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MEMORANDUM FOR:
L. C. Shao, Chief, Engineering Branch, D0R FROM:
B. D. Liaw, Engineering Branch, D0R l
THRU:
R. J. Stuart, Leader, Section 8 Engineering Branch, D0R
SUBJECT:
TRIP REPORT - COMBUSTION ENGINEERING FACILITIES AT i
WINDSOR, CONNECTICUT, ON JUNE 3. IC77 l
On June 3,1977 Mr. L. Frank (SD/ DOR), Mr. B. Turovlin (DSS), Dr. J.
R. Weeks (BNL/ DOR Consultant) and Dr. B. D. Liaw (D0R)*, met with representatives from Yankee Atomic Power Company (Main Yankee).
Northeast Nuclear Energy Company (Millstone Unit 2), and Combustion Engineering (CE) at the Windsor, Connecticut, CE Engineering offices.
The purpose of the meeting was to review and to discuss CE's program to investigate the steam gene ator tube denting problem.
The agenda of the meeting and a list of attendees are attached. Copies of view-graphs presented 11 the meeting will be available as soon as they are f
submitted.
The following is a summary of the highlights of discussion and the significant findings during the presentation:
1.
In describing the denting mechanism, CE has been able to confirm Potter and Mann's theories that denting, as the consequences of the non-protective growth of the magnetste, can occur without l
the phosphate as a precursor.
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2.
In CE's tests, they concluded that the copper was not an active participant in the corrosion process and its role was more of an innocent by-stander.
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No actual corrosion product at the tube / tube support plate crevices j
has been removed and chemically analyzed. Therefore, there is no i
correlation between the test condition (such as the amount of I
l chloride packed in the c evice in the test) and the actual condition l
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in the operating steam generators.
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4.
CE has identified the chemical cleaning to be the long term solution i
to the denting problem and has been actively pursuing along this route, in addition to other short and intermediate term solutions such as flushing and free-surface boiling to stop or to slow the fcrmation of the non-protective magnetite.
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- Dr. F. M. Almeter was scheduled to attend the meeting, but could not make it because of illness.
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We raised the issue of possible stress corrosion cracking of 5.
steam generator tubing in the primary coolant environment, at least, for the intermediate operating period before the long CE j */~
j tenn solution of the chemical cleaning was implemented.
has agreed that this issue should be addressed and will consider -i'N it in their over-all program which is to be re-structured.
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The tube support system designs for the sea-coast CE operating 6.
units are summarized as follows:
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Hillstone 2, Calvert Cliff 1. St. Lucie have the identical tube support system. There are only two partiel Jrilled plates near the top of the generators, with the remaining j
supports made of the eggcrate ty Approximately 25%
of the tubes in the tube bundle (pe.about 2200 tubes) pass j
through the lower drilled plate, and 10% (about 780 tubes) through the top drilled plate. Those tubes that pass through the top plate also pass through the lower drilled In the drilled support plates, tube holes are in plate.
a triangular pitch pattern with a 1/4 inen flow hole in the middle of these tube holes. The diameter of the tube hole is 0.776 inch; 0.750 inch tube 00 and 0.003 inch annulus-gap. The ligament thickness is about 1/16 inch between the tube and the flow holes.
ii)
Main Yankee's tube support system consists of eggcrate supports and two partial drilled plates. The top drilled plate is similar to that in the Millstone 2.
The lower drilled plate 1.s a strip which does not support tubes that pass through the top drilled support plate. The tube hole pattern is irientical to that described above.
iii) Palisades Unit 1 tube support system consists of two eggerate This suppor ; and full and partial drilled support plates.
r unit is unique 4 that it is the only domestic CE unit having several full drilled plates.
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Representatives from Yankee Atomic Power and Northeast Utilities 7.
These data were l
l presented steam generator blowdown chemistries.
requested in the meeting and will be submitted to us in the near
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i future.
i Regarding the chemical cleaning, Dr. Paul Bryant of CE indicated 8.
that the Russians are using chelating
- agents to keep their
- Chelating agents are compounds which have the property of combining with di or polyvolent metal ions, such as calcium, magnesium and G
aluminum and preventing their precipitation with negative ions such l
as sulfates, carbonates, etc.
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secondary water clean. This type of cleaning agent approach i
appears to be effective. He requested that NRC use its in-fluence to find out the details about it in helping the U. S.
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industry.
9.
A separate brief discussion was held with representatives of Millstone unit to examine their inspection patterns and the 4
preliminary results. The denting of tubes appears more severe in Millstone Unit 2 than in the Maine Yankee unit. Results of l
their inspection will be presented to NRC in a meeting to be
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I scheduled on June 9 or 10,1977. They planned to return the j
unit to power operation approximately on June 19, 1977.
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er B. D. Liaw Engineering Branch Division of Operating Reactors
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L. Frank Engineering Branch (on loan)
Division of Operating Reactors
Enclosures:
As stated cc:
V. Stello, Jr.
I R. Heineman i
D. G. Eisenhut J. P. Knight J. Scinto R. Stuart W. Hazelton
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J. C. Guibert R. Cudlin i
L. 01shan M. Fairtile D. Jaffe J. P.. Weeks (BNL) l l
J. Muscara
,i L. Frank l
B. Turovlin F. Almeter B. D. Liaw l-t l
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1 ATTACHMENT A FINAL AGENDA - MEETING WITH NRC, t%INE YAtlKEE AllD NORTHEAST UTILITIES ON STEAM GENERATOR DENTING JUNE 3, 1977 INTRODUCTION D.K. JAMES i
i 1.
DENTING MECHANISM D.J. MORGAN 2.
STEAM GENERATOR TUBE SUPPORT SYSTEMS. -
D.F. STREINZ i
3.
OPERATIllG DATA E.C. BIEMILLER D. STURilIOLO (F%It!E YAllKEE)
J.FACKELMAN(NORTHEASTUTILITIES)
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ECT INSPECTION.SUMi%RY D.F. STREINZ 5.
TESTING PROGRAMS AND DATA R.M. RENTLER SUMi%RY P.E.C. BRYANT l
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LIST OF ATTENDEES
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NAME ORGANIZATION Veikko Laakso CE
- 0. K. James CE P. L. Anderson MY J. M. Fackelmann NUSCO R. M. Rentler CE Corrosion Chemistry Eric C.' Biemiller CE Plant Chemistry John R. Weeks BNL Peter F. Santoro NUSCO Bernard Turovlin NRC Materials Engineer James McHugh NNE Co.
John R. Hoffman Yankee Mechanical Engr Mgr.
David Sturniolo, Jr.
Maine Yankee Paul Bryant CE Materials & Chemistry John Kufel NUSCO e
Norm Wilson NUSCO Don Streint CE Louis Frank USNRC B. D. Liaw USNRC/ DOR A. W. Cope CE Plant Engineering C. E. McCracken CE Chemistry K. Marugg CE Chemistry J. W. Klisiewicz CE Chemistry E. A. Elam CE D. J. Morgan CE Chemistry J. V. Strimaitis CE R. S. Bell CE J. J. Kelley Millstone i
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