Assessment of Passive Safety Injection Systems of ALWRs: Final report of the European Commission 4th Framework Programme Project FI4I-CT95-0004 (APSI)

Jari Tuunanen, Juhani Vihavainen, Francesco D'Auria, George Kimber

Research output: Book/ReportReport

Abstract

The European Commission 4th Framework Programme project "Assessment of Passive Safety Injection Systems of Advanced Light Water Reactors Reactors (FI4I-CT95-0004)" involved experiments on the PACTEL test facility and computer simulations of selected experiments. The experiments focused on the performance of Passive Safety Injection Systems (PSIS) of Advanced Light Water Reactors (ALWRs) in Small Break Loss-Of-Coolant Accident (SBLOCA) conditions. The PSIS consisted of a Core Make-up Tank (CMT) and two pipelines. A pressure balancing line (PBL) connected the CMT to one cold leg. The injection line (IL) connected it to the downcomer. The project involved 15 experiments in three series. The experiments provided valuable information about condensation and heat transfer processes in the CMT, thermal stratification of water in the CMT, and natural circulation flow through the PSIS lines. The experiments showed the examined PSIS works efficiently in SBLOCAs although the flow through the PSIS may stop in very small SBLOCAs, when the hot water fills the CMT. The experiments also demonstrated the importance of flow distributor (sparger) in the CMT to limit rapid condensation. The project included validation of three thermal-hydraulic computer codes (APROS, CATHARE and RELAP5). The analyses showed the codes are capable of simulating the overall behaviour of the transients. The codes predicted accurately the core heatup, which occurred when the primary coolant inventory was reduced so much that the core top became free of water. The detailed analyses of the calculation results showed that some models in the codes still need improvements. Especially, further development of models for thermal stratification, condensation and natural circulation flow with small driving forces would be necessary for accurate simulation of phenomena in the PSIS.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages79
ISBN (Electronic)951-38-5437-X
ISBN (Print)951-38-5436-1
Publication statusPublished - 1999
MoE publication typeNot Eligible

Publication series

SeriesVTT Tiedotteita - Meddelanden - Research Notes
Number1957
ISSN1235-0605

Keywords

  • nuclear power plants
  • nuclear reactors
  • simulation
  • injection
  • safety

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