Clean and Sustainable Nuclear Power Srikumar Banerjee Homi Bhabha Chair Professor, Bhabha Atomic Research Centre 6th Nuclear Energy Conclave, October 14, 2014

World Electricity Distribution % Population not having access to electricity 20% of World population (1300 million) 25% of India’s population (300 million) Earth at night Per Capita Electricity Consumption in kWh

Near-Term Energy Supply– Indian Scenario Meeting this requirement by burning fossil fuels (Coal) would result in 3-4 billion tonnes of CO2 emission Solution lies in enhanced deployment of primary energy sources : Solar Wind Nuclear 9% Growth 8% Growth Renewable + hydro potential Currently Installed Capacity ~ 220GWe 66% 12% 19% 3%

Projected Electricity Demand in 2032 Population in India in 2030 : 1.3 Billion (lower bound estimate) Per Capita Electricity Consumption to match present world average : 2500 KWh Total Demand of Electricity : 3250 TWh Total Electricity Consumption in 2011-12 : 770 TWh India needs at least 4 fold increase in electricity consumption / production in next two decades To control Carbon foot print capacity enhancement to be targeted Solar : 5 to 50 GW 220 TWh per year 25% capacity factor (intermittent) Wind : 15 to 50 GW Nuclear : 5 to 60 GW 450 TWh per year 85% capacity factor

Average Capacity Factors Wind : 25% Solar : 20% Nuclear : 90% Average Capacity Factors Footprint for 10 GW Installations Primary Energy Sources Distributed & Intermittent Source Concentrated & Continuous Source 5000 sq.Km 400 sq.Km 1 sq.Km

Conversion from fertile to fissile materials    232Th 233Th 233Pa 233U 1.4 x 1010 y 7.37 barns 22.3 min 1500 barns 27 days 20 barns 1.59 x 105 y a 47 b ; f 530 b Fertile Fissile   238U 239U  239Np 239Pu n 4.5 x 109 y 2.7 barns 23.5 min 22 barns 2.36 days 32 barns 2.4 x 104 y a 270 b ; f 752 b Fissile Fertile

Fertile partly converted Once Through Fuel Cycle Fuel cycle options Fuel Fissile+Fertile Fissile partly spent Fertile partly converted Spent Fuel Repository Nuclear Reactor Huge energy potential !! Once Through Fuel Cycle Fuel Fissile+Fertile Fissile partly spent Fertile partly converted Reprocessing Nuclear Reactor Fertile + Fissile Long lived waste Repository Fuel Manufacturing Closed Fuel Cycle

Adopting closed fuel cycle also reduces nuclear waste burden. Natural decay of spent fuel radiotoxicity With early introduction of fast reactors using (U+Pu+Am) based fuel, long term raditoxicity of nuclear waste will be reduced. 300 years Radiotoxicity of spent fuel is dominated by : FPs for first 100 years. subsequently, Pu (>90%) After Pu removal Minor Actinides specially Am (~ 9%) 200,000 years

Attractive Features of Thorium / Thoria High Abundance Uniformly distributed in earth crust 3 to 4 times abundant than uranium Better Fuel Performance Characteristics Higher melting point Better thermal conductivity Lower fission gas release Good radiation resistance Dimensional stability Better compatibility with coolant Relative ease in Waste Management No oxidation -Superior behavior Direct disposal in repository Generates less Pu and minor actinides Proliferation Resistant Spent fuel difficult to divert for weapon applications Sand containing monazite in Kerela (India) beach Minor actinide (g/T) U235 + U 238 U233 + Th232 Np 900 3 Am 470 0.0018 Cm 220 0.00064 Minor Actinides in Spent Fuel

Th based Fuels are attractive for both Thermal & Fast Reactors U233 has excellent nuclear characteristics both in thermal and fast neutron spectrum. Th is excellent host for Pu and enables deeper burning of Pu. Using external fissile material U235, Pu or an external accelerator driven neutron source,Th-U233 cycle can be made self sustaining .

Deploying Thorium Energy: Three approaches Thorium fuel in solid form in conventional reactors Thorium as fuel in molten salt reactors Accelerator-driven subcritical reactors using thorium fuel Irradiated in Indian power reactor KAMINI reactor in India (1996) ThO2-PuO2 fuel Burnup 18,400MWd/t UO2 fuel Burnup 15,000MWd/t 30kW experimental U233 (20wt%)-Al fuel Light Water Moderator and coolant Higher fission gas retention capability in ThO2 fuel

Thorium in Solid Fuel Reactor Advanced Heavy Water Reactor (AHWR) AHWR is a 300 MWe vertical pressure tube type, boiling light water cooled and heavy water moderated reactor using 233U-Th MOX and Pu-Th MOX fuel, and Low enriched U with Th. Major design objectives A large share of power from Thorium based fuel Several passive features No radiological impact in public domain Passive shutdown system to address extreme threat scenarios. Design life of 100 years. Easily replaceable coolant channels. Th-233U MOX Pu-Th MOX AHWR can be configured to accept a range of fuel types including enriched U, U-Pu MOX, Th-Pu MOX, and 233U-Th MOX in full core Low Enriched Uranium (LEU) Inner ring:18.0% LEUO2 Middle ring: 22.0% LEUO2 Outer 22.5% LEUO2

Thorium in Molten Salt Reactor Emergency Tanks Heat Exchanger-1 Heat Exchanger-2 To Turbine and generator Reactor Tank containing Fuel Salt under circulation Reprocessing plant Fission product removal Addition of fissile material Safe : Liquid fuel, No meltdown possibility, Passive shutdown by fuel dumping Minimal Waste : Online burning of long lived isotopes, Reduced higher Actinides Efficient : Higher operating temperature

Thorium utilization in Accelerator driven subcritical system In a sub-critical nuclear reactor, fission neutrons supplemented by external supply of neutrons produced in a spallation reaction, High neutron yield (~20 per proton) Neutrons used for fertile to fissile conversion – Th232 to U233 (Fissile factory) Incineration of long lived radio isotopes Spallation reaction 1 GeV proton beam Accelerator Subcritical reactor Spallation target

Indian Prototype Fast Breeder Reactor Core Layout Radial Blanket (U238/Th232) Axial Blanket Thermal Power (MWth) : 1250 Electrical output (MW): 500 Fuel material : (U,Pu)O2 Coolant : Molten Sodium

Indian Three Stage Nuclear Programme Stage 1 : Power generation and building fissile inventory for Stage 2 Stage 2 : Expanding power programme and building U233 inventory Stage 3: Thorium fuel for sustainable nuclear energy 2/3 energy from Thorium fuel Passive cooling and shutdown for safety 540 MW pressurized Heavy Water reactor (PHWR) Advanced Heavy Water Reactor (AHWR) Fast Breeder Reactor

Summary The Closed Nuclear Fuel Cycle can be a sustainable and environmentally benign energy source which can meet the base load requirement for the entire world for several centuries The Thorium – Uranium 233 fuel cycle is associated with significantly reduced radiotoxicity of the nuclear waste For the long term sustainability of Thorium – Uranium 233 fuel cycle a sufficient inventory of fissile materials (U235 and Pu239) needs to be generated Spallation neutrons from high energy accelerators can augment fissile inventory and can make Thorium – Uranium 233 fuel cycle self sustaining

Paradigm Shift Burning fossil fuel Usage of primary energy Forest Fire Thermal Power Fire Stone Discovery Wind Energy Solar Energy Nuclear Energy Thank you for your attention…