reply to post by zzombie
the reason they didn't pursue molten salt may have been success in a light water design:
t 12:30 am, on August 26, 1977, the operators at the Shippingport Atomic Power Station began lifting the central modules of the experimental breeder
reactor core into the blanket section. At 04:38 am, the reactor reached criticality. During the next five years, the core produced more than 10
billion kilowatt-hours of thermal power - equivalent to about 2.5 billion kilowatt hours of electrical power - with a current retail value of
approximately $200 million.
It showed no signs of approaching the end of its useful life. It was obvious from the core performance that the reactor was at least a very efficient
converter with a long life core. However, in October, 1982, the reactor was shut down for the final time under budgetary pressures and a desire to
conduct the detailed fuel examination needed to determine if breeding had actually occurred.
A report on the experiment was quietly issued in 1987. The core contained approximately 1.3% more fissile material after producing heat for five
years than it did before initial operation. Breeding had occurred in a light water reactor system using most of the same equipment as used for
conventional reactor plants.
the reactor was a pretty standard LWR including some thorium for breeding purposes. the advantages are clear, no new design, much less frequent
reloads, therefore longer operation intervals (barring some other limitation like fuel rod embrittlement) and tadaaa: much less byproducts, because
you can actually burn them over time, actually adding power....
that's why i'm truely sceptical about _ANY_ energy source like this (read: reliable and powerful) ever taking off, it has been done already (with
success) and ignored, the technology is apparently undesired by certain people who happen to have enough clout to stop it.
of course, part of the game is telling people about liquid sodium cooling, (slightly more) dangerous fast spectrum reactor designs, or unproven and
problematic types (pebble & molten salt, for example). just for the record: any 'nuclear waste' isotope can either be bred to a higher one or,
ultimately, fissioned by just thermal neutrons, as used in any light water reactor (most common type). the reason LWRs have to be refuelled is not
lack of fuel, but accumulation of neutron scavengers ('poisons'). breeding helps keeping the neutron balance positive for a longer time, which allows
more of these transuranic isotopes to be burned, alleviating the waste problem a great deal. with reprocessing, they could of course be subjected to
any number of cycles, effectively keeping the total amount existing at a given time to a minimum.
the only alterations needed for today's LWRs would be removal of absorbers that aren't breeding (except in emergencies of course), power fine tuning
using fuel and breeding material geometry rather than absorbing materials and a neutron reflecting blanket for optimized neutron economy for breeding
and better reactor shell life. it has been done (see above) why it's not in use is anybody's guess, but one thing is imho certain: we aren't going to
see it, which means energy is kept artificially scarce. Thorium is a cheap byproduct of rare earth mining, what's usually considered nuclear waste
isn't (it's just another type of fuel) and safety is a concern than can be alleviated by burying the thing (core) at an appropriate depth.
still, it's going to happen just as much as regenerative medicine, which means 'a long time ago in a galaxy far, far away'. there is just too much
fissile material around from bombs, which can be sold again at a premium (first as a bomb, now as a fuel, first enrichment then dilution
with the prospect of literally life long contracts for depositing and guarding perfectly usable transuranics, which could be unearthed and used in a
pinch - once people have paid three times through the nose already and for essentially the same thing.
edit on 2010.10.12 by Long Lance
because: (no reason given)