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The Nuclear Energy Alternative How does it work? The Nuclear Fuel Cycle Alternative Fuel Cycles Legacies Mr. Nicholas Lizzo

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Presentation on theme: "The Nuclear Energy Alternative How does it work? The Nuclear Fuel Cycle Alternative Fuel Cycles Legacies Mr. Nicholas Lizzo"— Presentation transcript:

1 The Nuclear Energy Alternative How does it work? The Nuclear Fuel Cycle Alternative Fuel Cycles Legacies Mr. Nicholas Lizzo

2 Nuclear Power Generation Reactor (primary loop)Steam Generator (Secondary Loop)Condenser (Tertiary Loop)

3 Reactor Coolant System – 4 Loop PWR

4 Reactor Vessel Height - 43’ Width – 15’ Weight Tons Active fuel region: 193 assemblies 3.5% enriched U-235

5 Fission Process Thermal “Uranium-235” Fission Fission Products Fast Neutrons Neutron + Energy

6 Key Components of the Reactor Design Neutron Energy Fission atom (fuel) Probability of Fission f(E) n, fuel Moderator Coolant Products of Reactions

7 Neutron Energy Distribution from Fission Neutron Energy ( 1 eV = x joules)

8 FISSILE AND FISSIONABLE NUCLIDES PRESENT IN LIGHT WATER REACTORS Nuclide Thermal Neutron Microscopic Cross Section for Fission (barns) Fissile or Fissionable 585Fissile 5  Fissionable 750 Fissile 0.05Fissionable 1010Fissile < 0.2Fissionable One barn = 1 x 10 – 24 cm 2

9 How do we characterize: Probability of fission?

10 Cross section (target area for incident particle)

11 Thermal region

12 How do we slow down (thermalize) the fission spectrum neutrons?

13 2 MeV NEUTRON EfEf EiEi COLLISION eV NEUTRON

14 BIRTH AT HIGH ENERGY ENERGY LOSSES UPON COLLISION 2 MeV AVERAGE THERMAL ENERGY NEUTRON ENERGY TIME  =logarithmic energy decrement E i =initial energy level of neutron E f =final energy level of neutron

15 H2OH2O MATERIAL COLLISIONS TO THERMALIZE  a a MODERATING RATIO   s s MICROSCOPIC CROSS SECTION (BARNS) D2OD2O Be C COMPARISON OF MODERATORS

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17 KINETIC ENERGY OF FISSION FRAGMENTS 165 MeV INSTANTANEOUS KINETIC ENERGY OF FISSION NEUTRONS 5 MeV INSTANTANEOUS GAMMA RAYS 7 MeV DELAYED KINETIC ENERGY OF BETA PARTICLES 7 MeV DECAY GAMMA RAYS6 MeV NEUTRINOS10 MeV TOTAL ENERGY RELEASED200 MeV FISSION ENERGY

18 TRACK LENGTH DESCRIPTION OF NEUTRON FLUX 1 CUBIC CENTIMETER NEUTRON DENSITY NEUTRON VELOCITY (Energy) NEUTRON FLUX

19 NEUTRON FLUX n n n n n 1 SQUARE CENTIMETER n n Neutrons cm 2 sec

20 Where: Reaction Rate (Fission) R=reaction rate (reactions/cm 3 sec) N=atomic density of the fuel (atoms/cm 3 )  =microscopic cross section (cm 2 )  =neutron flux (neutrons/cm 2 sec) R = N 

21 Where: REACTOR POWER P =thermal power output (MW t ) G=thermal energy produced per fission (3.2  MW t sec/fission) N=atomic density (fuel atoms/cm 3 )  f =microscopic fission cross section (cm 2 ) V=fuel volume in the core (cm 3 )  =neutron flux (neutrons/cm 2 sec) P = G N  f V 

22 THE SIX FACTOR REACTOR NEUTRON LIFE CYCLE U-235 FUEL MODERATOR 435 NEUTRONS FROM THERMAL FISSION START CYCLE HERE 965 THERMAL NEUTRON 1384 FAST NEUTRONS 1017 THERMAL NEUTRONS 1038 THERMAL NEUTRON 1442 FAST NEUTRONS 1400 FAST NEUTRONS BORN 1400 FAST NEUTRONS 346 RESONANCE LOSSES 21 THERMAL NEUTRON LEAKAGE 52 THERMAL NEUTRONS ABSORBED BY NON-FUEL ATOMS 58 FAST NEUTRON LEAKAGE U NEUTRONS FROM FAST FISSION 42 p f L th LfLf   Moderator Control Rods Prompt and Delayed Neutrons

23 Nuclear Power Generation Reactor (primary loop)Steam Generator (Secondary Loop)Condenser (Tertiary Loop)

24 The Existing Nuclear Fuel Cycle Interim Dry Cask StorageGeologic RepositorySpent Fuel Rods

25 Mining US Mines located in the SW

26 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 (U 3 O 8 )

27 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: U 3 O 8 + 2H 2 ===> 3UO 2 + 2H 2 O deltaH = -109 kJ/mole or UO 3 + H 2 ===> UO 2 + H 2 O 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: UO 2 + 4HF ===> UF 4 + 2H 2 O 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. UF 4 + F 2 ===> UF 6 Removal of impurities takes place at each step. U 3 O 8 is converted to gaseous UF 6

28 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 235 U

29 UF – a powder at room temperature, is shipped to a fuel fabrication Facility and converted to UO 2 powder

30 Density of UO 2 = g / cm 3, Length of active fuel = 12 feet

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40 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.

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45 Repository

46 The Existing Nuclear Fuel Cycle Interim Dry Cask StorageGeologic RepositorySpent Fuel Rods Mill tailings include depleted Uranium Depleted Uranium Actinides, including Uranium, Thorium, Plutonium

47 Neutron Energy Fast, Epithermal, Thermal Fission atom (fuel)Actinides Probability of Fission f(E) n, actinide ModeratorLW, HW, C, Be CoolantLW, Liquid Metals, Gases Products of ReactionsFission Products (Waste) Actinides (Fuel)

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49 Reactor Types Nuclear power plants in commercial operation Reactor typeMain CountriesNumberGWeFuelCoolantModerator Pressurised Water Reactor (PWR)US, France, Japan, Russia, China273253enriched UO2water Boiling Water Reactor (BWR)US, Japan, Sweden8176enriched UO2water Pressurised Heavy Water Reactor 'CANDU' (PHWR)Canada4824natural UO2heavy water Gas-cooled Reactor (AGR & Magnox)UK158natural U (metal),CO2graphite enriched UO2 Light Water Graphite Reactor (RBMK & EGP)Russia enriched UO2watergraphite Fast Neutron Reactor (FBR)Russia20.6PuO2 and UO2liquid sodiumnone TOTAL434372

50 billion kWhPercent ElectricUnits Output Argentina Armenia Belgium Brazil Bulgaria Canada China Czech Republic Finland France Germany Hungary India Iran Japan Korea RO (South) Mexico Netherlands Pakistan4.4 3 Romania Russia Slovakia Slovenia South Africa Spain Sweden Switzerland Ukraine United Kingdom USA WORLD**2359c 11436

51 LWR Uranium Recycle without plutonium recovery 30% to 50% improvement in energy extracted

52 LWR Uranium Recycle with plutonium recovery

53 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)

54 Legacies Waste Proliferation & weapons potential Fuel Proven designs / processes / materials Human performance methods (60 to 91%) Lessons Learned

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56 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

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63 Nuclear Generation Part of the Mix? 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 CO 2 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


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