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Best estimate plus uncertainty analysis of LBLOCA for Indian PHWR

  • A. Srivastava , A. K. Trivedi , H. G. Lele , P. Munshi and K. K. Vaze
Published/Copyright: May 18, 2013
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Abstract

Deterministic safety analysis is an important tool for confirming the adequacy of provisions within the defense-in-depth concept for the safety of nuclear power plants. One of the important design basis events is considered to be a complete double-ended guillotine rupture i.e. Loss of Coolant Accident (LOCA) of largest and coldest pipe in the primary coolant circuit. The present work deals with this scenario for an Indian PHWR. It highlights the identification of critical break size leading to the maximum clad temperature using the best estimate code RELAP5. Further, important parameters affecting the clad temperature are described along with results of initial sensitivity studies to select dominant uncertain parameters. For the uncertainty propagation, Latin Hypercube Sampling (LHS) is used instead of simple random sampling for Monte-Carlo simulation. The inherent characteristic of LHS is to reduce the required runs for Monte-Carlo simulation to manageable order for the current computing capability. The 95th percentile value of peak cladding temperature (PCT) is obtained by the method and compared with acceptance criteria.

Kurzfassung

Deterministische Sicherheitsanalysen sind ein wichtiges Instrument der Sicherheitsuntersuchungen von Kernkraftwerken. Einer der wichtigsten zu untersuchenden Auslegungsstörfälle ist ein kompletter 2F Bruch der größten und kältesten Leistung im Primärkreislauf – auch LBLOCA genannt. Im aktuellen Beitrag werden Untersuchungen eines LBLOCA für einen schwerwassermoderierten Druckwasserreaktor (PHWR) in Indien vorgestellt. Dabei werden die Einflussfaktoren, wie z.B. die kritische Leckgröße, die zu maximalen Brennstabtemperaturen führen, bestimmt und untersucht. Die Berechnungen mit RELAP5 werden durch eine Unsicherheitsanalyse basierend auf der Stichprobenmethode Latin Hypercube Sampling (LHS) ergänzt. Die so berechnete 95%-Perzentile der maximalen Brennstabtemperatur (PCT) wird mit den Akzeptanzkriterien verglichen.

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Received: 2011-10-25
Published Online: 2013-05-18
Published in Print: 2012-11-01

© 2012, Carl Hanser Verlag, München

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