ML17055B890
| ML17055B890 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 06/17/1986 |
| From: | Rotella T Office of Nuclear Reactor Regulation |
| To: | Bernero R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8606250355 | |
| Download: ML17055B890 (4) | |
Text
MEMORANDUM FOR:
Robert M. Bernero, Director Division of BWR Licensing THRU'ROM:
SUBJECT:
RE:
John A. Zwolinski, Director BWR Pro,iect Directorate gl Division of BWR Licensing Thomas S. Rotella, Acting Project Manager Nine Mile Point 1
BWR Project Directorate 81 Division of BWR Licensing STUB TUBE LEAKAGE CONCERNS Nine Mile Point 1 As you know, Nine Mile Point 1
(NMP1) was experiencing stub tube leakage prior to shutting down for their refueling outage.
During telephone conversations with representatives of Niagara Mohawk Power Corporation (the licensee) concerning the history of stub tube leakage at the NMP1 facility, the licensee presented their plans for repairs of the leaking stub tubes.
As discussed, the repair procedure included mechanical "rolling" of the control rod drive hotising for each leaking stub tube and a verification and inspection of the repaired stub tubes during the normal hydrostatic pressure test of the reactor coolant system.
Upon inspection of the stub tubes after shutdown for refueling, 2 stub tubes were identified as "leakers" and would require repair prior to restart from refueling.
One of the two leaking stub tubes had been repaired once before while the other stub tube was identified as a new "leaker".
As planned, the licensee "rolled" both of the associated control rod drive housings for the leaking stub tubes and performed a hydrostatic pressure test (hydro).
Upon inspection of the stub tubes during the hydro, it was discovered that the "rolling" repair was successful for both stub tubes, however a third stub tube, which had been repaired during the 1984 Refueling Outage, was leaking at approximately 4-8 drops per minute.
After discussions with NRC staff, with regard to the acceptability of this rate of leakage, the staff recommended the
'icensee perform an additional "rolling" of the control rod drive housing associated with the leaking stub tube since this stub tube had only been
-repaired once before.
The licensee related that no more than two "rolling" repairs would be made to a single control rod drive housing as wall thinning might then become a concern.
As suggested, the licensee performed the "re-roll" and re-pressurized the reactor coolant system.
Upon inspection of the "re-roll" repair no leakage wasidentified.
Further inspections verified no leakage was present from any, stub t'ube.
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'V The licensee, during a telephone conference, related their successful stub tube repairs.
Noting the above successful test results and our staff understanding of the licensee's procedure for repairs to the NMP1 stub tubes, the restart of the facility without requiring an exemption to 10 CFR 50 Appendix A, General Design Criteria 14, for abnormal pressure boundary leakage, is appropriate.
It is our staff position and understanding that during the upcoming fuel cycle, representatives from NMP1 and the NRC will pursue a permanent resolution to the leaking stub tube phenomena for the NMPl facility.
If you should have any questions concerning the information presented
- above, please contact me on extension X29419.
Sincerely, ORIGINAL SIGNED BY cc:
G. Lainas B. D. Liaw R.
Hermann J. Kelly Thomas S. Rotella, Acting Proiect Manager Nine Mile Point I BWR Proiect Directorate gl Division of BWR Licensing DISTRIBUTION BTWCTIEV7 NRC PDR Local PDR BWD-1 R/F J7wolinski TRotella CJamerson RBernero
- Attorney, OELD EJordan
-BGrimes JPartlow ACRS (10)
NAME :TRot DATE:6/ j</86 h :JZwolinski
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