Task 6.1 Material for heat transfer components for heavy liquid metal reactors – KIT contribution

1. Task 6.1 Material for heat transfer components for heavy liquid metal reactors (KIT-18, ENEA-3, UJV-7) Month 1 – 36 • Determine important mechanical properties of T91 with and without surface protection like creep and stress in combination with Pb of materials for heat transfer components • Transfer the surface protection process (GESA) to steam generator geometry • Determine the heat transfer properties of materials in contact with Pb • Assess the possibility to aluminize the entire reactor core internals inclusive pressure vessel - specific request from Design • Task responsible persons: • KIT: Alfons Weisenburger; ENEA: Alessandro Gessi; UJV: Anna Hojna • Deliverables:D33 – Summary of HLM reactors materials (M36) –KIT • Technical reports:T09 - Heat transfer properties (M24) – KIT • T13 - Surface aluminizing of steam generator components (M30) – KITT17 - Influence of lead on mechanical properties (M36) – KIT-G, ENEA, UJV

2. Task 6.1 Material for heat transfer components for heavy liquid metal reactors – KIT contribution Surface aluminizing – GESA process • Based on ELSY and DEMETRA surface treatment procedure using GESA will be optimized for cladding tubes: Operating GESA IV – cylindrical cathode - optimization Optimizing coating composition – (GETMAT – own R&D) • Transfer of surface aluminizing method to steam generator geometries. Tubes for steam generators with different bending radius shall be tested under different loads in lead environment. The creep and stress shall be measured in situ using high temperature strain gauges. Stress dependent significant influence of LBE on creep to rupture at 550 °C detected • Identification of threshold stresses of creep to rupture tests, below which the influence of the lead on the mechanical properties is negligible. Especially the stress limits for surface alloyed specimens will be addressed in this task. Thermal conductivity, Heat transfer of oxidized T91 in Pb is still discussed: • Dedicated tests to measure the thermal conductivity and/or thermal diffusivity of oxidized steel surfaces with adherent lead will be performed. Assess the possibility to aluminize the entire reactor core internals inclusive pressure vessel - specific request from Design • Looking for different aluminizing processes suitable for large components KIT will participate to all Technical reports and the Deliverable

3. GESA facility Magnetic- coil Anode Target Surface modification using Pulsed Electron Beams (GESA)(Process development in cooperation with NIIEFA, St. Petersburg) LPPS sprayed FeCrAl layer e--beam cathode Volumetric Heating: rate: < 109 K/s time: < 40 µs T91 Melt layer: depth: < 100 µm cooling: < 107 K/s (heat conduction) Surface alloyed layer Electron beam Parameter: Electron Energy:125 keV Power density :~ 2 MW/cm² Pulse duration controllable: < 40 µs Beam diameter: ~ 4cm GESA I Treatable length ~ 30 cm GESA IV Substrate temperature remains relatively low – no micro-structural changes in T91 observed

4. T91 + FeCrAlY layer before and after surface modification Al content ~ 10 wt% As sprayed After GESA treatment Surface smoothed, Pores are removed, layer densified, metallic bonding to substrate Al content ~ 5 - 7 wt%

5. Surface aluminizing – GESA process • Operating GESA IV – cylindrical cathode – optimization - ongoing R&D • measurement of beam homogeneity • Applying Pre-pulse to clean surface of cladding tube • Optimizing coating composition – (GETMAT – own R&D) • different powder compositions were selected: • Al12Cr14, Al7Cr14 – 1000h test’s in COSTA at 550°C and 650°C available • GESA treated Al12Cr14 FeCrAlY form in LBE - if coating quality is suitable - at 550 and 650 °C protective Al2O3 scales • Al content after GESA 6 – 9 wt% • GESA treated Al7Cr14 do not form generally at 550 and 650 °C protective Al2O3 scales - Al content after GESA < 4 wt% • Three “new” coatings Al12Cr14, Al12Cr9, Al12Cr14 Y-free – GESA treated – Al content after GESA ~ 5-10 wt% • Recently started – • start of exposure new coatings in Pb at 450, 500, 550°C and • respective Gas-atmosphere – short term quality proof test Al12Cr14 FeCrAlY after 1000h in LBE at 550°C

6. Surface aluminizing – GESA process Transfer of surface aluminizing method to steam generator geometries. Tubes for steam generators with different bending radius shall be tested under different loads in lead environment. The creep and stress shall be measured in situ using high temperature strain gauges. Can surface aluminized material be bended – what is limiting radius? Status: First bending test’s of GESA modified FeCrAlY coated T91 (Y. Dai PSI) 7% 16% 7% Up to 16% deformation no cracks – no delamination – surface graded material

7. Future steps:FeCrAlY coating to be applied on SG tube sections – bended and not bended – before March 2011GESA (GESAIV) - treatment of such tubes –should be due to larger diameter easier compared with cladding tubes(Bended tube sections can not be treated using GESA IV)Evaluation of max. bending radius after GESA treatment – flat specimens with miniaturized 3point bending test for SEM Test of bended specimens under load in Pb at 500 to 600°C with in-situ stress and strain measurement Influence of bending radius in stability of FeCrAlY surface aluminized T91part of a Master thesis officially starting in March 2011 until August 2011

8. Stress dependent significant influence of LBE on creep to rupture at 550 °C detected Identification of threshold stresses of creep to rupture tests, below which the influence of the lead on the mechanical properties is negligible. Especially the stress limits for surface alloyed specimens will be addressed in this task.

9. Influence of PbBi on time to rupture of T91 orig at 550°C Significant reduction in time to rupture of T91 due to contact with PbBi Oxide scale cracks  PbBi penetrates and reduces the surface energy – Rebinder effect – stress corrosion cracking

10. Comparison of secondary creep rates of T91 in air and PbBi at 550 °C Influence of PbBi Creep rate in PbBi up to 50 times higher than in air Ratio of creep rate in PbBi and air is stress dependant At low stresses – no cracking of oxide scale ?? – no direct contact with PbBi – no influence on creep strength - threshold stress ??

11. Creep tests at low stresses at 550°C – Threshold stress ?? 60Mpa Cracks PbBi can penetrate 120 MPa No cracks No PbBi No influence 60 to 120 MPa no change - as long as oxide scale intact no influence  cracks at 60 and 80 MPa  reduction in strength Any deterioration of the oxide scale results in reduced creep strength

12. Comparison of creep of GESA surface modified T91 in PbBi and T91 orig. in air at 550°C Stress 160 and 180 MPa Stress: 200 and 220 MPa T91 with GESA modified FeCrAl layer also shows an influence of LBE. However, this deterioration is significantly reduced compared to the T91 original. At 200MPa still a reduction in time to rupture from 3500 auf 2500h is observed. At a strain of about 3.5% influence of PbBi becomes visible.

13. Creep to rupture of T91 with and without GESA in PbBi and air at 550°C Stress over time to rupture of T91 original and T91 GESA Oxide scale cracks  PbBi penetrates the crack PbBi reduces surface energy of steel  dissolutes steel elements and penetrates the grain boundaries crack propagation GESA modified FeCrAlY layer reduces the negative influence of PbBi No cracking of oxide scale  no influence of PbBi

14. Stress dependent significant influence of LBE on creep to rupture at 550 °C detected Identification of threshold stresses of creep to rupture tests, below which the influence of the lead on the mechanical properties is negligible. Especially the stress limits for surface alloyed specimens will be addressed in this task. Status and planned tests: Creep to rupture tests in Pb at 550°C at stress levels of 100, 120, 140, 180, 200 MPa Specimens: T91, T91 surface alloyed with GESA Schedule: Preparation of specimens: March 2011 Coating deposition: August 2011 GESA treatment : October 2011 Creep to rupture tests: October 2012

15. Involvement of UJV In Task 6.1 Within the Task 6.1, the UJV Rez plc plan to perform T91 steel will be exposed in convectional loop COLONRI II in liquid lead environment of 550-650˚C. Then same samples will be mechanically tested in air and liquid lead and post test examined. Machine samples - tensile bars Pre-expositon in COLONRI II 550-650˚C liquid lead SSRT tests at 350 – 450˚C in air and liquid lead SEM Report Already shown at Kick – off meeting – no new information

16. Task 6.1 Material for heat transfer components for heavy liquid metal reactors – KIT contribution Surface aluminizing – GESA process • Based on ELSY and DEMETRA surface treatment procedure using GESA will be optimized for cladding tubes: Operating GESA IV – cylindrical cathode - optimization Optimizing coating composition – (GETMAT – own R&D) • Transfer of surface aluminizing method to steam generator geometries. Tubes for steam generators with different bending radius shall be tested under different loads in lead environment. The creep and stress shall be measured in situ using high temperature strain gauges. Stress dependent significant influence of LBE on creep to rupture at 550 °C detected • Identification of threshold stresses of creep to rupture tests, below which the influence of the lead on the mechanical properties is negligible. Especially the stress limits for surface alloyed specimens will be addressed in this task. Thermal conductivity, Heat transfer of oxidized T91 in Pb is still discussed: • Dedicated tests to measure the thermal conductivity and/or thermal diffusivity of oxidized steel surfaces with adherent lead will be performed. Assess the possibility to aluminize the entire reactor core internals inclusive pressure vessel - specific request from Design • Looking for different aluminizing processes suitable for large components KIT will participate to all Technical reports and the Deliverable

17. The sample is mounted on a carrier system which is located in a furnace. After the sample reaches a predetermined temperature, a burst of energy emanating from a pulsed laser is absorbed on the front face of the sample, resulting in homogeneous heating. The relative temperature increase on the rear face of the sample is then measured as a function of time by an IR detector. The thermal diffusivity is computed by the software using these time/ relative temperature increase data. For adiabatic conditions, ais determined by the equation: a = 0,1388 l^2/t (l: sample thickness, t: time at 50% of the temperature increase) Heat transport properties k = arCp k : thermal conductivity [W/(mK)] a : thermal diffusivity [m^2/s] r : density [kg/m3] Cp : specific heat capacity [J/(kgK)]

18. Status: Thermal diffusivity measurements were performed on disks made out of T91, Fe84Cr12Al4 alloy and T91+FeCrAlY+GESA Future steps: Exposure of specimens to oxygen containing Pb: Temperature: 550°C times: 1000h’s and 3000h’s Thermal diffusivity measurements on samples initially exposed to oxygen containing liquid Pb at different temperatures and for different periods: T91, 9Cr –ODS steel, T91+FeCrAlY+GESA, etc. T09 – Heat transfer properties will be in time (March 2012) Heat transport properties

19. Heat conduction as function of oxidescale thicknessin combination with heat transfer simulation Isolation Isolation cooling Pb Infrared camera Pb Temp. Measurement Pb Test section Pb at 500°C - Isolation is removed - Measurement area will be cooled – Cooling is stopped and warming up will be determined as function of time – repetition several times per month – influence of oxide scale thickness) – can be determined separately and at end of experiment Infrared camera records temperature development of steel surface

20. 2nd option use of calorimeter – actual preferred Isolation Isolation Pb calorimeter Pb Temp. Measurement in Pb Test section Use of calorimeter to heat or cool the liquid metal with high accuracy Measurement of liquid Pb temperature in front and after the calorimeter Using heat transfer simulations to calculate the heat conduction

21. TELEMAT at the KALLA-LabTest Loop for Lead Material Testing • Temperature up to 650 °C – 700°C possible • Pb-Inventory 150 l • DN 40 / DN 20 tubing • flexible test branch with • up to 2 m long test setup – can be used to address the „wrapper“ problem –direct flow impact – local turbulent flow pattern • EM Pump with 2 m³/h, resp. 2 m/s in • the test section • heater-recuperator-cooler-design • design for continuous operation • over several thousand hours Schedule: Loop should be ready beginning of 2011 Heat transfer measurements will be the 1st to be performed Temperature for this experiment 500 – 550°C

22. Assess the possibility to aluminize the entire reactor core internals inclusive pressure vessel - specific request from Design Very limited looking for different aluminizing processes suitable for large components Aluminization - Surface alloying of Al on Industrial level: Diffusion Coatings are applied for internal and external oxidation and corrosion protection. Chromalloy  Pack Aluminide The Aluminide Coating is applied by pack cementation to internal and external surfaces of Commercial Aero, Military Aero, Small Engines including APUs, and Aeroderivative/IGT compressor blades, disks and diaphragms and turbine blades, vanes, wheels and tip shoes.  Gas Phase Aluminide The Aluminide Coating is applied by gas phase to internal and external surfaces of Commercial Aero, Military Aero, Small Engines including APUs, and Aeroderivative/IGT turbine blades, vanes, wheels and tip shoes.

23. CVD Chemical vapor depositon

24. Ion Bond Chemical Vapor Aluminizing (CVA) is based on the CVD process and is used for depositing CVD aluminide coatings for high temperature applications. The Bernex ATL CVA is an advanced technology that offers a more environmentally friendly, better forming alternative to older pack, out of pack and slurry technologies. Process TemperatureThe typical process temperature for the CVA process is between 900(°) C and 1050(°) C. Items Typically CoatedThe CVA process is used to protect parts operating in high temperature environments against corrosion and oxidation. As a result, the most common parts coated are high temperature industrial and aero gas turbine components, such as the hot section turbine blades.   Coatings Typically DepositedThe CVA process produces a highly controllable, extremely homogeneous aluminide diffusion layer. Unlike other aluminizing processes, the Bernex ATL process is suitable for coating the internal cooling channels of turbine blades. Advantages of the process: Clean process compared to pack and slurry techniques The process is precisely controlled It is possible to coat internal cooling channels The coating is uniformly deposited Low surface defect density

25. Berolina Metallspritztechnik Wesnigk GmbH Chromin Maastricht BV bero-arc alutherm – Arc spraying of pure aluminum – Heat treament to diffuse the Al into the substrate – ALUMINUM/ALONIZING - alitieren (german acronym)

26. Summary: All three methods are basically similar: Coating deposition plus subsequent heat treatment Temperatures are for all processes relatively high – suitability for F/M steels like T91 is questionable but for 316 type steel off-course well suitable Next steps: Getting in contact with the different companies to discuss the possibility to aluminize large scale components like reactor vessel

27. Task 6.2 Materials formechanical pump for heavy liquid metalreactors (ENEA - 5, KIT - 5)Month 1 - 30 The erosion of structural materials in fluent lead is considered acceptable if the relative velocity between the lead and the structural surface is kept below 2 m/s. This limit cannot be respected for the mechanical pump where the relative velocity is up to 10 m/s or even higher at local areas. Material capable to operate in fluent lead with relative velocity up to 10 m/s and environment temperature up to 500°C with acceptable performance shall be individuated and qualified. Specific materials (Maxthal, SiSiC) tests in representative conditions (speed, mechanical load, thermohydraulic conditions) for heavy liquid metal reactors will be performed. Task responsible persons: ENEA: Mariano Tarantino; KIT: Adrian Jianu; Deliverables:D16 - Erosion stability of materials in fast flowing lead (M30) – ENEA, KIT

28. Task 6.2 Materials formechanical pump for heavy liquid metalreactors(ENEA, KIT-G)Month 1 - 30 • First test with specific conditions show severe erosion • Promising pump materials (Maxthal, SiSiC, ….) will be tested under such conditions • Detailed modeling of flow conditions at specimens to understand the flow impact • KIT will contribute to Deliverable D16 Test performed with 2.5 m/s

29. Actual running tests Temperature of Pb: 500°C Oxygen content: 10-6 wt% Speed of HLM: 2.5m/s – like in previous test Increasing the speed will be investigated Highly turbulent flow – Pb directed on the specimen Not only tangential action of the Pb Materials: SiSiC; Maxthal; FeCrAl GESA; Noriloy; Norihard Test started Oct. 6th 2000h‘s – until end of December Flow conditions will be modeled Pb