ML19325D411
| ML19325D411 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 10/03/1989 |
| From: | Diianni D Office of Nuclear Reactor Regulation |
| To: | Parker T NORTHERN STATES POWER CO. |
| References | |
| IEB-88-009, IEB-88-9, TAC-72674, TAC-72675, NUDOCS 8910230235 | |
| Download: ML19325D411 (4) | |
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UfelTED STATES
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NUCLEAR REGULATORY COMMISSION L
unemmoton,o,c sones
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October 3, 1989 l
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Docket Nos. 50-282 and 50-306 Mr. T. M. Parker, Manager j
Nuclear Support Services Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401
Dear Mr. Parker:
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SUBJECT:
RESPONSE TO BULLETIN 8809 THIMBLE TUBE THINNING FOR THE PRAIRIE ISLAND NUCLEAR GENERATING PLANT UNIT NOS 1 AND 2 (TAC NOS. 72674 AND 72675)
Bulletin 8809 " Thimble Tube Thinning in Westinghouse Reactors" requires all licensees having Westinghouse (W) designed. nuclear power. reactors utilizing bottom mounted instrumentation to implement an inspection program that periodically confirms the integrity of the incore neutron monitoring system 8-thimble tubes.
The amount of vibration the thimble tubes experience is determined by such plant-specific factors as the gap distance from the lower core plate to the fuel assembly instrument tube, the axial component of.the local fluid velocity, the thickness of the thimble tube, and the moment of inertia of the thimble tube. A review of the available data indicates that it is not possible to accurately predict thimble wear rates.
Thus, it appears that the only effective method for determining thimble tube integrity is through plant-specific inspections and periodic monitoring.
By letter dated October 31, 1988 you submitted a response to Bulletin 8809 I
indicating that an informal inspection program has been in place since early 1987 at the Prairie Island Nuclear Generating Plant Unit Nos. I and 2.
This l
program requires addy current inspection of all incore flux thimbles every refueling outage until such time that reliable wear rate data can be l
established. As result of Bulletin 8809 you intend to formalize the thimble tube inspection program conforming to requirements oY Criterion 1 of the l
Bulletin. We find that you.have provided an adequate response to Bulletin 8809 and the response provides assurance that rate of degradation of th'e' thimble n
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8910230235 891003 PDR ADOCK 05000282 G
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tubes will be adequately monitored.
This ?ulfills your requirement in respond-ing to Bulletin 8809.
You should maintain in auditable form, records of your inspection program since these records may be subject to future auditing.
7 This completes our. efforts under TAC Nos. 72674 and 72675.
Sincerely,
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W Dominic C. Dilanni, Project Manager Project' Directorate III-1 Division of Reactor Projects - III','IV, V J
& Special Projects
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tubes will be adequately monitored.' This fulfills your requirement in respond-ing to Bulletin 8809.
You should maintain in auditable form, records of your inspection program since these records may be subject to future auditing.
This completes our efforts under TAC Nos 72674 and 72675.
Sincerely, s
() e chem Dominic C, Dilanni, Project Manager
. Project Directorate III-1 Division of Reactor Projects - III, IV, V
& Special Projects cc:
See next page r
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Prairie Island Nuclear Generating i
Mr. T. M. Parker Ncrthern States Power Company Plant cc:
Gerald Charnoff Esq.
Shaw,Pittman,EcttsandTrowbridge l
2300 N'$treet, N.W.
Washington DC 20037 Dr. J. W. Ferman 1
Minnesota Pollution Control Agency l
i 520 Lafayette Road i
St. Paul, MN 55155 Mr. E. L. Watzl, Plant Manager Prairie Is1pr.a Nuclear Generating Plant Northern States Power Company Route 2 Welch, Minnesota 55089 Josept G. Maternowski Assistant Attorney General Environmental Protection Division Suite 200 520 Lafayette Road St. Paul, Minnesota 55155 U.S. Nuclear Regulatory Commission
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Resident Inspector's Office 1719 Wakonada Drive East Welch, Minnesota 55089 Regional Administrater, Region III i
1 U.S. Nuclear Regulatory Commission i
Office of Executive Director for 1
i 0prations 799 Roosevelt Road Glen Ellyn, Illinois 60137 i
Mr. William Miller, Auditor Goodhue County Courthouse Red Wing, Minnesota $5066
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