Corrosion study of Li-based blanket materials in RF

Transcription

1 Corrosion study of Li-based blanket materials in RF N.I., Loginov1 M.N. Arnoldov1, V.A. Morozov1, I.R. Kirillov2, A.E. Solomatin3 1-Institute of Physics and Power Engineering (IPPE), Obninsk; 2- D.V. Efremov Institute of Electrophysical Apparatus, St. Petersburg; 3-Institute of Nuclear Researches RAS, Troitsk

2 Introduction Lithium and lead-lithium alloy are considered as coolants and tritium breeding materials for fusion blankets. Compatibility of structure materials - vanadium alloy and ferritic-martensitic steels with lithium and lead-lithium alloy correspondingly is an important issue. Therefore, in the SSC RF-IPPE study of corrosion interaction of lithium with V-4Ti-4Cr alloy by means of Rotating Disk Facility (RDF) were started. The study was undertaken IPPE together with A.A. Bochvar and D.V. Efremov Institutes. It is supposed to fulfill the study at three lithium temperatures, namely, 400, 500, and 600 ºC, at 3-4 lithium velocities in 0 3 m/s range. Concentration of impurities in lithium has to corresponds to ITER requirements. It is supposed to test three identical specimens in each condition. Besides, several specimens were tested in ampoule, i.e. in static lithium, at the same conditions. More over, it is supposed to carry out ampoule tests at different concentrations of impurities in future. Three RDF were constructed, filled with lithium, and the first stage of testing was carried out. After completing these tests, RDF must be filled with eutectic led-lithium alloy to test ferritic-martensitic steels. It is supposed to test pure samples and cowered with insulating layer. It is very important to study role of impurities (O, N, H, C) at corrosion process. So, some methods for impurities control are under development in the IPPE. IPPE has also experimental circulating loops with Li and a small circulating loop with Pb-Li alloy is under construction now.

3 Research technique Research of corrosion in static lithium is carrying out in pressurized ampoules. Molybdenum cup with previously grinded specimen immersed in lithium was installed into stainless steel ampoule. The ampoule was fulfilled with helium, pressurized and heated into electric furnace. The needed temperature was controlled by means of thermocouple and automatic control system. The tests carried out simultaneously in three ampoules exposed at three above-mentioned temperatures. Mass of the specimens and lithium was determined by weighting. After exposition, the specimens was washed with ethyl alcohol, weighted and the dissolved mass of them can be determined. But, the vanadium can forms a ternary compounds of V l Li m N n type. It increases a specimen mass. On the other hand, lithium takes up oxygen from vanadium and decreases the specimen mass. So, there is some uncertainty in dissolved mass determination. Therefore, metallographic analysis of the specimens is needed to find thickness of corrosion layer and its composition, and to make conclusion on corrosion intensity. To determine solubility of the alloy elements (vanadium, titanium, chromium) in lithium it must be frozen in inert atmosphere and analyzed. Different specimen velocity comparatively with fluid can be implemented at the same disk, at the same rotational speed., Because peripheral velocity r changes along the disk radius from 0 to R, the authors suppose to use sectional disk made of three or four ring sections inserted one into another.

4 Test facilities Ampoules and samples after exposition Ampoule assembled

5 Test facilities Ampoule with molybdenum cup and frozen lithium (after 1450h at 450 o C) a m p molybdenum o cup and u frozen lithium (after l1450h at 450 o C) e

6 Test facilities RDF in complex Three Rotating Disc units RD diassembled

7 Test facilities Vacuum (pressure) chamber Mo crucibles into chamber are prepared for filling with Li

8 Test facilities Pb-Li circulating loop Inventory 20 liters Flow rate up to 2m 3 /h Temperature up to 450 o C Structure materials SS (Cr18Ni10Ti)

9 ì ì 3 2 Test facilities Ä 7 Ä 1 Ä 8 B Ã 4 5 B Ã 31 B Ã 32 Ä 2 B Ã 33 B Ã , Ä 3 B Ã 35 B Ã , Ä 4 B Ã 37 Ä 5 B Ã 39 B Ã 3 8 B Ã , , Ä 6 B Ã 41 B Ã , , 32 Ä î ç à ò î ð B Ã 47 Â Ã 4 8 Ë Ï 3 B Ã 43 B Ã 44 B Ã 4 6 Ä 9 B Ã 4 9 B Ã 5 1 Ä 1 ê ð à ì ï å B Ã 5 0 B Ã 5 2 Ë Ï 4 B H 1 Â Ð 10 Â Ð 2 2 Ï Ó Â Ð 19 Ï Í Á Ä Â Ð 2 0 Â Ð 15 Â Ð 10 9 Â Ð 2 1 Â Ð 17 Â Ð 18 Â Ð 13 Ë Ä Ï Î Â Â Lithium Test Facility (LTF) Li inventory 60 liters Li flow rate up to 8m 3 /h Maximum temperature 600 o C Structure material SS (Cr18Ni10Ti) Â Ð 5 Õ Ë Â Ð 12 Ð 5 Â Ð 8 Ð 3 Â Ð 9 Ò Ë Â Ð , 32 ì Â Ð 1 ì Ë Ï 1 Â Ð 2 2 7, 32 1 Â Ð 3 Ë Ï 2 Á Ñ 2 Ð 4 Â Ð 10 Â Ð 6 Ý Ð Í 1 Â Ð 11 Ñ 1 Ñ 2 Â Ð 14 Â Ð 16 Â Ð 7 Á Ç 2 Á Ñ Ï Î Â Ã 5 4 Â Ã 5 5 Í Ä

10 Some results #1 after 1450h at 600 o C #2 after 750h at 600 o C RD 100h 450 o C 1,6m/c #3 after 750 at 450 o C #4 after 1450h at 450 o C

11 Some results 3 Table of results sample s Temperat ure ºС Rotating speed, r/c Time of test, h Sample mass,mg Remarks Remarks Before test After test 0 (disc) mg mkm 1 (foil) Δ=0,1mm +4.8mg Black spots on both sides 2 (foil) Δ=0,1mm +4.9mg Clean 3 (foil) Δ=0,1mm Clean 4 (foil) Δ=0,1mm -0.3mg Clean

12 Е,mV P PI, mv Impurity control 1,4 Lithium flow rate versus temperature before purification 1,2 1,0 0,8 0,6 0,4 0,2 Plug indicator for lithium Lithium flow rate versus temperature after trapping and gettering Lithium flow rate versus temperature after trapping 1,50 1,25 1,00 0,75 0, T, o C 0, T, o C

13 Impurity control Tube sampler for metallic impurities and nitrogen

14 - G o, кдж/г.ат.о Impurity control Electrochemical oxygen sensor 540 [7] 530 [8] 520 (2) (1) [9] (3) [6 11] Literature data (calculations) [6], [10], [11] (1) ; (2) ; (3) the authors experimental data T, o C Thermodynamic potential of oxygen in lithium versus temperature

15 Conclusion 1. Preliminary tests of V-4Ti-4Cr in Li are carried out. 2. Rotating disc mass decreasing occurred 0.6mg, or 0.038mkm thickness, during 100 hours at 600 o C. It possibly means that oxygen go out from vanadium to lithium. 3. In static Li at 600 o C samples mass increasing is about 5mg during 750 and 1450 hours. It is possible nitrogen goes from Li to vanadium. 4. Samples mass changing absent practically at the temperature 450 o C during 750 and 1450 hours. 5. Three RDF are constructed in IPPE and corrosion study of Li-based blanket materials will be continued. 6. PbLi-based blanket materials are planned at the next year 7. PbLi circulating loop is under construction and several methods of impurity monitoring are proposed. 8. There is in IPPE circulating lithium test facility as well which can be used for long term corrosion studies.