Is there a safe future for nuclear energy? Dr John Roberts Dalton Nuclear Institute The University of Manchester

Rutherford Model of the Atom The atom The nucleus Few x 10-15 m Few x 10-10 m Z orbiting electrons

Periodic Table 235 U 92 protons, 143 neutrons, 238 U 92 protons, 146 neutrons

Key Themes What does safe mean? What exactly is nuclear energy? What are the future options for nuclear energy?

Safe?

Safer?

2,753

Deaths per Billion Passengers km Journeys Hours Air 0.05 Bus/Coach 4.3 Bus/Coach 11.1 Bus/Coach 0.4 Rail 20 Rail 30 Rail 0.7 Van 20 Air 30.8 Van 1.2 Car 40 Water 50 Water 2.6 Foot 40 Van 60 Car 3.1 Water 90 Car 130 Pedal cycle 44.6 Air 117 Foot 220 Foot 54.2 Pedal cycle 170 Pedal cycle 550 Motorcycle 108.9 Motorcycle 1,640 Motorcycle 4,840

Road Deaths by Age Source: Reported Road Casualties Great Britain: 2009 Annual Report

Deaths per TWh 180 160 140 120 100 80 60 40 20 0 161 36 12 12 4 1.4 0.15 0.10 0.04 Source: IBM

World Electricity Generating Capacity Total 20,269 TWh Coal 40.8% Hydro16.2% Other (inc Wind) 2.8% Oil 5.5% Gas 21.3% Nuclear 13.4%

UK Electricity Generating Capacity 2010 84 GWe Coal 34% Hydro 5% Wind 4% Oil 5% Gas 37% Nuclear 13%

China Electricity Generating Capacity 2010 962 GWe Coal 71% Hydro 22% Wind 3% Oil 2% Gas 1% Nuclear 1%

Notable Nuclear Accidents Accident Year Immediate Deaths Windscale Fire 1957 Three Mile Island 1979 Chernobyl 1986 Fukushima 2011 0 0 47 0

Turbines Converts mechanical to electrical energy ~86% of all worldwide electrical generation uses steam turbines Need a source of energy to convert water into steam Could be coal, gas or nuclear fission

Electrical Generator

Uranium is very energy dense 1 tonne of U = 20,000 tonnes of coal In a fast reactor = to 2,000,000 tonnes of coal Nuclear power station requires 40 tonnes of fuel per year one lorry load per fortnight Coal power station requires 3,000,000 tonnes per year two train loads per day

Nuclear Energy For 1 1150 MWe reactor (Sizewell B in the UK) 33% thermal efficiency ~ 3000 MWth 200 17x17 assemblies, 300 pellets/rod 3 GW is generated by 17,340,000 pellets 200 W/pellet (199 W/pellet) Pellets are ~ 1 cm in length linear power ~ 200 W/cm ~ 20 kw/m Pellets weigh ~ 5g specific power ~ 40 W/g

Nuclear Energy If the Fuel Pellet remains in the reactor for three years then the total energy produced by one pellet is given by 3 x 365.25 x 24 x 3600 x 200 W or Js -1 ~ 20 GJ Total energy per unit mass = 20 GJ/5 g = 4 GJg -1 = 4000 GJkg -1 = 4000 TJ t -1 = 46,000 MWdt -1 (MW per day per tonne) = 1.1 Billion kwht -1 Burning Gas = 0.4 MWdt -1 Eating Chocolate = 0.2 MWdt -1 t = tonne

Uranium Nuclear Fission reactors use uranium as the fuel Use of U as an oxide dates back many years - used to colour glass Discovered as a metal in pitchblende in 1789 Named after the planet discovered in 1781 Radioactive properties discovered by Henri Becquerel in 1896

Nuclear Fission Discovered in 1938 by Hahn and Strassman Theoretically calculated by Meitner and Frisch Bombardment of uranium by neutrons causes the nucleus to split into two main fragments n + 235 U à 144 Ba + 90 Kr + 2n Mass decrease due to this reaction is appreciable E = mc 2 Crucially other neutrons are emitted

Nuclear Fission neutron + 235 Uranium 144 Barium + 90 Krypton + 2 neutrons n+ 235 U 144 Ba + 90 Kr + 2n

Chain Reaction Release of new neutrons give possibility of a chain reaction Probability of interaction is greater at lower neutron energies

Stable Or Non-Stable Reactions Define a reproduction constant k = no. of neutrons in one generation no. of neutrons in previous generation k > 1 supercritical nuclear weapons k < 1 subcritical - reaction dies out k = 1 critical - stable chain reaction

Controlled Nuclear Fission

Fission Energy One pellet undergoes 6 x 10 12 fissions per second Each cubic micron has 10 fissions per second The total energy released per fission is about 200 MeV or 32 pj Kinetic Energy from fission fragments 165 ± 5 Prompt γ ray energy 7 ± 1 Kinetic Energy of fission neutron 5 ± 0.5 β rays from fission products 7 ± 1 α rays from fission products 6 ± 1 Neutrino s from fission products 10 ± 1

Reactor Operation Coolant & Moderator Fuel Rod Coolant & Moderator Control Rod Absorption Coolant & Moderator Fuel Rod Coolant & Moderator Fission Capture & Fission Moderation

Reactor Shutdown Coolant & Moderator Fuel Rod Coolant & Moderator Control Rod Absorption Coolant & Moderator Fuel Rod Coolant & Moderator Absorption Fission Moderation

Shielding

Negative void coefficient more voids lead to a decrease on power Positive void coefficient more voids lead to an increase in power Water is a better moderator than steam. Therefore an increase in temperature, creating voids, will lead to a decrease in power

First Commercial Reactor

Sizewell B

How dangerous is radiation?

Average Annual UK Radiation Dose

UK Radon Potential

Radiological Dose Activity Dose (msv) Living in Cornwall 7.8 From a brain scan 5 Average UK dose 2.6 Average additional dose for airline crews 2 Average annual dose received by coal miner 1.2 Dose from return flight from London to Los Angeles 0.14 Dose from return flight from London to Spain 0.02 Dose from 1 week holiday in Cornwall 0.1 Dose from drinking a glass of mineral water every day for 1 year 0.065 Dose from a single X-ray 0.02 Dose Limit for registered radiation workers per year 20

Radioactive Materials Material Activity 1 kg of granite 1,000 Bq 1 kg of coal ash 2,000 Bq 1 kg of coffee 1,000 Bq 1 kg of fertiliser 5,000 Bq 1 smoke detector 30,000 Bq 1 adult human (70 kg) 7,000 Bq 1 Bq = 1 disintegration per second

Humans are Radioactive Isotope Average Weight Activity U 90 µg 1.1 Bq Th 30 µg 0.11 Bq 40 K 17 mg 4.4 kbq Ra 31 pg 1.1 Bq 14 C 22 ng 3.7 kbq 3 H 0.06 pg 23 Bq 210 Po 0.2 pg 37 Bq

Radiation Shielding α particle (helium nucleus) Stopped by skin or paper β particle (electron) Stopped by aluminium plate γ ray (part of the electromagnetic spectrum) Stopped by dense materials

Uranium Decay Chain 92 234 U 238 U 91 234 Pa 90 89 230 Th 234 Th 88 226 Ra 87 Protons 86 85 218 At 222 Rn α decay 84 83 210 Po 210 Bi 214 Po 214 Bi 218 Po β decay 82 206 Pb 210 Pb 214 Pb 81 206 Tl 210 Tl 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 Neutrons

Linear No Threshold (LNT) Hypothesis Negative Effect Assumed Relationship Observed Effects Low Radiation Dose High

Threshold Hypothesis Negative Effect Low Radiation Dose High

Radiation Hormesis Negative Effect Low Radiation Dose High

Bad Gastein, Austria - Radon Spa EU Radon limit for new houses is 200 Bq m -3 EU Radon limit for old houses is 400 Bq m -3 Bad Gastein Radon Spa - 170,000 Bq m -3 Other therapeutic radon centres exist in Germany, Czech Republic, France, Italy, Ukraine, Russia, Japan and USA

Carbon Footprint gc0 2 /kwh 900 800 700 600 500 400 300 200 100 0 Coal Gas Biomass Solar Marine Hydro Wind Nuclear Source: POSTnote 268

Carbon Footprint gc0 2 /kwh 90 80 70 60 50 40 30 20 10 0 Biomass Solar Marine Hydro Wind Nuclear Source: POSTnote 268

g/kwh 2 1.5 1 0.5 0 Nuclear Electrical Generation Figures based on Torness AGR in 2002, Source: British Energy

Nuclear Capacity in the UK 14000 MWe 12000 10000 8000 6000 Oldbury Wylfa Hinkley Point B Hunterston B Hartlepool Heysham 1 4000 2000 Dungeness B Torness Heysham 2 0 2003 2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031 2033 2035 Existing stations

Plant Life Extension 14000 12000 10000 MWe 8000 6000 4000 2000 0 2003 2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031 2033 2035 Existing stations Potential AGR life extension

New Build 14000 12000 10000 MWe 8000 6000 4000 2000 0 2003 2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031 2033 2035 Existing stations Potential AGR life extension New Build

Future Electricity Requirements Source: Parsons Brinckerhoff Powering the Future

Future Scenario Source: Parsons Brinckerhoff Powering the Future

Carbon Reductions Source: Parsons Brinckerhoff Powering the Future

Global Gas Resources & Flows 2005

Global Gas Resources & Flows 2020

Evolution of Reactors

UK New Build Programme Westinghouse AP1000 Areva EPR

Passive Cooling

EPR Reactor

Protection Against Airplane Crash A thick highly reinforced concrete shell protects the inner walls and structures from direct impact and resulting vibrations Protection is provided for the reactor, fuel and safeguard buildings including the Main Control Room

EPR Safety Systems

Meltdown

Reactor 1 Image:TEPCO

Severe Accident Approach Core Damage loss of first barrier RPV failure - loss of the second barrier Mitigation approach is focused on ensuring containment integrity - third barrier

EPR Core Melt Retention All stages are fully passive: retention, spreading, flooding and cooling

EPR Core Melt Retention

Core Melt Spreading Compartment Olkiluoto 3

Corium Spreading Test Melt spreading phenomena have been extensively investigated VULCANO (real UO 2 with some Zr O 2 )

New Build Timeline

Findings/Issues To Date http://www.hse.gov.uk/newreactors

Global earthquake activity since 1973 and nuclear power plant locations 175,000 4.5+ magnitude earthquakes since 1973 Source: http://maptd.com, IAEA, USGS

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