Split pin replacement at Surry Unit 1
During the past seven years of operating experience with the Westinghouse nuclear steam supply system, failures of the control rod guide tube (CRGT) support pins on the lower flange have been encountered. These support pins, commonly referred to as split pins, orient and hold the CRGT in proper alignment with the upper end fitting of the fuel assembly. The failures of this pin have been attributed principally to the material heat treatment of the pins during the original fabrication and installation. In November 1984, Babcock and Wilcox replaced the CRGTs at Surry power station unit 1 with a set of spare CRGTs that were originally assigned to North Anna station. The replacement split pins in these CRGTs had improved heat treatment and geometric configuration to reduce stresses during operation. Failures have also been reported in components called flexures located in the upper section of the CRGT. The failures in the flexures have also been attributed to material heat treatment. Replacement flexures were also installed incorporating an improved heat treatment and geometric configuration to reduce the stresses in the area of reported failures. The modifications on the split pin and the flexures were performed to improve component performance, reducing the potential for a failure causing loose parts to migrate to the steam generator and cause significant damage.
- Research Organization:
- Babcock and Wilcox Co., Lynchburg, VA
- OSTI ID:
- 5146904
- Report Number(s):
- CONF-850894-
- Journal Information:
- Trans. Am. Nucl. Soc.; (United States), Journal Name: Trans. Am. Nucl. Soc.; (United States) Vol. 49 Suppl. 2; ISSN TANSA
- Country of Publication:
- United States
- Language:
- English
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210200 -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
22 GENERAL STUDIES OF NUCLEAR REACTORS
220400* -- Nuclear Reactor Technology-- Control Systems
ALARA
CONFIGURATION
CONTROL ROD DRIVES
DESIGN
ENRICHED URANIUM REACTORS
FAILURES
MAINTENANCE
OPERATION
PERFORMANCE
POWER REACTORS
PWR TYPE REACTORS
RADIATION PROTECTION
REACTOR COMPONENTS
REACTOR FUELING
REACTOR MAINTENANCE
REACTOR OPERATION
REACTORS
STRESSES
SURRY-1 REACTOR
THERMAL REACTORS
WATER COOLED REACTORS
WATER MODERATED REACTORS