Summary of proposed and completed reactor designs of the future. Includes Generation III+ through Generation V designs like Molten Lead Reactors and Nuclear Lightbulbs.
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Reactors of the Future
1. Reed Reactor Special Requal Lecture
Reactors of the Future
Generations III+ through V
Ian Flower
2. What will we cover?
Tour of Reactor Designs
Generation III+
Generation IV
Generation V
Limitations/Advantages of Each
Road Map for the future
Reed Reactor Special Requal Lecture
4. Advanced Reactors
Improvements on current designs:
ABWR (Advanced Boiling Water Reactor)
ESBWR (Economic Simplified BWR)
Subcritical Reactors
Thorium-Based Reactors
Reed Reactor Special Requal Lecture
5. ABWR
GE Hitachi
Huge improvements
on existing BWR
technology
Digital
Emergency Cooling
Recirculation
Cleanup Loop
Control Rod precision
Reed Reactor Special Requal Lecture
9. Gas-cooled Fast
Reactor
GFR
CO2 or He
Higher Temperature
Non activated coolant
No flashes to steam
Have to consider:
Neutron absorption leads to
positive void coefficient
Fuel Elements
Ceramics
Good at High Temperature
Retain Fission Fragments
Reed Reactor Special Requal Lecture
10. A Note About Fast
Reactors
No Moderator
Difficult to control
Control rods are too
slow to make
adjustments
Stabilized instead by:
Doppler Broadening
Neutron Poisons
Neutron Reflector
Acceptable fuels
Uranium, Obviously
But more things, too!
Thorium yields U233
Transuranics
Breeder potential
Reed Reactor Special Requal Lecture
12. Sodium-cooled Fast
Reactor
The closest to construction
Cons:
Sodium activates
Sodium is really reactive
Pros:
Can reuse high-level waste
soon
Sodium can be kept at
atmospheric pressure
Sodium is a bad moderator
Several reactors connected
to same water system
Reed Reactor Special Requal Lecture
13. Another Note About
Fast Reactors
Excess heat can be
used to produce
Hydrogen fuel
I’ll leave the
deciphering of this
diagram to others
Reed Reactor Special Requal Lecture
15. Lead-cooled Fast
Reactor
I know what you’re
thinking.
WHY LEAD?!
Shielding
Terrorism-Prevention
Non moderator
Non-reacting
Thermal conductivity
High Boiling Point
But current designs
would have cores that
last 10-30 years!
Reed Reactor Special Requal Lecture
16. A Final Note on Fast
Reactors
Nuclear Fuel Cycle
Life cycle of nuclear
fuel from mining to
disposal
Open Fuel Cycle (aka
once through)
Use the fuel once,
dispose of it
Closed Fuel Cycle
Fuel is reprocessed
Reed Reactor Special Requal Lecture
18. Molten Salt Reactor
Pros:
Leaks are easy to contain
High temperature leads to
good thermal efficiency
Work in all sizes
Already proven technology
Terrorist-proof
Refuel as you go
Cons:
Chemical processing plants
can pose additional risks
Reed Reactor Special Requal Lecture
19. A Note on the Thorium
Fuel Cycle
Thorium is 3-4 times as abundant as U238
Thorium comes in the isotope you want
Higher Melting Point
Higher Thermal conductivity
Reed Reactor Special Requal Lecture
20. What the H is
Supercritical Water?
Reed Reactor Special Requal Lecture
22. Supercritical Water
Reactor
Supercritical Water: not as
good of a moderator
Pros:
Could operate as a Thermal
Reactor or Fast Reactor
Much more efficient energy
gain
Simpler Designs
Don’t have to be as large
Cons:
Need better materials
Need to figure out how to
start up
Not sure how it will work
Reed Reactor Special Requal Lecture
23. Why would we still use
Thermal Reactors?
To augment the cycle
that we already have:
Fast reactors make the
waste disposal needs of
thermal reactors
obsolete
Thermal reactors
generate lots of power
Thermal reactors are
easy to build and
control
Reed Reactor Special Requal Lecture
25. Very High Temperature
Reactor
Most common design:
Pebble Bed Reactor
Tennis-ball sized spheres of
moderator and fissile material
Ceramics
Cooled by a gas, can be
cooled naturally
Pros:
Economic
Hydrogen Production
Safer than current reactors
Cons:
Materials research needed
Reed Reactor Special Requal Lecture
26. Generation V
Theoretical Designs:
Nuclear Thermal Rocket
Nuclear Lightbulb (Rocket)
Fission Fragment Reactor (Rocket)
There is a trend here
Reed Reactor Special Requal Lecture
27. Nuclear Thermal
Rocket
Pass a working fluid
through a reactor
Create thrust
Liquid Core designs
Liquid mixture of
fuel/working gas
Gas Core designs
Toroidal pocket of
gaseous fuel
Reed Reactor Special Requal Lecture
29. Nuclear Lightbulb
Gas Core
Very Hot
Approx. 25000 C
Hotter than the surface
of the sun
EM produced all
Ultraviolet
Quartz wall divides
core and propellant
Reed Reactor Special Requal Lecture
30. Nuclear Lightbulb
As a Power Reactor?
Closed loop
Working gas instead of
propellant
Pros:
Efficient conversion of
energy to power
Cons:
25000 C? Wow!
Neutron Flux would be
unwieldy Reed Reactor Special Requal Lecture
31. Gas Core EM Reactor
Reed Reactor Special Requal Lecture
Nuclear Lightbulb
Photo-Voltaics
Photo-Voltaics
33. Fission Fragment
Rocket
Reed Reactor Special Requal Lecture
a fissionable filaments,
b revolving disks,
c reactor core,
d fragments exhaust
A fission fragments ejected for propulsion
B reactor
C fission fragments decelerated for power generation
d moderator (BeO or LiH),
e containment field generator,
f RF induction coil
34. Fission Fragment
Reactor
But what about
power?
Part C produce
electricity
Pros:
Skip the Carnot Cycle
Incredibly efficient
Isotopic Separation
Reed Reactor Special Requal Lecture
35. Timeline
Viability:
Show that it all works
in theory
Performance
Show that it all works
individually in practice
Demonstration
Build large prototypes
and watch carefully
Reed Reactor Special Requal Lecture
Pb melts at, 327C. Pb/Bi melts at 135 degrees C, so coolant can be melted to be brought to power after shutdown. 2019 in Russia, US soonish
SNF: 3% of the mass consists of fission products of 235 U and 239 Pu About 1% of the mass is 239 Pu and 240 Pu  resulting from conversion of 238 U, which may be considered either as a useful byproduct, or as dangerous and inconvenient waste. 96% of the mass is the remaining uranium: most of the original 238 U and a little 235 U. Usually 235 U would be less than 0.83% of the mass along with 0.4% 236 U Traces of the minor actinides  are present in spent reactor fuel.
When cold, the fuel salts radiogenically produce corrosive, chemically reactive fluorine gas. Although a very slow process, the salts should be defueled and wastes removed before extended shutdowns to avoid (non-radioactive) fluorine gas production. Unfortunately, this was discovered the unpleasant way, while the MSRE (Oakridge) was shut-down over a 20-year period. Japan is building a 100-200 MW reactor, but full sized ones are 20 years away and no plans are under way yet.
Water: 22.1 Mpa, 374C
1700 MW Pressure: 25 Mpa Temperature: 550C
 The SCWR concept is being investigated by 32 organizations in 13 countries.
600MW Temperatures >1000C
Two full-scale pebble-bed HTGRs, each with 100 - 195 MW e  of electrical production capacity are under construction in China at the present as of November 2009. The US is thinking about it.