Containment is easier for Liquid Fluoride Thorium Reactor (LFTR)

Check this picture out.  It is a crane lifting a 40 meter wide, 4.5 cm thick dome for the top of a nuclear reactor containment building under construction in China.  The containment building is extraordinarily massive, the dome alone weighs 655 tonnes (1.4 million pounds).

Believe it on not, the containment building’s purpose is to capture a steam explosion.

Steam Explosion

Water boils at 100°C at one atmosphere of pressure, but the boiling temperature goes up at higher pressures.  For example, the water in your car radiator will go to higher than 100°C without boiling because the radiator is pressurized to about 2 atmospheres when the car is warmed up.  What happens if the pressure is suddenly released by a puncture or someone foolishly removing the radiator cap?  See the video below for a steam explosion…

Carnot engine efficiency increases with increasing temperature, so there is a great advantage to running a nuclear reactor (or any heat engine) at high temperatures, which requires very high pressures to keep the reactor’s water from completely boiling.  Conventional boiling water reactors and pressurized water reactors operate at around 70 atmospheres and 160 atmospheres to achieve temperatures of 285°C and 315°C respectively.  If water escapes from the reactor for any reason it will instantly expand to about 1600 times its liquid volume as it explodes into steam.  The containment building is supposed to capture that exploding steam.  It is so massive because it must restrain the steam under great pressure without exploding itself.

Containment building

But this type of massive containment building would not be necessary for a Liquid fluoride Thorium Reactor (LFTR)!  This type of reactor concept does not use water to transfer heat away from solid pieces of fissioning metals.  Instead, thorium is dissolved in liquid fluoride salts, where it is converted to uranium233, which fissions and generates heat.  One of the beauties of the LFTR is that the liquid fluoride salts can go to incredible temperatures before they boil – temperatures vastly exceeding the operating temperature of the reactor.    Consequently, the reactor operates at atmospheric pressure – no high pressure needed.  In the event of a liquid leak there would be no explosive effect like the water instantly boiling into steam in a conventional reactor.

The LFTR would operate at around 700°C, reaching a much higher carnot efficiency than boiling water reactors or pressurized water reactors.  Yet the fluid medium of the LFTR would not boil until reaching the extraordinary temperature of about 1400°C.

read more…

See the Energy from Thorium website for much more information about this revolutionary concept, or read “Thorium: Energy Cheaper Than Coal,” by Robert Hargraves.

James Lovelock says nuclear better than wind.

James Lovelock has worn many hats.  He worked with NASA to make instruments for studying extraterrestrial planetary atmospheres and surfaces.  He invented the electron capture detector for studying traces of various chemicals in gas.  He has been awarded multiple prizes from many academic and environmental groups.

However, he is best known as the founding father of the much-loved (by environmental groups) ”Gaia Theory.”  According to GaiaTheory.org…

“The Gaia Theory posits that the organic and inorganic components of Planet Earth have evolved together as a single living, self-regulating system. It suggests that this living system has automatically controlled global temperature, atmospheric content, ocean salinity, and other factors, that maintains its own habitability. In a phrase, “life maintains conditions suitable for its own survival.” In this respect, the living system of Earth can be thought of analogous to the workings of any individual organism that regulates body temperature, blood salinity, etc.”

This seductive reasoning ignores the reality that life evolves, as best it can, to survive in a given environment, and while life may change the environment it does not “automatically control” it to “maintain its own habitability.”  But my point here is not to argue with the Gaia theory.

Lovelock was an icon in environmentalist circles, but since he started publicly endorsing nuclear energy a few years ago his aura seems to be fading.  He has been condemned as being senile or worse (see here or comments here).

In a recent comment (see discussion at Bishop-Hill.net) Lovelock condemns a single proposed wind turbine in a bucolic English setting, calling it “industrial vandalism.”  But more importantly he goes on to say…

“we should look to the French who have wisely chosen nuclear energy as their principal source; a single nuclear power station provides as much as 3200 large wind turbines.”

I am not one to condemn wind turbines for aesthetic reasons.  In fact, I find that modern wind turbines have their own beauty in their graceful structure.  But Lovelock is certainly right in his comparison of the utility of wind turbines with nuclear energy.

Lovelock closes his comments with this homily…

I am an environmentalist and founder member of the Greens but I bow my head in shame at the thought that our original good intentions should have been so misunderstood and misapplied. We never intended a fundamentalist Green movement that rejected all energy sources other than renewable, nor did we expect the Greens to cast aside our priceless ecological heritage because of their failure to understand that the needs of the Earth are not separable from human needs. We need take care that the spinning windmills do not become like the statues on Easter Island, monuments of a failed civilisation.

WSJ put Fukushima panic in perspective

I have been working on renewable energy (photovoltaics) for 16 years as a scientist at the National Renewable Energy Laboratory.  It is quite obvious to me that abundant energy, in one form or another, has been the key to human advancement.  This fact is not going to change.  That is why it worries me  when largely uninformed, irrational and panic drive perspectives on nuclear energy come to dominate the issue.

It was refreshing to see a more down-to-earth perspective on the radiation hazard resulting from the tsunami driven Fukushima disaster in yesterday’s Wall Street Journal.  Here are a few glimpses of the article “The Panic over Fukushima” by Richard Muller.

Denver has particularly high natural radioactivity. It comes primarily from  radioactive radon gas, emitted from tiny concentrations of uranium found in local granite. If you live there, you get, on average, an extra dose of .3 rem of radiation per year…The International Commission on Radiological Protection recommends evacuation of a locality whenever the excess radiation dose exceeds .1 rem per year…It is worth noting that, despite its high radiation levels, Denver generally has a lower cancer rate than the rest of the United States…Applied strictly, the ICRP standard would seem to require the immediate evacuation of Denver.

The “hot spots” in Japan [after the Fukushima tsunami disaster] that frightened many people showed radiation at the level of .1 rem, a number quite small compared with the average excess dose that people happily live with in Denver.In hindsight, it is hard to resist the conclusion that the policies enacted in the wake of the disaster in Japan—particularly the long-term evacuation of large areas and the virtual termination of the Japanese nuclear power industry—were expressions of panic.

Read the entire article…