Halden Boiling Water Reactor H.M. Nordin, R. Szke 19 th - - PowerPoint PPT Presentation

▶
halden boiling water reactor
SMART_READER_LITE
LIVE PREVIEW

Halden Boiling Water Reactor H.M. Nordin, R. Szke 19 th - - PowerPoint PPT Presentation

Dec 23, 2023 179 likes •421 views

Corrosion and Deuterium Pickup in Zr-2.5Nb: Twenty Years of In-Reactor Testing at the OECD Halden Boiling Water Reactor H.M. Nordin, R. Szke 19 th International Symposium on Zirconium in the Nuclear Industry May 19 - 23, 2019, Manchester, UK.

slide-1
SLIDE 1
  • 1-

UNRESTRICTED / ILLIMITÉ

Corrosion and Deuterium Pickup in Zr-2.5Nb: Twenty Years of In-Reactor Testing at the OECD Halden Boiling Water Reactor

H.M. Nordin, R. Szőke

19th International Symposium on Zirconium in the Nuclear Industry May 19 - 23, 2019, Manchester, UK.

slide-2
SLIDE 2
  • 2-

UNRESTRICTED / ILLIMITÉ

Outline

  • 1. Introduction
  • CANDU Reactor
  • Pressure Tube
  • Pressure Tube Fabrication
  • Corrosion and Deuterium Ingress
  • 2. Experiment
  • Materials
  • Test Loop
  • 3. Results
  • 4. Summary
slide-3
SLIDE 3

UNRESTRICTED / ILLIMITÉ

  • 3-

CANDU Reactor

slide-4
SLIDE 4

UNRESTRICTED / ILLIMITÉ

  • 4-

CANDU Reactor Fuel Channel

Pressure tube Calandria tube Feeder pipe Temperature Flow Fast neutron flux [D]

  • Temperature: 250°C – 310°C
  • Pressure: 10 MPa
  • Flux: 0 – 3.5x1017 n/m2s
slide-5
SLIDE 5

UNRESTRICTED / ILLIMITÉ

  • 5-

Pressure Tube Fabrication

1990’s

Zirconium Feedstock Two vacuum arc melts (Double Melt) ingot

1960 – 1980’s

Press forge at 1015°C Rotary forge at 815°C Heat to 1015°C and β-Quench Extrude at 815°C Cold draw 27% Steam Autoclave at 400C for 24 hours

1980’s 1970’s

Four vacuum arc melts (Quad Melt) ingot Press forge at 1015°C Rotary forge at 815°C Heat to 1015°C and β-Quench Extrude at 815°C Cold draw 27%

slide-6
SLIDE 6

UNRESTRICTED / ILLIMITÉ

  • 6-

Pressure Tubes

  • Historically, extensive research programs have been under

taken to fabricate improved pressure tubes:

  • ~ 1960’s started investigating Zr-2.5Nb – improved

mechanical properties and corrosion

  • ~ 1980’s introduced β-quenching – improve strength
  • ~ 1990’s introduced quad melting and lowered initial

hydrogen content – reduce Cl and F for improved fracture toughness

  • ~ 2000’s increased Fe concentration to 1080 ppm and

reduced C concentration to 80 ppm – improve corrosion, deformation and fracture toughness

slide-7
SLIDE 7

UNRESTRICTED / ILLIMITÉ

  • 7-

Pressure Tubes

  • The extrusion process is known to result in microstructure and

texture variations along the pressure tube which in turn affects deformation, mechanical properties, oxidation and deuterium pickup.

slide-8
SLIDE 8

UNRESTRICTED / ILLIMITÉ

  • 8-

Corrosion and D Ingress

  • Corrosion and the associated deuterium ingress may be life

limiting degradation mechanisms in Zr-2.5Nb pressure tubes.

  • Corrosion and deuterium uptake in pressure tubes can be

influenced by:

  • environmental factors (flux, temperature or pH).
  • material properties (microstructure, microchemistry, texture

and state of the β-phase) which are influenced by fabrication processes.

  • To support pressure tube improvement programs, in-reactor

corrosion and deuterium ingress studies were conducted at the OECD Halden Boiling Water Reactor over a 20 year period.

  • Effect of environment and fabrication variables investigated:
  • ingot melting (double melted or quadruple melted)
  • non--quenched versus -quenched
  • cold work (12% or 27%)
  • pH
  • In-flux versus out-flux
slide-9
SLIDE 9

UNRESTRICTED / ILLIMITÉ

  • 9-

Materials

  • Corrosion test coupons were machined from twenty-one different

Zr-2.5Nb pressure tubes.

  • variations in fabrication history (e.g. β-quenched) and minor

element concentration, illustrating the development history of pressure tube fabrication processes.

  • The machined coupons tested had different surface finishes:

Machined coupons ~ 10 mm wide, 30 mm long and 1 mm thick

Machined Pickled HF, HNO3 and H2SO4 solution Pickled + Pre-filmed 400°C steam for 24 hours Machined + Pre-filmed 400°C steam for 24 hours

Note: Many variables!

slide-10
SLIDE 10

UNRESTRICTED / ILLIMITÉ

  • 10-

Schematic Diagram of In-Flux Test Loop 9

  • Operates under CANDU HTS conditions (pHa 10.2-10.8)
  • Two independently heated in-flux test channels,

three out-flux autoclaves

  • Temperature range: 250°C – 335°C
  • Neutron flux: 3-5x1013 n/cm2/s
  • Ratio of thermal flux\fast flux: 2:1
slide-11
SLIDE 11

UNRESTRICTED / ILLIMITÉ

  • 11-

Oxygen and Deuterium Pickup

  • Oxidation kinetics were linear after 150 days.
slide-12
SLIDE 12

UNRESTRICTED / ILLIMITÉ

  • 12-

Effect of Flux on Oxide Growth Rate

  • The in-flux oxide growth rate tends to be greater than the
  • ut-flux oxide growth rate (P-value = 0.0004).
  • Enhancement of in-flux oxide growth rate dependent on

initial microstructure and surface finish.

slide-13
SLIDE 13

UNRESTRICTED / ILLIMITÉ

  • 13-
  • No effect of flux on deuterium pickup (P-value = 0.96).

Effect of Flux on D Pickup Rate

slide-14
SLIDE 14

UNRESTRICTED / ILLIMITÉ

  • 14-
  • Oxide growth and deuterium pickup rate similar between Kroll and

electrolytic.

  • Larger extruded tube front-back differences in Kroll ingots.

Ingot Production

slide-15
SLIDE 15

UNRESTRICTED / ILLIMITÉ

  • 15-

Effect of Ingot Melting

  • Quad melting result in lower deuterium ingress rates.
slide-16
SLIDE 16

UNRESTRICTED / ILLIMITÉ

  • 16-

Effect of β-Quenching

  • β-quenching results in lower deuterium ingress rate.
slide-17
SLIDE 17

UNRESTRICTED / ILLIMITÉ

  • 17-

Effect of β-Quenching

Non-β-Quenched β-Quenched

  • More uniform grain structure in β-quenched material.
  • Curly nature of non-β-quenched grains may cause β-Zr filaments to be
  • riented perpendicular to free surface leading to faster oxidation along

these filaments.

slide-18
SLIDE 18

UNRESTRICTED / ILLIMITÉ

  • 18-

Comparison of Fabrication Methods

  • Fabrication modifications reduced oxide growth rate.

1960 - 1980 1980 - 1990 1990 - 2000 2000 - 2005

slide-19
SLIDE 19

UNRESTRICTED / ILLIMITÉ

  • 19-

Comparison of Fabrication Methods

1960 - 1980 1980 - 1990 1990 - 2000 2000 - 2005

  • Deuterium ingress reduced by a factor of 5.
slide-20
SLIDE 20

UNRESTRICTED / ILLIMITÉ

  • 20-

Discussion

  • A large number of confounding variables in tests making

comparison of data and interpretation of the results difficult.

  • The synergistic interactions between fabrication processes,

microstructure, texture, the state of the β-phase and the resulting pressure tube properties are difficult to assess.

  • With the tube improvements, the net total concentration of

hydrogen isotopes has been significantly reduced making Zr-2.5Nb pressure tubes much less susceptible to the deleterious effects of hydrides on fracture properties.

slide-21
SLIDE 21

UNRESTRICTED / ILLIMITÉ

  • 21-

Conclusions

  • Research programs undertaken to improve pressure tube

properties were successful in reducing corrosion and deuterium ingress.

  • Deuterium ingress reduced by a factor of 5.
  • This reduction should make Zr-2.5Nb pressure tubes much

less susceptible to the deleterious effects of hydrides on fracture properties.

slide-22
SLIDE 22
  • 22-

UNRESTRICTED / ILLIMITÉ

Acknowledgements

  • CNL’s (formerly AECL’s) in-reactor corrosion test program lasted for

approximately 20 years.

  • The contributions of many individuals need to be acknowledged:
  • From AECL/CNL (including former employees): V. F. Urbanic,

R.A. Ploc, G. McDougall, I. J. Muir, G.A. McRae, A. A. Bahurmuz, A.J. Elliott, A. Shaddick, S. Bergin, V. Hilton, C. Davis, M. Seguin, D. Wilkins, R. MacLeod, A. Britton,

  • R. Stuthers, P. Sullivan, D. Irvine, R. Beier, J. Hamel, Y.

Andrews and M. Godin.

  • From the Halden Reactor Project (including former

employees): M. A. McGrath, K-L Moum, I. Thoresen, H. Devold, H. Valseth, H. Thoresen, C. Helsengreen, M. Lundgren, K-W. Eriksen, C. Vitanza.

slide-23
SLIDE 23
  • 23-

UNRESTRICTED / ILLIMITÉ

Heidi.Nordin@cnl.ca Reka.szoke@ife.no