Nuclear Power: Status and Trends 1 ECE_New ECE_New Nukes The Diablo Canyon NPPT produces CO2-free electricity at half the W. Udo Schröder, 2011 state’s (CA) average cost (2¢/kwh) Nuclear Fission Energy in the U.S. Status and Trends in Technology I. Introduction: Energy Demand and Outlook II. Principles of Energy Generation from Nuclear Fission 2 . Fission chain reaction and reactor control . Open fuel cycle III. Strategic Issues for Nuclear Power IV. New Nukes: Advanced Nuclear Energy Technologies ECE_New ECE_New Nukes . Gen IV reactors . Closed fuel cycle V. Conclusion: Nuclear Power in a Sustainable Energy Future W. Udo Schröder, 2011 Introduction: World Energy Outlook Predictions (IEA) 1: World (US) demand up by +50 (28)% (25y: $20T, U.S. >$5T) Now : 450 Quad Btu/a 2030: 680 Quad Btu/a 2: Redistribution Industrial World vs. Developing World 40 Bbloe/a (220 GJ/a) vs. 6 Bbloe/a (34 GJ/a)) 3 Boundary conditions 1: Disappearing resources (IEA) Now, or soon: beyond peak oil > 2050(??) peak gas, but unconventional gas (shale) 235 > 2090(??) peak uranium ( U) 2: Mitigate anthropogenic pollution Improve energy efficiency Reduce GHG emissions (fossil fuels) Alternative energy sources (renewables, nuclear) ECE_New ECE_New Nukes 3: US energy security/independence in global context !? How to manage significant increases @ Boundary conditions? Moderate growth potential of individual technologies need diverse energy portfolio W. Udo Schröder, 2011 Energy Demand (US) 100 Quad Btu/a = 49 GJ/a 4 ECE_New ECE_New Nukes EIA: Annual Energy Outlook 2011 W. Udo Schröder, 2011 Present Energy Demand (U.S.) Total Coal Nuclear 2.4% 450 Quad Btu/a = 220GJ/a 25% Hydro 2.6% U.S. uses 25% of total global energy demand, Natural Gas Renewables 65% imported (Canada, Mexico,.., Middle East) 26% 0.2% 5 Oil & nat. Gas & Coal 95% Oil 44% Main Energy Uses: IEA 2004 Electricity •Industry •Transportation (liquid fuels) •Agriculture Coal 49.7% Nuclear •Commercial & public 19.3% •Residential ECE_New ECE_New Nukes Growth potential | bound. cond’s. Hydro 6.5% Renewables Nuclear Energy: high power Oil 3% 2.3% IEA 2004 Other density, scalability, economics 0.5% W. Udo Schröder, 2011 Trends in Nuclear Energy Production Steady increase of nuclear power output over past 20 years. Now equivalent: 24 quads of oil World (US) 443 (103) reactors 365 (100) GW 6 World 53 new reactors, US:3-4, > 20 planned, license applications US potential: ECE_New ECE_New Nukes several new reactors/a (@ $(2-3)B/GWe, 5¢/kWh) W. Udo Schröder, 2011 Nuclear Fission Energy in the U.S. Status and Trends in Technology I. Introduction: Energy Demand and Outlook II. Principles of Energy Generation from Nuclear Fission 7 . Fission chain reaction and reactor control . Open fuel cycle III. Strategic Issues for Nuclear Power IV. New Nukes: Advanced Nuclear Energy Technologies ECE_New ECE_New Nukes . Gen IV reactors . Closed fuel cycle V. Conclusion: Nuclear Power in a Sustainable Energy Future W. Udo Schröder, 2011 Nuclear Rearrangement Energies M(N,Z) < N·Mn + Z·Mp M B(A=N+Z) Einstein: equivalence 2 In assembly of a nucleus mass = energy E = M·c B=Mc2 is released to outside Energy release in fission A2A/2 8 Fe Ni ECE_New ECE_New Nukes 3 M235 U47 mg MM 10 E47 g c 2 4 10 9 J fission M TNT1 t MM E 4 109 J combustion W. Udo Schröder, 2011 Nuclear Fuels Enrichment for fuels 3-4 % fissile fissile Enrichment for weapons >90 % fissile 9 fertile fissile enrichment weapons + n ECE_New ECE_New Nukes fertile fissile hot enrichm.weapons + n W. Udo Schröder, 2011 Energy Generation from nth-Induced Fission 235 236 * Converts 0.1% of the mass U nth U 2 FF 2(3) n 200 MeV into energy 236 * 147 87 * 1g 235U/day = 1MW Example:2U La Br nfast 108 x chemical energies E = 168 MeV fission ff 10 fragment n En tot = 5 MeV Eg = 7 MeV FF b-decay = 27 MeV 236U* Qtotal = 207 MeV n Neutrons per fission: k = 2.5±0.1 k=1 critical =chain rxn n k>1 explosive chain rxn Fission neutrons are fast: ECE_New ECE_New Nukes n-energies <En>≈2 MeV fission Fast n’s do not induce 235U fragment fission need moderation Most fission neutrons are lost and/or not useful for further fission Fission fragments = reactor poison, stop chain reaction. k < 1 !!! W. Udo Schröder, 2011 Thermal-n Induced Fission Chain Reaction Leo Szilard Neutron multiplication through fission k=2.4, minus 1938 losses (capture, leaking,..), effective k < 2.4. One n used in fission effective multiplication k-1: dN 1 n kN 1 dt n 11 kt1 Nnn( t ) N (0) e k >1: avalanche of n = time betw. generations ( ~ 40s in reactors ~ ns in explosives) keff k prompt k delayed Reactor Control ECE_New ECE_New Nukes Characteristic T keff≈1 period: ()k1eff e.g.,keff=1.03 Most fission neutrons are lost and/or not useful for further fission W. UdoFission Schröder, 2011 fragments = reactor poison, stop chain reaction. k < 1 !!! Neutron Moderation Fast Neutrons from Fission neutrons too energetic, “thermalize” 235 Fission to maximize sf for U multiple elastic scattering (“moderation”) Slow moderator: small scapt ! down Need:2 MeV 0.025 eV/2MeV= 10-8 12 Need to “miss” 238U capture resonances (2eV< En <10keV) H2O, D2O, Be, C(graphite), prevent leakage n-reflector moderator A=238 ECE_New ECE_New Nukes U A=65 U U moderator A=12 A=1 d<lfast H can capture neutrons: H, D are best moderators H+nth D+2.2 MeV W. Udo Schröder, 2011 W. W. Udo Schröder,2011 ECE_New Nukes 13 Principle Boiling Water Reactor Nuclear Power Plant 1-2GW 2-3 B$/NPPt Fail-safe operation Negative Reactivity Negative feedback loops: Reaction subsides when 14 • coolant gets too hot or disappears (less dense, less moderation) • fuel gets too hot (n capture increases) • control rods are not moved out ECE_New ECE_New Nukes Passive safety: Pressure reactor vessel ~1’ thick steel, pressure tubes, Reactor containment building with several 3-4 foot thick concrete walls, concrete + water shielding on top of reactor vessel, gravitation replaces mechanical pumps. W. Udo Schröder, 2011 Nuclear Fuel Storage & Transport 15 ECE_New ECE_New Nukes Progress Energy W. Udo Schröder, 2011 US Now W. Udo Schröder, 2011 ECE_New Nukes 16 Radiotoxicity of Spent Nuclear Fuel Radio toxicity vs. time after shutdown, of spent fuel from •pressurized water uranium reactor (PWR), 17 • U/Pu breeder, and Natural • Th/U fuel cycle. uranium FP indicates the faster decay of fission products. Multiple reprocessing, less residuals. Reprocessing involves robotics ECE_New ECE_New Nukes because of Tl gamma radiation not for extremists’ garage! (David, Nifenecker, 2007) W. Udo Schröder, 2011 Nuclear Fission Energy in the U.S. Status and Trends in Technology I. Introduction: Energy Demand and Outlook II. Principles of Energy Generation from Nuclear Fission 18 . Fission chain reaction and reactor control . Fuel cycle III. Strategic Issues for Nuclear Power IV. New Nukes: Advanced Nuclear Energy Technologies ECE_New ECE_New Nukes . Gen IV reactors . Closed fuel cycle V. Conclusion: Nuclear Power in a Sustainable Energy Future W. Udo Schröder, 2011 Status 19 1. Operational reactor safety …………………………………. √ 2. Resource limits of nuclear fuel (235U/Pu, Th,…) … √ 3. Safe capture, storage and sequestration of radiotoxic nuclear waste ……………………………………. √ 4. Proliferation resistance (nations, individuals) …… (√) 5. Economy (Capital plus fuel costs) ………………………. √ 6. R&D requirements ………………………………………………. √ ECE_New ECE_New Nukes 7. Capability for rapid deployment …………………………. (√) 8. Public perception …………………………………………………. (√) W. Udo Schröder, 2011 Fatalities in Energy Production (1969-2000) 20 Chernobyl/ Ukraine 1986: 45 Ŧ LNG ECE_New ECE_New Nukes Paul Sherrer-Institute/Switzerland. Omitted: large hydro disasters Shimantan and Banqiao (China 1976: 26,000†). 2006 U.S. coal mines : 42† (equivalent 1 Chernobyl nuclear accident/a) W. Udo Schröder, 2011 Pollution Footprints of Energy Technologies GHG (fossile): CH4, CO2, NOx, SOx, H2O Other (fossile): 21 Particles PM2.5, Metals (coal, oil): (Be,…., Hg, U, Th) Chemical toxins (Solid-state PV) Radiotoxins ECE_New ECE_New Nukes (99% from coal, airbn: 80-100 t U/a nuclear fuel residues: High power density Fiss Frgm, Min Actind, small environmental footprint Nuclear localized + decays) W. Udo Schröder, 2011 The following few slides provide an overview of the Fukushima event (March 11, 2011) in Japan, where earthquake and subsequent tsunami disabled several nuclear power plants, leading to a release 22 of significant amounts of radioactivity into the environment. Lessons taken from this event will have consequences for the design criteria imposed on future nuclear power stations, as indicated by reports of government commissions and independent expert conferences. ECE_New ECE_New Nukes W. Udo Schröder, 2011 Fukuchima-Daiichi NPP Complex 6 reactors, 440-760 MW (1970). 23 ECE_New ECE_New Nukes W. Udo Schröder, 2011 Fukushima BW Reactor Design (GE & Toshiba) Note: absence of containment around the spent-fuel pool. 24 ECE_New ECE_New Nukes W. Udo Schröder, 2011 What Went Wrong, Hydrogen Explosion Nuclear fuel rods clad in Zr alloys (little corrosion, low capture cross section). But: reactivity against water Zr + 2H2O → ZrO2 + 2H2 – Operators vented H into the 25 maintenance hall of 1,2,3 H2/O2 mix detonated. Direct venting of H2 into atmosphere would have been preferred design option. – More modern reactors have a catalyst- based recombinator hydrogen and oxygen into water at room temperature before explosivity limit is reached. ECE_New ECE_New Nukes While a similar event would not have happened with the modern U.S. stations, there is an obvious need for more comprehensive risk/benefit analyses for all stations. W. Udo Schröder, 2011 Return of the People There have been no fatalities in the Fukushima event caused by radioactivity. Close vicinity of the Fukushima NPP is polluted by radioactivity released in the H2 explosions. 26 Clean-up of affected areas may take years and $$.