Marc A Wonders, Pierre-Clement Simon, Matthew Durbin, Pierre Bouhaddane, Will Searight The Pennsylvania State University, Ken and Mary Alice Lindquist Department of Nuclear Engineering

Introduction- Why Nuclear? Small Modular Reactors Generation IV Reactor Types • Generally reactors with generating capacities below 300 MWe (as opposed to ~1000 • Thermal vs Fast Reactors MWe) and designed with modular technology fabricated in factories. • Nuclear energy reliably supplies baseload energy • Refers to the energy • Economies of scale are replaced with economies of serial factory production • Low greenhouse gas emissions spectrum of neutrons • Cost-savings, improved manufacturing quality

inducing fission Table A.III.2 (Emissions (Emissions Table A.III.2selected of electricity supply technologies (gCO 2eq/kWh))" "IPCC Working Group III"IPCC • Lowering start-up costs and offering possibility of generating income before full site

ebook_1.pdf •

- Fast neutrons have

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- higher energy and can –

Mitigation Mitigation of Change,Climate IIMetrics Annex and Methodology • Smaller sizes make inherent safety and security easier to implement generation

- fission more isotopes next • Increased flexibility and versatility for novel locations and applications - including 238U

• Safety and Security by Design: incorporation of safety/security early in design process to nuclear/technology/the

- • Slow neutrons can only

/sites/prod/files/2019/01/f58/Ultimate%20Fast%20Facts%20Guide more efficiently yield effective safety/security. Examples features: fission fissile isotopes

– • Fully passive, natural convection cooling and air ventilation to remove decay heat www.energy.gov like 235U, but the (inherent safety in “physics”, not “engineering”) http://nuclearconnect.org/know likelihood of doing so is • Underground operation/resistance to projectile attacks much higher • No on-site refueling and longer fuel cycles • Land and material-efficient • Different physics involved 235 1 • Simpler design/fewer shutdown systems and components • Energy density of U is 2,000,000-3,000,000 greater than oil or coal leads to different 1www.euronuclear.org/info/encyclopedia/f/fuelcomparison.htm • Smaller physical footprints advantages of each type

Land use for different sources of electricity Case Study: NuScale Small Modular Reactor

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- Generation IV Thermal Reactors Generation IV Fast Reactors

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- Stevens, Stevens, of StrataL “The Policy. Footprint of Energy: Use Land of U.S. ElectricityProduction” Supercritical Water Reactor: Sodium-cooled fast reactor:

/2018/06/22/nuscales • Improvements in thermal efficiency over • Fast neutron spectrum

jamesconca normal water-cooled reactors more effectively uses /sites/ • Reactor coolant pumps unnecessary and uranium resources containment can be substantially smaller www.forbes.com • Nuclear is part of the most effective clean energy portfolios NuScale Model Plant showing five reactor modules Higher temperatures and • Challenges with heat transfer model lower pressures than From https:// From validation, and qualification of materials current reactors for

• Features- fully passive convection cooling in www.nuscalepower.com improved efficiency and operation and after shutdown for an indefinite safety

period; 24-month refueling cycle; installation in a /benefits/simplified • Most mature fast reactor design

water-filled pool below ground level; fully digital - Very High Temperature Reactor: design • Challenges with chemical How is it currently done? control system based on field programmable gate • High outlet temperatures could be reactivity of sodium 1 useful for industrial arrays applications/cogeneration of hydrogen • Commercial nuclear reactors are light water reactors and typically come in • 2018- Nuclear Regulatory Commission concluded • Uses special TRISO fuel that is a coated particle holding in uranium- “un- that NuScale’s design eliminated the need for class Lead-cooled fast reactor: two kinds, pressurized water reactors (~65% of reactors in the United States) meltable” • Similar to sodium-cooled 1E backup power, which is currently required for • High inherent safety, high thermal and boiling water reactors. Normal water serves as coolant and moderator, fast reactor but with lead- all U.S. nuclear power plants2 efficiency based coolant 2 • Challenges with high demands on generating a “thermal” or slow neutron energy spectrum for fission. • 2026- Expected to be commercially operational • Low pressure operation,

1 structural materials http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/small-nuclear-power-reactors.aspx

2International Atomic Energy Agency, “Advances in Small Modular Reactor Technology Developments,” A supplement to IAEA Advanced Reactors Information System 2018 Edition, Sep. 2018. good thermodynamic and www.energy.gov neutronics properties,

/sites/prod/files/2019/01/f58/Ultimate%20Fast%20Facts%20Guide and relative inertness Chinergy’s HTR-PM with air/water • Enhanced safety • To be connected to electric grid this • Challenges: high melting year (2019) as first deployed SMR temperature of lead, 3 TRISO fuel pellet cross section opacity, high coolant

and Gen IV reactor From www.blog.ngnpalliance.org/triso-fuel-news/ - ebook_1.pdf mass, and potential

3 corrosion 3www.neimagazine.com/features/featurehtr-pm-making-dreams-come-true-7009889/ Depiction of Chinergy’s HTR-PM Reactor

SMRs offer inherently safe, versatile, and economical energy options Molten Salt Reactor: Gas-cooled fast reactor: • Uranium fuel is typically enriched in the fissile isotope 235U up to 3.5-5% and • Unique fuel composition: fuel • Combines benefits of fast is dissolved in molten fluoride reactors with high temperature systems fabricated into UO2 ceramic pellets. salt that serves as coolant • Potential for online refueling, (efficiency and multiple- radiation damage of fuel purpose systems; fuel

Micro Reactors management) pellets

- unimportant, homogenous fuel - • https:// isotopic fuel Challenges: Poor heat www.energy.gov • Also called very small modular reactors (vSMRs) • Inherent safety in case of transfer and without graphite for thermal

/photos/yucca meltdown (draining of fuel) /media/342545/view/nuclear • Similar to SMRs but on even smaller scales (1-10

• Challenges with safeguards inertia; severe materials -

mountain MWe) requirements www.sciencephoto.com

https:// • Factory fabricated and transportable www.gen-4.org/gif/jcms/c_59461/generation-iv-systems • Targeted for even more remote or isolated www.gen-4.org/gif/jcms/c_59461/generation-iv-systems

locations Depiction of Megapower vSMR from Los Alamos National Laboratory Benefits: From www.lanl.gov/discover/publications/1663/2019-february/_assets/docs/1663-33-Megapower.pdf Benefits: • Refueling cycles typically last 18-24 months at which point used nuclear fuel • More versatile applications- seawater desalination, • Primary appeal of fast reactors is fuel management: • Cogenerative applications and industrial use is stored in wet storage (spent fuel pools) for up to five years, followed by dry district heating, hydrogen production, etc. closed fuel cycle • Higher thermal efficiencies • Military applications-operating bases to reduce • Fast neutron spectrum enables fissioning of many storage. • Enabling of more compact reactors fuel transportation losses nuclides, breeding of fissile material, and • Considerations throughout the process: safety and security (redundant safety • Novel fuel types with inherent safety • Could be used for emergency response to help transmutation of undesirable waste nuclides to features, backup power requirements, etc.), proliferation (safeguards, export restore power reduce waste burden controls, etc.), economics, used nuclear fuel storage • Longer core life-up to ten years without refueling Gen IV improves efficiency and safety while offering • Enables recycling of used nuclear fuel as a fuel source additional applications. Fast reactors enable While nuclear energy is currently clean and safe, advanced nuclear reactors https://www.energy.gov/sites/prod/files/2019/01/f58/Ultimate%20Fast%20Facts%20Guide-ebook_1.pdf • Can also be smaller and simpler than light-water based Filippone and Associates LLC’s Holos Gas-cooled Hardened Micro Modular Reactor improved fuel utilization and reduced waste production reactors would greatly aid in the continued use and further development of nuclear energy From www.nextbigfuture.com/wp-content/uploads/2017/07/fccb6b3b2f1058fbadee21cefa9403b3.png

Advanced Nuclear: Small Modular Reactors Conclusions Outlook-Near Term Developments Advanced reactors are a significant departure from previous reactor designs. While currently deployed nuclear Global Developments-Gen IV on the way! (SMRs) and Generation IV reactor designs provide reliable, clean, and safe energy and should be maintained, exciting new reactors are on • Chinergy’s HTR-PM (High Temperature Reactor-Pebble Bed Module) is scheduled to begin electricity the horizon. generation in 20191 • Russia’s BN-800 sodium-cooled fast reactor was completed in 2016 and is capable of producing 880 MWe2 Small modular reactors and micro reactors 1https://www.nextbigfuture.com/2019/04/will-new-nuclear-reactors-displace-coal.html SMRs Gen IV 2http://www.world-nuclear-news.org/NN-Russian-fast-reactor-reaches-full-power-1708165.html • Improve economic competitiveness and have reduced start-up capital costs of nuclear reactors • Larger scale (>300 • Light-water Gen • Advanced reactors • Possess greater flexibility in power production capacities to accommodate more locations and applications III+ (i.e. NuScale) based on different MWe) advanced In the United States- • More similar to concepts and reactors • Enable higher levels of inherent safety, security, and safeguards by design NuScale Small Modular Reactor: traditional efficiently designed. • 2018- Completed first and most intensive phase of review by Nuclear Regulatory Commission technology but • Many different Generation IV reactors • 2019- NuScale also signed a service agreement with Canadian Nuclear Safety Commission to submit an application under their with additional options- most likely • Utilize designs with greater inherent efficiencies engineered near-term pre-licensing Vendor Design Review advantages implementation of • Employ fast neutron spectra that enables much more comprehensive and effective fuel management • September, 2020- Nuclear Regulatory Commission scheduled to complete its review process Gen IV (i.e. HTR-PM in including recycling used nuclear fuel, reducing the quantity and quality of used nuclear fuel, and • 2026- First NuScale plant is scheduled to be operated by Utah Associated Municipal Power Systems China) transmutation of less desirable heavy elements www.nuscalepower.com/newsletter/nucleus-summer-2019/program-development-update • Provide industrial cogeneration capabilities Legislative Support: Advanced nuclear reactors bring a wide range of dramatic benefits to Nuclear Energy Innovation Capabilities Act (NEICA) passed in September 2018; Nuclear Energy Innovation and Modernization Act revitalize the industry as is necessary for the most effective climate (NEIMA) passed in January, 2019; Nuclear Energy Leadership Act (NELA) currently in the full Senate (September, 2019). All aim to remove roadblocks to advanced nuclear in the United States and support their development from multiple angles. en.wikipedia.org/wiki/Generation_IV_reactor drawdown- the future is bright! www.nei.org/news/2019/advanced-reactor-bills-congress-leading-clean