Structural Integrity Assessment of Steam Generator Tubes Using a New EPRI Statistical Approach

Conference · Mon Jul 01 04:00:00 EDT 2002

OSTI ID:21062338

Mattar Neto, Miguel ^[1]

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1. IPEN-CNEN/SP, inst. pesquisas energeticas nucleares, 05499 Sao Paulo (Brazil)

A fundamental step in tube plugging management of a Steam Generator (SG), in a Nuclear Power Plant (NPP), is the tube structural integrity evaluation. The degradation of SG tubes may be considered one of the most serious problems found in PWRs operation, mainly when the tube material is the Inconel 600. The first repair criterion was based on the degradation mode where a uniform tube wall thickness corrosion thinning occurred. Thus, a requirement of a maximum depth of 40% of the tube wall thickness was imposed for any type of tube damage. A new approach considers different defects arising from different degradation modes, which comes from the in-service inspections (NDE) and how to consider the involved uncertainties. It is based on experimental results, using statistics to consider the involved uncertainties, to assess structural limits of PWR SG tubes. In any case, the obtained results, critical defect dimensions, are within the regulatory limits. In this paper this new approach will be discussed and it will be applied to two cases (two defects) using typical data of SG tubes of one Westinghouse NPP. The obtained results are compared with 'historical' approaches and some comments are addressed from the results and their comparison. (authors)

• Research Organization: The ASME Foundation, Inc., Three Park Avenue, New York, NY 10016-5990 (United States)
• OSTI ID: 21062338
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
COMPARATIVE EVALUATIONS
CORROSION
DAMAGE
DEFECTS
EPRI
IN-SERVICE INSPECTION
INCONEL 600
MANAGEMENT
NUCLEAR INDUSTRY
NUCLEAR POWER PLANTS
PWR TYPE REACTORS
STATISTICS
STEAM GENERATORS
THICKNESS
TUBES
WALLS