ML13308A152
| ML13308A152 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/29/1982 |
| From: | Rood H Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8207140085 | |
| Download: ML13308A152 (23) | |
Text
JUN 2 9 1982 Docket Nos.:
50-361 and 50-362 LICENSEES: Southern California Edison Company (SCE)
San Diego Gas & Electric Company City of Anaheim, California City of Riverside, California FACILITY:
San Onofre Nuclear Generating Station, Units 2 and 3
SUBJECT:
SUMMARY
OF MEETING TO DISCUSS AFW PUMP MOTOR BEARINGS On June 24, 1982, members of the NRC staff met with the licensees in Bethesda, Maryland, to discuss the above subject. Attendees at the meeting are given in Enclosure 1. Material presented by the licensees at the meeting is given in Enclosure 2. The meeting was held to dis cuss the licensee's proposed 'solution to the problem of failure of the cast iron bearings used to quality the AFW pump motors for operation in the steam environment. This environment would result from a break in the steam line supplying the turbine-driven AFW pump.
At the meeting the licensees 'stated that they have concluded that the use of cast iron bearings in the AFW pump motor would unacceptably re duce system reliability. Therefore, the licensees propose to pursue alternative solutions to the-problem. Of the alternatives considered, four were found to be feasible. These are:
- 2. Install a forced lube oil system to cool the motor driven AFW pump motor bearings. This would allow Babbitt bearings to be used.
- 3. Purchase motors having qualified roller bearings and replace existing motors.
- 4. Prevent catastophic failure of the AFW steam line by augmented inser vice inspection.
The licensees propose to use alternative 4. above, and will submit a letter documenting this proposal in the near future.
8207140085 820629 PDR ADOCK 05000361 Harry Rood, Project Manager P
PDR Licensing Branch No. 3 Division of Licensing 11-
Enclosures:
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SUNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555
- JUN 2 9 1982 Docket Nos.:
50-361 and 50-362 LICENSEES: Southern California Edison Company (SCE)
San Diego Gas & Electric Company City of Anaheim, California City of Riverside, California FACILITY:
San Onofre Nuclear Generating Station, Units 2 and 3
SUBJECT:
SUMMARY
OF MEETING TO DISCUSS AFW PUMP MOTOR BEARINGS On June 24, 1982, members of the NRC staff met with the licensees in Bethesda, Maryland, to discuss the above subject. Attendees at the meeting are given in Enclosure 1. Material presented by the licensees at the meeting is given in Enclosure 2. The meeting was held to dis cuss the licensee's proposed solution to the problem of failure of the cast iron bearings used to qualify the AFW pump motors for operation in the steam environment. This environment would result from a break in the steam line supplying the turbine-driven AFW pump.
At the meeting the licensees stated that they have concluded that the use of cast iron bearings in the AFW pump motor would unacceptably re duce system reliability. Therefore, the licensees propose to pursue alternative solutions to the problem. Of the alternatives considered, four were found to be feasible. These are:
- 2. Install a forced lube oil system to cool the motor driven AFW pump motor bearings. This would allow Babbitt bearings to be used.
- 3. Purchase motors having qualified roller bearings and replace existing motors.
- 4. Prevent catastophic failure of the AFW steam line by augmented inser vice inspection.
The licensees propose to use alternative 4. above, and will submit a letter documenting this proposal in the near future.
Harry Rood, Project Manager Licensing Branch No. 3 Division of Licensing
Enclosures:
As stated cc w/enclosure: See next page
Mr. Robert Dietch Vice President Southern California Edison Company 2244 Walnut Grove Avenue P. 0. Box 800 Rosemead, California 91770 Mr. Gary D. Cotton Mr. Louis Bernath San Diego Gas & Electric Comoany 101 Ash Street P. 0. Box 1831 San Diego, California 92112 cc: Charles R. Kocher, Esq.
James A. Beoletto, Esq.
Southern California Edison Company 2244 Walnut Grove Avenue P. 0. Box 800 Rosemead, California 91770 Orrick, Herrington & Sutcliffe ATTN:
David R. Pigott, Esq.
600 Montgomery Street San Francisco, California 94111 Mr. George Caravalho City Manager City of San Clemente 100 Avenido Presidio San Clemente, California 92672 Alan R. Watts, Esq.
Rourke & Woodruff Suite 1020 1055 North Main Street Santa Ana, California 92701 Lawrence Q. Garcia, Esq.
California Public Utilities Comission 5066 State Building San Francisco, California 94102 Mr. V. C. Hall Combustion Engineering, Incorporated 1000 Prospect Hill Road Windsor, Connecticut 06095
-2 cc:
Mr. S. McClusky Bechtel Power Corporation P. 0. Box 60860, Terminal Annex Los Angeles, California 90060 Mr. Mark Medford Southeon-California Edison Company 2244 Walnut Grove Avenue P. 0. Box 800 Rosemead, California 91770 Henry Peters San Diego Gas & Electric Company P. 0. Box 1831 San Diego, California 92112 Ms. Lyn Harris Hicks Advocate for GUARD 3908 Calle Ariana San Clemente, California 92672 Richard J. Wharton, Esq.'
URiversity of San Diego School of Law Environmental Law Clinic San-Diego, California 92110 Phyllis M. Gallagher, Esq.
Suite 222 1695 West Crescent Avenue Anaheim, California 92701 Mr. A. S. Carstens 2071 Caminito Circulo Norte Mt. La Jolla, California 92037 Resident Inspector, San Onofre/NPS c/o U. S. Nuclear Regulatory Commission P. 0. Box 4329 San Clemente, California 92672 Charles E. McClung, Jr., Esq.
Attorney at Law 24012 Calle de la Plata Suite 330 Laguna Hills, California 92653
ENCLOSURE 1 LIST OF ATTENDEES JUNE 24, 1982 MEETING ON AFW PUMP MOTOR BEARINGS SAN ONOFRE UNITS 2 & 3 NRC H.. Rood R. Gramm R. Lobel
- 0. Parr SCE M. Medford H. Pemberton Bechtel B. Duncil J. Gutmann A. Sassi E. Richardson
PURPOSES OF TECHNICAL PRESENTATION PROVIDE STATUS REPORT ON ALL CAST IRON (CI) BEARINGS OPERATIONAL EXPERIENCE AND FAILURE (MOTOR 2MP504)
POSTULATED BEARING FAILURE CAUSES FUTURE OF ALL CI BEARINGS PROGRESS ON EVALUATION OF ALTERNATIVES FOR MEETING ENVIRONMENTAL REQUIREMENTS COST/SCHEDULE FOR IMPLEMENTATION OF ALTERNATIVES
BRIEF BACKGROUND REVIEW ORIGINAL AUXILIARY FEEDWATER (AFW) PUMP MOTORS EQUIPPED WITH BABBITT BEARINGS AFW PUMP ROOK CALCULATED ROOM TEMPERATURE AFTER POSTULATED STEAM LINE BREAK:
362 0F (REF:
FSAR SECTION 3.6A.3.5.2)
BABBITT BEARING ANTICIPATED TEMPERATURE:
363 0F BABBITT BEARING UNACCEPTABLE FOR USE ABOVE 300*F CONSULTANT (MECHANICAL TECHNOLOGY, INC.) DESIGNED ALL CAST IRON BEARING AND SELECTED NEW LUBRICATING OIL TO MEET PIPE BREAK CRITERIA BEARING AND LUBRICANT TESTED FOR CONFIRMATION OF LIFE EXPECTANCY AND STEAM BREAK SURVIVABILITY TO IEEE 323-74 REVISED MOTOR CONFIGURATION PASSED 48 HOUR ENDURANCE TEST AS REQUIRED BY OPERATING LICENSE
ALL CAST IRON BEARINGS OPERATIONAL EXPERIENCE MOTOR SUCCESSFULLY OPERATED IN EXCESS OF 50 HOURS VIBRATION EXCEEDING SPECIFIED LIMITS DURING ENDURANCE TEST (MOTOR COUPLED WITH PUMP)
BEARING INSPECTION REVEALED EXCELLENT CONDITIONS PUMP SIDE BEARING SEIZED UPON MOTOR COAST DOWN (UNCOUPLED)
SINCE FAILURE CAUSE WAS UNKNOWN,,
BRINGING QUESTION TO BEARING RELIABILITY, ALL UNIT 2 AND UNIT 3 MOTORS WERE RESTORED TO ORIGINAL CONFIGURATION WITH BABBITT BEARINGS
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POSTULATED FAILURE MECHANISM MISALIGNMENT RESULTING FROM REASSEMBLY FOLLOWING BEARING INSPECTION LEFT CLEARANCES TOO SMALL TO ACCEPT ROTOR SHAFT VIBRATION.
THE ABOVE RESULTED IN CONTACT OF NON-LUBRICATED SEAL LANDS WITH SHAFT, RESULTING IN RAPID HIGH HEAT.
SURFACE OF CAST IRON BEGAN TO MELT LOCALLY, RESULTING IN MATERIAL TRANSFER AND FURTHER REDUCTION IN CLEARANCE.
FAILURE PROGRESSED UP SHAFT UNTIL ROTOR STOPPED (MOTOR WAS IN COAST-DOWN AT TIME OF FAILURE).
MOLTEN MATERIAL THEN FUSED TO SHAFT.
CONTRIBUTORS TO POSTULATED CAUSE OF FAILURE BEARING RELATED FACTORS "UNFORGIVING" NATURE OF BEARING MISALIGNMENT OF BEARING RELATIVE TO ROTOR SHAFT LACK OF RELIEF AT SEAL LANDS MOTOR RELATED FACTORS INADEQUATE ALIGNMENT CONTROL FOR AN UNFORGIVING BEARING ROTOR VIBRATION POSSIBLE BENT SHAFT POSSIBLE UN-COUPLED ROTOR PEAK RESPONSE BELOW RUNNING SPEED
BEARING DESIGN CHANGES NECESSARY FOR RELIABILITY CHANGES TO IMPROVE BEARING DAMPING:
o RELIEF ON BEARING SEAL LANDS CHANGES TO IMPROVE ALIGNMENT (KEY REQUIREMENT) o CHANGE IN MOTOR BEARING HOUSING DESIGN o ASSEMBLY PROCEDURES CHANGES TO INCREASE OIL ARC LENGTH o DECREASE BEARING CLEAPANCE o INCREASE OIL SUPPLY o CHANGE OIL DISTRIBUTION SLOT DESIGN
SUMMARY
MOTOR MANUFACTURER HAS DETERMINED THE NECESSARY CHANGES TO THE HOUSING WOULD BE TOO SIGNIFICANT FOR MOTOR QUALIFICATION BY HISTORY.
o SENSITIVITY OF CAST IRON BEARINGS TO MISALIGNMENT WOULD MAKE QUALIFICATION BY TYPE TESTING QUESTIONABLE.
o WITHOUT THE HOUSING MODIFICATIONS HIGH CONFIDENCE IN CAST IRON BEARINGS IS NOT POSSIBLE.
o FURTHER USE OF CAST IRON BEARINGS REDUCES, NOT ENHANCES, SYSTEM RELIABILITY.
USE OF BABBITT BEARINGS ADVANTAGES o
STANDARD TIME PROVEN DESIGN -
STANDARD MAINTENANCE PROCEDURE o
ACCOMODATES MISALIGNMENT TO EXTENT OF BABBITT MATERIAL o
FAILURE IS PROGRESSIVE (NOT GENERALLY CATASTROPHIC) o BEARINGS ARE FIELD-ADJUSTABLE o
EASE OF REPAIR o
AVAILABILITY OF REPLACEMENT PARTS DISADVANTAGES o
CANNOT SURVIVE STEAM LINE BREAK ENVIRONMENT
DEVELOPMENT OF ALTERNATIVES o
RELOCATE TURBINE DRIVEN PUMP OUTSIDE ROOM*
o INSTALL ENCLOSURE AROUND TURBINE DRIVEN PUMP*
o INSTALL MOTOR BEARING FORCED LUBE SYSTEM*
o INSTALL CONTROL VALVES IN PIPING OUTSIDE ROOM*
o FORCED AIR COOLING OF MOTORS*
o INSTALL GUARD PIPING AROUND STEAM LINE*
o PURCHASE CLASS 1E QUALIFIED MOTORS OPTIONS INCLUDE USE OF BABBITT BEARINGS
RELOCATE TURBINE DRIVEN PUMP OUTSIDE ROOM IMPLEMENTATION:
NEW FOUNDATIONS FOR RELOCATION OF CHEMICAL FEED EQUIPMENT MOVE CHEMICAL FEED EQUIPMENT, REPIPE & REWIRE AS REQUIRED NEW TURBINE/PUMP FOUNDATION & BUILDING FLOOR
- ERECT BUILDING MOVE TURBINE/PUMP REPIPE STEAM, AUXILIARY FEEDWATER PUMP SUCTION/DISCHARGE REWIRE PUMP/TURBINE CONTROLS LIGHTING, HVAC & FIRE PROTECTION ADVANTAGES:
RELIABILITY -
USES PROVEN BABBITT BEARINGS MAINTENANCE -
NO ADDED EQUIPMENT ELIMINATES POSTULATED STEAM LINE BREAK ENVIRONMENT ESTIMATED COSTS:
$2,400,000 FOR UNIT 2 LEAD TIME FOR IMPLEMENTATION:
18 MONTHS
FORCED LUBE OIL SYSTEM IMPLEMENTATION:
INSTALL COOLING SKIDS IN CHEMICAL FEED AREA INSTALL OIL PIPING TO/FROM MOTORS & SKIDS ROUTE COMPONENT COOLING WATER PIPING TO/FROM SKIDS PROVIDE ELECTRICAL FEED RUN ALARM SIGNALS TO CONTROL ROOM ERECT MISSILE SHIELD ADVANTAGE:
FORCED LUBE BACKED UP BY BEARING OIL RING DURING NORMAL OPERATION DISADVANTAGE:
ADDITIONAL EQUIPMENT INCREASES AFW SYSTEM COMPLEXITY ESTIMATED COST:
$1,250,000 FOR UNIT 2 LEAD TIME FOR IMPLEMENTATION:
15 MONTHS
PURCHASE CLASS 1E QUALIFIED MOTORS IMPLEMENTATION:
QUALIFICATION OF ROLLER BEARING DESIGN REMOVE EXISTING MOTORS REWORK BASE PLATE AS REQUIRED INSTALL NEW MOTORS ADVANTAGE:
SYSTEM COMPLEXITY/MAINTENANCE NOT IMPACTED DISADVANTAGES:
MOTORS NOT CURRENTLY ENVIRONMENTALLY QUALIFIED LONG LEAD TIME FOR QUALIFICATION ESTIMATED COST:
$420,000 FOR UNIT 2 LEAD TIME FOR IMPLEMENTATION:
24 MONTHS
AUGMENTED ISI IN USE ON SAN ONOFRE 2 & 3 FOR PIPE BREAK DELETION -
MAIN STEAM LINES FSAR 3.6A.2.4 FSAR AUGMENTED ISI CRITERIA -
SECTION 6.6.10 STRESS LEVEL CRITERIA -
MEB 3-1 STRESS LEVELS IN STEAM LINE TO AUXILIARY FEEDWATER PUMP TURBINE
THE BASIS FOR INTERIM RELIEF UNTIL AUGMENTED ISI CAN BE ACCOMPLISHED IS AS FOLLOWS:
- 1.
THERE IS A LOW PROBABILITY OF A PIPE BREAK IN THE 40 FEET OF HIGH ENERGY LINE INVOLVED.
- 2.
THE PLANT CAN BE SHUTDOWN WITHOUT THE AUXILIARY FEEDWATER PUMPS BY USING THE MAIN FEEDWATER AND CONDENSATE PUMPS.
- 3.
THE LIMITED TIME INVOLVED DECREASES THE PROBABILITY OF A SIGNIFICANT EVENT OCCURRING.
- 4.
THE MOTORS WITH BABBITT BEARINGS HAVE PASSED THE 48 HOUR ENDURANCE TEST.
- 5.
STRESS RATIOS IN THE STEAM LINES ARE WELL BELOW LIMITS.
- 6.
THE AUXILIARY FEEDWATER PUMP TURBINE STEAM LINES WILL BE VISUALLY INSPECTED ON A DAILY BASIS TO DETECT LEAKS.
PROBABILITY OF PIPE BREAK IN AUXILIARY FEEDWATER PUMP ROOM TYPE OF FAILURE PROBABILITY FAILURE PROBABILITY IN FAILURE (FAILURES PER FOOT YEAR)
AFW PUMP ROOM ALL LEVELS I X 10 4 X 10 OF FAILURE CATASTROPHIC OR NEAR 9 X 10-3.6 X 10 CATASTROPHIC FAILURE LOSS OF OFFSITE LESS THAN
-2 POWER PROBABILITY 10
/YR RESULTANT LESS THAN PROBABILITY 3.6 X 10-7 /YR
REFERENCES:
- 1.
DRAFT PAPER BY HALL, R. E., ET. AL.,
"LARGE BORE PIPE RUPTURE PROBABILITIES AS APPLIED TO A STEAM LINE BREAK,"
BROOKHAVEN NAT. LAB., UPTON, N.Y. 11973.
- 2.
REACTOR SAFETY STUDY, "AN ASSESSMENT OF ACCIDENTAL RISK IN U.S. COMMERCIAL NUCLEAR POWER PLANTS," U.S. NRC, WASH-1400, NUREG-75/014 (OCT. 1975).
- 3.
BUSH, S. H., "RELIABILITY OF PIPING IN LIGHT WATER REACTORS,"
IAEA-SM-218/12, (OCT. 1977).
Meeting Summary 2
San Onofre Units 2 & 3 DISTRIBUTION Document Control (50-361/362)
NRC PDR L PDR PRC System NSIC LB#3 Reading File FMiragl ia JLee H Rood Attorney, OELD I&E Regional Administrator, Region i Resident Inspector NRC
Participants:
R. Gramm R. Lobel
- 0. Parr Service List