Karl Denninger considers the problem of energy production in a world of increasingly expensive oil and coal:
We experimented with Thorium as a nuclear fuel in the 1950s
and 1960s. Carried in a molten salt there are a number of significant
advantages to this fuel cycle. Chief among them is that the reactors
operate at atmospheric pressure, have a strongly-negative temperature
coefficient (that is, reactivity drops as temperature increases) and
because they operate with their fuel dispersed in the coolant and rely
on a fixed moderator in the reaction vessel shutting them down is
simply a matter of draining the working fuel into a tank with sufficient
surface area to dissipate decay heat. This can be accomplished
passively; active cooling of a freeze plug in the bottom of the reactor
vessel can be employed during normal operation and if for any reason
that cooling is lost the plug melts, the coolant and working fluid
drains to tanks and the reactor shuts down. In addition thorium is about as abundant in the environment as is lead, making its supply effectively infinite.
Finally, these reactors operate at a much
higher temperature; the units we have run (yes, we’ve built them
experimentally in the 1950s – 1970s!) run in the neighborhood of 650C.
This allows closed-cycle turbine systems that are more efficient than
the conventional turbines in existing designs, making practical the
location of reactors in places that don’t have large amounts of water
available. That in turn means that the risk of geological and other
similar accidents (e.g. tsunamis!) is greatly reduced or eliminated.
Finally, the fuel cycle is mostly-closed internally;
that is, rather than requiring both fast-breeder reactors and external
large-scale reprocessing plants to be practical, along with a way to
store a lot of high-level waste these units burn up most of their
high-level waste internally and produce their own fuel internally as
well as an inherent part of their operation.
So why didn’t we pursue this path for nuclear power?
That’s simple: It is entirely-unsuitable for production of nuclear bombs as it produces negligible amounts of plutonium.
A decision that might have made sense in the middle of the 1950s arms
race doesn’t make sense more than 60 years later. So, why aren’t we
utilizing thorium-based nuclear power plants?