ML20052E594
| ML20052E594 | |
| Person / Time | |
|---|---|
| Issue date: | 03/19/1982 |
| From: | Wichman K Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20052E591 | List: |
| References | |
| FOIA-82-124 NUDOCS 8205110261 | |
| Download: ML20052E594 (4) | |
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SUMMARY
OF MEETING WITH WESTINGHOUSE REGARDING STEAM GENERATORS HELD ON MARCH 2,1982 l
A meeting was held with Westinghouse representatives on March 2,1982, in Bethesda, MD. The purpose of this meeting was to have Westinghouse present their views with respect to steam generator tube degradation and steam generator tube rupture (SGTR) accident management. A list of attendees is shown in Enclosure 1.
Westinghouse presented the steam generator configurations of various models with fe'ed ring design and pre-heater design and identified the major differences among the models, especially with respect to the feedwater flow path.
It was indicated that out of the five SGTR events experienced by Westinghouse steam generators in the past seven years, only two SGTR events are corrosion related. Two SGTR events are considered.
preventable because one event was caused by the presence of a foreign l
object and one was due to excess tube ovality in a tube fabricated by a foreign supplier. The latest SGTR event is still under study. Westing-house also indicated that with 708,000 steam generator tubes in service, approximately 18,000 tubes (2.6%) were plugged and 45% of those plugged tubes were in four plants.
Steam generator tube degradation was classified into two groups (large leak and minor leak) based on the potential magnitude of primary coolant i
leakage. The types of tube degradation with the potential of causing a large leak are those at the U-bend apex area, those resulting from the presence of foreign objects, and IGA / SCC above the tubesheet. Other types of tube degradation resulting from denting; IGA attack in the tube sheet crevices and in the rolled tube; pitting; thinning; wear at anti-vibration bars (AVB) and the preheater baffle areas.will in general, l
result in small leaks. Westinghouse considers the types of tube' degradation l
with the potential of causing large leakage as mentioned above are control-lable. Leakage from the U-bend apex can be prevented by plugging since experience has shown that this type of degradation usually occurs only in the tubes of first or second rows.
Degradation due to the presence of foreign objects can be prevented by stringent administrative control of tools and materials used during secondary side maintenanch and visual examination aided by advanced optical equipment for areas not directly accessable.
In addition, Westinghouse recommended the following methods to control '
crevice and sludge pile corrosion, (1) reduce the operating temperature for plants when such corrosion is evident, (2) sleeving, (3) reduce containment inventory by sludge lancing, isothermal soaks or depressured flushing.
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' l In addition, Westinghouse recommended the following methods to control crevice and sludge pile corrosion, (1) reduce the operating temperature for plants when such corrosion is evident, (2) slesving, (3) reduce containment inventory by sludge lancing, isothermal soaks or depressured flushing.
A brief status summary, based on inspections of 51 operating Westinghouse plants, was presented on the tube denting problem.
It was indicated that 25 plants showed various degrees of denting activity; the rest did not show any sign of denting. Among the 25 plants,12 plants are considered active, the other 13 plants are stabilized.
Of the 12 active plants, Westinghouse rated denting in three plants as extensive and the other nine plants, minor.
Westinghouse recommended frequent monitoring of hydrogen content in the primary water as a means to estimate the extent of ongoing tube denting activities. This is based on the theory that the corrosion process associated with denting generates substantial amount of hydrogen in forming magnetite.
The guidelines for SGTR emergency response (EGR), which are sponsored by the Westinghouse Owners Group were presented. The basis for SGTR EGR's are operator intensive and include operating experience obtained from SGTR events. The status and issues in SGTR ERG review pertaining to pre-TMI guidelines (pre 3/28/79) and post-TMI guidelines were outlined.
Items, issues, and guidelines, developed or to be developed, in Phase I ERG (11/81) and Phase II ERG-(6/82) were discussed. Westinghouse also identified the areas to be emphasized in post Ginna Review of ERG which are, (1) a continuing effort to develop optimum ERG's and (2) review of ERG training methods.
Westinghouse concluded that the steam generator tube degradation problem is under control as demonstrated by the decrease in the number of tubes required to be plugged in'recent years. Westinghouse also emphasized that out of the 18,000 plugged tubes which is 2.6% of the total tubes in l
service, 45% are in four plants.
i Since the information presented by Westinghouse was proprietary, Westing-l house agreed to document the information pursuant to 10 CFR 2.790.
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4 Keith R. Wichman j
Operating Reactors Assessment Branch l
Division of Licensing l
Enclosure:
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Attendance List
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ATTENDANCE LIST MEETING WITH WESTINGHOUSE MARCH 2, 1982 NRC Participants G. Lainas, DL S. Hariauer, DST L. Shao, RES C. McCracken, CMEB S. Reynolds, Region I W. Johnston, DE T. Spets, DSI K. Wichman, DL D. Eisenhut, DL R. Mattson, DSI M. Williams, DL H. Conrad, CMEB J. Laaksonen. DSI J. Mazetis, DSI S. Newberry, DST W. Koo, DL E. Murphy, DE P. Matthews, DE S. Pawlicki, DE W. Hazelton, DE C. Cheng, DE Westinghouse Participants D. Rawlins P. Rahe, Jr.
J. Esposito O. Woodruff D. Malinowski 1
ACRS Participant E. Igne e
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MAR J.o y,
MEETING
SUMMARY
DISTRIBUTION NRC/PDR G. Lear Local PDR W. Hazelton TIC /NSIC/ TERA V. Benaraya H. Deraton Z. Rosztoczy E. Case W. Haass D. Eisenhut D. Muller R. Purple R. Ballard B.J. Youngblood W. Regan A. Schwencer R. Mattson F. Miraglia P. Check J. Miller
- 0. Parr G. La,as F. Rosa R. Vollmer W. Butler J.P. Knight W. Kreger R. Bosnak R. Houston R. Schauer W. Gammill R.E. Jackson L. Rubenstein f
OIE (3)
T. Speis ACRS (16)
W. Johnston R. Tedesco S. Hanauer N. Hughes T. Murley V. Wilson F. Schroeder D. Skovholt M. Ernst NRC
Participants:
K. Kniel G. Knighton i
G. Lainas A. Thadani l
S. Hanauer D. Tondi L. Shao J. K-amer C. McCracken D. Vassallo S. Reynolds P. Collins W. Johnston D. Ziemann T. Speis F. Congel K. Wichman J. Stolz D. Eisenhut M. Srinivasan R. Mattson H. Minners M. William,s C. Berlinger H. Conrad E. Adensam L
J. Laaksonen l
J. Mazetis i
' S. Newberry Westinghouse Electric Corp'.:
W. Koo E. Murphy D. Rawlins P. Matthews P. Rahe, Jr.
l S. Pawlicki J. Esposito W. Hazelton
- 0. Woodruff C. Cheng D. Malinowski I
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