The Nuclear Energy Alternative
How does it work?
The Nuclear Fuel Cycle
Alternative Fuel Cycles
Legacies
Mr. Nicholas Lizzo
nslizzo@gmail.com
Nuclear Power Generation
Reactor (primary loop)
Steam Generator (Secondary Loop)
Condenser (Tertiary Loop)
Reactor Coolant System – 4 Loop PWR
Reactor Vessel
Height - 43’
Width – 15’
Weight - 435 Tons
Active fuel region:
193 assemblies
3.5% enriched U-235
Fission Process
Thermal
Neutron
“Uranium-235”
Fission Fission Products Fast Neutrons
+ Energy
Key Components of the Reactor Design
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•
•
•
•
•
Neutron Energy
Fission atom (fuel)
Probability of Fission f(E)n, fuel
Moderator
Coolant
Products of Reactions
Neutron Energy ( 1 eV = 1.602 x 10-19 joules)
Neutron Energy Distribution from Fission
FISSILE AND FISSIONABLE NUCLIDES PRESENT
IN LIGHT WATER REACTORS
Nuclide
235
92
U
238
92
U
Thermal Neutron
Microscopic
Cross Section
for Fission (barns)
585
5  10-6
239
94
Pu
750
240
94
Pu
0.05
241
94
1010
242
94
< 0.2
Pu
Pu
One barn = 1 x 10 – 24 cm2
Fissile or
Fissionable
Fissile
Fissionable
Fissile
Fissionable
Fissile
Fissionable
How do we characterize:
Probability of fission?
Cross section (target area for incident particle)
Thermal region
How do we slow down (thermalize) the fission spectrum neutrons?
2 MeV
NEUTRON
0.025 eV
NEUTRON
Ei
Ef
COLLISION
Ei
  ln
Ef
BIRTH AT
HIGH ENERGY
2 MeV
ENERGY LOSSES
UPON COLLISION
NEUTRON
ENERGY
AVERAGE
THERMAL ENERGY
TIME

=
logarithmic energy
decrement
Ei
=
initial energy level of
neutron
Ef
=
final energy level of
neutron
COMPARISON OF MODERATORS
MATERIAL

COLLISIONS
TO
THERMALIZE
MICROSCOPIC
CROSS SECTION
(BARNS)
sa
MODERATING
RATIO
ss
H2 O
0.948
19
0.66
103
148
D2 O
0.570
35
0.001
13.6
7752
Be
0.209
86
0.0092
7.0
159
C
0.158
114
0.003
4.8
253
FISSION ENERGY
INSTANTANEOUS
KINETIC ENERGY OF
FISSION FRAGMENTS
KINETIC ENERGY OF
FISSION NEUTRONS
INSTANTANEOUS
GAMMA RAYS
165 MeV
5 MeV
7 MeV
DELAYED
KINETIC ENERGY OF
BETA PARTICLES
DECAY GAMMA RAYS
NEUTRINOS
TOTAL ENERGY RELEASED
7 MeV
6 MeV
10 MeV
200 MeV
TRACK LENGTH DESCRIPTION OF
NEUTRON FLUX
1 CUBIC
CENTIMETER
NEUTRONS
cm
NEUTRONS


sec
cm3
cm 2 sec
NEUTRON
DENSITY
NEUTRON
VELOCITY
(Energy)
NEUTRON
FLUX
NEUTRON FLUX
Neutrons
cm2 sec
n
n
n
1 SQUARE
CENTIMETER
n
n
n
n
Reaction Rate (Fission)
R=Nsf
Where:
R
=
reaction rate
(reactions/cm3 sec)
N
=
atomic density of the fuel (atoms/cm3)
s
=
microscopic cross section (cm2)
f
=
neutron flux
(neutrons/cm2 sec)
REACTOR POWER
P = G N sf V f
Where:
P
=
thermal power output (MWt)
G
=
thermal energy produced per fission
(3.2  10-17 MWt sec/fission)
N
=
atomic density (fuel atoms/cm3)
sf
=
microscopic fission cross section (cm2)
V
=
fuel volume in the core (cm3)
f
=
neutron flux
(neutrons/cm2 sec)
k eff  e L f p L th f h
Control Rods
21
THERMAL NEUTRON
LEAKAGE
346
RESONANCE
LOSSES
p
1038
THERMAL
NEUTRON
Lth
1017
THERMAL
NEUTRONS
f
965
THERMAL
NEUTRON
U-235 FUEL
MODERATOR
1400 FAST
NEUTRONS
BORN
1384 FAST
NEUTRONS
Lf
58
FAST NEUTRON
LEAKAGE
52
THERMAL NEUTRONS
ABSORBED BY
NON-FUEL ATOMS
1442 FAST
NEUTRONS
U235
238
239
1400 FAST
NEUTRONS
h
435
NEUTRONS
FROM
THERMAL
FISSION
START CYCLE
HERE
e
Moderator
NEUTRONS
FROM
FAST FISSION
42
Prompt and Delayed
Neutrons
THE SIX FACTOR REACTOR NEUTRON LIFE CYCLE
Nuclear Power Generation
Reactor (primary loop)
Steam Generator (Secondary Loop)
Condenser (Tertiary Loop)
The Existing Nuclear Fuel Cycle
Spent Fuel Rods
Interim Dry Cask Storage
Geologic Repository
Mining
US Mines located in the SW
Uranium mines operate in 20 Countries
Half of the world’s supply comes from six operating mines
Current mining practice results in minimal ecological disturbance
Uranium slurry extracted from mines is
filtered and then injected with sulfuric acid.
Uranium Oxides are a precipitate of the
Solution. The precipitate is filtered again
and then dried to produce “yellow cake”
powder (U3O8)
U3O8 is converted to gaseous UF6
Purified U3O8 from the dry process and purified uranium oxide
UO3 from the wet process are then reduced in a kiln by hydrogen to
UO2:
U3O8 + 2H2 ===> 3UO2 + 2H2O deltaH = -109 kJ/mole
or UO3 + H2 ===> UO2 + H2O deltaH = -109 kJ/mole
This reduced oxide is then reacted in another kiln with gaseous
hydrogen fluoride (HF) to form uranium tetrafluoride (UF4), though in
some places this is made with aqueous HF by a wet process:
UO2 + 4HF ===> UF4 + 2H2O deltaH = -176 kJ/mole
The tetrafluoride is then fed into a fluidised bed reactor or flame tower
with gaseous fluorine to produce uranium hexafluoride, UF6.
Hexafluoride ("hex") is condensed and stored.
UF4 + F2 ===> UF6
Removal of impurities takes place at each step.
Gaseous UF is used to separate the heavier
isotopes of uranium from the lighter in
a series of high speed centrifuges.
The gas extracted from the center of the
centrifuge is enriched in 235U
UF – a powder at room temperature, is shipped to a fuel fabrication
Facility and converted to UO2 powder
Density of UO2 = 10.97 g / cm3 , Length of active fuel = 12 feet
SPENT FUEL STORAGE
• 55 of 103 US LWRs now using “DRY CASK STORAGE” to store
spent fuel.
• The Department of Energy was supposed to provide a
national storage facility by the mid 1990’s. Yet to materialize
• Dry Cask Storage is a method of removing spent fuel from
spent fuel pools and storing it in a steel and concrete cask.
• Each “Cask” holds 32 Fuel assemblies and is stored on a
concrete pad.
Repository
The Existing Nuclear Fuel Cycle
Mill tailings include depleted Uranium
Depleted Uranium
Spent Fuel Rods
Interim Dry Cask Storage
Geologic Repository
Actinides, including Uranium, Thorium, Plutonium
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Neutron Energy
Fission atom (fuel)
Probability of Fission
Moderator
Coolant
Products of Reactions
Fast, Epithermal, Thermal
Actinides
f(E)n, actinide
LW, HW, C, Be
LW, Liquid Metals, Gases
Fission Products (Waste)
Actinides (Fuel)
Reactor Types
Nuclear power plants in commercial operation
Reactor type
Pressurised Water Reactor (PWR)
Boiling Water Reactor (BWR)
Pressurised Heavy Water Reactor 'CANDU' (PHWR)
Gas-cooled Reactor (AGR & Magnox)
Light Water Graphite Reactor (RBMK & EGP)
Fast Neutron Reactor (FBR)
Main Countries
US, France, Japan, Russia, China
US, Japan, Sweden
Canada
UK
Russia
Russia
TOTAL
Number GWe Fuel
273 253 enriched UO2
81
76 enriched UO2
48
24 natural UO2
15
8 natural U (metal),
enriched UO2
11 + 4
10.2 enriched UO2
2 0.6 PuO2 and UO2
434 372
Coolant
water
water
heavy water
CO2
Moderator
water
water
heavy water
graphite
water
liquid sodium
graphite
none
billion kWh
Percent
Electric
Units
Output
Argentina
5.7
4.4
3
Armenia
2.2
29.2
1
Belgium
40.6
52
7
Brazil
13.8
2.8
2
Bulgaria
13.3
30.7
2
Canada
94.3
16
19
China
104.8
2.1
21
29
35.9
6
Finland
22.7
33.3
4
France
405.9
73.3
58
Germany
92.1
15.4
9
Hungary
Czech Republic
14.5
50.7
4
India
30
3.4
21
Iran
3.9
1.5
1
Japan
13.9
1.7
48
Korea RO (South)
132.5
27.6
23
Mexico
11.4
4.6
2
Netherlands
2.7
2.8
1
Pakistan
4.4
4.4
3
Romania
10.7
19.8
2
Russia
161.8
17.5
33
Slovakia
14.6
51.7
4
Slovenia
5
33.6
1
South Africa
13.6
5.7
2
Spain
54.3
19.7
7
Sweden
63.7
42.7
10
25
36.4
5
78.2
43.6
15
United Kingdom
64.1
18.3
16
USA
790.2
19.4
100
WORLD**
2359
c 11
436
Switzerland
Ukraine
LWR Uranium Recycle
without plutonium
recovery
30% to 50% improvement
in energy extracted
LWR Uranium Recycle
with plutonium
recovery
Fuel Cycle Design Imperatives Determine Fuel Cycle Implementation
• Minimization of HLW
• Proliferation Concern
• Radiological Accident Dimension (Design Basis and Beyond)
• Energy Output
• Carbon Footprint (vs. alternatives in energy mix)
Legacies
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Waste
Proliferation & weapons potential
Fuel
Proven designs / processes / materials
Human performance methods (60 to 91%)
Lessons Learned
App R, Physical Train Separation, Access for Emerg Psnl
Training, Staffing, I&C, NUREG 0636, RG 1.97, INPO,
Human Factors, Emergency Prep
Removal of mid scale failure modes, Auto IB transfer
Natural Circ Cooldown Parametersand Training
BWR Scram discharge volume & ATWS improvements
ATWS procedures, breaker maintenance and design
Rod misalignment specs and procedures
Focus on failure modes in design / installation of mods
Improved criticality monitoring and approach to
criticaility procedures
MOV PMs, ABFP mods
IPTE focus, WANO created
FAC inspection s and PM
Nuclear Generation Part of the Mix?
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One hundred US facilities provide 20% US electric power (780 Billion kWh)
Power generation 24/7 as base load provides grid stability & reliability
One fuel pellet = 17,000 cubic feet of natural gas, one ton of coal
Current HLW volume = one football field, 21 feet deep
Russian Federation weapons supplied 500 tons of US uranium supply
(20,000 weapons)
$40 million in wages, 500 jobs per 1000 MW v. 50 jobs for wind or natural
gas
Carbon emission, including mining, construction, fuel fabrication = 17 tons
of CO2 equivalent per GWh (geothermal = 15, wind = 14)
Only type of electric generation with required emergency plans and
support facilities
Current reactor designs could provide 100% (2014 level) of electric supply
for 800 years – without mining an additional gram of uranium