ASSESSMENT OF GAS COOLED FAST REACTOR WITHINDIRECT SUPERCRITICAL CO2 CYCLE

P. HEJZLAR1, M.J. DRISCOLL,V. DOSTAL,P. DUMAZ, G. POULLENNEC, N. ALPY 한국원자력학회 2006 Nuclear Engineering and Technology Vol.38 No.2

ASSESSMENT OF GAS COOLED FAST REACTOR WITH INDIRECT SUPERCRITICAL $CO_2$ CYCLE

Hejzlar, P.,Dostal, V.,Driscoll, M.J.,Dumaz, P.,Poullennec, G.,Alpy, N. Korean Nuclear Society 2006 Nuclear Engineering and Technology Vol.38 No.2

Various indirect power cycle options for a helium cooled gas cooled fast reactor (GFR) with particular focus on a supercritical $CO_2(SCO_2)$ indirect cycle are investigated as an alternative to a helium cooled direct cycle GFR. The balance of plant (BOP) options include helium-nitrogen Brayton cycle, supercritical water Rankine cycle, and $SCO_2$ recompression Brayton power cycle in three versions: (1) basic design with turbine inlet temperature of $550^{\circ}C$, (2) advanced design with turbine inlet temperature of $650^{\circ}C$ and (3) advanced design with the same turbine inlet temperature and reduced compressor inlet temperature. The indirect $SCO_2$ recompression cycle is found attractive since in addition to easier BOP maintenance it allows significant reduction of core outlet temperature, making design of the primary system easier while achieving very attractive efficiencies comparable to or slightly lower than, the efficiency of the reference GFR direct cycle design. In addition, the indirect cycle arrangement allows significant reduction of the GFR &proximate-containment& and the BOP for the $SCO_2$ cycle is very compact. Both these factors will lead to reduced capital cost.

TERRAPOWER, LLC TRAVELING WAVE REACTOR DEVELOPMENT PROGRAM OVERVIEW

Hejzlar, Pavel,Petroski, Robert,Cheatham, Jesse,Touran, Nick,Cohen, Michael,Truong, Bao,Latta, Ryan,Werner, Mark,Burke, Tom,Tandy, Jay,Garrett, Mike,Johnson, Brian,Ellis, Tyler,Mcwhirter, Jon,Odedra, Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.6

Energy security is a topic of high importance to many countries throughout the world. Countries with access to vast energy supplies enjoy all of the economic and political benefits that come with controlling a highly sought after commodity. Given the desire to diversify away from fossil fuels due to rising environmental and economic concerns, there are limited technology options available for baseload electricity generation. Further complicating this issue is the desire for energy sources to be sustainable and globally scalable in addition to being economic and environmentally benign. Nuclear energy in its current form meets many but not all of these attributes. In order to address these limitations, TerraPower, LLC has developed the Traveling Wave Reactor (TWR) which is a near-term deployable and truly sustainable energy solution that is globally scalable for the indefinite future. The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared to conventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowest cost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferation concerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generation infrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need to be built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costs and 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel. With advanced technological development and added cost, TWRs are also capable of reusing both their own used fuel and used fuel from LWRs, thereby eliminating the need for enrichment in the longer term and reducing the overall societal waste burden. This paper describes the origins and current status of the TWR development program at TerraPower, LLC. Some of the areas covered include the key TWR design challenges and brief descriptions of TWR-Prototype (TWR-P) reactor. Selected information on the TWR-P core designs are also provided in the areas of neutronic, thermal hydraulic and fuel performance. The TWR-P plant design is also described in such areas as; system design descriptions, mechanical design, and safety performance.

TerraPower, LLC Traveling Wave Reactor Development Program Overview

PAVEL HEJZLAR,Rovert Petroski,Jesse Cheatham,Nick Touran,Michael Cohen,Bao Truong,Ryan Latta,Mark Werner,Tom Burke,Jay Tandy,Mike Gattett,Brian Johnson,Tyler Ellis,Jon Mcwhirter,Ash Odedra,Pat Schweig 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.6

Energy security is a topic of high importance to many countries throughout the world. Countries with access to vast energy supplies enjoy all of the economic and political benefits that come with controlling a highly sought after commodity. Given the desire to diversify away from fossil fuels due to rising environmental and economic concerns, there are limited technology options available for baseload electricity generation. Further complicating this issue is the desire for energy sources to be sustainable and globally scalable in addition to being economic and environmentally benign. Nuclear energy in its current form meets many but not all of these attributes. In order to address these limitations, TerraPower, LLC has developed the Traveling Wave Reactor (TWR) which is a near-term deployable and truly sustainable energy solution that is globally scalable for the indefinite future. The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared to conventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowest cost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferation concerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generation infrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need to be built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costs and 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel. With advanced technological development and added cost, TWRs are also capable of reusing both their own used fuel and used fuel from LWRs, thereby eliminating the need for enrichment in the longer term and reducing the overall societal waste burden. This paper describes the origins and current status of the TWR development program at TerraPower, LLC. Some of the areas covered include the key TWR design challenges and brief descriptions of TWR-Prototype (TWR-P) reactor. Selected information on the TWR-P core designs are also provided in the areas of neutronic, thermal hydraulic and fuel performance. The TWR-P plant design is also described in such areas as; system design descriptions, mechanical design, and safety performance. Energy security is a topic of high importance to many countries throughout the world. Countries with access to vast energysupplies enjoy all of the economic and political benefits that come with controlling a highly sought after commodity. Given thedesire to diversify away from fossil fuels due to rising environmental and economic concerns, there are limited technologyoptions available for baseload electricity generation. Further complicating this issue is the desire for energy sources to besustainable and globally scalable in addition to being economic and environmentally benign. Nuclear energy in its currentform meets many but not all of these attributes. In order to address these limitations, TerraPower, LLC has developed theTraveling Wave Reactor (TWR) which is a near-term deployable and truly sustainable energy solution that is globally scalablefor the indefinite future. The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared toconventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowestcost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferationconcerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generationinfrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need tobe built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costsand 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel. Withadvanced technological development and added cost, TWRs are also capable of reusing both their own used fuel and used fuelfrom LWRs, thereby eliminating the need for enrichment in the longer term and reducing the overall societal waste burden. This paper describes the origins and current status of the TWR development program at TerraPower, LLC. Some of the areascovered include the key TWR design challenges and brief descriptions of TWR-Prototype (TWR-P) reactor. Selectedinformation on the TWR-P core designs are also provided in the areas of neutronic, thermal hydraulic and fuel performance. The TWR-P plant design is also described in such areas as; system design descriptions, mechanical design, and safetyperformance.

Reactor Physics Challenges in GEN-IV Reactor Design

MICHAEL J. DRISCOLL,PAVEL HEJZLAR 한국원자력학회 2005 Nuclear Engineering and Technology Vol.37 No.1

An overview of the reactor physics aspects of Generation Four(GEN-IV) advanced reactors is presented, emphasizing how their special requirements for enhanced sustainability, safety and ecoomics motivates consideration of features not thoroughly analyzed in the past. The resulting concept-specific requirements for better data and methods are surveyed, and some approaches and initiatives are suggested to meet the challenges faced by the international reactor physics community. No unresolvable impediments to successful development of any of the six major types of proposed reactors are identified, given appropriate and timely devotion of resources.

REACTOR PHYSICS CHALLENGES IN GEN-IV REACTOR DESIGN

DRISCOLL MICHAEL J.,HEJZLAR PAVEL Korean Nuclear Society 2005 Nuclear Engineering and Technology Vol.37 No.1

An overview of the reactor physics aspects of Generation Four(GEN-IV) advanced reactors is presented, emphasizing how their special requirements for enhanced sustainability, safety and ecoomics motivates consideration of features not thoroughly analyzed in the past. The resulting concept-specific requirements for better data and methods are surveyed, and some approaches and initiatives are suggested to meet the challenges faced by the international reactor physics community. No unresolvable impediments to successful development of any of the six major types of proposed reactors are identified, given appropriate and timely devotion of resources.

Evaluation of system codes for analyzing naturally circulating gas loop

Lee, J.I.,No, H.C.,Hejzlar, P. North-Holland Pub. Co 2009 Nuclear engineering and design Vol.239 No.12

Steady-state natural circulation data obtained in a 7m-tall experimental loop with carbon dioxide and nitrogen are presented in this paper. The loop was originally designed to encompass operating range of a prototype gas-cooled fast reactor passive decay heat removal system, but the results and conclusions are applicable to any natural circulation loop operating in regimes having buoyancy and acceleration parameters within the ranges validated in this loop. Natural circulation steady-state data are compared to numerical predictions by two system analysis codes: GAMMA and RELAP5-3D. GAMMA is a computational tool for predicting various transients which can potentially occur in a gas-cooled reactor. The code has a capability of analyzing multi-dimensional multi-component mixtures and includes models for friction, heat transfer, chemical reaction, and multi-component molecular diffusion. Natural circulation data with two gases show that the loop operates in the deteriorated turbulent heat transfer (DTHT) regime which exhibits substantially reduced heat transfer coefficients compared to the forced turbulent flow. The GAMMA code with an original heat transfer package predicted conservative results in terms of peak wall temperature. However, the estimated peak location did not successfully match the data. Even though GAMMA's original heat transfer package included mixed-convection regime, which is a part of the DTHT regime, the results showed that the original heat transfer package could not reproduce the data with sufficient accuracy. After implementing a recently developed correlation and corresponding heat transfer regime map into GAMMA to cover the whole range of the DTHT regime, we obtained better agreement with the data. RELAP5-3D results are discussed in parallel.

Safety Analysis of High-Power-Density Annular Fuel for PWRs

Feng, D.,Morra, P.,Sundaram, R.,Lee, W.-J.,Saha, P.,Hejzlar, P.,Kazimi, M. S. AMERICAN NUCLEAR SOCIETY 2007 Nuclear technology Vol.160 No.1

Design of a direct-cycle supercritical CO2 nuclear reactor with heavy water moderation

Robert Petroski,Ethan Bates,Benoit Dionne,Brian Johnson,Alex Mieloszyk,Cheng Xu,Pavel Hejzlar 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3

A new reactor concept is described that directly couples a supercritical CO2 (sCO2) power cycle with aCO2-cooled, heavy water moderated pressure tube core. This configuration attains the simplification andeconomic potential of past direct-cycle sCO2 concepts, while also providing safety and power densitybenefits by using the moderator as a heat sink for decay heat removal. A 200 MWe design is describedthat heavily leverages existing commercial nuclear technologies, including reactor and moderator systemsfrom Canadian CANDU reactors and fuels and materials from UK Advanced Gas-cooled Reactors(AGRs). Descriptions are provided of the power cycle, nuclear island systems, reactor core, and safetysystems, and the results of safety analyses are shown illustrating the ability of the design to withstandlarge-break loss of coolant accidents. The resulting design attains high efficiency while employingconsiderably fewer systems than current light water reactors and advanced reactor technologies, illustratingits economic promise. Prospects for the design are discussed, including the ability to demonstrateits technologies in a small (~20 MWe) initial system, and avenues for further improvement of the designusing advanced technologies.