Characterization of Irradiation - Assisted Degradation of Reactor Internal Materials · 2014-06-02 · Characterization of Irradiation-Assisted Degradation of Reactor Internal Materials

John Burke U.S. Nuclear Regulatory Commission

Branch Chief, Structural, Geotechnical & Seismic Engineering Branch IAEA CRP Coordinated Research Meeting

June 11 – 13, 2014 Vienna, Austria

Characterization of Irradiation-Assisted Degradation of Reactor

Internal Materials

2 © 2014 Electric Power Research Institute, Inc. All rights reserved.

Contents

• Introduction to Zorita Materials ……….………...........……. 3

• Fluence Matrix for Zorita Materials Testing……………...... 7

• Zorita Project with Additional Irradiation ………………...... 8

• Zorita Weld Testing Program ……………….…….....…….11

• Summary …………………………………………………….13


Characterization of Irradiation-Assisted Degradation of Reactor Internal Materials

Objective: Characterize the effects of neutron irradiation on stainless steel reactor internal materials to understand material behavior at end of service life (40, 60 years and beyond)

• Jose Cabrera NPP “Zorita” – Westinghouse design – 1968 – 2006 (~26 EFPY)

• Type 304 SS – Baffle plate material (up to 50 dpa) – Core barrel welds and heat affected

zone (HAZ) materials (up to 4 dpa) • Computational analyses completed

– Irradiation (fluence) profile – Temperature profile – Critical operational history


Zorita Internals Materials Cutting Plan – Baffle Plates Type 304 stainless steel •Doses ranging from a few dpa to ~50 dpa •Thickness 28.6 mm •Currently planned programs use Piece C1

= 52 dpa= 32 dpa= 15 dpa= 11 dpa

41.2

2”

7.8”

6.67”

Plate A (41.22” wide)

Plate B (7.8” wide)

Plate C (7.8” wide)


Zorita Internals Materials Cutting Plan – Core Barrel Weld

Weld Piece 1 (between 1st and 2nd Formers)

Weld Piece 2 (between 3rd and 4th formers)


Zorita Internals Materials Core Barrel Weld Pieces

Weld Piece 1

Weld Piece 2


Fluence Matrix for Zorita Materials Testing

• Zorita Internals Research Program (ZIRP) uses baffle plate material at ~26 EFPY – Mechanical and microscopic testing – Project will be completed in 2016

• Additional Irradiation Project – Accumulate additional dose on Zorita materials to represent extended operation

• Zorita Weld Testing Program – Investigate mechanical behavior of weld/HAZ materials at end-of-life conditions

Fluence ↓ / Materials → Plate Weld Heat-Affected Zone 4 dpa Zorita Weld Testing Program

10 dpa

ZIRP 20 dpa Additional Irradiation Program 30 dpa

N/A 50 dpa 65 dpa Additional

Irradiation Program 80 dpa


Zorita Project with Additional Irradiation

• Objective: Subject Zorita baffle plate and core barrel weld/heat affected zone (HAZ) materials to additional irradiation (~15 dpa and up to 30 dpa) under PWR conditions and subsequently characterize the mechanical and microscopic properties of the materials • Project uses Zorita baffle plate, core barrel weld, and HAZ

materials

Baffle Plate Piece C1


Zorita Project with Additional Irradiation Proposed Mechanical Testing

Purpose Specimen

Type Material

Component

Calculated Initial

Dose (dpa)

Target Final Dose (dpa) Piece

Crack Growth Rate/ Fracture Toughness

0.5T CT 0.5T CT 0.5T CT 0.5T CT

Weld HAZ Plate Plate

3.9 3.9 50 50

20 20 65 80

Weld 2 Weld 2

C1 C1

Crack Initiation O-ring/UCL Plate 50 65 C1

Yield Measure Tensile Tensile Tensile Tensile

Weld HAZ Plate Plate

3.9 3.9 50 50

20 20 65 65

Weld 2 Weld 2

C1 C1

Void Swelling TEM TEM TEM TEM

Plate HAZ Weld Plate

50 3.9 3.9 50

65 20 20 80

C1 Weld 2 Weld 2

C1


Zorita Project with Additional Irradiation Project Timeline

• Extraction and shipping of materials is completed – material is currently available • Effort to begin in 2014 upon selection of irradiation and

testing contractor(s)


Zorita Weld Testing Program

• Determine combined effects of irradiation and elevated temperature on embrittlement of stainless steel welds and characterize environmental effect on fracture toughness in irradiated stainless steel welds

• Fracture toughness testing in air and PWR environment

Thermal and Irradiation Embrittlement Testing of Stainless Steel Welds

• Develop IASCC CGR data in irradiated stainless steel weld and HAZ materials for comparison to existing data for base materials

• CGR testing at 3 different temperatures and 2 stress intensities

Crack Growth Rate Testing of Irradiated Stainless Steel Weld and HAZ Materials


Zorita Weld Testing Program Project Timeline


Summary

• U.S. NRC and EPRI are working collaboratively to further characterize Zorita materials • Additional participants are being sought to ensure a

technically-robust testing matrix can be pursued


Contact Information

U.S. Nuclear Regulatory Commission

Matthew Hiser – Materials Engineer – [email protected] – +1-301-251-7601

• U.S. Nuclear Regulatory Commission

Washington DC 20555-0001 www.nrc.gov

Electric Power Research Institute

Jean Smith, PhD, PE – Senior Technical Leader -

Materials Reliability Program – [email protected] – +1-650-855-8775

• Electric Power Research Institute

3420 Hillview Avenue Palo Alto, CA 9430 www.EPRI.com

http://www.nrc.gov/

mailto:[email protected]

http://www.epri.com/

Questions?


Zorita Project with Additional Irradiation

• Subject Zorita baffle plate and core barrel weld/heat affected zone (HAZ) materials to additional irradiation (~15 dpa) under PWR conditions and subsequently characterize the mechanical and microscopic properties of the materials

• Project uses Zorita baffle plate, core barrel weld, and HAZ materials

Project with Additional Irradiation

• Characterize the IASCC crack growth rates of weld and HAZ materials irradiated under service conditions to increase the understanding of fluence effects at end of life

• Study the synergistic effects of thermal and irradiation embrittlement and environmental effects on stainless steel welds • Projects use Zorita core barrel weld and HAZ materials

Projects without Additional Irradiation

Characterization of Irradiation - Assisted Degradation of Reactor Internal Materials · 2014-06-02 · Characterization of Irradiation-Assisted Degradation of Reactor Internal Materials

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