Coordinated project KAPSELI

Transcription

1 VTT TECHNICAL RESEARCH CENTRE OF FINLAND LTD Coordinated project KAPSELI KYT Mid-term Seminar Finlandia house J. Rantala, VTT

2 The effect of reaction product layers on copper corrosion in repository conditions (REPCOR)

3 REPCOR Background and Aims The estimated general corrosion rates are in the range 1-3 mm/a, often less than 1 mm/a. Deep pitting is not considered probable. The combined effect of different stages on loss of thickness is usually maximum few millimeters for 10 5 or 10 6 years. Some situations can result in high corrosion rates, but these are expected to be short. Preparation of corrosion product layers in vapour phase and under immersion, and characterization of the reaction product layers. Determining the effect of reaction product layer on corrosion of copper in oxic conditions in vapour phase and immersion. Determining the effect of the reaction product layer on corrosion in anoxic conditions under immersion KYT 2018 Midterm seminar 3

4 REPCOR Corrosive environment Saline, neutral ground water. The corrosion of copper is electrochemical and obeys mixed potential theory. Increase in [Cl - ] and [O 2 ] will increase corrosion rate. Based on steady state models approximately 0.1 mm/y in oxic and 0.1 nm/y in low-oxygen environment. Chloride has stronger effect in oxic systems. Evaporation and condensation of water and uneven bentonite swelling can cause increased corrosion. Previous work has shown that copper corrosion increases with: Temperature Chloride concentration Acidity Oxic conditions KYT 2018 Midterm seminar 4

5 REPCOR Research Scenarios during different transient situations: Corrosion in gas phase Concentrated solutions due to rewetting of corrosion products Uneven corrosion product layers Weight loss tests using Quartz Crystal Microbalance. Measuring surface film thickness with cyclic voltammetry. Regression models for dissolution rates. Copper, ph = 4 S = ppm T = 40 o C, N d KYT 2018 Midterm seminar

6 REPCOR Research Copper in moist atmosphere can show weight increase due to reaction product formation or weight decrease due to corrosion. Synthetic low-salinity ground water in N ng/cm 2 /s. Oxic conditions ng/cm 2 /s, upper value corresponds to 70 mm/year thinning KYT 2018 Midterm seminar 6

7 REPCOR Research Changes in water composition have been tested using OL-SR synthetic groundwater with three TDS levels. OL-SR salinity is ppm, more concentrated waters were ppm and ppm. ph levels 4, 6 and 8. Temperature 40, 60 and 80 o C. Air or nitrogen purging during the 16 hours test. Pure copper and oxidized copper (7 days at 100 o C). Corrosion rates at room temperature in OL-SR water under nitrogen purging were 1-2 mm/a for copper and oxidized copper, hundreds mm/a in hot, acid and oxic solution. Decreasing ph, increasing salinity and temperature and air purging vs. nitrogen purging increased corrosion rate. Corrosion rate of oxidized copper was 6 times higher than pure copper. KYT 2018 Midterm seminar

8 MICOR Microbially induced corrosion during the oxic stage of repository KYT

9 MICOR Microbially induced corrosion during the oxic stage of repository AIM to examine the role of microbiologically influenced corrosion of copper under aerobic conditions that prevail at the early stages of repository of high level nuclear waste SET-UP FOR EXPERIMENTS Long term laboratory experiment To monitor corrosion behavior of copper in environment simulating oxic warm phase of repository, in the presence and absence of microbes Biofilm growth experiment To determine the effect of biofilm on the pitting potential of copper 06/04/2017 9

10 MICOR Long term laboratory experiment OFP-Cu specimens, groundwater from the planned disposal site (with the microbes) Bentonite added into the containers; sterilised/as-received Micro organism enrichment added into two containers, biocide into one Incubation conditions: 37 C, ambient atmospheric conditions Experiment period 3 and 11 months 06/04/

11 MICOR Long term laboratory experiment Korroosionopeus µm/vuodessa µm / vuodessa kk 11kk 3kk 11kk 3kk 11kk Abioottinen Bioottinen Bioottinen ster. Bentoniitti 06/04/

12 MICOR Biofilm growth experiment Biofilm grown on copper specimens for 3, 7, 21 and 49 days, ammonia oxidising bacteria enrichment culture Corresponding environment without microbes in sterile culture medium, 3 and 21 days Anodic polarization and impedance measurements in a capillary cell 06/04/

13 MICOR Biofilm growth experiment 06/04/

14 MICOR Summary Long term laboratory experiment Independent from the test environment (microbes, sterile) the corrosion behavior and surface phenomena were quite similar Corrosion was primarily general corrosion Results demonstrate that groundwater chemistry has important role in the corrosion of copper under the early stage of repository Biofilm growth experiment Biofilm s corrosion inducing or inhibiting properties change with the exposure time and RedOx area of the environment Under slightly oxidative conditions and with mature biofilm the effect was protective In the beginning of the experiment the effect was corrosion inducing 06/04/

15 MICOR Publications P. Rajala, M. Bomberg Reactivation of deep subsurface microbial community in response to methane or methanol amendment. Front. Microbiol. 8:431. E. Huttunen-Saarivirta, P. Rajala, M. Bomberg, L. Carpén, EIS study on aerobic corrosion of copper in ground water: influence of micro-organisms. In review in Electrochimica Acta P. Rajala, L. Carpén, E. Huttunen-Saarivirta, I. Tsitko, M. Bomberg. Vuosiraportti VTT-R Presentation (E. Huttunen-Saarivirta) EIS study on aerobic corrosion of copper in ground water: influence of microorganisms. EIS2016 conference, A Toxa, Espanja /04/

16 Place for a photo (no lines around photo) The effect of microbial activity on corrosion of copper in anoxic state of repository (BASUCA) KYT2018 Midterm seminar Leena Carpén, Pauliina Rajala, Malin Bomberg

17 AIMS To estimate and clarify the effects of microbiological activity on the corrosion behavior of copper canister in the nuclear waste disposal conditions in Finland This part of the study is concentrated on the anaerobic later stage of the disposal period and the effect of sulfate reducing bacteria (SRB) together with methanogens in a simulated groundwater environment temperature stabilized to that of the surrounding bedrock all oxygen consumed Cu in direct contact with ground water (chemistry stabilized with bentonite) 06/04/2017 L.Carpén et al. KYT2018 Midterm seminar

18 Materials and methods Material: Oxygen-free phosphorusdoped copper (OFP-Cu), 600 gritt Artificial sterile ground water (abiotic), artificial ground water with SRB and methanogen enrichment SRB and methanogens retrieved from the deep borehole of the future disposal site enrichment culture Temperature: 10 C Time: 4 and 12 months Measurements: Open circuit potential (OCP) Redox-potential Electrochemical measurements for corrosion and surface phenomena Weight loss for corrosion rate U-bends for stress corrosion cracking Characterization: Photography FE-SEM XRD Quantitative PCR to quantitate the microbes HTP-sequencing for the microbial community Water quality 06/04/2017 L.Carpén et al. KYT2018 Midterm seminar

19 RESULTS 4BIO SRB+MA 12BIO SRB+MA Cu 2 O Cu 2 S, Cu 2 O, CuO 06/04/2017 L.Carpén et al. KYT2018 Midterm seminar

20 RESULTS cont Biofilm/cm 2 16S bacteria 16S archaea dsrb Biofilm developed on surfaces of copper in biotic environments, including bacteria and archaea Species composition evolved during the exposure time 0 Abiotic Copper 4m Bioti Copper 4m Abiotic Bioti Copper Copper 12m 12m Water /ml 16S bacteria 16S archaea dsrb Biofilm, bacteria Abiotic Water 4m Biotic Water 4m Abiotic Water 12m Biotic Water 12m 06/04/2017 L.Carpén et al. Eurocorr

21 Summary The results show that the inocculation of microbes was succesfull: microbes attached to the surfaces and formed biofilm In the simulated groundwater enriched with SRB and methanogens, copper sulfide (Cu 2 S) together with copper oxides were detected on the surface of copper after the exposure In the sterile environment the deposit formed during the exposure was containing copper oxides In the shorter (4 months) exposure the formed biofilm seemed rather to protect than to accelerate average corrosion of copper. However, in both environments some localized corrosion had occurred including small cracks in biotic environment indicating the possible role of stress corrosion cracking In the longer (12 months) exposure the corrosion rates in both systems were relatively equal ( 1 µm/a), but three times more copper was dissolved in the biotic water These as well as results of previous studies show that the prediction of microbiological activity and its effects to corrosion is challenging. More research, especially long exposure studies are needed to be able to evaluate the possible influence of MIC to the long-term safety of nuclear waste disposal concept 06/04/2017 L.Carpén et al. KYT2018 Midterm seminar

22 Publications Peer-reviewed articles: M. Raunio, P. Rajala, E. Huttunen-Saarivirta, A, Legat, A, Kranjc, T, Kosec, L, Carpe n. Copper corrosion monitoring by electrical resistance probes in abiotic and biotic anoxic groundwater environments. Under review in Corrosion. P. Rajala, M. Bomberg Reactivation of deep subsurface microbial community in response to methane or methanol amendment. Front. Microbiol. 8:431 E. Huttunen-Saarivirta, P. Rajala, M. Bomberg, L. Carpén Corrosion of copper in oxygen-deficient groundwater with and without deep bedrock micro-organisms: characterisation of microbial communities and surface processes. Applied Surface Science, 396: E. Huttunen-Saarivirta, P. Rajala, L. Carpén. Corrosion behaviour of copper under biotic and abiotic conditions in anoxic ground water: electrochemical study. Electrochimica Acta, 203: L.Carpén, P. Rajala, M. Bomberg Microbially Induced Corrosion in Deep Bedrock. AMR, 1130: P. Kinnunen, M. Bomberg, P. Rajala, L. Carpén. Industrial Views to Microbe-Metal Interactions in Sub-Arctic Conditions AMR, 1130: H. Kutvonen, P. Rajala, L. Carpén, M. Bomberg Nitrate and ammonia as nitrogen sources for deep subsurface microorganisms. Front. Microbiol 6:1079. Conferences and workreports: L. Carpén, P. Rajala, E. Huttunen-Saarivirta, M. Bomberg Corrosion Behavior of Copper in Simulated Anoxic Groundwater Inoculated with Sulfate Reducing Bacteria and Methanogens. CORROSION2017 C , New Orleans, USA, March L.Carpén, P. Rajala, M. Bomberg, M. Raunio, E. Huttunen-Saarivirta. BASUCA - Vuosiraportti 2016, VTT-R L.Carpén, P. Rajala, M. Bomberg, M. Raunio, E. Huttunen-Saarivirta. BASUCA- Vuosiraportti VTT-R L.Carpén, P. Rajala, M. Bomberg Microbially induced corrosion of copper in simulated anoxic groundwater. Abstract and presentation at Eurocorr 2016, September 11-15, Montpellier, France. L.Carpén, P. Rajala, M. Bomberg Microbially Induced Corrosion in Deep Bedrock. IBS2015, Sanur, Bali E. Huttunen-Saarivirta, P.Rajala, L. Carpén. Corrosion behaviour of copper under biotic and abiotic conditions in anoxic ground water: electrochemical study EMCR 2015 Tróia, May /04/

23 Mechanical strength of copper canister, MECHACOP Hannu Hänninen, Antti Forsström, and Yuriy Yagodzinskyy KYT2018 puoliväliseminaari

24 Determination of the effect of weld defects on the mechanical properties of the EB and FSW welds with utilization of optical strain measurement system Zwick/Roell Z020 electromechanical testing machine and LaVision optical strain measurement system in operation Fragment of novel type of strain sensor pattern Distribution of EB weld defects through the thickness of the weld (ultrasonic NDT) and locations at which sampling for mechanical testing was performed

25 Localization of plastic deformation High strain over the whole specimen gauge length Lower strain rate made deformation localize into a narrower zone Low strain outside of the weld zones

26 Localization of plastic deformation: defective EB-welds Early fracture of the defective area: low strain outside of the defective weld zone Defect Defect

27 SCC in anaerobic sulphide containing solution EBSD map of SCC crack tip SEM image of SCC crack SCC crack Grain boundary Twin boundary Test parameters: Temperature ( C) 90 NaCl (M) 0.1 Na 2 S (M) 1*10-3 Autoclave flow (l/h) 1 Strain rate (s -1 ) 1*10-7 to 5*10-7 Max strain (%) 10 Test time (weeks) 2 ph 7.2

28 SCC in anaerobic sulphide containing solution Initiating SCC cracks?

29 SEM-images of Cu exposed to water and radiation. Dose rate: 0,135 Gy/s, total dose: 69 kgy Islands of needle-shaped crystals formed on the surface of metallic copper in oxygen-free water after the γ-radiolysis (irradiation dose of 69 kgy): (a, b, c) scanning electron microscopy images taken at different magnifications, (d) optical image, (e) scanning electron microscopy backscattered electron image and corresponding energy dispersive X-ray maps obtained using K-lines of O, Cu and C. C. Lousada et al., 2016

30 Hydrogen uptake by copper induced by gamma radiation Plot of the desorption rate of hydrogen from copper samples as a function of temperature (K) measured by temperature-programmed desorption (TPD). 69 kgy γ- irradiated copper sample ( ); non-irradiated sample, background ( ). C. Lousada et al., 2016

31 Hydrogen uptake by copper induced by gamma radiation Amounts of H 2 ( ) and H 2 O ( ) measured in samples of copper metal irradiated in water as a function of the total dose of γ-radiation deposited (D) (Gy). The measurements of H 2 and H 2 O were performed after irradiation. Each data point corresponds to a different irradiation experiment. Both sets of data are normalized for the background values. C. Lousada et al., 2016

32 VTT TECHNICAL RESEARCH CENTRE OF FINLAND LTD Experimentally verified model based predictions for integrity of copper overpack (PRECO) KYT Mid-term Seminar Finlandia house J. Rantala, P. Auerkari VTT

33 Hydrostatic pressure 41 bar + bentonite swelling pressure Concentration of stresses and strains at the weld region Deformation capacity exceeded? Concentration of strain in the weld? Creep crack growth? Load history dependence? Picture: Posiva Oy 06/04/

34 Cylinder Closure of the lid by Friction Stir Welding (FSW) Lid 06/04/

35 Oxide particle zone cracked in creep testing - current practice: in argon 06/04/

36 06/04/

37 FE analysis with relaxation model Mesh at the weld root: Total strain after 1000 years 06/04/

38 Oxide particle zone in a CT specimen Old weld: welded in air New weld: welded in argon, after hydrogen annealing Natural notch extended by wire erosion 06/04/

39 Load history dependence under investigation - slow loading leads to higher deformation Load applied in steps: 69% - 84% -100% 06/04/

40 Summary Prediction of stresses and strains in the copper canister Creep Relaxation Oxide particle zone Load history dependence 06/04/