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Hermes CP Doc - Presentation for the 5-22-2023 Pre-Submittal Meeting on Kairos Power Fuel Qualification Supporting the Hermes Operating License Application
	ML23139A270
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Issue date:	05/19/2023
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From: Samuel Cuadrado de Jesus Sent: Friday, May 19, 2023 5:22 PM To: KairosPower-CPDocsPEm Resource

Subject:

Presentation for the 5-22-2023 PreSubmittal Meeting on Kairos Power Fuel Qualification Supporting the Hermes Operating License Application Attachments: Presentation for the 5-22-2023 PreSubmittal Meeting on Kairos Power Fuel Qualification Supporting the Hermes Operating License Application.pdf

Samuel Cuadrado de Jesús Project Manager Advanced Reactor Licensing Branch (UARL)

Division of Advanced Reactors and Non-Power Production and Utilization Facilities (DANU)

U.S. Nuclear Regulatory Commission Phone: 301-415-2946 Samuel.CuadradoDeJesus@nrc.gov

Hearing Identifier: KairosPower_CPDocs_Public Email Number: 40

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Presentation for the 5-22-2023 Pre-Submittal Meeting on Kairos Power Fuel Qualification Supporting the Hermes Operating License Application Sent Date: 5/19/2023 5:22:11 PM Received Date: 5/19/2023 5:22:16 PM From: Samuel Cuadrado de Jesus

Created By: Samuel.CuadradoDeJesus@nrc.gov

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Files Size Date & Time MESSAGE 333 5/19/2023 5:22:16 PM Presentation for the 5-22-2023 Pre-Submittal Meeting on Kairos Power Fuel Qualification Supporting the Hermes Operating License Application.pdf 616969

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KPNRC2305003

May19,2023 DocketNo.507513

USNuclearRegulatoryCommission ATTN:DocumentControlDesk Washington,DC205550001

Subject:

KairosPowerLLC PresentationMaterialsfortheMay22,2023PreSubmittalMeetingonKairosPower FuelQualificationSupportingtheHermesOperatingLicenseApplication

References:

Letter,KairosPowerLLCtoDocumentControlDesk,ApprovedVersionofFuel QualificationMethodology,March30,2023(ML23089A396)

ThislettertransmitspresentationmaterialsforthesubjectmeetingbetweenKairosPowerandthe NuclearRegulatoryCommission(NRC)stafftobeheldonMay22,2023.Thepurposeofthismeetingis todiscusspreapplicationplanstoaddresslimitationsandconditionsincludedinthefuelqualification topicalreport(Reference)withintheOperatingLicenseApplicationfortheHermesnonpowerreactor.

ThepresentationslidesinEnclosure1areconsiderednonproprietaryandareprovidedforNRCstaff information.KairosPowerauthorizestheNRCtoreproduceanddistributethesubmitted nonproprietarycontent,asnecessary,tosupporttheconductoftheirregulatoryresponsibilities.

Ifyouhaveanyquestionsorneedanyadditionalinformation,pleasecontactJimTomkinsat tomkins@kairospower.comor(805)2156129,orDarrellGardneratgardner@kairospower.comor (704)7691226.

Sincerely,

PeterHastings,PE VicePresident,RegulatoryAffairsandQuality

Enclosure:

1) PresentationMaterialsfortheMay22,2023PreSubmittalMeetingonFuelQualification

KairosPowerLLC www.kairospower.com 707WTowerAve,SuiteA 5201HawkingDrSE,UnitA 2115RexfordRd,Suite325 Alameda,CA94501 Albuquerque,NM87106 Charlotte,NC28211

KPNRC2305003 Page2

xc(w/enclosure):

WilliamJessup,Chief,NRRAdvancedReactorLicensingBranch BenjaminBeasley,ProjectManager,NRRAdvancedReactorLicensingBranch MatthewHiser,ProjectManager,NRRAdvancedReactorLicensingBranch EdwardHelvenston,ProjectManager,NRRAdvancedReactorandLicensingBranch SamuelCuadradodeJesus,ProjectManagerNRRAdvancedReactorLicensingBranch

KPNRC2305003

Enclosure1 PresentationMaterialsfortheMay22,2023PreSubmittalMeetingonFuelQualification (NonProprietary)

(Notethattheenclosedinformationispreliminaryandpredecisionalandissubjecttochangeduring detailedplanningandprojectexecution.Itisprovidedforplanningandfamiliarizationpurposesin supportofpreapplicationdiscussionswiththeNRCStaff.)

KP-FHR Fuel Qualification Methodology Topical Report KAIROS POWER

(OPEN SESSION)

MAY 22, 2023

No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.

Introduction

Topical Report Applicability This report presents a methodology for qualifying fuel for use in KP-FHRs Qualification is subject to the conditions in the topical report Demonstration of qualification will be addressed in safety analysis report documents as part of licensing applications under Part 50 or Part 52 This methodology is applicable to a KP -FHR test reactor or power reactor provided that the report conditions are met The conditions are different for test reactors and power reactors in some cases

2

KP-FHR Over view

Parameter Description / Value

Reactor Name Hermes KP-X

Reactor Type Non-Power Test Reactor Commercial Electric Po w e r Re a c t o r

Reactor Vessel Size 3 m dia., 4.4 m ht. 4 m dia., 6 m ht.

Coolant / Reflector Flibe / Graphite Flibe / Graphite Reactor Thermal /

Electric Power 35 MWth / N /A 320 MWth / 140 MWe Reactor Operating Pressure <0.2 MPa <0.2 MPa Reactor Inlet / ° C / 620° C 550° C / 650° C Outlet Temperature 550

No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC. 3 Annular Fuel Pebble and TRISO Particle Design

40mm diameter

<1mm diameter

4

Particle Design

Fuel System Component Purpose UCO Kernel

The kernel contains the fissile material.

UO2 + UC + UC2

The addition of a limited amount of uranium carbide suppresses CO production mitigating kernel migration, particle over-pres s ure, and corrosion of the SiC l ayer.

Oxygen remains sufficient to oxidize fission products that would otherwise diffuse through the IPyC and atta ck SiC in the higher mobility carbide fo r m.

Porous Carbon Buffer Layer

The porous carbon buffer l ayer provides void volume to accommodate fission product ga s es limiting pres s ure as burnup increases.

This l ayer mechanically de-couples the kernel from the outer coating l ayers and accommodates fuel kernel swelling.

This l ayer protects the IPyC from damage by fission product reco i l.

IPyC Laye r

This coati ng l ayer is considered to be the secondary structural and fission product ga s barrier after the SiC l ayer.

This l ayer introduces a compressive stress on the SiC l ayer that reduces SiC deformation and the risk of SiC l ayer fai l ure during irradiation.

This l ayer serves to protect the SiC from fission product atta ck.

The IPyC l ayer protects the kernel from chlorine attack during SiC5 deposition in the manufacturing process.

Particle Design (continued)

Fuel System Component Purpose

SiC Laye r

The SiC l ayer is the primary structural l ayer and fission product barrier.

This l ayer is a diffusion barrier to mobile metallic and ga s e o us fission products.

OPyC Laye r

This coati ng l ayer is considered to be a secondary structural and fission product ga s barrier after the SiC l ayer.

This l ayer introduces a compressive stress on the SiC l ay er during irradiation that reduces SiC deformation and the risk of SiC l ayer fai l ure.

The OPyC l ayer protects the SiC l ayer during manufacture separating the SiC l ayer from the carbon over-coat.

Pebble - Particle Carbon Over-Coat

The TRISO particle overcoat with carbon matrix materia l prevents particle-to-particle contact during manufacture.

The overcoat also facilitates obtaining the nominal packing fraction in the pebble fuel regi o n during manufacture.

6

Pebble Design (continued)

Fuel System Component Purpose

Low-density Carbon Core

Reduces the pebble density ensuring pebble has net positive buoyancy in the Flibe coolant.

Fuel Region

The fuel re gi o n is a shell of carbon matri x material surrounding the porous carbon inner co re.

Embedded with TRISO fuel particles at the nominal packing fraction.

This regi o n locates fuel near the coolant decreasing the thermal resistance allowing particle po wers to be high while keeping fuel temperatures within limits.

Fuel-Free Carbon Outer Shell

The fuel-f ree carbo n outer shell protects the fuel re gi o n f ro m mechanical damage and separates the fuel particles from the coolant.

7

Fuel Qualification Methodology

U.S. and International Experience Foundation of TRISO fuel particle technology NRC SER on EPRI TRISO topical report

Kairos Fuel Pebble and Particle PIRT The fuel element PIRT is used to identify high priority phenomena for investigation in the fuel qualification program

Fuel Specification, Manufacturing, and Quality Control through Inspection Fuel specification equivalent to the AGR program with quality controlled through inspection

Fuel Qualification Envelope Operation is within the bounds of the AGR qualification envelope, otherwise an irradiation test is needed to expand the operational envelope

8

Fuel Qualification Methodology (continued)

Fuel Pebble Laboratory Testing Demonstrate reasonable assurance that pebble will meet functional requirements

Fuel Irradiation Testing An irradiation test of a statistically significant number of TRISO fuel particles at conditions that extends the bounds of AGR irradiation test data to support a wider operational envelope

Fuel Performance Model Physics based models in KP-BISON are a quantifiable representation of fuel knowledge used for core design and source term analysis

Fuel Sur veillance Program Ongoing confirmation of fuel performance

9

Summar y of U.S. and International Experience

The use of UO2 TRISO-coated particle fuel first occurred in the UK in the early 1960s with irradiation in the Dragon Reactor.

The German pebble-bed reactor designs (mid-1970s thru 1988) led to extensive testing and real time irradiation in the AVR of full Average Pe a k Pe a k Pe a k commercial scale production fuel National Particle Power Temperature Burnup Fluence

China and Japan have successfully developed TRISO fuel production P r o g ra m (mW) (°C) (%FIMA) (x1025n/m2, and irradiated fuel in prototype and commercial reactors of the E>0.1MeV) prismatic and pebble bed type German 100 - 250 800 - 1320 6.7 - 15.6 0.2 - 8.5

In the US, General Atomics operated prototype and demonstration Chinese 150 - 250 1017 - 1067 9 - 11 3.8 - 4.9 gas reactors using uranium/thorium carbide based coated fuel Japanese 550 1156 6.7 2.8 particles in prismatic cores

The AGR program was built on this extensive experience to qualify a U.S. Legacy 100 - 400 915 - 1350 12 - 80 2.1 - 11.5 UCO TRISO coated fuel particle, Kairos Power leverages this DOE U.S. AGR 18 - 247 800 - 1400 13.2 - 19.6 3.5 - 6.1 p ro g ra m AGR-2 UCO TRISO compacts < 8.1x10-5 TRISO failure fraction

10

Fuel Particle and Pebble PIRT

Kairos PIRT built on the foundation of the 2004 TRISO PIRT -

NUREG/CR-6844

PIRT findings are addressed by:

Manufacturing Development Program Leverages German and AGR program experience Fuel Pebble Laboratory Testing Program Mechanical - Tribology, Compression, Impact, Molten Salt Infiltration (MSI)

Material Compatibility - Pebble in Flibe, Pebble in Air

11

Fuel Specification, Manufacturing, and Quality Control

TRISO Particle Specification Based on AGR Specification Equivalent specification to AGR-2 and AGR-5/6/7 TRISO fuel particles

Pebble Specification Similar to historic HTGR fuel pebbles with features for FHRs

Manufacturing Kernels fabricated using sol-gel process to form microspheres Coated particles are fabricated in a fluidized bed through a continuous chemical vapor deposition (CVD) process

Pebbles are formed from a mixture of matrix graphite powders, binderparticles and pressed to shape and heat treated, and TRISO fuel

Inspection Products are characterized to demonstrate compliance with specifications

12

Fuel Operating Envelope and Qualification Limits

Qualification Anticipated Parameter E nve l o p e Anticipated Non-Po wer Commercial Electric (AGR-2, EPRI TR) Te s t K P-FHR Conditions Po wer K P-FHR Conditions Normal Operation Pea k SiC Layer Temperature (°C) 1360 < 900 < 1100 Burnup (%FIMA) 13.2 < 10 < 20 Peak Particle Power (mW) 155 < 155 < 350 Peak Fluence (x1025n/m2, E>0.1MeV) 3.8 < 2.0 < 4.0 Postulated Events Pea k SiC Layer Temperature (°C) 1600 < 1200 < 1200 Peak Kernel Temperature (°C) 2350 < 1500 < 1500

13

Fuel Pebble Laboratory Testing Program -

Mechanical Tests and Tribology

Pebble Laboratory Treasonable assurance the annular pebble will meet functional requirementsesting in the fuel qualification program demonstrates

Demonstrate pebbles do not fracture from static and dynamic loads in the reactor and wear behavior is acceptable for a pebbles lifetime

Compression test Compression test (crush test)

Pebble is loaded in compression until failure

Impact test Pebble fracture under cyclic impacts

Tribology Wear rate and coefficient of friction

No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC 14 Fuel Pebble Laboratory Testing -

MSI, Buoyancy, and Material Compatibility

Flibe Infiltration and Buoyancy Demonstrate pebbles are buoyant Test temperature up to 900°C and pressure up to 500 kPa Measurement of weight change

Flibe Compatibility Pebble carbon matrix interaction with Flibe

Air Compatibility Oxidation rate behavior of pebble carbon matrix in Air Oxidation tests in the temperature range 450-700° C Measurement of mass loss with time to create an Arrhenius correlation

No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC 15 Irradiation Testing

Irradiation testing is not required for Hermes, which operates inside the qualification envelope based on AGR-2 d ata

Irradiation testing would be needed to expand the fuel qualification envelope Irradiation testing required for the commercial electric power reactor

Irradiation Tests would be performed in a non-KP-FHR test facility

Online fission gas release data used to determine the TRISO fuel particle failure fraction

Destructive PIE is used to confirm the TRISO fuel particle failure fraction

Acceptance criteria TRISO fuel particle failure fraction with a 95% one-sided upper confidence bound

16

Fuel Performance

KP-BISON is an engineering-scale multi-dimensional finite-element model used to evaluate TRISO fuel particle performance Based on INLs BISON code Determines fuel temperature, the probability of coating layer failure and fission product release

Fuel Pebble DEM modeling

Fuel Pebble Finite Element Modeling

17

Fuel Sur veillance Program

Fuel sur veillance in Hermes confirms fuel performance

The inert cover gas and Flibe coolant activity levels are monitored to detect an increase in fuel particle failure

Fuel pebbles are examined in the pebble handling and storage system (PHSS) after exiting the core

Gross damage - wear, cracking, missing surfaces Burnup is measured to confirm it is less than the qualification envelope, allowing pebble recirculation

Post irradiation examination in Hermes (and initial KP -X)

TRISO particle failure fraction Pebble surface wear Molten salt infiltration

Over fifty years of operating experience and testing of TRISO fuel including extensive testing of TRISO fuel particles in AGR-1 and AGR -2, including for both steady state and transient conditions.

Successful completion of a KP-FHR fuel element PIRT and implementation of associated actions to further the understanding of the annular fuel pebble and TRISO fuel particles.

Manufacturing and inspection of the KP-FHR fuel to a specification that ensures the fuel is equivalent in performance to the fuel tested in AGR-2 and meets the conditions in the EPRI TRISO topical report SER.

Operation within a set of defined fuel qualification limits which ensure that the fuel remains within its qualification envelope during both normal operation and licensing basis events.

19

No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC. 19 Summary (continued)

Irradiation testing (if TRISO fuel particle will operate outside of the AGR-2 fuel performance envelope)

Sur veillance program confirms that the pebble form does not have an adverse impact on the fuel particles.

The ability to examine fuel pebbles as they exit and re-enter the core over their expected lifetime, including the ability to remove them if necessary for disposal or PIE.

20

Fuel Qualification Topical Report Limitations

The design of the annular pebble, TRISO particle-based fuel and the KPincluding the presence of a Flibe primary coolant. - FHR design overview are as described in Section 1.1.2,

Operating and transient conditions for the KPunder 10 CFR 50 and 10 CFR 52 to remain within the fuel qualification envelope values specified in Table 3-FHR are demonstrated in safety analysis reports submitted with license application-11, which is based on the s AG R pro gram.

If the fuel qualification envelope is to be extended beyond the AGR-2 based limits, an irradiation test program will be conducted.

Demonstration that the conditions and limitations of the EPRI TRISO Topical Report Safety Evaluation Report are met for the Kfuel design. P-FHR

Future license applications for commercial electric power KPmethodology) of the applicability of this methodology during rapid reactor transient events for irradiated fuel.- FHRs will include justification (testing or analysis based on an approved

Future license applications for commercial electric power KPapproved methodology) that Flibe does not adversely impact irradiated fuel pebble buoyancy. - FHRs will include additional justification (testing or analysis based on an

This methodology applies only to KP-FHRs with a safety-related positive flux rate trip.

Future license applications for nonreactor transient events-power KP-FHRs shall include justification of the applicability of this methodology during rapid

Future operating license applications for a commercial power KPfailures due to chemical attack from impurities (e. g., Fe, Cr, or Ni) in the molten salt coolant during expected reactor cond-FHR shall provide information demonstrating that TRISO particle iti o ns are precluded or can be demonstrated to be insignificant. This information shall include test data from representative fuel pebbles in salt under irradiated conditions (e. g., in a test reactor) 21

Fuel Qualification Topical Report Conditions

There are two issues we would like to discuss in more detail:

Condition on Rapid Transients Condition on Positive Flux Rate Trip

There is a related condition for transient behavior from the Fuel Performance topical:

Qualification of Fuel Performance Code for transients

Rapid Transient Condition

Condition requires justification of the applicability of the fuel qualification methodology for rapid reactor transients for irradiated fuel.

The Hermes design is not prone to rapid transients because it has:

Limited excess reactivity (online refueling)

Long neutron migration length (graphite moderator)

Long neutron generation time (graphite moderator)

Negative reactivity coefficients (-4 to -5 pcm/ °C for fuel)

Short fuel thermal time constant (TRISO thermal properties)

Low operating pressure (control element ejection not credible)

All of these attributes together lead to mild reactivity transients

The AGR program transient testing heated the fuel to very high temperatures (1600 to 1800°C) for very long durations (up to 300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br />)

There are no credible transients in a KP-FHR that even approach these conditions

Analysis in the topical report shows that:

For a control element withdrawal, fuel temperatures reach the 1200°C range assuming no reactor trip SiC layer remains in compression (layer fails in tension) throughout the transient

Rapid Transient Condition (continued)

NRC/CNSC study concludes that no additional TRISO transient testing is needed for reactivity transients that add reactivity over a time frame of more than one second This is due to the fact that the longer time frame allows heat to be conducted out of the fuel particle The mild reactivity addition transients of the KP-FHR are well in excess of one second The Japanese and Russian testing of fresh fuel particles supports this as energy pulses were in milliseconds and still demonstrated that there were no increase in failures until fuel temperature was above 1600° C

The intend to meet the SER condition without additional transient testing based on the above arguments

These arguments will be documented in the OLA to resolve this condition

Positive Flux Rate Trip

Preliminary studies of reactivity insertion events show that the KP-FHR reactor trips on high power and fuel particle temperatures remain well below 1600° C

These studies do not include crediting a positive flux rate trip

The evaluation of analytical limits associated with the flux rate trip could yield a trip that would never be achieved

A safety related positive flux rate trip is not needed to demonstrate safety

This will be documented in the OLA.

The Fuel Performance topical report provides the methodology for performing fuel performance calculations using the KP-BISON code

The KP-BISON qualification methodology safety evaluation includes a condition requiring additional justification of the applicability of the methodology for transients.

As discussed previously (in Slide 24), KP-FHRs have physical and design characteristics that result in very slow transients that do not challenge the TRISO and fuel pebbles ability to remove heat adequately

As a result, the models in KP-BISON can be used for transients as a series of quasi-steady statepoint s for the KP-FHR technology

This conclusion will be documented in the Hermes OLA

No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC. 26 End of Presentation

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