Experimental and analytical investigation of the operation mode of the emergency condenser of the SWR1000

Siemens AG is developing the new innovative boiling water reactor concept S WR1000. New features are passive safety systems, such as emergency condense rs, building condensers, passive pressure pulse transmitters, and gravity-d riven core flood lines. For experimental investigation of emergency condenser effectiveness, the NO KO test facility has been constructed at Forschungszentrum Julich in cooper ation with siemens. This test facility has an operating pressure of 10 Mpa and a maximum power of 4 MW for steam production. The emergency condenser b undle consists of eight tubes and is fabricated wit planned geometry and ma terial of the SWR1000. In more than 200 experiments, the emergency condense r power was determined as a function of pressure, water level, and concentr ation of noncondensables in the pressure vessel as well of pressure, water level, and temperature in the condenser. Posttest calculations of NOKO experiments were performed with an improved v ersion of ATHLET. To calculate the heat transfer coefficients during conden sation in horizontal tubes, it was necessary to develop the KONWAR module a nd to implement it in ATHLET. KONWAR is based on the flow regime map on Tan don and includes several semiempirical correlations for the determination o f the heat transfer coefficients. The comparison between calculations and e xperiments shows good agreement.