Spontaneous water hammers in a steam line in case of cold water ingress


Spontaneous water hammers in a steam line in case of cold water ingress

Prasser, H.-M.; Ezsöl, G.; Baranyai, G.

Some of the accident scenarios discussed for VVER-440 reactors assume an overfeed of the secondary side of the steam generators by water coming either from the primary side or from the feed water system. This may happen, for example, in case of a leakage from the primary to the secondary side as well as during earthquakes and may lead to a water ingress into the main steam-lines, where condensation induced water hammer may be the consequence. The present work was initiated to study this phenomenon experimentally. For this purpose the PMK-2 test facility of KFKI-AEKI Budapest, an integral thermo- hydraulic model of a VVER-440 / W213, was extended by a steam-line model, which is equipped with a novel two-phase flow instru-mentation as well as fast pressure and strain-gauge transducers. The applied mesh sensor de-veloped by Forschungszentrum Rossendorf allows a visualisation of the transient flow section during the water hammers. Local void probes detect the propagation of slugs along the pipe. The applied new kind of probe is equipped with micro-thermocouples to provide local instan-taneous temperature measurements beside the phase detection. This allows to assess tempera-ture gradients at the boundary between water and steam. The paper describes test facility and new instrumentation. The results of the first tests are presented and discussed. The work is part of the WAHALoads project, which was performed within the 5th EU framework programme.

Keywords: pressurized water reactor; main steam line; two-phase flow; water hammer; void collapse

  • Multiphase Science and Technology 20(2008), 239-263

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Publ.-Id: 8008