SGTR and SGTL

1. SGTR and SGTL

2. Overview • Background to SGTR and SGTL • Present status of cooperation on SGTL between KTH and JRC • SGTR experiments to be executed at FZK on behalf of JRC • Conclusions

3. Pool design and SGTR, SGTL 15..25 MPa, 330..500 oC Steam Generator Tube Rupture (SGTR) SGTR at PWR ~103–104 liter/hour Steam Generator Tube Leakage (SGTL) SGTL Rate: 10 - 103 liter/day Leakage less than 1 liter/day – allowed in normal operation of PWR SGTR SGTL 0.3 MPa, 400..500 oC From P. Kudinov

4. Liquid fraction liquid water Water injection (at 30 MPa, 335 oC) into lead at 0.8 MPa • Beznosov et al (2005) “a steam–water mixture, and 100–350°C, 1–25 MPa steam were bubbled through 0.6–2 mm in diameter openings (tube 14x2 mm), under a layer of lead ranging in thickness from 100 to 3000 mm, at temperatures 350–600°C” Limited expansion. No explosion reported. From P. Kudinov A.V. Beznosov, ”Experimental Studies of the Characteristics of Conatct Heat Exchange between lead Coolant and the Working Body”, Atomic Energy, 98(3), 2005

5. Size distributions of water/steam droplets Beznosov et al, 2005 From P. Kudinov

6. Life time of small droplet From P. Kudinov Time scale is ~10s of seconds for droplets ~1mm in diameter Guido Bleiker and Eckehard Specht Film evaporation of drops of different shape above a horizontal plate International Journal of Thermal Sciences, Volume 46, Issue 9, September 2007, Pages 835-841

7. Vapor bubbles formation • Evaporation of water droplet in a bubble will lead to growth of bubble diameter. • Big bubbles most likely will not be stable due to high We number and high turbulence level. • As a result we will have larger number of middle size bubbles up to 10 mm in diameter. From P. Kudinov

8. Vapor bubbles formation and transport phenomena Terminal speed of rising bubbles with dmax~10mm is ~0.2-0.3 m/s Importance of resolution of 3D structure of the coolant flow for reliable prediction of void flux into the core Mendelson: Lehrer: From P. Kudinov

9. Stream lines and flow field Stream lines during normal operation Flow field during normal operation

10. Following calculation step • Small leakage is assumed in this study. • Next step will be to introduce individual steam bubbles at different locations in the HX. These bubbles will be followed along their trajectories. • Different sizes of bubbles will be studied. • The probability that bubbles reach the core will be estimated.

11. SGTR experiment The bunker (at FZK funded by JRC) where the experiment be performed

12. Experimental facility

13. Experiments to be performed • Steam of 200 bar pressure released into water simulating break of 8 pipes – will be performed during summer of 2008 • Injection of 3 liters of superheated steam (25 bar, 160C) into Pb of 340C. • Injection of 3 liters supercritical steam (240 bar, 400C into Pb of 480C. Simulating break of 8 pipes of the EFIT or ELSY design.

14. Summary • Cooperation between KTH and JRC concerning studies on small leakages. Results from this study expect this autumn. • SGTR experiments will be performed at FZK. The first one will be performed this summer.