Corrosion and SCC material testing in SCW in JRC IET Petten

Transcription

1 # Joint Research Centre (JRC) Safety of Future Nuclear Reactors Unit AMALIA laboratory Corrosion and SCC material testing in SCW in JRC IET Petten R. Novotny, P. Moilanen*, P. Janik, S. Penttilä*, P. Hähner, M. Negyesi IE - Institute for Energy Petten - The Netherlands VTT Finland

2 Outline 1. Introduction - JRC IET - Material challenges for SCWR - JRC IET - SCW Experimental Facilities 2. Corrosion in SCW 3. SCC tests in SCW SSRT tests 4. SCC tests in SCW CGR tests 5. Development of a new type of CGR SCC device 6. Summary

3 JRC IET Petten Our Structure: 7 Institutes in 5 Member States IRMM - Geel, Belgium Institute for Reference Materials and Measurements ITU - Karlsruhe, Germany Institute for Transuranium Elements IE - Petten, The Netherlands Ispra, Italy Institute for Energy IPSC - Ispra, Italy Institute for the Protection and Security of the Citizen IES - Ispra, Italy Institute for Environment and Sustainability IHCP - Ispra, Italy Institute for Health and Consumer Protection IPTS - Seville, Spain Institute for Prospective Technological Studies

4 JRC IET Petten MATerials performance assessment for INnOvative reactor systems Cross-cutting tasks Action leader: P. Hähner 1. Pre-normative R&D and Materials Data Management 2. Modelling and Simulation 3. Advanced Microstructural Characterisation Methods System specific tasks 1. Materials Testing for LFR 2. Materials Testing for HPLWR (SCWR) 3. Materials Testing for VHTR and Process Heat Applications

5 Introduction Main Objectives of HPLWR Phase 2 and FQT SCWR EU projects: Investigate materials behavior in supercritical water and to select optimal in-core and out-ofcore materials with respect to: Oxidation resistance Stress Corrosion Cracking (SCC) resistance Creep resistance IASCC Tasks: Autoclave experiments: Oxidation mechanisms of ferritic/martensitic, O.D.S. and austenitic steels, Ni-based alloys Combined mechanism of creep and oxidation Stress corrosion cracking tests

6 JRC IET - SCW Experimental Facilities JRC-IE autoclaves : 3 x (650 C / 30 MPa) with different loading systems: Aut. 1: SSRT system and CER Contact Electric Resistance Measurement Aut. 2: PSCFM Pneumatic Servo-Controlled Fracture resistance Measuring loading devices - Single bellows: CL, CD or slow RDT by 3PB loading system Charpy type of specimen Aut. 3: PSCFM Pneumatic Servo-Controlled Fracture resistance Measuring loading devices - Double Bellows: CL, CD, LCF or slow RDT (5 DC(T) type of the specimen) 1 x Miniature autoclave (650 C / 30 MPa) with different loading systems: - Double Bellows: CL, CD, LCF or slow RDT (5 DC(T) type of the specimen) Water preparation Loops: 3 x (ph, Conductivity, Dissolved O 2, H 2 measurement) Monitoring: DCPD (8 channels), Acoustic Emission, Gamry PCI4 potentiostat, Gamry ECM8 Multiplexer (up to 8 electrode systems).

7 Corrosion in SCW - Experimental water loop # Inlet control: DO2 ph redox κ Outlet monitor: DO2 ph redox Κ DH2 Autoclave Pressure Temperature Flow Volume: 1.8l flow: up to 20l/h

8 Corrosion in SCW Weight gain # Influence of surface preparation on the weight gain results Cr Al Ti C Y 2 O 3 MA PM [1] J.H. Lee et al., J. Nucl. Mater. (2011)

9 Corrosion in SCW SEM, EDS and XRD # SEM, EDS and XRD Cross-section morphology of oxide layers MA956-0 & 600 & 1800h exposure in SCW 0H 600H a b MA 956 grinding initial Ra<0.5µm M11,1800H c d milling initial Ra~5µm M3; 1800H PM 2000

10 weight gain (mg/dm 2 ) oxide thickness [µm/year] Corrosion in SCW Weight gain & thickness of oxide layer # Interpolation of preliminary results Results of 400, 1000, 1800H exposure were recalculated to 8760h (gain after 1year in 650 C) based on (stable gain only for MA956 milled, weight loss was not considered) On condition of linear relation between oxide thickness and weight gain the oxide thickness on MA956 approx. 13mg/dm 2 /year ~ 11µm (16µm PM2000) /year ODS in SCW - oxide thickness as function of temperature SOC Cr-3.44Al [1] y = e x R² = MA956 in SCW - weight gain in time 12.91mg/dm 2 /year y = x R² = MA956, 150PPB DO2, 650 C SOC Cr-3.5Al (500 C, 8ppm DO2) [1] 16CrODS no Al; 510 C [2] 16Cr2Al ODS, 510 C [2] 16Cr4Al ODS, 510 C [2] time (h) Temperature [K] 400,500,600 C, SCW, 8PPM 1year [1]J.H. Lee et al., J. Nucl. Mater. (2011) [1] J.H. Lee et al., J. Nucl. Mater. (2011) [2] A. Kimura et al., J. Nucl. Mater. (2011)

11 SCC tests in SCW Most SCC tests have been conducted using the SSRT and CERT Tests using pressurized capsules or U- bend specimens reported by a few groups Different test techniques can sometimes produce very different results regarding the SCC susceptibility of an alloy. Inter-laboratory comparisons are difficult to make very few labs. have used the same test conditions (temperature, pressure, strain rate, water chemistry)

12 SCC tests in SCW CGR tests Engineering applications require a research output either in terms of measures to avoid SCC, or in terms of components durability. A need for some predictive models relating local parameters, which drive the crack evolution - Disposition curve.

13 SCC tests in SCW - CGR tests Bellows based loading device controlled by pressurizing loop VTT, JRC design The objective was to develop bellows based loading device for measurement of SCC CGR in supercritical water by using actively loaded pre-cracked spec. It is very difficult to attach and use any externally controlled loading devices that go through the pressure boundaries at supercritical temperatures. Furthermore, there is a severe size requirement on the autoclave and on the specimen dimensions.

14 SCC tests in SCW - CGR tests Material: 08Cr18Ni10Ti - Ti-stabilized austenitic stainless steel (AISI 321) Material C Si Mn S P Cr Ni Ti Mo 08Cr18Ni10Ti SEN(B) Charpy type specimens pre-cracked in air, a/w = 0.5 T-L Orientation SCWR environment Temperature [ o C] 288, 550 Pressure [bar] 230 Inlet Conductivity [ S.cm -1 ] 0.09 Outlet Conductivity [ S.cm -1 ] Inlet Dissolved O 2 [ppb] Outlet Dissolved O 2 [ppb]

15 SCC tests in SCW - CGR tests SCC tests in SCWR : t = 550 o C, p = 230 bar, dissolved O 2 = 8000 ppb K IINIT = 9.2 MPa.m 1/2 K IMAX = 13 MPa.m 1/2 a SCC = 0.25 mm da/dt SCC (df/dt = 0) = 2.6x10-8 mm.s -1

16 SCC tests in SCW - CGR tests - Fractographic analysis SCC tests in SCWR : t = 550 o C, p = 230 bar, dissolved O 2 = 8000 ppb

17 SCC tests in SCW - CGR tests - Summary K IINIT = 12.5 MPa.m 1/2 K IMAX = 18.2 MPa.m 1/2 08Cr18Ni10Ti a SCC = 0.55 mm da/dt SCC (df/dt = 0) = 1.3x10-7 mm.s -1 BWR vs. SCW K IINIT = 9.2 MPa.m 1/2 K IMAX = 13 MPa.m 1/2 a SCC = 0.25 mm da/dt SCC (df/dt = 0) = 2.6x10-8 mm.s -1 T.M. Karlsen, 2005 Q. Peng, 2007

18 Development of a new type of CGR SCC device Why? Too high pressure in the bellows, high risk of failure( servo valves) Primary bellows not in contact with the environment Simplification of pressurizing loop New type of specimen: 10, 8DC(T) (W = 20 mm, B = 10 mm) Double bellows loading system high pressure (> 250 bar) SCW (or HT LMFR testing conditions) Advantages: - Bellows 1 generates force - Bellows 2 compensates the effect of the environmental pressure

19 New modifications of CGR SCC device - On-line load measurement (load cell incorporated in the design) - On-line calibration (by using calibrated single bellows directly in the autoclave) Double Bellows Miniautoclave Calibrated single bellows LVDT sensor

20 Summary Operational system available Successfully tested in SCW (Super Critical Water) environment Two possible ways of use: - Small Miniature autoclaves independent - More double bellows devices placed in one big autoclave Mechanistic studies need for reference electrode (HRR) Design for irradiated materials - hot cell & HFR

21 Thank you for attention