Zorita Internals Research Project · © 2019 Electric Power Research Institute, Inc. All rights reserved. Jean Smith, PhD PE Principal Technical Leader May 21-22, 2019 Rockville,

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

Jean Smith, PhD PEPrincipal Technical Leader

May 21-22, 2019Rockville, MD

Zorita Internals Research Project2019 NRC-Industry Technical Exchange Meeting

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

Content Zorita Internals Research Project (ZIRP) Summary

– Mechanical Testing Results– Microstructural Testing Results Testing Programs using Zorita Materials Remaining Zorita Material Inventory


Introduction Jose Cabrera NPP “Zorita”

– Westinghouse 1-loop design– 1968 – 2006 (~26 EFPY)

ZIRP Participants: – EPRI Materials Reliability Program– U.S. NRC– CSM (Spanish Regulator)– SSM (Swedish Regulator)– Tractebel– AXPO


Zorita Internals Research Project Timeline• Extensive effort on the front end of the project• Testing represents only a small portion of the project timing


Baffle Plate Pieces Type 304 baffle plate material

removed between 3rd and 4th

former levels Range of doses across the face of

baffle plate and through plate thickness Extensive temperature history and

radiation analyses performed– Specimen geometries mapped to

dose gradients– Specimen orientation with

respect to dose gradients


ZIRP Summary – Mechanical Testing

Tensile Testing• Tensile testing of 10, 30, &

50 dpa material at room temperature & 320 °C

• Significant radiation hardening observed at all doses

Fracture Toughness• Fracture toughness testing

of 9, 24, & 35 dpa material at 320 °C in air and 9 dpa material also in PWR environment at 320 °C

• Low fracture toughness values observed

• PWR environment showed slight reduction in fracture toughness

Crack Initiation• Crack initiation testing of

UCL and O-ring specimens of ~40-45 dpa material to 9,000 hours

• No failures of O-ring specimens

• Failure of UCL specimens ranging from 60 to 100% YSirr with failure time increasing with decreasing stress

Crack Growth Rate• Crack growth rate testing of

9, 24, & 41 dpa material at 3 temperatures and 2 K levels in PWR environment

• Low crack growth rates with no apparent K dependency

• Rapid crack growth rates after decrease in test temperature or operational upset (chemistry or load)


ZIRP Summary – Microstructural Testing

Void Swelling•TEM examination of nine

areas including highest temperature and highest dose regions

•Maximum average swelling value was 0.08% at the location of the highest temperature

Microstructure•Grain size typical of Type

304 stainless steel•Gamma prime phase and

Frank loop sizes and densities quantified

•Precipitates analyzed

Hardness•Vickers hardness testing

(1.0 kg and 0.1 kg) of three areas

•Results typical of irradiation-hardened Type 304 material

Gas Content•Hydrogen (thermal

conductivity) and helium (mass spec) gas analyses of specimens from 3 locations

•Microstructural bubbles <3.0 nm considered to be helium bubbles


ZIRP Summary– Status All testing has been completed Draft report has been prepared ZIRP funders’ meeting April 25-26, 2019

– Reviewed results and discussed conclusions– Provided feedback to contractor

Revised draft expect early June Final EPRI technical report due by end of

October 2019


Testing Programs using Zorita MaterialsMaterials Reliability

Program

Zorita Internals Research Program

Zorita Weld Testing Program

Crack Growth Rate Tests in Halden under PWR Conditions

Thermal Aging Analysis of Stainless Steel Welds

IASCC Testing Program for Baffle Former Bolts

Primary Systems Corrosion Research

Microstructural Database of Irradiated Stainless Steels and of

Models

K-size Effects on IASCC Testing

Correlation of Microstructure to Mechanical Properties

Boiling Water Reactor Vessel Integrity Program

Fracture Toughness and CGR in High Fluence BWR Materials

U.S. Nuclear Regulatory Commission

IASCC and Fracture Toughness Testing Program


Remaining Zorita Baffle Plate Material

Piece Dose Range (dpa)Approx. Number of

0.5CT Specimens CommentsB1 25-50 2 1 at highest dose possibleB2 14-30 ~12 4 at highest dose possibleB3 7-17 18 3 at lowest dose possibleD 25-50 8 Bolted to Piece B1C1 25-50 12 50% at highest dose possibleA 15-27 60 50% at highest dose possibleA3 0.04-0.15 32BFBs 25-25 0 Corner of Pieces B1 and C1

In addition to the baffle plate material used for ZIRP, additional baffle plate material and core barrel material (base metal, weld, HAZ) were extracted Range of doses available


Remaining Zorita Core Barrel MaterialPiece Material

Dose Range (dpa)

Approx. Number of 0.5CT Specimens Comment

Weld 1

Weld

0.1-1.1*

15 No HAZ specimens if all 20 are weldHAZ 15 No weld specimens if all 20 are HAZ

Base Metal 5-10 Number depends on weld & HAZ specimens

Weld 2Weld

1-20

HAZ 0Base metal 20

*Material at dose in the range ~0.2 to 0.9 remains


Summary Zorita Internals Research Project is a first-

of-a-kind, comprehensive testing program using ex-plant material– Extensive temperature history and radiation

analyses– Broad range of temperature and dose levels– Large volume of material allows for robust

test matrices Significant effort at the onset of the

program to harvest and ship materials Additional testing programs have

benefited from the versatility of Zorita materials

Baffle plate and core barrel materials still available

Soil washing; Courtesy of Enresa


Together…Shaping the Future of Electricity

Documents

Zorita Internals Research Project · © 2019 Electric Power Research Institute, Inc. All rights reserved. Jean Smith, PhD PE Principal Technical Leader May 21-22, 2019 Rockville,