Development of engineering and safety evaluations for steam generator chemical cleaning

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Transactions of the American Nuclear Society

OSTI ID:552655

Olech, B J; Kramer, C E; Yhip, K ^[1]

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1. Southern California Edison Co., San Clemente, CA (United States)

Recently, chemical cleaning of the San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 steam generators was successfully completed during the units cycle 9 refueling outages. The SONGS site is located on the Pacific Ocean coast in northern San Diego County and is operated by Southern California Edison Company (SCE). Units 2 and 3 are dual-reactor, coolant-loop, pressurized water reactor plants designed by Combustion Engineering (CE). Each loop utilizes a vertical U-tube steam generator to transfer heat to the secondary plant. SCE contracted Framatome Technologies Incorporated to provide the chemical cleaning services. However, design of the chemical cleaning system piping and development of the engineering and safety evaluations remained the responsibility of SCE. In recent years, evidence of bridging deposits causing tube freespan cracking was found in some CE plants. In addition, a progressive loss of steam generator secondary-side pressure was observed at SONGS over the last several operating cycles. Pressure degradation became severe enough to result in loss of generation despite operating the units with the governor valves wide open. Introduction of alternate chemistry control and sludge lancing during outages did not result in arresting this negative trend in the steam generator performance. Facing a potential for accelerated steam generator aging caused by excessive tube plugging and a progressive loss of the units capacity caused by degradation of steam generator thermal- hydraulic performance, SCE launched an extensive effort to investigate the root causes of these phenomena and define remedial actions. As a result of this effort, a decision was made to chemically clean both steam generators in each SONGS operating unit to remove secondary-side deposits and to restore steam generator performance.

• OSTI ID: 552655
• Report Number(s): CONF-971125--
• Journal Information: Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 77; ISSN 0003-018X; ISSN TANSAO
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
CLEANING
DEPOSITS
OUTAGES
SAFETY ANALYSIS
SAN ONOFRE-1 REACTOR
SAN ONOFRE-2 REACTOR
STEAM GENERATORS
VALVES