Managing the aging of BWR control rod drive systems

Conference · Wed Apr 01 04:00:00 EST 1992

OSTI ID:10136762

Greene, R H ^[1]; Farmer, W S ^[2]

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1. Oak Ridge National Lab., TN (United States)
2. Nuclear Regulatory Commission, Rockville, MD (United States)

This Phase I Nuclear Plant Aging Research (NPAR) study examines the aging phenomena associated with BWR control and rod drive mechanisms (CRDMs) and assesses the merits of various methods of ``imaging`` this aging. Information for this study was acquired from (1) the results of a special CRDM aging questionnaire distributed to each US BWR utility, (2) a first-of-its-kind workshop held to discuss CRDM aging and maintenance concerns, (3) an analysis of the Nuclear Plant Reliability Data System (NPRDS) failure cases attributed to the control rod drive (CRD) system, and (4) personal information exchange with nuclear industry CRDM maintenance experts. The report documenting the findings of this research, NUREG-5699, will be published this year. Nearly 23% of the NPRDS CRD system component failure reports were attributed to the CRDM. The CRDM components most often requiring replacement due to aging are the Graphitar seals. The predominant causes of aging for these seals are mechanical wear and thermal embrittlement. More than 59% of the NPRDS CRD system failure reports were attributed to components that comprise the hydraulic control unit (HCU). The predominant HCU components experiencing the effects of service wear and aging are value seals, discs, seats, stems, packing, and diaphragms.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: Nuclear Regulatory Commission, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 10136762
• Report Number(s): CONF-920375--5; ON: DE92010435
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210100
22 GENERAL STUDIES OF NUCLEAR REACTORS
220400
220900
AGING
BWR TYPE REACTORS
CONTROL ROD DRIVES
CONTROL SYSTEMS
EMBRITTLEMENT
FAILURES
MAINTENANCE
MANAGEMENT
POWER REACTORS
NONBREEDING
LIGHT-WATER MODERATED
BOILING WATER COOLED
REACTOR SAFETY
SEALS
SURVEYS
VALVES