PHYSICAL PROPERTIES MEASUREMENTS WITHIN MASCA PROJECT. Asmolov V.G., Abalin S.S., Merzlyakov A.V. Russian Research Centre “KURCHATOV INSTITUTE” Abstract Measurements of corium physical properties started within of RASPLAV project have been continued within MASCA project. Experimental data on viscosity, density and liquidus temperature of C-32 corium are presented in report. Within MASCA project the phenomenon of uranium and zirconium extraction was found at interaction of molten corium and metal iron. The melt is stratified on oxide and metal parts. Physical properties of the metal part were studied within MASCA project. The experimental data on conductivity, thermal conductivity, viscosity and liquidus temperature of “metallic body” are presented in report. 1 Introduction Within the context of the OECD MASCA project, the works on the measurement of the corium physical properties started under the RASPLAV project were proceeded. Physical properties of the “metallic body”, the alloy produced on the suboxidized corium interaction with steel (iron), were measured too. This report presents the results of the corium C-32 viscosity and density measurements and data on the measurements of electric conductivity, thermal conductivity, viscosity and temperatures for phase transients. Viscosity of the c-32 corium The method of damping of torsional oscillation of a cylinder filled with studied liquid was employed for the measurement of viscosity as it was in the OESD RASPLAV project. The technique theoretical basis, the procedures for the test performance and for the experimental data processing were described earlier [1]. Figure 1 illustrates the test facility layout. Figure 2 demonstrates the example of the test thermogram. Figure 1. The Test Facility Layout 1 – Vessel 2 – Heater 13 3 – Inductor coil 12 10 4 – Support 9 5 - Corium 6 – Cylinder 8 7 – Rod 8 – Diaphragms 11 9 – Mirror 3 10 – Laser He-Ne 1 11 – Scale 13 7 12 – Thread 2 13 – Windows 14 - Pyrometer 6 14 4 5 Figure 2. The Example of the Test Thermogram on the Measurement of Viscosity 2700 2600 2500 2400 2300 C) 2200 o e ( 2100 ur at 2000 per 1900 m e 1800 T 1700 1600 1500 1400 1300 24 36 48 60 72 84 96 108 120 Time (min) Experimental Results Figure 3 shows the damping decrement of the torsional vibrations of the cylinder with a molten corium versus the temperature. Up to 2200°C (Figure 3 does not show this area), the system behaves as a solid body and is characterized by a low damping factor that is practically independent of the temperature. Under the temperatures higher than 2370°C, the system is characterized by a high damping factor that is slowly decreased with the temperature increase. This behaviour is typical of normal liquids. Within the temperature range 2200 - 2370°C, the system is characterized by a noticeable growth of the damping factor with the temperature increase. This temperature range may be considered as a simultaneous existence of a solid and liquid phases. Figure 3. The Damping Decrement versus the Temperature 150 100 00 10 * c e D 50 0 2200 2300 2400 2500 2600 Temperature(oC) 3 The values were calculated for the corium C-32 kinematic viscosity under the temperatures higher than 2370°C. Figure 4 presents the kinematic viscosity versus the temperature. Figure 4. The Kinematic Viscosity versus the Temperature 0.85 0.80 0.75 0.70 ) /s 2 m ( 0.65 V*E6 0.60 0.55 0.50 0.45 2350 2400 2450 2500 2550 2600 Temperature (oC) It should be noted that the obtained dependence is very close to that measured earlier for the C-22 corium [1]. Conclusion The C-32 corium kinematic viscosity was measured within the temperature range 2380 - 2600°C. The obtained dependence is close to that measured earlier for the C-22 corium. Density of the C-32 Corium A modification of the hydrostatic weighing method called the submersible cylinder method was chosen to measure density. The Test Facility Figure 5 illustrates the test facility layout. 4 Figure 5. The Test Facility Layout 16 15 14 12 5 13 4 8 3 7 6 2 1 9 10 11 The corium (3) was placed into the tungsten crucible (2). The crucible was covered with a tungsten cover with a pipe the end of which came out into the facility cold area. A tungsten cylinder (4) was hanged in the crucible above the corium. The upper part of the pendant consisting of a thin tungsten rod (5) and metal wire (14) was attached to the platform of the electronic scales (16). The weight measurement accuracy was 5 mg. A microprocessor was installed into the scales that allowed to record their readings in the computer. The scales protective shielding (15) and the facility casing were conjugated through the hermetic seal (13). The scales protective shielding (15) with the scales inside could move relative to the facility casing (1). Their relative positions might be noted at the scale (12) accurate to 0.05 mm. The crucible with the corium was placed on the support (9) inside the heater. The crucible bottom temperature was measured by a pyrometer. A thermostating embedding (7) of a high thermal conductivity was attached around the heater to reduce the temperature gradients. The whole facility was enclosed by a thick layer of thermal insulation (8). The Test Procedure and Results At the test beginning, the tungsten cylinder position was chosen to be above the melt level. Then, the protective shielding with the scales inside went down with a pitch of one millimeter. At each position of the scales, the difference between the initial cylinder weight and the current one was noted. Figure 6 demonstrates the example of this dependence. 5 Figure 6. Dependence of the Difference between the Initial Value for the Cylinder and Pendant Weight and the Current Value of that at Each Position of Scales 6.0 4.0 ) g 2.0 dM ( 0.0 -2.0 -5 0 5 10 15 20 25 30 35 H (mm) The change in the weight is not observed in the course of the scales relocation when the tungsten cylinder bottom does not touch the melt surface (Scale divisions higher than 26 mm correspond to this case in Figure 6). A drastic increase in the weight due to the corium surface tension forces is observed on the cylinder bottom touching the melt surface. On the further cylinder immersion into the melt, the cylinder weight is linearly decreased with the immersion depth due to the buoyancy force. The inclination of line was determined by the least-squares method. The melt density was calculated by the following formula: 1 1 dM ρ = − ⋅ ⋅ s s dx 1+ SC − s P − P(h) dM (h) = 0 g where: ρ - density; S – the cylinder cross-section area; SC – the crucible cross section area; P0 – the cylinder weight in argon; P(h) – the cylinder weight immersed in the depth h; X – cylinder position. The measurements were performed at several temperature values. Table 1 presents the obtained results. Table 1. The C-32 Corium Density Temperature (oC) Density (g/cm3) Dispersion (g/cm3) 2482 7.40 0.17 2482 7.61 0.24 2534 7.42 0.21 2585 7.39 0.19 6 The C-32 corium surface tension was measured earlier within OECD RASPLAV project. Simultaneously, the melt density might be evaluated. The following value for density 7.49 ± 0.44 g/cm3 was obtained from the data of the surface tension measurement. Conclusions The facility was developed, designed and fabricated to measure density of high-temperature melts. The facility operating temperatures ranges up to 2700ºC. The test facility, procedures of the measurement and data processing were tested in the experiments with water. Measured water density coincides with the tabular data. Dispersions are less than the experimental errors. Data on the C-32 corium density were obtained within the temperature range 2482 - 2585ºC. C-32 Corium Liquidus Temperature Measurement Several techniques can be used to measure liquidus temperature of corium. These techniques have been developed within OECD RASPLAV&MASCA projects • Viscosity technique • Gas bubble technique • Thermogram recording technique. The example of liquidus determination by viscosity technique is presented in Figure 7. Figure 7. Decrement vs Temperature (62UO2 + 38ZrO2 mol%) Liquidus temperature ent 1000 m Decre o Temperature ( C) The facility schematic for liquidus measurement by gas bubble technique is presented in Figure 8. 7 Figure 8. Gas Bubble Technique: Test Section 1.Vessel; 2.Tungsten crucible; 3.Corium; 4.Capillary; 5.Guide; 6.Heater; 7.Thermostat; 8.Thermal insulation; 9.Support; 10.Peep hole; 11.Pyrometer; 12.Scale; 13.Pressure-gauge; 14.Ar-admission valve; 15.Sealing unit. The dependence of pressure vs. temperature is presented in Figure 9. Figure 9. Gas bubble technique: Pressure vs. temperature. (54.5UO2 + 14.5ZrO2 + 31 Zr) 9 8 ) 7 Pa k e ( r 6 su es Liquidus r 5 P 4 3 2320 2340 2360 2380 2400 2420 2440 Temperature (oC) 8 Figure 10. Comparison of Liquidus Measurement by Three Different 9 0.12 0.6 Pressure Decrement 7.5 0.1 0.5 ) t Pa) s k en C/ ( dT/dτ o e m ( r 6 e 0.08 0.4 τ u d cr s / e s e D dT Pr 4.5 0.06 0.3 3 0.04 0.2 2300 2325 2350 2375 2400 2425 2450 Technique Temperature (oC) As one can see three different techniques gave very close results. The Choice of the Material for the “Metallic Body” Melt Retention The choice of the material for the “metallic body” retention presents quite a complicated problem. The thing is that such metals as iron and zirconium are parts of the “metallic body” composition.