Topic: Question about HEU.

[Rocky]

What is the temperature of highly enriched uranium?

[Astronuc]

Under what conditions, in what form, and of what enrichment?

If one has a mass of HEU, it will be at ambient temperature or perhaps a few degrees above ambient depending on the rate of radioactive decay, mass and heat transfer (thermal conductance) at the surface.

If HEU is placed in an environment where fission is induced, the temperature will increase as a function of fission density.

In a light water reactor, the fuel (usually in form of UO₂) temperature would be on the order of 400-1200°C during normal steady-state operation.  In a fast reactor, the temperature could be higher - 600-1800°C.  The fuel could be in the form of UO₂, UC or UN.

If a compact sphere of the HEU material goes prompt supercritical, as in a detonated nuclear weapon, the temperature is on the order of 10 million degrees (K) for a few micro-seconds before it cools due to radiation and rapid expansion.

[yale]

HEU is similar to lead. Heavy dense metal. As astro said, it may be slightly warmed by the mild level of decay and minor amount of spontaneous fission, but its pretty inert stuff - until it is fissioned.

It may be the most dangerous material humans have ever produced. I don't mean its heavy-metal lead-like toxicity which is manageable, nor its radioactive hazard, which is relatively minor. I mean its explosive properties. While plutonium is excellent bomb material, it requires relatively sophisticated implosion systems to detonate it.

Highly-enriched Uranium, on the other hand is a no-brainer. The Hiroshima bomb, which trashed a city the size of denver, was never even tested before use.

A country, group, or individual, at almost any level of technical expertise, can build a weapon capable of Hiroshima scale destruction with common materials.

Do a google search on "nuclear weapon uranium enriched" and you will see how terrible a threat it is.

yale

[Rocky]

Okay, I know it's a strange question, but I was wondering if I just happened to have, oh, let's say 300 pounds of the stuff enriched to ninety percent in the deep end of my swimming pool, whether or not it would keep the water warm at night.

[yale]

You would have a nuclear explosion if you assembled the mass quickly enough, or if you did it a bit slower, you would have a major power excusion vaporizing the mass (and you) and messing up the neighborhood.

If you carefully assembled it in a barely critical array, you would, in fact, create a nuclear reactor and heat your pool into the FAR distant future. (Altho 300 pounds is serious overkill! very punny  ;) )

Astronuc could assist you in the design.

Good luck on your project!

 :end.gif:

Image of Rocky's first prototype Atomic Pool Heater:

[Orstio]

:yukyuk

[yale]

Some added benefits are:

No pool lights are needed

No need for chlorine to disinfect

Less unwelcome use of pool by neighbors



Plus you can earn extra money doing some part-time fish farming!

[Rocky]

lol well, thanks.

[yale]

Altho you specified Highly Enriched Uranium (HEU) as your heat source, there may be better alternatives.

HEU only generates less than 3 ten thousandths of a watt per kilogram as decay heat.

(In a reactor or bomb, the HEU is fissioned and can produce enough heat to erase your town, but it is an expensive and messy process)

If you choose Plutonium 238 instead, you may achieve success.

Pu238 has a decay heat output of 1/2 kilowatt per kilogram. (Hot Stuff!)

Since a pool heater is about 5 to 10 kilowatts, then you would need a chunk of Pu238 weighing only 30 to 50 pounds tossed into the deep end of the pool.

You would have a RadioIsotope Heater Unit or RTU.

The mars rovers use little RTUs to stay warm and solar power for electricity.

[Rocky]

Yeah, but Pu-238 isn't typically used in nuclear weaponry, is it?  I'm throwing around some ideas for a story I was thinking about writing.  Admittedly, it's kind of silly, which is why one of the characters has been swimming around in the uranium he was going to use to build a bomb with.  It's just one of those cheap James Bond villain touches... those villains sometimes had some kind of stupid trademark that a real person would never do.

What kind of bomb could be built with Pu-238, if it's even possible?

And did anyone catch 60 minutes tonight?

And has anyone else had trouble logging into the forums lately?

[Astronuc]

What kind of bomb could be built with Pu-238, if it's even possible?

And has anyone else had trouble logging into the forums lately?

Like anything radioactive, Pu-238 could be used to make a 'dirty' conventional bomb.  But it is a controlled material, so access to it is limited, at least for now.

Re: access to forums - minor techical difficulty.  Looks like Orstio took care of it.

[Rocky]

I was thinking anyone who would go through the trouble to get Plutonium would just go ahead and build an all out nuclear weapon... but then again, a dirty bomb with Plutonium would be a dirtier dirty bomb, huh?  At least compared to one that used radium or such.

[yale]

I see where you are going.
I would say your best bet would be to use your original idea of using HEU or weapons-grade Pu239 (not 238) being stored or hidden in the swimming pool.

The evil villian, to amuse himself, has some of the fissiles formed into a nuclear fission reactor. The pool water would provide the moderator. I picture something along the lines of a beryllium tube about the size of an oil drum, with tubes containing uranium or plutonium running the length. pool water will convect up and thru the container.  Altho one could likely swim with relative safety in the shallow end, it would be pretty radiactive in the deep end.

The bad guy could threaten to toss the good guy into certain death in the deep end.

Or, if the villian is intending on keeping it secret, the reactor might form by mistake, helping our hero locate the fissiles by the heat, or glow, or intense radiation.

It would be very cool looking with an eerie blue glow.

Again, I suspect that astronuc could spec out a plausable critical array, sufficient to seem functional enough for fiction.

yale

[Rocky]

Thanks for the help.  You really put me on the right track for my research.  It usually takes me about a year to write these things, but when I'm done with the story I'll post the scene here for you guys to nitpick the errors.