“Hot” coffee cup

Not if you’re dipping a cup in a hot spring at Yellowstone to warm up your coffee.

That reminds me of this weird thing…

I’m not sure DPRK’s correct and relevant observation got the attention it so richly deserves. Beta radiation may be fairly easy to stop, but for more energetic Beta emitters, stopping it creates Gamma rays. They’re much harder to stop.

A few years I built a Sr-90 source into a machine, and felt encouraged to do a fair bit of extra work to avoid possible operator exposure to this secondary radiation.

“Jim never has an extra dose of bremsstrahlung when I make coffee”

If you want to heat your coffee quickly, you need to think outside the box of mundane nuclear processes. X-ray laser is the way to go.

But how long does it take to recharge that thing to blast again? The goal is to keep the coffee hot, not to get it hot in the first place.

Sorry, did not read the thread carefully enough - I just realized that you had already posted a link to a different account of the Oklo natural reactor.

No worries! It should be on everyone’s reading list.

I feel like this deserves more attention.

The heat capacity of water is 4 J/g/K, so if we assume that our insulated container cools by about 1K every 400s, we need an energy input of 10^-2 J/g/s.

If we take the obvious approach of using half anti-water to make our coffee (containment and modulation of the annihilation is left as an exercise for the reader), and noting recent expert commentary that we can probably get 92% efficiency…

Nuclear fission / fusion? - #45 by Pasta

…we have 8 x 10^13 J/g available.

So we can keep our coffee warm for 8 x 10^15 s, or 250 million years as a rough approximation. Of course, the volume of coffee would steadily decrease, which is a drawback to this method.

If, despite best efforts, you do happen to achieve criticality, you’ll want to have a hafnium stir stick or access to borated creamer to keep things in check. We don’t want to boil off the coffee, after all.

Don’t remove the stir stick too rapidly or you risk prompt criticality and splattering coffee absolutely everywhere.

Is Borated creamer a requirement?? Frankly, it sounds awful. I’m partial to Half & Half myself. Milk is too thin, Cream is too thick. “Arf and Arf” is just right. I’m almost certain Carly Simon noticed this, too.

Radioactive power sources are a waste stream nightmare.

Which is why we’d only make these nuclear-thermal coffee cups as a reusable design, not as disposable to-go coffee containers. Gotta control that waste stream.

I think as long as you start with borated cows, you can have borated half&half

I think you’d struggle to make a Boron (VI) ion when it only has 5 electrons, but if you did it would probably react with Neon. (Okay, to be pedantic I guess I need some Oxygen in there too.)

Yep. If it happens in Vegas, it needs to stay in Vegas.

Sorry. I don’t know anything about animal husbandry.

OK, I’m not getting this one.

You’re not missing anything, it was a weak attempt to do something with Bovine.

Perhaps “farm structure constant” has more mileage.

An insulated mug obviously doesn’t solve the problem, but it does make it substantially more tractable. In fact, the lid on an insulated mug is an enormously important factor. See the measurements here:

If room temperature is 20 C, and we want the coffee to be 55 C, then we have a 35 C delta, which according to this chart only requires about 2.5 W of heat input to sustain, as long as we use a lid.

That’s only about 5 grams of Pu238. Just 0.25 cm^3. And 2.5 W is small enough that it shouldn’t be particularly unsafe while sitting in a closed cabinet, etc.

I can imagine some passive safety measures to help as well. Consider a small button of material attached to the bottom of the mug. Since the mug is stainless steel, which isn’t particularly conductive as far as metals go, it might get unsafely hot around the button after a while–probably not enough to start a fire, but enough to burn a finger if you touched it, or melt plastic that got dropped in.

One possible measure is to have bimetallic heat conductors within the vacuum area. When they get unsafely hot, they bend outwards, touching the outer surface of the mug. There’s now a shortcut path for excess heat to the outside, and 2.5 W over the outer surface of a mug is not very much to dissipate. When there’s coffee in the mug, the liquid moderates the temperature.

There are many other possibilities; that’s just the first that came to mind. I think it’s a fairly straightforward engineering problem aside from the acquisition and disposal of the material.