ML20091C440
| ML20091C440 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 07/31/1991 |
| From: | Parker T NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-89-001, IEB-89-1, NUDOCS 9108060296 | |
| Download: ML20091C440 (4) | |
Text
- _ - _ - _ - _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _.
Northom States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 1927 Telephone (612) 330-5500 July 31,1991 Bulletin 89-01 Supplement 2 U S Nuclear Regulatory Commission Attn:
Document Control Desk Washington, DC 20555 PRAIRIE IS1AND NUCLEAR CENERATING PIANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Resnonse to NRC Bulletin 89-01, Supplement 2 Failure of Westionhouse Steam Generator Tube Mechanical Pluns Our-response to NRC Bulletin No. 89-01, Supplement 2, " Failure of Westinghouse Steam Generator Tube Mechanical Plugs" dated June 28, 1991, is attached.
Please contact us if you have any questions related to our response to this NRC Bulletin.
Nih 1 tomas M Parker Manager Nuclear Support Services c: Regional Administrator - Region III, NRC Senior Resident Inspector, NRC NRR Project Manager, NRC J E Silberg Attachments 9108060296 910731 PD5 ADOCK 05000282
/fo/
o PDR
'/
y[
/
I I L.
.~
i UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY PRAIRIE IS1AND NUCLEAR GENERATING PLANT DOCKET NO. 50-282 50-306 RESPONSE TO NRC BULLETIN 69 01, SUPPLEMENT 2 Northern States Power Company, a Minnesota corporation, with this letter is submitting information requested by NRC Bulletin 89-01, Supplement 2.
This letter contains no restricted or other defense information, NORTHERN STATES POWE CC MPANY
' 4 By
/d.
A iTi6 mas M ' Parker Manager Nuclear Support Services O'n this3 / day o olt r.
/AAAefore me a notary public in and for said County, perspnh11y/,1ppeared Tlidmas M Parker, Manager, Nuclear Support Services, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made in it are true and that it is not interposed for delay, Aul b<tnien d y
g7 / /
~
. _ _,,, = =.
~
JUDY L KLAPPERICK NOTARY PUDUC-M;NNESOTA h
ANOKA COUNTY My Commeon Emres Sept 29,1991 $
ut:::::::NN::===:Nwwwwvwn
w Attachment-Page 1 of 2 RESPONSE TO NRC BULLETIN 89-01 SUPPLEMENT 2 Actions Reauested and Responses Action Reauested #1 Addressees are requested to verify that information contained in Table 2 of Reference 4 for their plants is correct for plugs fabricated from group 2
-heats.
(Addressees have previously verified similar information for group 1 plugs in response _to the original bulletin.) The specific information to be verified is the number of Westinghouse mechanical plugs installed in the o
hot-leg and cold-leg side of each steam generator, categorized by heat number and date of installation.
The plug operating temperatures for each plant given_in this Table should also be verified.
If information from this_ Table is incorrect, addressees should provide correct information. Addressees are requested to so state if their plants have not installed Vestinghouse mechanical plugs from group 2 heats.
Response
The information contained in Table 2 of Reference 4 to Bulletin 89-01, Supplement 2, has been reviewed. One error was_found. Note 4 does not apply.
sinen all plugs in the hot legs of Unit 1 steam generators from heat 3513 have been removed.
Action Reauested #2 Addressees are requested to take the following actions, to be implemented initially during any refueling outage or extended outage (greater than four weeks) which ends 60 days or more following receiptLof this bulletin and 1during all future-refueling outages.
For the period of time between receipt of the bulletin and 60 days, the actions requested in the original version of
- this bulletin continue to be applicable for plugs fabricated from group 1
- heats, a)
Addressees should implement appropriate remedial actions (i.e., repair and/or replacement) for all plugs whose estimated lifetime in item 2b, below does not-extend to the next refueling outage, b)
Remaining lifetime estimates (in effective full power. days (EFPD)) are given in Table 2 of Reference 4 in the column entitled (Remain EFPD to MIN."
These remaining lifetime estimates are relative to reference dates given in the column entitled (Reference CALC Dates."
These remaining lifetime-estimates may be used directly. These estimates should be adjusted to reflect any corrections noted in Actions Reouested. item 1.
c)
For refueling outages or extended outages ending prior to November 30, 1991, remedial actions for plugs fabricated from NX-5222 may be deferred until the next scheduled refueling outage,
- m...
j
-Attachment Page 2 of 2 d)
Installation of Westinghouse mechanical plugs fabricated from Inconel 600 should be -discontinued.
e)
If for any refueling outage, the addressee does not plan to satisfy items 2a to 2d above, an alternative plan for insuring plug integrity, with appropriate technical justification, should be submitted to the NRC at least 30 days before the end of the refueling outage, f)
Prior to any plug repairs or replacement, addressees are reminded that their responsibilities under AhARA require analysis of the various plug repair or replacement methods.
In choosing a plug repair or replacement-method, the licensee should consider the accessibility of the plugs and vthe dose reduction benefit of using robotic manipulators.
Prior to plug repair or replacement, the licensee should consider steam generator decontamination and/or local chielding to reduce working area dose rates, Fesconse The next refueling outages for Prairie Island Units 1 and 2 are scheduled for
= November 1992 and February 1992, respectively. No other extended outages (greater than four weeks) are planned for either unit.
a)
Hot leg plugs from heats 5222 and 6323 will be repaired or replaced at the next refueling outage or extended outage (greater than four weeks) for each unit.
b)
Estimated lifetime (based on actual operating history) for the Unit 1 plugs from heat 5222 is carly 1991.
Estimated lifetime (based on actual operating history) for the Unit 2 plugs from heat 6323 is September 1992, c)
-No additional refueling or extended outages are planned prior to November 30, 1991.
d)
No further use cf Westinghouse mechanical plugs fabricated from Alloy 600 is allowed at Prairie Island, e)
Susceptible plugs will be removed during the Unit 2 refueling outage scheduled for February 1992, and during the Unit I refueling outage scheduled for November 1992, f)
The Prairie Island Steam Generator Committee has considered the various plugging and. replacement options.
Plug removal operations have been conducted remotely twice at Prairie Island and will continue to be conducted in the future using remote manipulators in order to ensure as low as reasonably achievable radiation exposure.
{
_ _ _ _ _ _ _ _ _ _ _ _ _