ML19249D965
| ML19249D965 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 09/04/1979 |
| From: | Dunenfeld M Office of Nuclear Reactor Regulation |
| To: | Kniel K Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7909250618 | |
| Download: ML19249D965 (5) | |
Text
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f[L), [1 UNITED STATES NUCLEAR REGULATORY COMMISSION 5
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SEP 4 1979 e
XW Karl Kniel, Chief, Core Perfomance Braach, DSS MEMORANDUM FOR:
Daniel Fieno, Leader, Reactor Physics Section, CPB/ DSS THRU:
M. Dunenfeld, Reactor Physics Section, CPB/ DSS FROM:
MEETING ON NORTH ANNA QUADRANT FLUX TILTS, 8/22/1979
SUBJECT:
A meeting was held at the VEPCO offices in Richmond, Virginia to discuss A
the quadrant flux tilt present in the North Anna Unit 1 reactor.79-076,79-079 and As described in LERs list of attendees is attached.79-085, North Anna Unit 1 has had a quadrant flux tilt which has exceeded the Technical Specification limit of 2% on three occasions involving At full power the tilt has been 1.3 to 1.4% since its power reduction.
appearance following an extended shutdown in April.
As part of the investigation of possible causes of the tilt VEPC0 personnel looked at and rejected for various reasons flow distribution, misprediction of burnable poison effects on detector locations, control bank misalignment and enrichment variations. A special test was run The VEPC0 physics to show that the control bank was in alignment.
people have been able, however, to simulate the power distribu The fact that the are dropped control rodlets in three fuel assemblies. tilt does not a the control material is so black that control rodlets being the cause:
little change in its effect would take place over a period of months with a rodlet in the core at full power.
VEPCO specifically will look for broken redlets during the refueling of It would seem highly unlikely that three North Anna Unit 1 in October.
failures could have occurred during the April shutdown, which was only It would also a cooldown cycle as far as the reactor core is concerned.
seem a significant problem if there were three failures, because that would suggest a comon mode failure mechanism, and the possibility of There was such a problem in the more failures with continued use.
Salem Unit 1 reactor
- in which there were eight rodlet failures and which led to the replacement of 25 control pod assemblies in the Cycle Other rodlet failures in the past appear to have been random 2 reload.
i i
- W. Ross, MRC, Docket No. 50-272, "Sumary of Meeting Held on July 17, 1978 to Discuss Salem 1 Reload," July 25, 1979.
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1020 107
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. and consist of three separate occasions on which the vane holding the l
e rodlets separated at the braze joint holding the vane to the contro
, yf*Cc We will pay particular attention to the findings y('
rod assembly hub.
made by VEPCO when the core is unloaded.
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The return trip was made via the North Anna site, so that a tour of a-In the Unit 1, Unit 1 and the nearly completed Unit 2 could be made.
control room APDMS operation was demonstrated and a themoccuple map All of the thennoccuples are operative, and the map is easy to get, but the thennoccuple readings appear to have only was obtained.
limited utility in operation of the reactor, p
M Mar Dunenfel Reactor Physics Section Core Perfomance Branch Division of Systems Safety Mr. Anthony Gambarade.;a cc:
Office of the Attorney General 11 South 12th Street - Room 308 Richmond, Virginia 23219 Richard M. Foster, Esq.
211 Stribling Avenue 22903 Charlottesville, Virginia Michael W. Maupin, Esq.
Hunton, Williams, Gay & Gibson P. O. Box 1535 Richmend, Virginia 23212 Mrs. June Allen 412 Owens Drive Huntsville, Alabama 35801 Mr. James Torson 501 Leroy Socorro, New Mexico 87801 Mrs. Margaret Dietrich Route 2, Box 568 Gordonsville, Virginia 22942 4
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l cc: Continued T'ft
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I Clarence T. Kipps, Jr., Esq.
William H. Rodgers, Jr., Esq.
1700 Pennsylvania Avenue. N. W.'y.
Georgetown University Law Center 600 New Jersey Avenue, N. W.
Washington, D. C.
20006 i
Washington, D. C.
20001 Mr. James C. Dunstan Mr. Peter S. Hepp State Corporation Comission Executive Vice President Sun Shipping & Dry Dock Company Corrmonwealth of Virginia Blanden Building P. O. Box 540 Chester, Pennsylvania 19013 Richmond, Virginia 23209 Carroll J. Savage, Esq.
Mr. R. B. Briggs 1700 Pennsylvania Avenue, N. W.
Associate Director Washington, D. C.
20006 110 Evans Lane Oak Ridge, Tennessee 37830 Mr. Michael S. Kidd Alan S. Rosenthal, Esq.
i Atomic Safety and Licensing Appeal U.S. Nuclear Regulatory Comission s
P. O. Box 128 Board U.S. Nuclear Regulatory Comisson Spots 1vania, Virginia 22553 Washington, D. C.
20555 Michael C. Farrar, Esq.
Dr. John H. Buck Atomic Safety and Licensing Appeal Atomic Safety and Licensing Appeal Board Scard U.S. Nuclear Regulatory Comission U.S. Nuclear Regulatory Comission Washington, D. C.
20555 Washington, D. C.
20555 Atomic Safety and Licensing Appeal Dr. Paul W. Purdom Department of Civil Engineering Board U.S. Nuclear Regdatory Comission Drexel University Washington, D. C.
20555 Philadelphia, Pennsylvania 19104 1020 109
L MEETING ATTENDEES 18'
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NRC
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T. Snow M. Dunenfeld E. Lozito M. Chatterton M. Bowling D. E. Bessette L. Johnson P
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1020 1!0 8
MEETING
SUMMARY
DISTRIBUTION Docket Files /'entral Files NRC PDR-Local POR
[
CPB R/F DSS R/F NRR R/F H. Denton E. Case D. Crutchfield D. Bunch D. Vassallo S. Varga D. Skovholt D. Gammill F. Williams J. Stolz R. Baer
- 0. Parr L. Rubenstein T. Speis W. Morrison R. Bernero Craig Roberts Robert Purple R. Vollmer B. Grimes J. Miller J. P. Knight R. Tedesco R. Denise T. Novak
- 5. Hanauer W. Kreger V. Moore M. Ernst C. Kelber Long Tong L. Shao J..Durst Jared Davis R. M. Scroggins R. Mattson/F Schroeder R. Fraley, ACRS (16J IE (3}
Z. Rosztoczy W. Butler 1020 111
.