Horizontally challenged

摘要

The VVER's horizontal steam generator (SG) design is based on a different geometry from those used in the West and the tube material is stainless steel (08Kh18N10T grade). The benefits of this design are: 1. A high water inventory and smooth behaviour in transients. 2. Effective removal of non-condensable gases in accidents to provide natural circulation. 3. The steam generation surface is under moderate load and has a simple separation scheme. 4. Low velocities on the secondary side reduce damage from vibration and foreign object impacts. 5. There is good access to the tubing from both primary and secondary side. 6. There is space where sludge can accumulate. 7. The horizontal tubing is resistant to degradation. 8. The stepwise evaporation is effective in removing impurities. 9. The tubes seldom rupture because they have a high load-carrying capacity.