear_weapon)#Christy_pits

Edit: Whoops, the article does say 1960, but it also specifically mentions Fat Man. So disregard.

 

[Vanadium 50]

This scenario is 1942.

I don't think a plutonium pit would have been available in 1942. In any event, irrespective of future metallurgical developments, the chemistry of plutonium would all but require some kind of cladding.

 

[DaveC426913]

I don't think a plutonium pit would have been available in 1942. In any event, irrespective of future metallurgical developments, the chemistry of plutonium would all but require some kind of cladding.

The ep took place in 1962, so it was a ... achronism.

 

[rbelli1]

If they would have used a tungsten sphere it would have been about the right weight. That would have been a couple thousand dollars worth so not out of the question. But where would you pick up a softball sized tungsten bearing?

BoB

 

[f95toli]

I might be wrong here (my books about the Manhattan project are in a box somewhere), but I am pretty sure that I've read that when the first Pu bomb was assembled (Trinity) the Pu core was delivered by a guy who was was carrying it in a (substantial) briefcase. Also, people certainly handled the Pu with just a pair of gloves and no special protection (there are plenty of photos showing how the bomb was assembled). The Pu was apparently warm to the touch.

Hence, this would suggest that the Pu was coated in something that stopped most of the alpha radiation. Pu is indeed extremely toxic if it gets into your body, but blocking the radiation is not very difficult.