EnCore™ FuelWe’re changing nuclear energy … again

EnCore Fuel Cladding and Pellet MaterialsThe chromium coated zirconium cladding will inhibit the zirconium-steam reaction, increasing LOCA margins to provide intermediate improvements in beyond-design-basis accident tolerance comparable to those offered by stainless steel alloys. Recent autoclave and irradiation tests for chromium-coated cladding have shown excellent corrosion resistance and irradiation stability. Coated cladding has a negligible neutronic penalty compared to stainless steel cladding.SiC cladding development will take longer to finalize and make available commercially, but is intended to provide revolutionary safety margin improvements. SiC cladding reacts 10,000 times slower with water and steam than zirconium, resulting in minimal generation of heat and hydrogen in beyond-design-basis accident scenarios. Since U3Si2 pellets allow significantly more uranium to be packed into the same volume than UO2, reduced fuel assembly loadings or longer fuel cycles also can be achieved while staying below the 5 percent enrichment limit. Due to a higher thermal conductivity than UO2, U3Si2 provides a safety improvement through less stored energy while allowing a much higher linear heat rate before it melts.

Westinghouse can also deliver an improved chromium-doped UO2 pellet, ADOPT™. The ADOPT pellet improves pellet clad interaction (PCI) margin, reduces wash-out in the event of a fuel rod leaker and reduces fission gas release in a transient scenario.

Enhancing Safety with Westinghouse EnCore FuelOn Dec. 2, 1957, Westinghouse changed the world when Shippingport, the first commercial nuclear power station in the U.S., came online. Today, Westinghouse is changing nuclear energy again, building on our legacy of innovation with our revolutionary new accident-tolerant fuel (ATF) design, EnCoreTM Fuel.EnCore Fuel will offer design-basis-altering safety, greater uranium efficiency and estimated economic benefits up to hundreds of millions of dollars. Delivered in two phases, the initial EnCore Fuel product is comprised of coated cladding loaded with uranium silicide pellets, which set EnCore Fuel apart from other accident-tolerant fuel solutions because of their higher density and higher thermal conductivity. The reduced oxidation and hydrogen pickup of the coated cladding during normal operation (250° - 350°C) is intended to prolong cladding life, provide enhanced resistance to wear and increase margins, allowing use of higher density pellets.

The coated cladding also supports extended exposure to high temperature steam and air (1300° - 1400°C) during a loss-of-coolant accident (LOCA), reactivity-initiated accident (RIA) and beyond-design-basis conditions. The second phase of EnCore Fuel features silicon-carbide (SiC) cladding, which is intended to offer significant safety benefits in beyond-design-basis accident scenarios, enabled by its extremely high melting point and minimal reaction with water. While current Westinghouse fuel designs have operated extremely well under normal plant conditions, any existing nuclear fuel designs can be challenged under beyond-design-basis severe-accident scenarios. In the event of a beyond-design-basis condition, the long-term loss of coolant and the resulting high temperatures of the fuel can lead to the degradation of the fuel cladding and the release of fission products, such as what occurred in both the Three Mile Island and Fukushima accidents. EnCore Fuel is “game changing” for the nuclear industry, significantly increasing safety margins in severe accident scenarios.

U3Si2 Based Fuel Key CharacteristicsUO2 U3Si2 Improvement

Uranium Content (gm/cm3) 9.66 11.3 17%

Average Thermal Conductivity (w/cm/°C) 0.032 0.209 550%

Max. Power to Centerline Melt (Kw/ft) 22.5 94 318%

Fuel Cycle Costs ($/MWhre)

$9.21 $8.87 -3.6%

Enhanced safety. Game-changing economics. Clean energy.

3000ºC

2500ºC

2000ºC

1500ºC

1000ºC

500ºC

0ºC

330°COperating core temperature

1200°CHydrogen and heat generation from Zirconium - H2O reaction

1850°CZircaloy-2 melting point

1900°CHydrogen generation from SiC – H2O reaction

2800°C(or higher) SiC melting point

1450°CStainless steel melting point

Fuel Assembly StructureMaterials and modifications to existing fuel assembly design structures have been identified to support the EnCore Fuel features. Zirconium-based structures appear to be feasible for both SiC and coated cladding. Further evaluation and confirmatory testing will be performed to demonstrate that adequate margins exist to support the increased uranium weight, changes in pressure drop and heat transfer rate of EnCore Fuel. Lead test rods (LTRs) will utilize current fuel assembly designs with a combination of UO2 and U3Si2 rods to minimize structural impacts.

Codes and Methods for EnCore Fuel ModellingEfforts on codes and methods for EnCore Fuel are being prioritized, with early focus on what will be needed for LTR and lead test assembly (LTA) design and licensing. Modifications will be made to incorporate properties and characteristics of the new claddings and fuel pellet materials, including empirical data from critical experiments to support full-region licensing.

Licensing InitiativesLicensing of the EnCore Fuel design will be implemented in three stages – LTRs, LTAs and full regions. The U.S. Nuclear Regulatory Commission (NRC) has been engaged to obtain guidance, and an initial review of NRC Standard Review Plan 4.2 Criteria has been completed.Actions needed for LTR and LTA licensing are currently being defined. Additional effort and data is required to address:• Licensing of full regions• Taking credit for EnCore Fuel for full operation and

maintenance cost benefits

Utility BenefitsEnCore Fuel’s economic benefits come from fuel cycle impacts of replacing UO2 with U3Si2 and from positive impacts on plant core damage frequencies, primarily from incorporating coated zirconium and SiC composite cladding. Along with the increased safety margins inherent in accident-tolerant fuels, utility benefits will be realized from the following:• Risk-based technical specifications and resulting relaxed

requirements for testing, safety class designation of equipment and systems, redundancy (allowing elimination of equipment / systems), procurement;

• Reduction in the emergency planning and evacuation zones; and

• Improved fuel cycle economics estimated at $2.9M for 1000 MWe, 18-month cycles.

Program MilestonesTest fuel rods manufactured in 2017 will undergo exposure in the Advanced Test Reactor (ATR) and TREAT reactor at Idaho National Laboratory and the Halden Reactor in Norway to develop the data required for licensing as a prelude to loading lead test assemblies in commercial reactors. The test protocols will include PWR operating conditions and transient tests.The current schedule targets insertion of LTRs and LTAs in reactors by 2022, with LTRs manufactured as early as 2018.

2003 – 2012Westinghouse program explored SiC cladding and fuel options U3Si2

2012 – 2015DOE Phase 1A:Westinghouse and DOE initiate U3Si2 testing at the ATR and develop coatings and SiC cladding technologies

2014 – 2016DOE Phase 1B:Irradiation in ATR in PWR conditions; licensing and manufacturing development for LTRs/LTAs

2016 – 2022DOE Phase 2:Irradiation in test reactors; PWR operating conditions and transient tests; licensing and manufacturing development for LTRs/LTAs

2019 – 2022EnCore Fuel LTR irradiation begins

2022 – 2026Irradiation of EnCore Fuel LTAs begins

2026+EnCore Fuel full region implementation

CoatedZr w/ U3Si2

U3Si2UN Fuel pellets

Zr-Alloys TiN/TiAlN coatingCr coating

Fuel rod claddings SiC/SiC composites

FeCrAlY coating

SiC / SiCw/ U3Si2

EnCore and ADOPT are trademarks of Westinghouse Electric Company LLC, its subsidiaries and/or its affiliates in the United States. This mark may also be used and/or registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited.

Global Project Partners and RolesThe pursuit of accident-tolerant fuel is being carried out by an international, multidisciplinary team, funded in part by the U.S. Department of Energy direct awards to Westinghouse, General Atomics and several of the United States national labs. The team members and their primary missions on this project include:• Westinghouse Electric Company LLC – Program lead

and fuel design• General Atomics – SiC/SiC composite cladding

development• Ceramic Tubular Products and United Technologies

Research Center – SiC cladding manufacturing development

• Idaho National Laboratory – High Density Fuels (U3Si2), Irradiation Testing (Advanced Test Reactor, TREAT), and Post-irradiation Examination

• National Nuclear Laboratory (United Kingdom) – U3Si2 powder and pellets

• Los Alamos National Laboratory – Studies on U3Si2 oxidation and manufacturing development

• Massachusetts Institute of Technology – In-reactor testing of SiC/SiC composites and coated Zr cladding out-of-reactor high temperature oxidation and quench studies

• Institute for Energy Technology (Norway) – Test rod assembly and testing

• Southern Nuclear Operating Company and Exelon Nuclear – Customer-based evaluation of ATF

• University of Wisconsin – Coated Zr rods• Paul Scherrer Institute (Switzerland) – Evaluation

of SiC properties

Westinghouse Electric Company1000 Westinghouse DriveCranberry Township, Pennsylvania 16066

www.westinghousenuclear.com

©2017 Westinghouse Electric Company, LLC. All Rights Reserved. 06/2017 12190

Testing of the EnCore Fuel silicon carbide cladding at greater than 1300ºC at the Westinghouse ultra-high temperature (UHT) facility.

Westinghouse EnCore Fuel:

Provides significantly

increased safety margins in severe accident scenarios

The suite of EnCore Fuel

products offers economic

benefits of up to hundreds of

millions of dollars

Accelerated delivery timeline

Superior design provides

enhanced fuel cycle and

plant economics

World's largest supplier of

nuclear fuel with world-class

partner network