MELCOR Analysis of Steam Generator Tube Creep Rupture in Station Blackout Severe Accident
- Purdue University (United States)
A pressurized water reactor steam generator tube rupture (SGTR) is of concern because it represents a bypass of the containment for radioactive materials to the environment. In a station blackout accident, tube integrity could be threatened by creep rupture, particularly if cracks are present in the tube walls. Methods are developed herein to improve assessment capabilities for SGTR by using the severe-accident code MELCOR. Best-estimate assumptions based on recent research and computational fluid dynamics calculations are applied in the MELCOR analysis to simulate two-dimensional natural circulation and to determine the relative creep-rupture timing in the reactor coolant pressure boundary components. A new method is developed to estimate the steam generator (SG) hottest tube wall temperature and the tube critical crack size for the SG tubes to fail first. The critical crack size for SG tubes to fail first is estimated to be 20% of the wall thickness larger than by a previous analysis. Sensitivity studies show that the failure sequence would change if some assumptions are modified. In particular, the uncertainty in the countercurrent flow limit model could reverse the failure sequence of the SG tubes and surge line.
- OSTI ID:
- 20840329
- Journal Information:
- Nuclear Technology, Vol. 152, Issue 3; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); ISSN 0029-5450
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COMPUTERIZED SIMULATION
CONTAINMENT
COOLANTS
CRACKS
CREEP
FLUID MECHANICS
NATURAL CONVECTION
OUTAGES
PWR TYPE REACTORS
RADIOACTIVE MATERIALS
REACTOR ACCIDENTS
RUPTURES
SENSITIVITY ANALYSIS
STEAM GENERATORS
THICKNESS
TUBES
TWO-DIMENSIONAL CALCULATIONS
WALLS