Lessons for the Liquid-Fluoride Thorium Reactor
(from history)
Kirk Sorensen
July 20, 2009
Mountain View, California
Executive Summary
Energy Generation Comparison
230 train cars (25,000 MT) of bituminous coal or,
600 train cars (66,000 MT) of brown coal,
(Source: World Coal Institute)
=
or, 440 million cubic feet of natural gas (15% of a
125,000 cubic meter LNG tanker),
6 kg of thorium metal in a liquid-fluoride
reactor has the energy equivalent (66,000
MW*hr electrical*) of:
*Each ounce of thorium can therefore produce
$14,000-24,000 of electricity (at $0.04-0.07/kW*hr)
or, 300 kg of enriched (3%) uranium in a
pressurized water reactor.
2007 World Energy Consumption
The Future:
5.3 billion tonnes of
coal (128 quads)
Energy from Thorium
31.1 billion barrels
of oil (180 quads)
2.92 trillion m3
of natural gas
(105 quads)
65,000 tonnes of
uranium ore (24
quads)
6600 tonnes of thorium
(500 quads)
Today’s Uranium Fuel Cycle vs. Thorium
mission: make 1000 MW of electricity for one year
35 t of enriched uranium
(1.15 t U-235)
250 t of natural
uranium
containing 1.75 t
U-235
Uranium-235 content is
“burned” out of the fuel; some
plutonium is formed and
burned
35 t of spent fuel stored
on-site until disposal at
Yucca Mountain. It
contains:
• 33.4 t uranium-238
215 t of depleted uranium
containing 0.6 t U-235—
disposal plans uncertain.
• 0.3 t uranium-235
• 0.3 t plutonium
• 1.0 t fission products.
Within 10 years, 83% of
fission products are
stable and can be
partitioned and sold.
One tonne
of natural
thorium
Thorium introduced into
blanket of fluoride reactor;
completely converted to
uranium-233 and “burned”.
One tonne of
fission products; no
uranium, plutonium,
or other actinides.
The remaining 17%
fission products go to
geologic isolation for
~300 years.
How it all began…
The Discovery of Thorium
 Thorium was discovered in 1828 by the Swedish
scientist Jons Jacob Berzelius.
 Berzelius named thorium after Thor, the Norse
god of thunder.
 There was little to say about thorium when it was
first discovered apart from its specific weight and its
high-temperature capabilities.
 “thallium, thorium, thulium…”
Thorium is Radioactive
 In 1898, Marie Curie made a remarkable
discovery:
 Thorium and uranium were radioactive!
 But with a 15 billion-year half-life
(older than the universe), it didn’t
decay very often and had very
low radioactivity…
 Eventually thorium decays to
lead-208.
Natural Decay Chains
 There are four natural decay chains, three of which still exist on
Earth. The fourth is extinct due to rapid decay.
Tl,Pb
208
10
hr
Tl,Pb,Bi
209
207
208
206
“Neptunium”
(4n+1)
Pb,Bi
211
36
min
Pb,Bi,Po
214
0.0018
sec
Pb,Bi,Po
212
47
min
3
min
Polonium
215
0.15
sec
Bi,Po
213
Polonium
218
4
sec
Polonium
216
0.032
sec
Radon
219
55
sec
Astatine
217
Radon
222
3.8
day
11
days
Radon
220
5 min
1600
yr
Fr,Ra
223
3.64
day
Francium
221
Radium
226
10
days
Ac,Th
227
21
yr
Radium
224
80000
yr
6.7
yr
Ra,Ac
225
Thorium
230
32500
yr
Ra,Ac,Th
228
7340
yr
247
kyr
Th,Pa
231
14.1
Gyr
Thorium
229
Th,Pa,U
234
700
Myr
4.5
Gyr
Uranium
238
Uranium
235
Thorium
232
162
kyr
Pa,U
233
2.14
Myr
Neptunium
237
233
234
235
236
237
238
“Thorium”
(4n)
26
min
224
225
226
227
228
229
230
231
232
Tl,Pb
207
Pb,Bi,Po
210
209
210
211
212
213
214
“Actinium”
(4n+3)
21
yr
215
216
217
218
219
220
221
222
223
“Uranium”
(4n+2) Lead
206
Three Conceptual Breakthroughs
Nuclear Fission (1939)—Otto Hahn
and Lise Meitner discover that
neutrons cause uranium atoms to split,
releasing energy.
The true nature of the nucleus (1935)—
Hideki Yukawa hypothesizes that the
nucleus consists protons and neutrons
bound together by a “nuclear force” that
overcomes the inherent repulsion of the
protons to one another.
Radioactivity (1896)—Henri Becquerel
discovered that some elements
(uranium and thorium) emit particles
spontaneously.
Lesson for LFTR:
Once you’ve figured out how matter really works,
you realize that if you’re looking for a dense source
of energy, nuclear fission is your answer.
Three basic options for fission
The fission of U-235
was discovered by
Otto Hahn and Lise
Meitner in 1938.
Uranium-235
(0.7% of all U)
Pu-239 as a fissile
fuel was discovered
by Glenn Seaborg in
March 1941.
Uranium-238
(99.3% of all U)
Thorium-232
(100% of all Th)
Plutonium-239
Uranium-233
U-233 as a fissile
fuel was discovered
by Seaborg’s student
John Gofman in
February 1942.
Could weapons be made from the fissile material?
Uranium-235
(“highly enriched
uranium”)
Natural
uranium
Isotope separation
plant (Y-12)
Hiroshima, 8/6/1945
Depleted
uranium
Isotope Production
Reactor (Hanford)
Thorium?
Isotope
Production
Reactor
Pu separation from
exposed U (PUREX)
uranium
separation
from exposed
thorium
Trinity, 7/16/1945
Nagasaki, 8/9/1945
PROBLEM: U-233 is contaminated
with U-232, whose decay chain
emits HARD gamma rays that make
fabrication, utilization and
deployment of weapons VERY
difficult and impractical relative to
other options. Thorium was not
pursued.
U-232 decays into Tl-208, a HARD gamma emitter
Thallium-208 emits “hard” 2.6 MeV
gamma-rays as part of its nuclear decay.
These gamma rays destroy the electonics
and explosives that control detonation.
14 billion years
to make this
jump
232U
Some 232U
starts decaying
immediately
They require thick lead shielding and
have a distinctive and easily detectable
signature.
Uranium-232 follows the same decay
chain as thorium-232, but it follows it
millions of times faster!
This is because 232Th has a 14 billionyear half-life, but 232U has only an 74
year half-life!
Once it starts down “the hill” it gets to
thallium-208 (the gamma emitter) in just
a few weeks!
U-232 Formation in the Thorium Fuel Cycle
Lesson for LFTR:
Thorium’s no good for nuclear weapons.
Of course, if it’s wartime, this fact isn’t going to help
you get developed.
The “chain-reaction”
Nuclear Criticality: A Condition of Balance
10,000 fissions lead to 9999 fissions…
the reactor is subcritical and the
fission rate will decrease.
10,000 fissions lead to 10,000 fissions…
the reactor is critical and the fission
rate will stay the same.
10,000 fissions lead to 10,001 fissions…
the reactor is supercritical and the
fission rate will increase.
Self-controlling Fission Reactors are Possible
Analogy: mass-spring system
Implementation: fission reactor
 It was clear that achieving perfect
criticality (multiplication factor of
1.00000000000000000) was
impossible by any active control
 But natural effects could be used
to “tune in” the reactor to perfect
criticality
 Expansion of water (reduced
moderation)
 Expansion of fuel (reduced fuel)
 Increased neutron absorption in
fuel (Doppler coefficient)
 This is the principle of the
“temperature coefficient of
reactivity”, which needs to be
prompt, negative and strong
Gravity pulls downward on
the mass...but the spring’s
force is proportional to its
extension.
The rate of fission governs
the amount of heat added
to the water…but the
density of the returning
water governs the fission
rate (through moderation)
1942: The First Nuclear Reactor – CP1
Lesson for LFTR:
You want a reactor with a negative, prompt, and
strong temperature coefficient of reactivity.
1944: A tale of two isotopes…
 Enrico Fermi argued for a program of
fast-breeder reactors using uranium238 as the fertile material and
plutonium-239 as the fissile material.
 His argument was based on the
breeding ratio of Pu-239 at fast neutron
energies.
 Argonne National Lab followed Fermi’s
path and built the EBR-1 and EBR-2.
 Eugene Wigner argued for a thermalbreeder program using thorium as the
fertile material and U-233 as the fissile
material.
 Although large breeding gains were
not possible, THERMAL breeding was
possible, with enhanced safety.
 Wigner’s protégé, Alvin Weinberg,
followed Wigner’s path at the Oak
Ridge National Lab.
Fission/Absorption Cross Sections
Lesson for LFTR:
Only thorium can be fully consumed in a thermal
spectrum reactor.
To fully consume uranium you MUST have a fast
spectrum reactor.
Protactinium-233
Thorium-233 decays
quickly to
protactinium-233
Protactinium-233 decays
slowly over a month to
uranium-233, an ideal fuel
Uranium-233
Thorium-233
Uranium-233 fissions,
releasing energy and
neutrons to continue the
process
Natural thorium
absorbs a neutron
from fission and
becomes Th-233
Thorium-232
1944: A tale of two isotopes…
“But Eugene, how will you reprocess the fuel fast
enough to prevent neutron losses to protactinium233?”
“We’ll build a fluid-fueled reactor, that’s how…”
Th-232 in
Chemical
separator
Fertile
Th-232 blanket
Fissile
U-233 core
Chemical
separator
n
n
New U-233 fuel
Fission
products
out
Heat
Lesson for LFTR:
In fluid form, many of the drawbacks of thorium can
be overcome.
In fluid form, the xenon-135 can be removed
continuously.
1951: Experimental Breeder Reactor 1
In 1951, Fermi’s protégé Walter Zinn and his
Argonne team successfully operated the first
liquid-metal-cooled fast spectrum breeder
reactor at a site in Idaho.
The reactor produced enough power to light
a few light-bulbs, but was heralded as the
first power-producing reactor in the world.
1952: Homogeneous Reactor Experiment - 1
In 1952, Weinberg’s ORNL team
duplicated this accomplishment by
building the first aqueous homogenous
reactor (HRE-1), which produced about
100 kWe of electrical power.
The HRE was not a thorium breeder
(yet) but was intended to prove the
technology for one.
1958: Homogeneous Reactor Experiment - 2
HRE-2 was built to a thermal power of 5
megawatts and further developed AHR
technology.
ORNL Fluid-Fueled Thorium Reactor Progress (1947-1960)
1947 – Eugene Wigner
proposes a fluid-fueled
thorium reactor
1950 – Alvin
Weinberg becomes
ORNL director
1952 – Homogeneous Reactor
Experiment (HRE-1) built and operated
successfully (100 kWe, 550K)
1959 – AEC convenes “Fluid
Fuels Task Force” to choose
between aqueous homogeneous
reactor, liquid fluoride, and liquidmetal-fueled reactor. Fluoride
reactor is chosen and AHR is
cancelled.
1958 – Homogeneous Reactor
Experiment-2 proposed with 5 MW of
power
Weinberg attempts to keep both
aqueous and fluoride reactor
efforts going in parallel but
ultimately decides to pursue
fluoride reactor.
Aircraft Nuclear Program
Between 1946 and 1961, the USAF
sought to develop a long-range
bomber based on nuclear power.
The Aircraft Nuclear Program had
unique requirements, some very
similar to a space reactor.
 High temperature operation (>1500° F)
 Critical for turbojet efficiency
 3X higher than sub reactors
 Lightweight design
 Compact core for minimal shielding
 Low-pressure operation
 Ease of operability
 Inherent safety and control
 Easily removeable
Aircraft Nuclear Program allowed ORNL to develop reactors
It wasn’t that I had suddenly become
converted to a belief in nuclear airplanes.
It was rather that this was the only avenue
open to ORNL for continuing in reactor
development.
That the purpose was unattainable, if not
foolish, was not so important:
A high-temperature reactor could be
useful for other purposes even if it never
propelled an airplane…
—Alvin Weinberg
Radiation Damage Limits Energy Release
 Does a typical nuclear reactor
extract that much energy from
its nuclear fuel?
 No, the “burnup” of the fuel is
limited by damage to the fuel
itself.
 Typically, the reactor will only
be able to extract a portion of
the energy from the fuel before
radiation damage to the fuel
itself becomes too extreme.
 Radiation damage is caused
by:
 Noble gas (krypton, xenon)
buildup
 Disturbance to the fuel lattice
caused by fission fragments
and neutron flux
 As the fuel swells and distorts,
it can cause the cladding
around the fuel to rupture and
release fission products into
the coolant.
Ionically-bonded fluids are impervious to radiation
 The basic problem in nuclear fuel
is that it is covalently bonded and
in a solid form.
 If the fuel were a fluid salt, its ionic
bonds would be impervious to
radiation damage and the fluid
form would allow easy extraction
of fission product gases, thus
permitting unlimited burnup.
The Birth of the Liquid-Fluoride Reactor
The liquid-fluoride nuclear reactor was invented
by Ed Bettis and Ray Briant of ORNL in 1950 to
meet the unique needs of the Aircraft Nuclear
Program.
Fluorides of the alkali metals were used as the
solvent into which fluorides of uranium and
thorium were dissolved. In liquid form, the salt
had some extraordinary properties!
 Very high negative reactivity coefficient
 Hot salt expands and becomes less critical
 Reactor power would follow the load (the aircraft
engine) without the use of control rods!
 Salts were stable at high temperature
 Electronegative fluorine and electropositive alkali
metals formed salts that were exceptionally stable
 Low vapor pressure at high temperature
 Salts were resistant to radiolytic decomposition
 Did not corrode or oxidize reactor structures
 Salts were easy to pump, cool, and process
 Chemical reprocessing was much easier in fluid
form
 Poison buildup reduced; breeding enhanced
 “A pot, a pipe, and a pump…”
The Aircraft Reactor Experiment (ARE)
In order to test the liquid-fluoride
reactor concept, a solid-core, sodiumcooled reactor was hastily converted into
a proof-of-concept liquid-fluoride reactor.
The Aircraft Reactor Experiment ran for
100 hours at the highest temperatures
ever achieved by a nuclear reactor (1150
K).
 Operated from 11/03/54 to 11/12/54
 Liquid-fluoride salt circulated through
beryllium reflector in Inconel tubes
 235UF4 dissolved in NaF-ZrF4
 Produced 2.5 MW of thermal power
 Gaseous fission products were removed
naturally through pumping action
 Very stable operation due to high negative
reactivity coefficient
 Demonstrated load-following operation
without control rods
The “Fireball”
The “Fireball”, or Aircraft Reactor
Test, was the culmination of the
ANP effort at ORNL.
 235UF4 dissolved in NaF-ZrF4
 Designed to produce 60 MW of thermal
power
 Core power density was 1.3 MW/L
 NaK used to transport heat to jet
engines at 1150 K
 1500 hours (63 days) design life
 500 hours (21 days) at max power
 The “Fireball” pressure shell was only
1.4 meters in diameter!
 Contained core, reflector, and
primary heat exchanger inside
The “Fireball” was considered the
superior design for the ANP, but
the program was cancelled in 1961
before it was built.
Lesson for LFTR:
Sometimes the right answer comes from an
unexpected direction.
Fluoride fuel is the only practical way to build a
high-temperature, high-power-density reactor.
Weinberg wanted a civilian fluoride reactor program
“Until then I had never quite
appreciated the full significance of
the breeder. But now I became
obsessed with the idea that
humankind’s whole future depended
on the breeder.”
—Alvin Weinberg
MSBR’58 Reactor Plant Isometric
Image source: ORNL-2634: MSRP Status Report, pg 3
Fluorination made separating UF4 and ThF4 easy
Fluorination was a basic chemical
advantage of the fluoride-fueled approach
UF4 (in solution) + F2 → UF6 (gaseous)
Bred uranium-233 could be easily
removed from a thorium fluoride mixture
using this approach.
Lesson for LFTR:
Nature is sometimes kind.
The ability to separate uranium from thorium under
high radiation and at high temperatures argues
strongly for a fluoride fueled reactor.
A chance meeting leads to the MSRE
By the end of 1959, our engineering development program had
proceeded far enough that we felt justified in proposing an MSR
experiment (MSRE), but getting money and permission appeared
difficult. Then one day I heard a rumor that Frank Pittman, who had
succeeded Ken Davis as director of the DRD, had expressed interest
in funding as many as four “quick and dirty” reactor experiments
provided that each one should cost less than a million dollars. As I
remember it, I wrote a proposal that night and submitted it through
channels the next day. I outlined the general features of the reactor,
and by analogy with another reactor system for which a cost estimate
had been made. I came up with a cost estimate of $4.18 million. The
proposal was accepted, although by the time the design had been
detailed the cost estimate had doubled.
—H.G. “Mac” MacPherson
from “The Molten-Salt Adventure”
Conceptual Framework of the Molten-Salt Reactor Experiment
The conceptual design of the MSRE was arrived at as follows. To keep the
reactor simple we intended to simulate only the fuel stream of a two-fluid
breeder reactor, so that no thorium fluoride was included. We wanted the
neutron spectrum to be near thermal, as it would be in a commercial reactor,
and since graphite was the moderator, this dictated the minimum physical size.
The moderator was in the form of a 1.37-m-diam x 1.62-m-high right circular
cylinder. Had it been smaller, the neutron leakage would have caused the
neutron spectrum to be more energetic than we wished. We would have liked
to have a higher power density, but cost considerations limited us to ~10 MW
of heat. There was also another reason for limiting the power of the reactor.
The AEC accounting rules at the time allowed us to build a 10-MW reactor as
an experiment, using operating funds. A higher power reactor would have
required us to obtain a capital appropriation and would have limited our
freedom to make changes. Actually we miscalculated the heat transfer
characteristics and the reactor operated at only 8 MW.
—H.G. “Mac” MacPherson
from “The Molten-Salt Adventure”
Molten Salt Reactor Experiment (1965-1969)
View inside the MSRE test cell
Water-cooled
Fuel Salt
Pump Motor
MSRE
Reactor
Vessel
Heat Exchanger
MSRE Demonstrated Refueling, Fluorination and Distillation
Online
Refueling
Fluorination
Vacuum
Distillation
An amazing safety feature—the freeze plug
 The reactor is equipped
with a “freeze plug”—an
open line where a frozen
plug of salt is blocking
the flow.
 The plug is kept frozen by
an external cooling fan.
Freeze Plug
 In the event of TOTAL loss of
power, the freeze plug melts
and the core salt drains into a
passively cooled
Drain Tank
configuration where nuclear
fission is impossible.
MSRE Building (ORNL 7503) today
Lesson for LFTR:
Be ready for an opportunity to demonstrate your
idea.
A working example is worth stacks of documents
and theory.
Two-Fluid 1000-MWe MSBR: July 1964
ORNL-3708
Two-Fluid 250-MWe MSBR: February 1967
ORNL-4119, sec 5
Two-Fluid 250-MWe MSBR: August 1967
ORNL-4191, sec 5
ORNL-4528, sec 5
Two-Fluid 250-MWe MSBR: August 1967
ORNL-4191, sec 5
ORNL-4528, sec 5
Two-Fluid 250-MWe MSBR:
Plan View of Steam Generator and Drain Tank Cells
ORNL-4528, pg 22
Two-Fluid 250-MWe MSBR:
Sectional Elevation of Reactor Cell
ORNL-4528, pg 21
A Simple Fuel Cycle
Uranium Absorption
and Reduction
UF6
Fluoride
Volatility
Fertile
Salt
Recycle
Fertile Salt
UF4
UF6
Fluoride
Volatility
Fuel
Salt
Core
Blanket
Two-Fluid Reactor
Vacuum
Distillation
Fission
Product
Waste
Recycle
Fuel Salt
Two-Fluid Reprocessing with Details
Image source: ORNL-3791, pg 119
Graphite Lifetime Limits Fluence
 The primary consideration for
reactor lifetime is the graphite
distortion, which is a strong
function of fluence and
temperature.
Lesson for LFTR:
The “plumbing” problem is a real problem for the
two-fluid reactor.
Graphite’s problems need to be understood and
managed.
But the overall appeal of the two-fluid reactor is
great.
One-Fluid 1000-MWe MSBR
Image source: ORNL-4832: MSRP-SaPR-08/72, pg 6
One-Fluid Concept had very complicated reprocessing
Lesson for LFTR:
“Fixing” one problem can create another, often
bigger than the first.
Perhaps the two-fluid reactor should be revisited!
A Pressurized-Water Reactor
Typical Pressurized-Water Reactor Containment
 This structure is steel-lined
reinforced concrete, designed to
withstand the overpressure expected
if all the primary coolant were
released in an accident.
 Sprays and cooling systems (such
as the ice condenser) are available
for washing released radioactivity
out of the containment atmosphere
and for cooling the internal
atmosphere, thereby keeping the
pressure below the containment
design pressure.
 The basic purpose of the
containment system, including its
spray and cooling functions, is to
minimize the amount of released
radioactivity that escapes to the
external environment.
Close-Fitting Containments
Lesson for LFTR:
If you want a close-fitting containment, don’t have
anything in there that changes phases when the
pressure changes (like water) or undergoes violent
reactions (like liquid sodium).
“I found myself increasingly at odds with the reactor division of the
AEC. The director at the time was Milton Shaw. Milt was cut very
much from the Rickover cloth: he had a singleness of purpose
and was prepared to bend rules and regulations in achievement
of his goal. At the time he became director, the AEC had made
the liquid-metal fast breeder (LMFBR) the primary goal of its
reactor program. Milt tackled the LMFBR project with
Rickoverian dedication: woe unto any who stood in his way. This
caused problems for me since I was still espousing the moltensalt breeder.”
“Milt was like a bull. He enjoyed [congressional] confidence so
his position in the AEC was unassailable. And it was clear that
he had little confidence in me or ORNL. After all, we were
pushing molten-salt not the LMFBR. More that that, we were
being troublesome over the question of reactor safety.”
“[Congressman] Chet [Holifield] was clearly exasperated with me,
and he finally blurted out, “Alvin, if you are concerned about the
safety of reactors, then I think it may be time for you to leave
nuclear energy.” I was speechless. But it was apparent to me
that my style, my attitude, and my perception of the future were
no longer in tune with the powers within the AEC.”
“As I look back on these events, I realize that leaving ORNL was
the best thing that could have happened to me. My views about
nuclear energy were at variance with those of [the AEC and
Congressional leadership]. After all, it was I who had called
nuclear energy a Faustian bargain, who continued to promote
the molten-salt breeder…”
Lesson for LFTR:
Even if you invented the light-water reactor, your
bosses will still fire you if you interfere with their
plans.
Dose
Radiotoxicity of fission products decays in a few hundred
years.
fission products
101
102
103
104
105
http://www.europhysicsnews.org/index.php?option=article&access=standard&Itemid=129&url=/articles/epn/pdf/2007/02/epn07204.pdf
106
Years
107
Radiotoxicity of fission products decays in a few hundred
years, relative to natural U ore.
Dose
U ore mined to fuel the reactor
fission products
101
102
103
104
Years
105
106
107
Radiotoxicity of unburned plutonium etc from uranium reactor
decays more slowly.
109
108
plutonium etc
107
Dose
106
105
104
103
102
101
101
102
103
104
Years
105
106
107
Dose
Radiotoxicity of unburned plutonium etc from an LFTR is
10,000 x less.
plutonium etc
101
102
103
104
Years
105
106
107
“Incomplete Combustion”
Lesson for LFTR:
Avoid making transuranics while you make power.
You can do this with thorium.
Spent Fuel Accumulates from each LWR
Projected Spent Fuel Accumulation
without Reprocessing
300x103
Spent Fuel, metric tons
EIA 1.5% Growth
MIT Study
200x103
6-Lab Strategy
Capacity based on
limited exploration
100x103
Legislated
capacity
Constant 100 GWe
Secretarial
recommendation
0
2000
2010
2020
2030
Year
2040
2050
Lesson for LFTR:
Under current regulations, Yucca Mountain can’t
hold all the spent nuclear fuel.
Especially if you build more LWRs.
GNEP Technology Demonstration Facilities
Aqueous Reprocessing works but is complicated
Fluoride reprocessing is very simple in comparison
238U
Thorium
tetrafluoride
Fertile Salt
Uranium Reduction
Fluoride Volatility
Recycle Fuel Salt
Core
UF6
Fuel Salt
Recycle Fertile Salt
H2
Hexafluoride
Distillation
xF6
HF
HF Electrolyzer
Uranium
AbsorptionReduction
Blanket
UF6
F2
External “batch”
processing of core salt,
done on a schedule
Recycled
7LiF-BeF2
“Bare” Salt
Fluoride
Volatility
Vacuum
Distillation
MoF6, TcF6, SeF6,
RuF5, TeF6, IF7,
Other F6
Fission
Product
Waste
Could we use fluoride reprocessing for existing spent fuel?
YES!
1. Fluorinate the oxide
fuel
2. Separate the uranium
3. Burn the TRUs
4. Isolate the fission
products
5. Build LFTRs to stop
making more waste
Long-term Radiotoxicity of Fission Products is low
Lesson for LFTR:
Use fluoride reprocessing technology to help fix
current concerns with spent nuclear fuel.
Use it to start new LFTRs that don’t contribute to
the problem.
Waste generation from 1000 MW*yr uranium-fueled light-water
reactor
Mining 800,000 MT of
ore containing 0.2%
uranium (260 MT U)
Generates ~600,000 MT of waste rock
Enrichment of 52 MT of
(3.2%) UF6 (35 MT U)
Generates 314 MT of depleted
uranium hexafluoride (DU);
consumes 300 GW*hr of
electricity
Milling and processing to
yellowcake—natural U3O8
(248 MT U)
Generates 130,000 MT of mill tailings
Fabrication of 39 MT of enriched (3.2%)
UO2 (35 MT U)
Generates 17 m3 of solid waste and 310 m3
of liquid waste
Uranium fuel cycle calculations done using WISE nuclear fuel material calculator: http://www.wise-uranium.org/nfcm.html
Conversion to natural
UF6 (247 MT U)
Generates 170 MT of solid
waste and 1600 m3 of liquid
waste
Irradiation and disposal
of 39 MT of spent fuel
consisting of unburned
uranium, transuranics,
and fission products.
Waste generation from 1000 MW*yr thorium-fueled liquidfluoride reactor
Mining 200 MT of ore
containing 0.5%
thorium (1 MT Th)
Milling and processing to thorium nitrate ThNO3 (1 MT Th)
Generates 0.1 MT of mill tailings and 50 kg of aqueous wastes
Generates ~199 MT of waste rock
Conversion to metal and
introduction into reactor blanket
Breeding to U233 and
complete fission
Thorium mining calculation based on date from ORNL/TM-6474: Environmental Assessment of Alternate FBR Fuels: Thorium
Disposal of 0.8 MT of
spent fuel consisting
only of fission product
fluorides
Today’s Uranium Fuel Cycle vs. Thorium
mission: make 1000 MW of electricity for one year
35 t of enriched uranium
(1.15 t U-235)
250 t of natural
uranium
containing 1.75 t
U-235
Uranium-235 content is
“burned” out of the fuel; some
plutonium is formed and
burned
35 t of spent fuel stored
on-site until disposal at
Yucca Mountain. It
contains:
• 33.4 t uranium-238
215 t of depleted uranium
containing 0.6 t U-235—
disposal plans uncertain.
• 0.3 t uranium-235
• 0.3 t plutonium
• 1.0 t fission products.
Within 10 years, 83% of
fission products are
stable and can be
partitioned and sold.
One tonne
of natural
thorium
Thorium introduced into
blanket of fluoride reactor;
completely converted to
uranium-233 and “burned”.
One tonne of
fission products; no
uranium, plutonium,
or other actinides.
The remaining 17%
fission products go to
geologic isolation for
~300 years.
2007 World Energy Consumption
The Future:
5.3 billion tonnes of
coal (128 quads)
Energy from Thorium
31.1 billion barrels
of oil (180 quads)
2.92 trillion m3
of natural gas
(105 quads)
65,000 tonnes of
uranium ore (24
quads)
6600 tonnes of thorium
(500 quads)
Conclusions
 Thorium and the liquid-fluoride reactor give us many options for
inherently safe, proliferation-resistant, economic nuclear power
that can last for thousands, if not millions of years.
 Fluoride reactor technology offers real options for solving the
long-term issues surrounding spent nuclear fuel and ultimately
preventing the formation of new transuranic waste.
Thanks Google!