KP-FHR Fuels Qualification Program

1

A Facet of KP-FHR Fuel Qualification

2

Qualification Aspects from AGR Program

• The DOE advanced gas reactor (AGR) TRISO fuel irradiation program is completing a topical report on fuel manufacturing, which demonstrates confidence in manufacturing methods for low defect rate fuel from manufacturing and in-service. This timely submission and response by DOE to the subsequent RAI’s is important. • AGR irradiation programs, especially AGR-5/6/7, provide in-service irradiation data on TRISO

defect rates for millions of particles that are same design to be used for the KP-FHR. PIE and subsequent release of the data for use to support our fuel licensing basis is needed as part of our long-term fuel qualification effort.

The AGR program is an important aspect of the qualification strategy for KP-FHR fuel. The program relies AGR data, especially through NRC topical reports, to support our fuel licensing effort.

Fuel Element Manufacturing and Performance

3

DOE national laboratories and BWXT have demonstrated the ability to implement robust manufacturing processes and quality control for TRISO fuel particles and compacts, and demonstrated excellent performance in the AGR irradiation tests.

Fission Product Sources• Manufacturing defects - Particles fabricated with dimensions and/or characteristics that do not comply with

TRISO particle design specifications leading to early failure• Heavy metal contamination – Heavy metal outside the fuel kernel from the fabrication process and heavy

metal impurities in materials used to fabricate the fuel

Manufacturing and Fuel Performance• Particle fuel performance is known and repeatable due to fuel particle design specifications.• Consistency is maintained through manufacturing process specifications and quality control through inspection• A high level of fuel performance can be obtained by implementing these manufacturing processes and controls

as demonstrated in AGR irradiation tests

Known and consistent fuel particle irradiation performance is maintained by meeting fuel particle design specifications through manufacturing specifications and quality control through inspection.

AGR-1/2 Topical Report Conclusions

4

• EPRI already held first drop-in meeting with NRC to discuss the process for submission of the AGR-1/2 campaign topical report

Primary Conclusions of Topical Report1. The testing of particles in AGR-1 and AGR-2 constitute a performance demonstration of these

particle designs over a range of normal operating and off-normal accident conditions and thus serves as a foundational basis for use of these particle designs in the fuel elements of a variety of TRISO-fueled HTR designs (i.e., designs with pebble or prismatic fuel and helium or salt coolant).

2. Aggregate AGR-1 and AGR-2 fission product release data and AGR-1 and AGR-2 fuel failure fraction, as summarized in this report, and provided in more detail in the referenced literature, can be used for licensing of reactors employing TRISO-coated fuel particles.

3. The kernels and coatings of the UCO particles tested in AGR-1 and AGR-2 exhibited some degree of property variation and were fabricated under different conditions and at different scales with remarkably similar excellent irradiation and accident safety performance. Thus, there is some allowance in terms of the actual values for key critical characteristics of the kernels and coatings necessary to impart satisfactory performance.

AGR-5/6/7 Experiment

5

W.F. Skerjanc, AGR-5/6/7 Irradiation Test Predictions using PARFUME, INL/EXT-17-43189

Fuel qualification tests (AGR-5/6) and margin test (AGR-7) of the U.S. DOE AGR program

• Irradiation started in Q1-2018• Irradiation ends in Q4-2020 (scheduled)• PIE 2021-2025

⇒ Will confirm irradiation and safety performance of AGR fuel. No failure reported by online R/B to this date.⇒ Will provide fission product release data over a wide range of temperatures (600-1500°C).

Upper range of KP-FHR irradiation temperaturesLow fractional release expected

Kairos will rely on AGR-5/6/7 Capsule 5 compact data for fission product release data to support fuel

performance modeling and source term analysis.

Upper range of KPLow fractional release expected

Timely completion of PIE, analysis, and reporting is critical to support Kairos’ fuel qualification strategy.

Fuel Pebble Evolution in the KP-FHR

6

TimeframeKP-FHRStartup

KP-FHR Transition

AGR-1 (2009)AGR-2 (2013)

AGR-5/6/7(2020)

Particles per Fuel Element 15,800 15,800 4,100 / 3,200 2,200 / 3,400Packing Fraction 0.38 0.38 0.37 0.25 / 0.38Particle Peak Power (mW) 150 150 150 190 / 140Particle Average Power (mW) 67 67 60 / 70 130 / 80U-235 Enrichment (at%) 10 19.75 19.5 / 13.8 15.3Burnup (%FIMA) ~5 ~10 16.7 / 11.1 18 / 11Peak Fluence(´1025n/m2, E> 0.10 MeV)

~4.0 ~8.0 4.7 / 3.8 8.1 / 6.5

Time (EFPD) ~300 ~600 620 / 559 510

Confirmatory Irradiation Test

DOE national lab support for PIE will be an important part of this irradiation test program

Kairos is currently planning an irradiation test of the KP-FHR fuel pebble. The fuel particle performance requirements for this test are bounded by the AGR irradiation tests.

Fuel Surveillance Program in KP-FHR

7

Schematic of KP-FHRFuel surveillance program in the KP-FHR is used to confirm the technical bases of fuel qualification and mechanistic source term

Fission product monitoring • Molten salt and cover gas activity – indirect measurement

of fuel particle failures

Fuel pebble inspection• NDE (in the re-fueling machine)

• ‘Visual’ inspection to observe damage• Gamma scanning to measure burnup

• DE (pebbles extracted from re-fueling machine)• Extract pebbles for periodic PIE destructive exams• Perform necessary and relevant PIE to support

KP-FHR operations

Fuel surveillance program in the KP-FHR is used to confirm the technical bases of fuel qualification and mechanistic source term

Fuel Performance Modeling Plan

8

• Development of TRISO UCO model in BISON• Material properties (UCO, irradiation effects, thermal, etc.)• Physical models (fission yields, Pd penetration, R/B, fission

product transport, etc.)• “Particle” and “pebble” models (temperature / fission products)• Statistical treatment of a population of TRISO particles• Coupling “failure probability” + “fission product release”• Comparison with INL’s PARticle FUel ModEl code (PARFUME)

• Verification & Validation• BISON test matrix (incl. dedicated unit tests)• IAEA CRP-6 and Gen-IV benchmark on TRISO fuel performance• Additional experimental benchmark (AGR UCO, KP fuel qual.)• Uncertainty quantification & sensitivity analysisTangential stress in spherical (left) and

aspherical (right) TRISO particlesHales et al., J. Nuclear Materials 443 (2013) Kairos will be seeking sustained support from INL and

DOE for BISON code development and verification

9

Questions?

Backup Slides

10

Fuel Performance Analysis Methodology

11

GeometryØ radius, thickness, etc.Fuel characteristicsØ composition, densities, etc.Variation in as-fabricated properties

Material properties in KP-BISONIrradiation conditionsØ Fission rate densityØ Fast fluenceØ Coolant temperature

Results Support KP-FHR Fuel Roadmap

12

Fuel temperature, fission gas pressure,

displacements, stress

Illustrations only – Not actual calculation results

Failure probability (Weibull statistics / strength)

Fission product release (Fick’s law / diffusivities)

⇒

TRISO fuel performance modeling will support modeling of accident conditions and roadmap to higher particle power fuel