Generator conneted

[dennis]

AFAIK there are no space craft (from Earth) that use fission (as in nuclear reactors). They just use the heat from decay.

[Martin Brown]

It isn't fission powered. It is from short half life radioactive decay.

A concentrated solution of plutonium will boil under its own steam! And they are running out of the favoured isotope PU238

Brown

[Andy Burns]

And a chunk of plutonium oxide will glow cherry red

[Alan Braggins]

>> Thermopiles are only really cost effective for space flight.

There's research aimed at changing that:

don't hold your breath.

(PV panels that are also solar thermal panels are another matter:

But no-one's suggesting they'll get hot enough to be worth using the heat for additional electricity generation.)

[The Natural Philosopher]

decay comes from fission

[Jethro]

But doesn't some geothermal energy come from the expansion/compression of the earth due to solar gravity ?

I was amazed, watching Prof. Cox "Wonders of the Solar System" to learn that one of the moons of Saturn has a molten core due to this effect.

[Tim Watts]

Isn't there some idea that nuclear reactions are also happening in the earth's core?

[docholliday]

u connected a working generator

I remember doing this experiment about ten years later - if you included the time to write it up it made the best part of half a day's work. I remember the lab also had a kit for doing measurments on a DC motor using another DC motor, used as a generator, to provide the load to be driven. Once it was up and running the external DC supply would only be supplying power to make up for the losses in the system; the generator would be supplying most of the current to drive the motor. Sadly I never saw it run up - it must have been pretty impressive; they were motors out of a German WW1 submarine, as I recall, and something over a metre diameter and a metre long. Mike

[Jethro]

Not heard that one, but it seems entirely plausible. At those temperatures and pressures ...

There's a certain irony in some people running around wittering on about the evils of nuclear power when they're sat atop a massive nuclear reactor.

[Chris J Dixon]

That sort of thing is commonly found on industrial test beds.

Back in the 70s, at the time of the 3-day week and power cuts, GEC (as it was then) had 6 diesel-electric locos at Preston which had been ordered by Pakistan, which became embroiled in political problems, and they hadn't taken delivery.

As I recall, the locos were split between the sites at Trafford Park, Sheffield and Preston.

The pair sent to Trafford Park were placed adjacent to the main electrical test area, and connected through one of the rotary converter sets to feed back into the site supply. Together with the existing diesel sets, they enabled work to continue without interruption.

Chris

[Martin Brown]

And Io around Jupiter has sulphur volcanoes that are tidally powered, but they are in a pretty extreme gravitational environment.

Only if you count radioactive decay. There is no fission.

These days is it predominantly from radioactive decay and some input from flexure of the Earths crust from lunar/solar tides. A very long time ago it was just about possible to have a natural nuclear reactor form in uranium ore bodies when the U235/U238 ratio was higher. eg. Oklo

Martin Brown

[Martin Brown]

No it doesn't.

Pu238 is formed by neutron capture from Np237, which is itself a product of either 2x neutron capture by U235 or 1x neutron spallation by U238.

Heat in the Earth today comes from long lived radio isotopes like U235, Th232, K40 that are left over from the Earths formation. Most of the species stil providing heat in the Earths core are left overs from nuclear synthesis in a supernova explosion 4.5By ago.

Decay can be by alpha, beta or gamma or more usually a mixture depending on the isotopic species. Only for alpha decay is a non-trivial other element, Helium produced in the reaction.

Fission reactions are conventionally taken to mean nuclear reactions with particle in (usually a thermal neutron) to disturb the heavy nucleus and two energetic fragments of roughly equal mass out.

Regards, Martin Brown

[Chris J Dixon]

Perhaps if you read more carefully, you would have noticed "...would only be supplying power to make up for the losses in the system..."

Not doomed, but a rather useful test technique.

Chris

[Andrew Gabriel]

GEC had an energy rental division which rented out industrial power generation. It's now folded into Aggreko, which is a large world-wide industrial generation rental company.