Advances In Small Modular Reactor Technology Developments

INTRODUCTIONThe IAEA’s Department of Nuclear Energy within its structure contains the Section for Nuclear PowerTechnology Development that is tasked to facilitate efforts of Member States in identifying key enablingtechnologies in the development of advanced reactor lines and addressing their key challenges in near termdeployment. By establishing international networks and ensuring coordination of Member State experts,publications on international recommendations and guidance focusing on specific needs of newcomercountries are issued.There is increasing interest in small modular reactors (SMRs) and their applications. SMRs are newergeneration reactors designed to generate electric power up to 300 MW, whose components and systems canbe shop fabricated and then transported as modules to the sites for installation as demand arises. Most of theSMR designs adopt advanced or even inherent safety features and are deployable either as a single or multimodule plant. SMRs are under development for all principal reactor lines: water cooled reactors, hightemperature gas cooled reactors, liquid-metal, sodium and gas-cooled reactors with fast neutron spectrum,and molten salt reactors. The key driving forces of SMR development are fulfilling the need for flexiblepower generation for a wider range of users and applications, replacing ageing fossil-fired units, enhancingsafety performance, and offering better economic affordability.Many SMRs are envisioned for niche electricity or energy markets where large reactors would not be viable.SMRs could fulfil the need of flexible power generation for a wider range of users and applications,including replacing aging fossil power plants, providing cogeneration for developing countries with smallelectricity grids, remote and off grid areas, and enabling hybrid nuclear/renewables energy systems. Throughmodularization technology, SMRs target the economics of serial production with shorter construction time.Near term deployable SMRs will have safety performance comparable or better to that of evolutionaryreactor designs.Though significant advancements have been made in various SMR technologies in recent years, sometechnical issues still attract considerable attention in the industry. These include for example control roomstaffing and human factor engineering for multi-module SMR plants, defining the source term for multimodule SMR plants with regards to determining the emergency planning zone, developing new codes andstandards, and load-following operability aspects. Some potential advantages of SMRs like the elimination ofpublic evacuation during an accident or a single operator for multiple modules are under discussion withregulators. Furthermore, although SMRs have lower upfront capital cost per unit, their generating cost ofelectricity will probably be substantially higher than that for large reactors.Currently there are more than 50 SMR designs under development for different application. Three industrialdemonstration SMRs are in advanced stage of construction: in Argentina (CAREM, an integral PWR), inPeople’s Republic of China (HTR-PM, a high temperature gas cooled reactor) and in the Russian Federation(KLT40s, a floating power unit). They are scheduled to start operation between 2019 and 2022. In addition,the Russian Federation have already manufactured six RITM-200 reactors (an integral PWR) with four unitsalready installed in the Sibir and Arktika icebreakers, to be in service in 2020.This booklet provides a brief introductory information and technical description of the key SMR designs andtechnologies under different stages of development and deployment. To assist the reader to easily understandthe status of deployment, Table 1 lists all the SMR designs with the applicable technology along with theoutput capacity, type of reactor and design institute information.The 2018 edition comprises of six (6) parts arranged in the order of the different types of coolants, theneutron spectrum adopted, and a sixth part (a new category) on other SMRs that do not make use of thetraditional coolants and/or fuel design.Part One (Land-based water-cooled SMRs) presents the key SMR designs adopting integral light waterreactor (LWR) technologies. This represents the most mature technology since it is like most of the largepower plants in operation today.1

Table 1: Summary of Main Design Features and Status of SMRs included this CNEAArgentinaUnder constructionPART 1: WATER COOLED SMALL MODULAR REACTORS (LAND BASED)CAREM30PWRACP100100PWRCNNCChinaBasic DesignCAP200150/200PWRCGNPCChinaConceptual aBasic DesignIRIS335PWRIRIS ConsortiumMultiple CountriesConceptual DesignDMS300BWRHitachi GEJapanBasic DesignIMR350PWRMHIJapanConceptual DesignSMART100PWRKAERIRepublic of KoreaCertified DesignELENA68 kW(e)PWRNational Research Centre“Kurchatov Institute”Russian FederationConceptual DesignKARAT-45/10045/100BWRNIKIETRussian FederationConceptual DesignRITM-20050 2PWROKBM AfrikantovRussian FederationUnder DevelopmentRUTA-7070 MW(t)PWRNIKIETRussian FederationConceptual DesignUNITHERM6.6PWRNIKIETRussian FederationConceptual DesignVK-300250BWRNIKIETRussian FederationDetailed DesignUK-SMR443PWRRolls-Royce and PartnersUnited KingdomMature ConceptmPower195 2PWRBWX TechnologiesUnited States ofAmericaUnder DevelopmentNuScale50 12PWRNuScale PowerUnited States ofAmericaUnder DevelopmentSMR-160160PWRHoltec InternationalUnited States ofAmericaPreliminary DesignW-SMR225PWRWestinghouseUnited States ofAmericaConceptual DesignPART 2: WATER COOLED SMALL MODULAR REACTORS (MARINE BASED)ACPR50S60PWRCGNPCChinaPreliminary DesignABV-6E6-9Floating PWROKBM AfrikantovRussian FederationFinal designKLT-40S70Floating PWROKBM AfrikantovRussian FederationUnder constructionRITM-200M50 2Floating PWROKBM AfrikantovRussian FederationUnder DevelopmentSHELF6.4Immersed NPPNIKIETRussian FederationDetailed DesignVBER-300325Floating NPPOKBM AfrikantovRussian FederationLicensing StagePART 3: HIGH TEMPERATURE GAS COOLED SMALL MODULAR REACTORS2HTR-PM210HTGRINET, Tsinghua UniversityChinaUnder ConstructionGTHTR300300HTGRJAEAJapanBasic DesignGT-MHR285HTGROKBM AfrikantovRussian FederationPreliminary DesignMHR-T205.5х4HTGROKBM AfrikantovRussian FederationConceptual DesignMHR-10025 – 87HTGROKBM AfrikantovRussian FederationConceptual DesignA-HTR-10050HTGREskom Holdings SOC Ltd.South AfricaConceptual DesignHTMR-10035HTGRSteenkampskraal ThoriumLimitedSouth AfricaConceptual DesignPBMR-400165HTGRPBMR SOC LtdSouth AfricaPreliminary DesignSC-HTGR272HTGRAREVAUnited States ofAmericaConceptual DesignXe-10035HTGRX-energy LLCUnited States ofAmericaConceptual Design

PART 4: FAST NEUTRON SPECTRUM SMALL MODULAR REACTORS4S10LMFRToshiba CorporationJapanDetailed DesignLFR-AS-200200LMFRHydromine Nuclear EnergyLuxembourgPreliminary DesignLFR-TL-X5 20LMFRHydromine Nuclear EnergyLuxembourgConceptual DesignBREST-OD-300300LMFRNIKIETRussian FederationDetailed DesignSVBR-100100LMFRJSC AKME EngineeringRussian FederationDetailed DesignSEALER3Small LeadCooledLeadColdSwedenConceptual DesignEM2265GMFRGeneral AtomicsUnited States ofAmericaConceptual DesignSUPERSTAR120LMFRArgonne NationalLaboratoryUnited States ofAmericaConceptual DesignWLFR450LFRWestinghouseUnited States ofAmericaConceptual DesignPART 5: MOLTEN SALT SMALL MODULAR REACTORSIMSR190MSRTerrestrial EnergyCanadaBasic DesignCMSR100-115MSRSeaborg TechnologiesDenmarkConceptual Design20MSRCopenhagen AtomicsDenmarkConceptual DesignCA Waste umBasic DesignFUJI200MSRInternational ThoriumMolten-Salt Forum: ITMSFJapanExperimental PhaseStable Salt Reactor37.5 8MSRMoltex EnergyUnited KingdomConceptual DesignStable Salt Reactor300 900MSRMoltex EnergyUnited KingdomPre-Conceptual DesignLFTR250MSRFlibe EnergyUnited States ofAmericaConceptual DesignMk1 PB-FHR100MSRUniversity of California,BerkeleyUnited States ofAmericaPre-Conceptual DesignMCSFR50MSRElysium IndustriesUSA and CanadaConceptual DesignWestinghouseUnited States ofAmericaUnder DevelopmentPART 6: OTHER SMALL MODULAR REACTORSeVinci0.2 15Small HeatPipePart Two (Marine-based water-cooled SMRs) presents concepts that can be deployed in a marineenvironment, either under water or on a barge. This unique application provides many and more flexibledeployment options, but also face many challenges if is to be deployed internationally, i.e. such aspermission to cross national and international waters.Part Three (High Temperature Gas Cooled SMRs) provides information on the modular type HTGRsunder development and under construction. HTGRs provide high temperature heat ( 750 C) that can beutilized for more efficient electricity generation, a variety of industrial applications as well as forcogeneration.Part Four (Fast Neutron Spectrum SMRs) presents the SMRs with fast neutron spectrum with all thedifferent coolant options. In the booklet on “Status of Innovative Fast Reactor Designs and Concepts” (seeAnnex IV) the four major fast reactor options were described. They are sodium cooled fast reactor (SFR), theheavy liquid metal-cooled (HLMC, i.e. lead or lead-bismuth) fast reactor, the gas-cooled fast reactor (GFR)and molten salt fast reactor (MSFR). In this booklet fast reactor designs with only the first three types ofcoolant are included, since none of the molten salt fast reactors are SMRs. The MSR designs included allhave thermal neutron spectra and are included in part five.Part Five (Molten Salt SMRs) presents the SMRs that utilize molten salt fuelled (and cooled) advancedreactor technology.3

Part Six (Other SMRs) presents the SMRs that cannot be classified into any of the above categories.In this booklet, effort has been made to present all SMR designs within the above categories. Eachdescription includes a general design description and philosophy, target applications, development milestone,nuclear steam supply system, a table of the major design parameters, and then descriptions of the reactorcore, engineered safety features, plant arrangement, design and licensing status. Not all small reactor designspresented can strictly be categorized as small modular reactors. Some strongly rely on proven technologiesof operating large capacity reactors, while others do not use a modular or integral design approach. They arepresented in this booklet for reason of completeness and since designers foresee certain niche markets fortheir products.The technical description and major technical parameters were provided by the design organizations withoutvalidation or verification by the IAEA. All figures, illustrations and diagrams were also provided by thedesign organizations.Annex I provides a summary as a function of different power ranges while Annex II shows SMR designsbased on the core exit coolant temperature. This may be helpful to select designs for specific power orprocess heat applications, further illustrated in Annex III for different non-electric applications.It is hoped that this Booklet will be useful to Member States with a general interest in SMRs, as well as tothose newcomer countries looking for more specific technical information. It should also further promotecontributions to and the use of the IAEA Advanced Reactor Information System (ARIS).Other recent booklets published in support of ARIS are listed in Annex IV. Annex V contains a list ofcommonly used acronyms.This booklet is a supplement to the IAEA Advanced Reactor Information System (ARIS, http://aris.iaea.org).4

WATER COOLEDSMALL MODULAR REACTORS(LAND BASED)

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CAREM (CNEA, Argentina)All content included in this section has been provided by, and is reproduced with permission of, CNEA, Argentina.MAJOR TECHNICAL PARAMETERSParameterValueTechnology developer,country of originCNEA, ArgentinaReactor typeIntegral PWRCoolant/moderatorLight water / light waterThermal/electrical capacity,MW(t)/MW(e)100/ 30Primary circulationNatural circulationSystem pressure (MPa)12.25Core inlet/exit temperatures(oC)284/326Fuel type/assembly arrayUO2 pellet/hexagonalNumber of fuel assemblies61Fuel enrichment (%)3.1% (prototype)Fuel burnup (GWd/ton)24 (prototype)Fuel cycle (months)14 (prototype)Main reactivity controlmechanismApproach to engineeredsafety systemsControl rod driving mechanism(CRDM) onlyPassiveDesign life (years)40Plant footprint(m2)Not availableRPV height/diameter (m)11/3.2RPV, internals and SGsweight (metric ton)267Seismic design0.25Distinguishing featuresDesign statusCore heat removal by naturalcirculation, pressure suppressioncontainmentUnder construction (asprototype)1. IntroductionCAREM is a national SMR development project, based on LWR technology, coordinated by Argentina’sNational Atomic Energy Commission (CNEA) in collaboration with leading nuclear companies in Argentinawith the purpose to develop, design and construct innovative small nuclear power plants with high economiccompetitiveness and level of safety. CAREM is an integral type PWR, based on indirect steam cycle withfeatures that simplify the design and support the objective of achieving a higher level of safety. CAREMreactor was developed using domestic technology, at least 70% of the components and related services forCAREM were sourced from Argentinean companies.2. Target ApplicationCAREM is designed as an energy source for electricity supply of regions with small demands. It can alsosupport seawater desalination processes to supply water and energy to coastal sites.3. Specific Design FeaturesDesign PhilosophyCAREM is a natural circulation based indirect-cycle reactor with features that simplify the design andimprove safety performance. Its primary circuit is fully contained in the reactor vessel and it does not need7

any primary recirculation pumps. The self-pressurization is achieved by balancing vapour production andcondensation in the vessel, without a separate pressurizer vessel. The CAREM design reduces the number ofsensitive components and potentially risky interactions with the environment.Some of the significant design characteristics are:-Integrated primary cooling system;Self-pressurized;Core cooling by natural circulation;In-vessel control rod drive mechanisms;Safety systems relying on passive features;Nuclear Steam Supply SystemCAREM is an integral reactor. Its high-energy primary system (core, steam generators, primary coolant andsteam dome) is contained inside a single pressure vessel. Primary cooling flow is achieved by naturalcirculation, which is induced by placing the steam generators above the core. Water enters the core from thelower plenum. After being heated, the coolant exits the core and flows up through the chimney to the uppersteam dome. In the upper part, water leaves the chimney through lateral windows to the external region. Itthen flows down through modular steam generators, decreasing its enthalpy.Reactor CoreThe reactor core of CAREM-25 has fuel assemblies of hexagonal cross section. There are 61 fuel assemblieswith about 1.4 meters active length. Each fuel assembly contains 108 fuel rods with 9 mm outer diameter, 18guide thimbles and one instrumentation thimble. The fuel is 1.8% - 3.1% enriched UO2. The fuel cycle canbe tailored to customer requirements, with a reference design for the prototype of 510 full-power days and50% of core replacement.Reactivity ControlCore reactivity is controlled using Gd2O3 as burnable poison in specific fuel rods and movable absorbingelements belonging to the adjustment and control system. Neutron poison in the coolant is not used forreactivity control during normal operation and in reactor shutdown. Each absorbing element consists of acluster of rods linked to a structural element (‘spider’), so the whole cluster moves as a single unit. Absorberrods fit into the guide tubes. The absorbent material is the commonly used Ag-In-Cd alloy. Absorbingelement

DISCLAIMER This is not an official IAEA publication. The material has not undergone an official review by the IAEA. The . Part One (Land-based water-cooled SMRs) presents the key SMR designs adopting integral light water reactor (LWR) technologies. This represents the most mature technology since it is like most of the large