A pendulum clock with a plutonium mass at the end of the pendulum. When the pendulum swings upwards, the plutonium mass comes into contact with another plutonium mass large enough to cause a critical mass, and large release of energy. The thermal energy is harnessed to power the clock. Beta radiation strikes a phosphor screen to light the face of the clock for many, many years.
Inspired by mouseposture's comment on the Nukem's Cradle idea.
I like radiation.-- DIYMatt, Sep 21 2011 Nukem's Cradle Nukem_27s_20CradleLike this, but a clock. [DIYMatt, Sep 21 2011] Did someone say energy standard? Watt-backed_20moneyI am shameless. [Voice, Sep 25 2011] Apart from the massive shielding required to contain the neutron pulses, the mechanism itself would be reasonably compact.-- 8th of 7, Sep 21 2011 If unranium was named after Uranus, then plutonium was named after Pluto...and if Pluto is no longer a planet...is plutonium no longer an element?
(just saying)-- xandram, Sep 21 2011 (Preapology for predictable poor joke)
Uranium was not named after my anus - speak for yourself.
And everyone knows Pluto is a dog.
Coat - gone..-- Twizz, Sep 21 2011 Run fast, [Twizz], those tumbleweeds are catching up on you... @ .......... @ .........-- 8th of 7, Sep 21 2011 //Uranium was not named after my anus - speak for yourself.// Some people think the sun shines out of their ass, but [Twizz] is a modest sort: they think it's Cherenkov radiation.-- mouseposture, Sep 21 2011 Forgive me, since this topic is way out of my league, but wouldn't repeated near-critical events lead to accelerated degradation, making the clock run slower and slower as time went on?-- Alterother, Sep 22 2011 I'm banking on the energy surplus being so high that the clock can run for years regardless of degredation.-- DIYMatt, Sep 22 2011 Aren't there new regulations against that sort of banking?-- pertinax, Sep 22 2011 Yeah, I don't know if we want to put our economy on the "energy standard"-- what happens if the lights go out?-- Alterother, Sep 22 2011 Fear not; the Democrats will increase taxes, then print lots and lots of banknotes that can be burnt for warmth and light.-- 8th of 7, Sep 22 2011 Oh, well, I'll be fine, then.-- Alterother, Sep 22 2011 random, halfbakery