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Characterization of A508/A533B Pressure Vessel Steel VHTR R&D FY12 Technical Review Meeting May 22-24, 2012 Salt Lake City, Utah

Barry H. Rabin, Ph.D. Idaho National Laboratory

Background •  Next Generation Nuclear Plant (NGNP) reactor pressure vessel

(RPV) is a class 1 component –  Rules covered by American Society of Mechanical Engineers

(ASME) Boiler & Pressure Vessel Code (BPVC) under Division 1, Section III •  Subsection NB for operating temperatures below 371°C •  Subsection NH for operating temperatures above 371°C

Background •  A508/A533B low alloy steel is the preferred choice for

construction of the NGNP RPV –  Fe-2¼Cr-1Mo has insufficient elevated temperature mechanical

properties –  Grade 91 is unavailable as large ring forgings and has potential

welding issues

Background (cont.) •  A508/A533B is approved for Class 1 components under

Section III, Subsection NB –  Extensive experience with fabrication, welding and irradiation effects

from current light water reactor (LWR) fleet –  NGNP RPV operating temperatures may be higher than LWR, but

fluence will be lower •  No irradiation damage testing currently planned

–  NB limits the RPV design temperature for Level A (normal) conditions to 371°C •  Current NGNP focus on “Cold Vessel” option •  Other vessel options possible in future designs

Background (cont.) •  ASME Code Case N-499-2

–  Permits short-term off-normal temperature excursions above 371°C –  Subsection NH design rules apply –  Currently, only RPV steel approved is Grade 91

Key Research Issues •  Lack of A508/A533B experience at ~350°C for 60 years and

under impure He –  Need confirmatory data on thermal aging and environmental effects

•  Code Case N-499-2 –  Effects of elevated temperature excursions beyond 371°C? –  Negligible creep assumption for cold vessel option (i.e. applicability

of Subsection NB)? –  Role of creep-fatigue and ratcheting?

Testing Plan (PLN-2803)

complete" in progress not planned"revision"

Material •  A508 (UNS K12042) A533B (UNS K12539) low-alloy steel •  Heat (QA# 156245)

–  Vendor: Industeel France (ArcelorMittal, Chateauneuf plant) –  Dual Certification

•  SA 508 Grade 3, Class 1 (forgings) •  SA 533 Type B, Class 1 (rolled plate)

–  Base metal:

•  As-received: quenched, tempered, stress relieved •  Given simulated stress relief (SSR) treatment to account for weldments during RPV

fabrication (607°C for 19.7 hours, controlled heating and cooling rate above 425°C)"–  Weldments:"

•  Qualified submerged arc welds (SAW) produced by Precision Custom Components, LLC (York, PA)

•  Given post-weld heat treatment (PWHT) for stress relief, same as SSR conditons

Microstructure – SSR Condition

Transverse section

Baseline Tensile (cont.)

0"

100"

200"

300"

400"

500"

600"

700"

800"

0" 100" 200" 300" 400" 500" 600"

Strength"(M

Pa)"

Test"Temperature"(°C)"

Tensile"Strength"1"Tensile"Strength"2"Yield"Strength"1"Yield"Strength"2"Min."Tensile"Strength"Min."Yield"Strength"

371°C"

ASME"Code"SecGon"II,"Part"D"Table"2A"

Baseline Tensile (cont.)

0"

20"

40"

60"

80"

100"

0" 100" 200" 300" 400" 500" 600"

Elon

ga0o

n"or"Red

uc0o

n"in"Area"(%

)"

Test"Temperature"(°C)"

Elonga0on(8.3ED5/s)"Elonga0on"(1.0ED3/s)"Reduc0on"in"Area"(8.3ED5/s)"Reduc0on"in"Area"(1.0ED3/s)"

Creep Rupture, Base Metal (Table A1, Confirmatory)

Temp. (°C)

Initial Stress (MPa) Performer Status

Rupture Time (hrs.)

Creep Strain at Rupture (%)

350 552 Dirats complete 96.1 7.72

350 552 Dirats complete 120.5 8.132

350 517 Dirats complete 9589.3 16.222

350 517 Dirats complete 7239.6 13.039

350 483 INL in progress >10200 >2.5

350 483 INL not started - -

371 517 Dirats complete 197 11.565

371 517 Dirats complete 276 10.547

371 483 Dirats complete 5472.3 16.553

371 483 Dirats complete 6130 17.683

371 448 INL in progress >7000 >2.8

371 448 INL in progress >3100 >2.7

390 483 Dirats complete 215.5 11.565

390 483 Dirats complete 256.2 12.494

390 448 Dirats complete 5046.6 17.628

390 448 Dirats complete 5827.1 17.661

390 414 INL in progress >10200 >2.5

390 414 INL not started - -

Creep Rupture, Base Metal (Table A30, Short-term)

No. Temp. (°C)

Initial Stress (MPa) Performer Status

Rupture Time (hrs.)

Creep Strain at Rupture (%)

1 350 524 Metcut complete 9892.1 20.6

2 350 524 Metcut complete 6920.4 13.7

3 371 483 Metcut complete 4548.2 9.4

4 371 483 Metcut complete 7571 16.9

5 427 414 Metcut complete 474.7 17.5

6 427 414 Metcut complete 348 12.3

7 482 296 Metcut complete 937.3 14.7

8 482 296 Metcut complete 827.9 25.5

9 538 172 Metcut complete 559.4 37.0

10 538 172 Metcut VOID VOID VOID

11 593 62 Metcut complete 1524.5 35.0

12 593 62 Metcut complete 1397.3 44.1

13 427 414 Metcut complete 633.9 17.5

14-RP 538 172 Metcut complete 693.5 29.6

Creep Rupture, Base Metal

0"

200"

400"

600"

800"

1000"

13000" 14000" 15000" 16000" 17000" 18000"

Stress"(M

Pa)"

Larson8Miller"Parameter,"P"

Table"A1"(Confirmatory)"Table"A30"(Short8term)"

Creep Rupture, Base Metal (Table A7, Long-term Qualifying)

Low Cycle Fatigue (LCF)

Stress Relaxation

Fatigue-Stress Relaxation 350°C, 1% total strain range

Fracture Toughness, Base Metal

Courtesy of R. K. Nanstad and M. A. Sokolov, ORNL

Damage + Tensile •  LCF Damage Treatment: 427°C, 180 cycles, 1% strain range,

hold time = 0, 10, 30 min.

0

200

400

600

800

0 200 400 600

Ulti

mat

e Te

nsile

Stre

ngth

(MP

a)

Test Temperature (ºC)

0 minutes 10 minutes 30 minutes no LCF damage (baseline)

0

200

400

600

800

0 200 400 600

Yie

ld S

tress

(MP

a)

Test Temperature (ºC)

0 minutes 10 minutes 30 minutes no LCF damage (baseline)

Damage + Tensile (cont.)

0

20

40

60

80

100

0 200 400 600

Red

uctio

n in

Are

a (%

)

Test Temperature (ºC)

0 minutes 10 minutes 30 minutes no LCF damage (baseline)

Damage + Creep Rupture

0

50

100

150

200

250

300

0 10 20 30

Tim

e to

Rup

ture

(hrs

.)

LCF Hold Time (min.)

350 ºC, 552 MPa 371 ºC, 517 MPa 390 ºC, 483 MPa Baseline-No LCF Damage Baseline-No LCF Damage

Baseline (no LCF damage)

Creep Conditions

•  LCF Damage Treatment: 427°C, 180 cycles, 1% strain range, hold time = 0, 10, 30 min.

Path Forward •  Weldments

–  All non-aged specimens are currently being machined –  Short-term aging in progress

•  Compact tension (CT) fracture toughness –  Testing of base metal and weldments will be performed at Oak

Ridge National Laboratory (ORNL) •  Short-term aging of base metal complete in June, test in FY12

–  Tensile –  CT fracture toughness

Challenges •  Stress relaxation testing behind schedule

–  Problems with frame controls stopped testing –  Now have path forward, testing will resume in July

•  Time required for aging treatments on weldments (short-term aging requires up to 6500 hr.)

•  Duration of long-term creep rupture tests

Summary •  A508/A533B test plan has been scaled back from PLN-2803 to

focus only on key issues for ASME Code Case N-499-2 •  Complete as many tests as possible in FY12 •  Complete carryover scope and remaining tests in FY13 •  Plan to keep one or more long-term qualifying creep tests

running

Richard Wright Technical discussions Sam Sham (ORNL) Test planning & data analysis Karen Miller Subcontracting & logistics Randy Nanstad (ORNL) Fracture toughness testing Randy Lloyd Stress relaxation testing Dennis Kunerth Heat treatment, welding Julian Benz Creep testing Tom Lillo Creep testing Nancy Lybeck Data analysis & database

Team

Barry Rabin Idaho National Laboratory Barry.Rabin@inl.gov (208) 526-2304