Chemical, Biological and Environmental Engineering Nuclear
Power: Conventional Fission, Advanced Concepts and Remarks on
Fusion
Slide 2
Advanced Materials and Sustainable Energy Lab CBEE NUCLEAR
POWER PLANT
Slide 3
Advanced Materials and Sustainable Energy Lab CBEE The Core
Reactor core is the portion of the nuclear reactor which contains
the nuclear fuel where the nuclear reaction takes place The main
function of a core is to create an environment which establishes
and maintains the nuclear chain reaction It provides a means for
controlling the neutron population and removing the energy released
within the core
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Advanced Materials and Sustainable Energy Lab CBEE NUCLEAR
POWER PLANT
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Advanced Materials and Sustainable Energy Lab CBEE MODERATOR
Newly released neutrons after a nuclear fission move at 300,000
km/sec Fast neutrons Think of the energy contained as kinetic
energy E=h =1/2mv 2 Slow moving neutrons are much more likely to be
absorbed by uranium atoms to cause fission than fast moving
neutrons Moderator is a material which slows down the released
neutrons from the fission process
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Advanced Materials and Sustainable Energy Lab CBEE MODERATOR
Neutrons must be slowed down or moderated to speeds of a few km/sec
epi-thermal neutrons This is necessary to cause further fission and
continue the chain reaction
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Advanced Materials and Sustainable Energy Lab CBEE Common
Moderators Water - H 2 O Light water reactor Not efficient it slows
neutrons and absorbs them Heavy water (D 2 O) Heavy water reactor
Efficient slows neutrons and bounces them back CANDU (Canada
Deuterium Uranium) reactor can use natural/low enriched Uranium!
Graphite RBMK design Efficient, but graphite (carbon) can burn
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Advanced Materials and Sustainable Energy Lab CBEE NUCLEAR
POWER PLANT
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Advanced Materials and Sustainable Energy Lab CBEE Control Rods
Too many neutrons could lead to runaway reaction (not a good thing)
Number of neutrons in reactor controlled by absorbing some Made of
neutron-absorbing material Cadmium Hafnium Boron Rods inserted or
withdrawn from the core to control rate of reaction
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Advanced Materials and Sustainable Energy Lab CBEE CONTROL
ROD
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Advanced Materials and Sustainable Energy Lab CBEE NUCLEAR
POWER PLANT
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Advanced Materials and Sustainable Energy Lab CBEE COOLANT
Liquid or gas circulating through the core Carries the heat away
from the reactor It generates steam in the steam generator May not
have separate steam and coolant cycles The most common coolant is
pressurized water Others include Helium, CO 2, molten Na/K, molten
Pb/Bi, molten Na 2 AlF 6
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Advanced Materials and Sustainable Energy Lab CBEE 1000 psi,
285 o C Boiling Water Reactor
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Advanced Materials and Sustainable Energy Lab CBEE Pressurized
Water Reactor 2300 psi, 315 o C
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Advanced Materials and Sustainable Energy Lab CBEE
CANDU-PHWR
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Advanced Materials and Sustainable Energy Lab CBEE Pressure
Tube Graphite moderated R (PTGR) Note: this is the RBMK reactor
design as made famous at Chernoybl
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Advanced Materials and Sustainable Energy Lab CBEE HTGR
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Advanced Materials and Sustainable Energy Lab CBEE STEAM
GENERATOR It is a heat exchanger Uses heat from the core which is
transported by the coolant Produces steam for the turbine
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Advanced Materials and Sustainable Energy Lab CBEE NUCLEAR
POWER PLANT
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Advanced Materials and Sustainable Energy Lab CBEE CONTAINMENT
The structure around the reactor core Protects the core from
outside intrusion More important, protects environment from effects
of radiation in case of a malfunction Typically it is meter thick
concrete and steel structure
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Advanced Materials and Sustainable Energy Lab CBEE Containment
Structure
Slide 22
Advanced Materials and Sustainable Energy Lab CBEE SPENT FUEL
POOL Stores the spent fuel from the nuclear reactor About of the
total fuel is removed from the core every 12 to 18 months and
replaced with fresh fuel Removed fuel rods still generate a heat
and radiation Spent fuel kept in pool filled with poisoned water
Water that absorbs neutrons Usually Li/B salts dissolved in
water
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Advanced Materials and Sustainable Energy Lab CBEE SPENT FUEL
POOL The spent fuel is typically stored underwater for 10 to 20
years before being sent for disposal or reprocessing
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Advanced Materials and Sustainable Energy Lab CBEE CATEGORIES
OF RADIOACTIVE WASTE Low Level Radioactive Waste Clothing used by
workers, gasses and liquid emitted by reactor Hospital waste, etc
Stored in metal containers on site, later permanently disposed
Shallow land burial (often incinerated first) Intermediate Level
Radioactive Waste Fuel element claddings, materials from reactor
decomissioning Deep burial High Level Radioactive Waste Spent fuel
(fission products and actinides after cooling) Remainder from
reprocessing Currently disposed at WIPP
Advanced Materials and Sustainable Energy Lab CBEE Remaining
activity after storage Activity (Ci) after10 years100 years1000
years Fission products300000350015 Actinides100002200600 Curie
(Ci): 37,000,000,000 disintegrations per second (1 gram pure
radium)
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Advanced Materials and Sustainable Energy Lab CBEE Nuclear
Waste
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Advanced Materials and Sustainable Energy Lab CBEE Radiation
Units Rad: radiation absorbed dose: 0.01 J / kg body tissue SI unit
is Gray (1 rad = 10 mGy) US customary unit still rad Rem: roentgen
equivalent man The dose equivalent in rems is numerically equal to
the absorbed dose in rads multiplied by modifying factors for each
radiation type. Alpha: 1/10 Beta: 1 Gamma: 1 SI unit is Sievert
(Sv, 100rem = 1 Sv)
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Advanced Materials and Sustainable Energy Lab CBEE Exposure
levels 500 rem dose fatal to 1/2 of population 100 - 200 rem:
vomiting, temporary sterility, hair loss, spontaneous abortion,
cancer 5 rem: maximum allowable sustained exposure AY dosimeters
from XRD: never greater than 0.5 rem
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Advanced Materials and Sustainable Energy Lab CBEE Exposure
Pathways
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Advanced Materials and Sustainable Energy Lab CBEE Effects of
Ionizing Radiation Chemistry in Context, Chapter 7 Ionizing
radiation has sufficient energy to knock bound electrons from atom
or molecule Can form highly reactive free radicals with unpaired
electrons E.g., H 2 O [H 2 O. ] + e - Rapidly dividing cells are
particularly susceptible to damage Pregnancy Used to treat certain
cancers
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Advanced Materials and Sustainable Energy Lab CBEE
http://www.doh.wa.gov/ehp/rp/factsheets/factsheets-htm/fs10bkvsman.htm
NCRP Report No. 93 www.epa.gov/rpdweb00/docs/402-f-06-061.pdf
Natural sources (81%) include radon (55%), external (cosmic,
terrestrial), and internal (K-40, C- 14, etc.) Man-made sources
(19%) include medical (diagnostic x-rays- 11%, nuclear medicine-
4%), consumer products, and other (fallout, power plants, air
travel, occupational, etc.)
Slide 33
Advanced Materials and Sustainable Energy Lab CBEE
www.epa.gov/rpdweb00/docs/402-k- 07-006.pdf
Slide 34
Advanced Materials and Sustainable Energy Lab CBEE Effect of
Smoking on Radiation Dose Average annual whole body radiation dose
is about 360 mrem If you smoke, add about 280 mrem Tobacco contains
Pb-210 from fertilizer Decays to Po-210. Pb-210 deposits in bones.
Po-210 works on liver, spleen, kidneys
http://www.doh.wa.gov/ehp/rp/factsheets/factsheets-htm/fs10bkvsman.htm
http://web.princeton.edu/sites/ehs/osradtraining/backgroundradiation/background.htm
Slide 35
Advanced Materials and Sustainable Energy Lab CBEE Waste Fuel
reprocessing Geological repositories Identify solutions that are
both safe and publicly acceptable Use retrievable form, rather than
irreversible solution Allow adoption a better solution in future
Sweden site selection for nuclear waste repository Finland Proposal
to build repository in cavern near the NPPs at Olkiluoto.
Construction start in 2010, operation about 2020 (parliament
approval?) Yucca Mountain Other R&D reduce actinide generation
transmutation using accelerator driven system Change long-lived
nuclear waste to low or medium nuclear waste
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Advanced Materials and Sustainable Energy Lab CBEE WIPP? Waste
Isolation Pilot Plant Waste from research and weapons programs Open
in 1999
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Advanced Materials and Sustainable Energy Lab CBEE
Transmutation? Isnt that what alchemists do? This is where
Actinides (IUPAC: actinoids) come from Example:
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Advanced Materials and Sustainable Energy Lab CBEE
Transmutation 238 U can be made into fissile 239 Pu 232 Th can be
transmuted to 233 U Fertile material: can be transmuted to fissile
material After 5 years in fast breeder reactor can get enough 239
Pu to fuel another reactor from 238 U Natural U is 99.3% 238 U
Similar for 232 Th, also theres 4x as much Th as U in the world
Fissile material: actual nuclear fuel
Slide 39
Advanced Materials and Sustainable Energy Lab CBEE Waste Fuel
Reprocessing UREX process (URanium EXtraction) Dissolve waste fuel
in HNO 3 Extract with tributylphosphate/alkane mixture Crash out
recovered U using reductant (e.g., NaBH 4 ) AY worked on e-chem
variant of this (used depleted 238 U) PUREX is a variant also
extracts Pu Remaining aqueous stuff has actinides, fission products
Dispose by vitrification/synroc
Slide 40
Advanced Materials and Sustainable Energy Lab CBEE Future
Reactor Designs Research is currently being conducted for design of
the next generation of nuclear reactor designs. The next generation
designs focus on: Proliferation resistance of fuel Passive safety
systems Improved fuel efficiency (includes breeding) Minimizing
nuclear waste Improved plant efficiency (e.g., Brayton/combined
cycle) Hydrogen production Economics
Slide 41
Advanced Materials and Sustainable Energy Lab CBEE Future
Reactor Designs (cont.)
Slide 42
Advanced Materials and Sustainable Energy Lab CBEE Design
improvements (Generation III Designs) New thermal management
systems Advanced Boiling Water/Pressurized Water Light water
reactors (LWRs) Heavy water reactors (HWRs) Gas cooled reactors
Liquid metal cooled Improved core designs Pebble bed modular
reactor (110 MWe reactor at ca. $1k/kW) Sub-critical hybrid systems
Improved Safety Passive thermal management if failure Waste
management
Slide 43
Advanced Materials and Sustainable Energy Lab CBEE Pebble Bed
Reactor No control rods needed Intrinsically safe fuel elements He
cooled Use of Th fuel cycle
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Advanced Materials and Sustainable Energy Lab CBEE Pebble Bed
Fuel Elements
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Advanced Materials and Sustainable Energy Lab CBEE Advanced
Boiling Water Reactor (ABWR) More compact design: cuts construction
costs increases safety Additional control rod power supply improves
reliability Designed for ease of maintenance Two built and
operating in Japan
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Advanced Materials and Sustainable Energy Lab CBEE
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Advanced Materials and Sustainable Energy Lab CBEE
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Advanced Materials and Sustainable Energy Lab CBEE
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Advanced Materials and Sustainable Energy Lab CBEE Generation
IV Concepts Very High Temperature Reactor (VHTR) Supercritical
Water-Cooled Reactor (SCWR) Lead-Cooled Fast Reactor (LFR) Molten
Salt Reactor (MSR) Sodium-Cooled Fast Reactor (SFR)
Slide 50
Advanced Materials and Sustainable Energy Lab CBEE Very High
Temperature Reactor (VHTR) Thermal neutron spectrum Helium-cooled
core (1000 o C+) Potential H 2 production
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Advanced Materials and Sustainable Energy Lab CBEE
Supercritical Water-Cooled Reactor (SCWR) Operates above the
critical point of water Thermal efficiency approaching 44%
Slide 52
Advanced Materials and Sustainable Energy Lab CBEE Lead-Cooled
Fast Reactor (LFR) Ability to seal core Refueling 15-20 years
Relative small capacity Use of MoX fuel
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Advanced Materials and Sustainable Energy Lab CBEE Molten Salt
Reactor (MSR) Thorough fuel burnup Fuel cycle variability Can use
Th directly in coolant to generate fiissile material
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Advanced Materials and Sustainable Energy Lab CBEE
Sodium-Cooled Fast Reactor (SFR) Actinide burning Capable of
burning weapons grade fuel (to get rid of nuclear stockpile) Can be
used as Fast Breeder reactor
Slide 55
Chemical, Biological and Environmental Engineering A Few
Comments About Fusion
Slide 56
Advanced Materials and Sustainable Energy Lab CBEE Binding
Energy Energy released when nucleus created from protons and
neutrons Larger binding energy per nucleon means more stable
nucleus
Slide 57
Advanced Materials and Sustainable Energy Lab CBEE Fusion vs.
Fission Fusion Fission
Slide 58
Advanced Materials and Sustainable Energy Lab CBEE Relevant
fusion reactions
Slide 59
Advanced Materials and Sustainable Energy Lab CBEE Calculation
of energy released Released energy follows from the mass deficit.
Consider the reaction Masses of products are The mass deficit
(Total mass before minus total mass after) for reaction is
Slide 60
Advanced Materials and Sustainable Energy Lab CBEE Energy then
follows from Einsteins formula Physicists unit of energy is
electron volt (eV) (kilo-electron volt, keV; mega-electron volt
MeV) Calculation of released energy
Slide 61
Advanced Materials and Sustainable Energy Lab CBEE Energy
released by 1kg of D-T mixture 1 kg of a Deuterium/Tritium mixture
would allow for a number of fusion reactions N This would generate
If released over 24h, this is around 4 GW
Slide 62
Advanced Materials and Sustainable Energy Lab CBEE Availability
of the fuel Natural abundance of D is 0.015% of all H (1 in 6700)
However, at current rate of energy use there is enough H in the
ocean for 10 11 years Deuterium is also very easy to separate
(i.e., cheap) Tritium is unstable with a half age of 12.3 years
There is virtually no naturally occuring Tritium
Slide 63
Advanced Materials and Sustainable Energy Lab CBEE Availability
of the fuel: T Tritium can be bred from Lithium Note that the
neutron released in the D-T fusion reaction can be used for this
purpose Enough Lithium on land for 10k to 30k years, also at low
cost If the oceans included, enough Li for 10 7 years
Slide 64
Advanced Materials and Sustainable Energy Lab CBEE Why fusion .
A large amount of fuel is available, at a very low cost The fuel is
available in all locations of the earth. Like fission, fusion is CO
2 neutral Fusion would yield only a small quantity of high level
radioactive waste. There is only a small threat to
non-proliferation of weapon material
Slide 65
Advanced Materials and Sustainable Energy Lab CBEE But... An
energy producing working concept is yet to be demonstrated. The
operation of a fusion reactor is hindered by several difficult (and
rather interesting) physics phenomena Also bear in mind that the
cost argument thus far focuses on the fuel only However, the cost
of the energy is largely determined by the cost of the
reactor...
Slide 66
Advanced Materials and Sustainable Energy Lab CBEE Key problem
of fusion . Is the Coulomb barrier
Slide 67
Advanced Materials and Sustainable Energy Lab CBEE Break-even
and Ignition The break-even condition is defined as the state in
which the total fusion power is equal to the heating power Note
that some power could be externally supplied... Ignition is defined
as the state in which the energy produced by the fusion reactions
is sufficient to heat the plasma Remember that neutrons (80% of the
energy) escape reactor; energy in He remains for plasma heating
(20%)
Slide 68
Advanced Materials and Sustainable Energy Lab CBEE Inertial
Containment Fusion: high n low E Rapid compression and heating of a
solid fuel (high n) pellet using laser or particle beams. Fusion
occurs for a few mS... (low t) Idea is to obtain a sufficient
amount of fusion reactions (P fusion ) to generate energy (P heat )
before the material flies apart
Slide 69
Advanced Materials and Sustainable Energy Lab CBEE Magnetic
confinement: low n high E In a plasma, all particles are charged If
strong magnetic field applied, Lorentz force can be used to trap
charged particles Force causes charged particles to gyrate around
the field lines with a typical radius At 10 keV and 5 Tesla this
radius of 4 mm for Deuterium and 0.07 mm for the electrons
Slide 70
Advanced Materials and Sustainable Energy Lab CBEE Tokamak /
Stellarator
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Advanced Materials and Sustainable Energy Lab CBEE Tokamak
progress as n-T-tau Current experiments are close to break- even
The next step ITER is expected to operate above break-even but
still below ignition
Slide 72
Advanced Materials and Sustainable Energy Lab CBEE ITER Goals
Achieve steady-state plasma with Q > 5 (5x break even)
Momentarily achieve Q > 10 (ten times more thermal energy from
fusion heating than is supplied by auxiliary heating Maintain
fusion pulse for up to eight minutes. Develop technologies needed
for fusion power plant Verify tritium breeding concepts. Refine
neutron shield/heat conversion technology (most of energy in the
D+T fusion reaction is released in the form of fast neutrons)
