Assessment of thermal fatigue crack propagation in safety injection PWR lines

Conference · Mon Jan 01 04:00:00 EST 1990

OSTI ID:7048866

Simos, N; Reich, M; Costantino, C J ^[1]; Hartzman, M ^[2]

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1. Brookhaven National Lab., Upton, NY (USA)
2. Nuclear Regulatory Commission, Washington, DC (USA). Mechanical Engineering Branch

Cyclic thermal stratification resulting in alternating thermal stresses in pipe cross sections has been identified as the primary cause of high cycle thermal fatigue failure. A number of piping lines in operating plants around the world, susceptible to thermal stratification, have experienced circumferential cracking as a result of high levels of alternating bending stresses. This paper addresses the mechanisms of crack initiation and crack growth and provides estimates of fatigue cycles to failure for a typical safety injection line with such cyclic load history. Utilizing a 3-D finite element analysis, the temperature profile and the corresponding thermal stress field of a complete thermal cycle in a safety injection line consisting of a horizontal pipe section and an elbow, is obtained. Since the observed cracking occurred in the region of the elbow-to-horizontal pipe weld, the analysis performed assessed (1) the impact of the level of local geometric discontinuities on the initiation of an inside surface flaw is greatest and (2) the number of thermal cycles required to drive a small surface crack through the pipe wall. 12 refs., 14 figs., 2 tabs.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• Sponsoring Organization: NRC
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 7048866
• Report Number(s): BNL-NUREG-44323; CONF-900617--5; ON: DE90008820
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210200 -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
22 GENERAL STUDIES OF NUCLEAR REACTORS
220900* -- Nuclear Reactor Technology-- Reactor Safety
AGING
COOLING SYSTEMS
CRACK PROPAGATION
CRACKS
ECCS
ENERGY SYSTEMS
ENGINEERED SAFETY SYSTEMS
FAILURE MODE ANALYSIS
FATIGUE
FLUID FLOW
FRACTURE MECHANICS
MECHANICAL PROPERTIES
MECHANICS
PIPES
PWR TYPE REACTORS
REACTOR COMPONENTS
REACTOR COOLING SYSTEMS
REACTOR PROTECTION SYSTEMS
REACTOR SAFETY
REACTORS
SAFETY
SAFETY INJECTION
STRESS ANALYSIS
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
TEMPERATURE EFFECTS
THERMAL FATIGUE
WATER COOLED REACTORS
WATER MODERATED REACTORS