Thorium nuclear reactor.

[Michael Press]

Thorium is not fissile. When it captures a neutron it becomes
U233 that is fissile. Mix Th232 and U233 to breed more U233 which
fissions and produces heat. This is the basis for a Thorium
energy producing reactor.

Liquid fluoride thorium reactors (LFTR) are being built by
Canada, India, Japan, UK and Czech Republic. They are small. They
work at higher temperature leading to higher heat to electricity
efficiencies. A single small design can be perfected and
practically air lifted into place, then swithed on.

All other breeder species are not self sustaaining. They need to
be periodically replenished with fissile fuel. LFTRs need to be
charged once at start up, then new thorium can be addeed without
shutting down the reactor.

| In a LFTR, thorium and uranium-233 are dissolved in carrier
| salts, forming a liquid fuel. In a typical operation, the liquid
| is pumped between a critical core and an external heat exchanger
| where the heat is transferred to a nonradioactive secondary salt.
| The secondary salt then transfers its heat to a steam turbine or
| closed-cycle gas turbine.[2] This technology was first
| investigated at the Oak Ridge National Laboratory Molten-Salt
| Reactor Experiment in the 1960s, though the MSRE did not use
| thorium. It has recently been the subject of a renewed interest
| worldwide.[3] Japan, China, the UK and private US, Czech,
| Canadian[4] and Australian companies have expressed intent to
| develop and commercialize the technology. LFTRs differ from other
| power reactors in almost every aspect: they use thorium that is
| turned into uranium rather than uranium directly, receive fuel by
| pumping without shutdown, use a salt coolant and produce higher
| operating temperatures.[5] These distinctive characteristics give
| rise to many potential advantages, as well as design challenges.

--
Michael Press

[Richard OKeefe]

Take a look at the "plumbing" required to operate a thorium reactor and
compare it to the Boiling Water and Pressurized Water Reactors that are
in use today. Big differences. A thorium reactor also needs a neutron
source.

The Navy built it's second nuclear sub, the Seawolf, with a liquid
sodium reactor back in the mid fifties and ended up staying with the
Nautilus type PWR because it was easier to operate and maintain.

Dick OKeefe