presentation slides: collaboration on the thermal modeling ...steering committee chair: hatice...

© 2019 Electric Power Research Institute, Inc. All rights reserved.w w w . e p r i . c o m

Aladar A. CsontosTechnical Executive

September 18, 2019

NRC NMSS REGCON

Collaboration on the Thermal Modeling/Fuel Performance Nexus Path Forward to Improving Safety and Operational Benefits

© 2019 Electric Power Research Institute, Inc. All rights reserved.w w w . e p r i . c o m2

ESCP Thermal Modeling Subcommittee: R&D Activities

Stee

ring

Com

mitt

eeCh

air:

Hatic

e Ak

kurt

(EPR

I)St

eerin

g Co

mm

ittee

Chai

r: Ha

tice

Akku

rt (E

PRI)

CISCC SubcommitteeChair: Shannon Chu (EPRI)

CISCC SubcommitteeChair: Shannon Chu (EPRI)

NDE SubcommitteeChair: Jeremy Renshaw (EPRI)

Vice-Chair: Randall Granaas (SCE)

NDE SubcommitteeChair: Jeremy Renshaw (EPRI)

Vice-Chair: Randall Granaas (SCE)

Canister Mitigation/Repair SubcommitteeChair: Gary Cannell (Fluor)/Jon Tatman (EPRI)

Canister Mitigation/Repair SubcommitteeChair: Gary Cannell (Fluor)/Jon Tatman (EPRI)

Fuel Assembly SubcommitteeChair: Mike Billone (ANL) /

Vice-Chair: Sven Bader (Orano)

Fuel Assembly SubcommitteeChair: Mike Billone (ANL) /

Vice-Chair: Sven Bader (Orano)

Thermal Modeling SubcommitteeChair: Al Csontos

Vice-Chair: Sam Durbin

Thermal Modeling SubcommitteeChair: Al Csontos

Vice-Chair: Sam Durbin

International SubcommitteeChair: Jose Conde (Enusa)

Vice-Chair: Brady Hanson (PNNL)

International SubcommitteeChair: Jose Conde (Enusa)

Vice-Chair: Brady Hanson (PNNL)

Phase IBWR DCS

Simulator

NRC/ DOE Lead

Phase IIHBU DemoProject

EPRI Lead

Phase IIIHorizontal Simulator

DOE Lead

Bringing It All TogetherPhenomena Identification

Ranking Table (PIRT)

Gap Analysis

EPRI Lead


Stakeholder Spent Fuel Integrity: R&D Activities Since 2000, substantial domestic and international R&D to

assess SNF integrity for storage, transportation, and disposal: – High Burnup Demo/Sibling Rod Testing ─ NFIR Testing– ORNL CIRFT Testing ─ SCIP Testing (Studsvik)– ANL Hydrided Cladding Testing ─ SPAR (IAEA)– Other tests (KAERI, CRIEPI, etc.) ─ Thermal Modeling General results:

– Temperatures and pressures lower than originally understood– Cladding more robust and less susceptible to degradation PIRT Gap Analysis (EPRI Lead):

– Use NRC accepted process to put the global R&D results into practice– Thermal Modeling, Decay Heat Modeling, and Fuel Performance


Benefits of Improved Thermal Methodology Occupational dose benefits:

– Temporary shielding restrictions (blankets)– Time limits to keep mating device door open

Dry storage operational benefits:– More flexible SNF loadouts– Drying time limits and time to boil– Supplemental cooling requirements– Vent surveillance requirements– Fuel and canister degradation mechanisms– Risk informing aging management

Reactor operations/safety benefits:– Reduced SFP temperatures/time-to-boil

Accelerate decommissioning:– Active to passive cooling of SNF

Informs repository loading footprint

Time to Boil Calculations

(SFP)

Fuel Loading into

Storage

Degradation Mechanisms Dry Storage

Repository

Decommissioning

Transportation


Thermal Measurements – Transient Data from LoadingTransient Peak Cladding Temperature (Cell 14) = 237°C

Video provided by ORNL

40 80 120 160 200 240Celsius


Phase II: Thermal Modeling Key TakeawaysDLB

Margin

Cell 14 (Hottest Cell) Reasonable surface temperatures Reasonable PCT axial distribution shape Best-estimate PCT biased to higher temps

due to limiting design licensing inputs Best-estimate vs. Licensing Basis Inputs:

– Decay Heat Loadouts: Assume upper bound– Ambient Temps: Assume upper bound– Cask/Canister Design Features (gaps, etc.)

Margins exist between best-estimate vs. limiting design licensing basis models:– Quantifying input sensitivities is the key to

technical/regulatory strategy to gain margins


Phase II: Key Takeaways Steady state PCTs from all models and measurements

significantly lower than the design licensing basis:

Parameter FSAR LAR Best-Estimate

HBU Cask Measurements

PCT (model vs data) 348°C 318°C 254-288°C 229°C

Heat Loadouts 36.96kW 32.934kW 30.456kW 30.456kW

Ambient Temperature 100°F 93.5°F 75°F 75°F

Design Specifics Gaps Gaps Gaps No Gaps?


Thermal Modeling Technical/Regulatory Strategy Goals PIRT Product Objectives:

– Provide an independent, objective, and technically defensible reference from a committee of recognized subject matter experts

– Provide technical insights for developing margin assessments– Assist in defining and prioritizing R&D testing and modeling needs PIRT Scope:

– Focused and Technically Driven with Recognized Subject Matter Experts– Thermal & Decay Heat Modeling / Fuel Performance Nexus (PCT Limit) Project Goals:

– Streamlined regulatory path – Reduced model DLB input penalties– Improved operational flexibilities – Improved Thermal Models


Steering Committee

NRC/DOE/EPRI/ Stakeholders

Project Manager(s)Al Csontos (EPRI)

Thermal Model Inputs & Uncertainty

Quantification TeamDavid Richmond (PNNL)

Decay Heat Modeling & Uncertainty

Quantification TeamHatice Akkurt (EPRI)

Fuels/Cladding Performance &

Uncertainty Quantification TeamKeith Waldrop (EPRI)

Esta

blish

Com

mitt

ee S

cope

, Lea

ders

hip,

and

SM

Es

SME

Deve

lop

PIRT

s, An

alys

es, &

Rep

ort

Roles & ResponsibilitiesDefine the problem (e.g., licensing, operational, or programmatic)Define the specific objectives Define the hardware and scenarioDefine the evaluation criterion Ensure resources are available - experts and expert reviewers to participate on panel(s)

Roles & ResponsibilitiesProject management of the Committee members to achieve the PIRT objectives

Roles & ResponsibilitiesIdentify plausible phenomena Identify & review available tech dataRank importance and rationalesAssess phenomenon uncertainty Develop Independent PIRT report

Proj

ect

Man

agem

ent

PIRT StructureMichael Layton (NRC)Ned Larson (DOE)Sylvia Saltzstein (SNL)Randy Stark (EPRI)Jeremy Renshaw (EPRI)Suzanne Leblang (Entergy Services)Zita Martin (TVA - Holtec)Neil Fales (3 Yankees - NAC)Steven Edwards (Duke Energy - Orano)


PIRT Activities and Path Forward Steering Committee Meetings:

– March and July 2019 Resolved steering committee feedback:

– Multiple charter revisions and meetings to address comments Joint Agreement of the Charter and Team Leadership/Members:

– Team leadership meetings to coordinate PIRT next steps– Provide PIRT Questionnaire to send to the team SME members Schedule:

– PIRT Expert Panel Meetings: October 2019– Draft Final PIRT Report: March 2020– Final PIRT Report: June 2020


Thermal Modeling Technical/Regulatory Nexus

Near Term (1 Year): Vendor Amendments

PIRT/Gap Analysis:• ▪ Thermal Model Gaps Q2:• - Thermal Model Inputs• - Decay Heat Models• ▪ Examine approaches for

immediate utility impacts▪ Provide technical basis for

• regulatory decision-making• ▪ PIRT Report Q2 2020 • ▪ Implement through vendor

amendments and/or 72.48

Mid Term (1-2 Years): ISG-11 R3 PCT Limits

PIRT/Gap Analysis:▪ Fuel Performance:

- NUREG-2224 HBU Report- DOE CIRFT/Sister Rod Tests- HBU Demo Gas Sampling

Regulatory Vehicle:▪ NRC Reg Guide or Topical

Report for NRC Review▪ Vendor amendments

Long Term: Topical Report

Topical Report for NRC Review: ▪ Establish generic approach for

use of actual data vs. designlicensing basis approach forthermal and other modeling


Summary

400350300250Temperature, °C

Axia

l Ele

vatio

n Design Basis vs.

Actual Margin PCTMargin

Overall Thermal Margins

High Burnup Demo: An Opportunity• Cask Loaded in 2017• Data used for blind benchmarking of models• Data supports license renewals

Biases Identified in Thermal Models• 25-90°C bias in best-estimate models• Licensing models biases of 80°C to >100°C• PIRT as a vehicle for regulatory considerations

Next Steps• Hold PIRT meetings (Q4 2019)• PIRT Report (2020)• Possible Topical Report (2022)


Together…Shaping the Future of Electricity

presentation slides: collaboration on the thermal modeling ...steering committee chair: hatice...

Documents