have a big announcement to make today and i 'm really excited about this
and this may be a little bit of a surprise to many of you who
i realized that the really biggest problem we face what all these other problems come down to is energy is electricity the flow of electrons and i decided that i was going to set out to try to solve this problem and this
probably is not what you 're expecting you 're probably expecting me to come up here and talk about fusion because that 's what i 've done most of my life but this is actually a talk about okay
and a fission reaction is controlled and maintained at a proper level and that reaction heats up water the water turns to steam
and i thought you know is this the best way to do it
this is what it is this is a small modular reactor so it 's not as big as
the reactor you see in the diagram here this is between fifty and one hundred megawatts but that 's a ton of power that 's between
extol to you how great having something buried below the ground is for proliferation and security concerns and inside this reactor
is a molten salt so anybody who 's a fan of thorium they 're going to be really excited about this because
but i 'm not really concerned about the fuel you can run these off they 're really hungry they really like down blended weapons pits so that 's highly enriched uranium and weapons grade plutonium that 's been down blended it 's made into a grade where it 's not usable for a nuclear weapon but they love this stuff
and we have a lot of it sitting around because this is a big problem you know in the cold war we built up this huge arsenal of nuclear weapons and that was great and
we don 't need them anymore and what are we doing with all the waste essentially what are we doing with all the pits of those nuclear weapons well we 're securing them and it would be great if we could burn them eat them up and this reactor loves this stuff
so it 's a molten salt reactor it has a core
and it has a heat exchanger from the hot salt the radioactive salt to a cold salt which isn 't radioactive it 's still thermally hot but it 's not radioactive and then that 's a heat exchanger to what makes this design
really really interesting and that 's a heat exchanger to a gas so going back to what i was saying before about all power being produced
that 's actually not that efficient and in fact in a nuclear power plant like this it 's only roughly thirty to thirty five percent efficient that 's how much thermal energy the reactor 's putting out to how much electricity it 's producing
and the reason the efficiencies are so low is these reactors operate at pretty low temperature they operateanywhere from you know maybe two hundred to three hundred degrees celsius
and these reactors run at six hundred to seven hundred degrees celsius which means the higher the temperature you go to thermodynamics tells you that you will have higher efficiencies and this reactor doesn 't use water it uses gas so supercritical co two or helium
and that goes into a turbine and this is called the brayton cycle this is the thermodynamic cycle that produces electricity and this makes this almost fifty percent efficient between forty five and fifty percent efficiency
and i 'm really excited about this because it 's a very compact core molten salt reactors are very compact by nature but what
what 's inside of it so you have what 's called the xenon pit and so some of these fission products love neutrons they love the neutrons that are going on and helping this reaction take place
and they eat them up which means that combined with the fact that the cladding doesn 't last very long you can only run one of these reactors for roughly say eighteen months without refueling it so these reactors run for thirty years without refueling
which is in my opinion very very amazing because it means it 's a sealed system no refueling means
and they 're not going to have either nuclear material or radiological material proliferated from their cores
after fukushima had to reassess the safety of nuclear and one of the things when i set out to design a power reactor was it had to be passively and intrinsically safe and i 'm really excited about this reactor for essentially two reasons
one it doesn 't operate at high pressure
so traditional reactors like a pressurized water reactor or boiling water reactor they 're very very hot water at very high pressures and this means essentially in the event of an accident if you had any kind of breach of this stainless steel pressurevessel the coolant would leave the core
these reactors operate at essentiallyatmosphericpressure so there 's no inclination for the fission products to leave the reactor in the event of an accident
also they operate at high temperatures and the fuel is molten so they can 't melt down but in the event that the reactor ever went out of tolerances
you could actually just drain the core into what 's called a sub criticalsetting basically a tank underneath the reactor that has some neutrons absorbers and this is really important
because the reaction stops in this kind of reactor you can 't do that the fuel like i said is ceramic inside zirconium fuel rods and in the event of an accident in one of these type of reactors fukushima and three mile island looking back at three mile island we didn 't really see this for a while
but these zirconium claddings on these fuel rods what happens is when they see high pressure water steam in an oxidizing environment they 'll actually produce hydrogen and that hydrogen has this explosive capability to release fission products
so the core of this reactor since it 's not under pressure and it doesn 't have this chemical reactivity means that there 's no inclination for the fission products
to leave this reactor so even in the event of an accident yeah the reactor may be toast which is you know sorry for the power company but we 're not going to contaminate large quantities of land so i really think that in the
say twenty years it 's going to take us to get fusion and make fusion a reality this could be the source of energy that provides carbon free electricitycarbon free electricity
and it 's an amazing technology because not only does it combatclimate change
but it 's an innovation it 's a way to bring power to the developing world because it 's produced in a factory and it 's cheap you can put them anywhere in the world you want to
and maybe something else
as a kid i was obsessed with space well i was obsessed with nuclear science too to a point but before that i was obsessed with space and i was really excited about you know being an astronaut and designing rockets which was something that was always exciting to me but
i think i get to come back to this
because imagine having a compact reactor in a rocket that produces fifty to one hundred megawatts
that is the rocketdesigner 's dream that 's someone who is designing a habitat on another planet 's dream
not only do you have fifty to one hundred megawatts to power whatever you want to provide propulsion to get you there but you have power once you get there you know rocket designers who use solar panels or fuel cells i mean a few watts or kilowatts wow that 's a lot of power
at the same time that i explore my nuclear passion and people say oh well you 've launched this thing and it 's radioactive into space and what about accidents
but we launch plutonium batteries all the time everybody was really excited about curiosity and that had this big plutonium battery on board that has plutonium two hundred and thirty eight which actually has a higher specific activity than the low enriched uranium fuel of these molten salt reactors
which means that the effects would be negligible because you launch it cold and when it gets into space is where you actually activate this reactor
so i 'm really excited i think that i 've designed this reactor here that can
be an innovative source of energy provide power for all kinds of neat scientific applications and i 'm really prepared to do this i graduated high school in may and
and i decided that i was going to start up a company to commercialize these technologies that i 've developed these revolutionary detectors for scanning cargo containers and these systems to produce medical isotopes
but i want to do this and i 've slowly been building up a team of some of the most incredible people i 've ever had the chance to work with and i 'm really prepared to make this a reality and i
think i think that looking at the technology this will be cheaper than or the same price as natural gas and you don 't have to refuel it for thirty years which is an advantage for the developing world
and i 'll just say one more maybe philosophical thing to end with which is weird for a scientist but i think there 's something really poetic about using nuclear power to propel us to the stars because the stars are giant fusion reactors they 're giant nuclear cauldrons in the sky
the energy that i 'm able to talk to you today while it was converted to chemicalenergy in my food originally came
from a nuclear reaction and so there 's something poetic about in my opinion perfecting
生词表: