Using an Radioisotope heater unit(RHU), used to heat spacecraft in the deep cold of space, embed it within a thermos flask to keep the content hot or at least warm for a long long time.
Unlike a spaceflight, we wont need such a big pellet. A coin cell is likely to be enough to keep the content pretty damn hot. The extra space can then be better used for creating extra radiation shielding.
It is perfectly safe as the pellet doesn't have to be in direct contact with the content, it can just be inserted into a cavity underneath the flask. (Which means easy replacement when the 10 years lifespan is up!)
Of course, if you feel excessive heat building up on the outside of the flask, its probably over 500degrees inside the flask. In that case you should start worrying and come see us, because that's not supposed to happen. But don't worry! This thermos has a 10 year warranty. We'll ship you a replacement instantly! Frankly you should be paying us!-- mofosyne, May 10 2011 RTG http://en.wikipedia...oelectric_generator [mofosyne, May 10 2011] RHU http://en.wikipedia...isotope_heater_unit [mofosyne, May 10 2011] Design suggestion http://www.google.c...oAg&ved=0CBwQ9QEwAA [pocmloc, May 10 2011, last modified May 11 2011] Alternative design suggestion http://en.wikipedia...ntMissileSystem.png [pocmloc, May 10 2011] Nuclear balloon Nuclear_20BalloonPerfectly place to store your thermos [metarinka, May 11 2011] Another design suggestion http://farm5.static...4310_dd5e2bc21a.jpgIn America we supersize everything. [DIYMatt, May 12 2011] Hello Kitty design suggestion http://dl.dropbox.c...extreme/sku.666.htmFor [xandram] [pocmloc, May 15 2011] Well, no pyrotechnics, but still [+].-- 8th of 7, May 10 2011 Waiting for these to appear on the market and be snapped up by would-be terrorists, to make dirty bombs.-- infidel, May 10 2011 [+] ... math ?-- FlyingToaster, May 10 2011 [Infidel], they'd never,ever do that beause then they'd have to drink their beverages cold. They're not going to be motivated and wound-up for their suicide bombing mission by a couple of mouthfulls of cold coffee, are they?-- 8th of 7, May 10 2011 [+] OK - I like to learn about this stuff from you smart guys, but I would like one with an untradional shape...you know, thermos shapes are kind of boring.-- xandram, May 10 2011 Not really related to this but ... I read a great story yesterday about one of the people who witnessed one of the early A-bomb tests in the Nevada desert. He got a small parabolic mirror from his lab and pointed it at the blast site with a cigarette positioned at the mirror's focus. So, after the blast he was able to tell people that he had lit his cigarette with an A-bomb.-- hippo, May 10 2011 [x], perhaps it should be smooth, spherical and black, with the cap protruding from one side, and a cord attached to the centre of the cap (to help you pull it off I suppose).-- pocmloc, May 10 2011 You could switch it from heating mode to charging mode, and plug your phone into it! You could put a phosphor screen on the bottom and make a flashlight! You could place it end-to-end with a friend's, and make a criticality! +++
(dosimeter not included)-- DIYMatt, May 11 2011 Fun concept but RHU's don't throw out enough heat, most are designed to give out way less than 100 w, usually in the 1-25w range. I think one that did give off a useable amount of heat would also probably give off useable amounts of radiation. Guess you wouldn't have to worry about the hot coffee spilling in your lap...
That being said it's the perfect thermos to take in your nuclear balloon (see link)-- metarinka, May 11 2011 [pocmloc] cute, but I was thinking more like Hello Kitty!-- xandram, May 12 2011 [metarinka] You would only need about 4 watts to keep the contents of a thermos flask close to 100ºC.-- spidermother, May 15 2011 [x] see link.-- pocmloc, May 15 2011 random, halfbakery