ML19250B891
| ML19250B891 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/17/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19250B890 | List: |
| References | |
| NUDOCS 7911060005 | |
| Download: ML19250B891 (2) | |
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S AFETY E'.'ALUATION BY THE OFFICE OF !'UCLEAR REACTOR :EGULATION FEE 74ATER SYSTEM HYCRAULIC TRANSIE!T MONITCRING P:.0 GRAM CUCUESNE LIGHT COMPANY OHIO EDISCN COMPANY PENNSYLVANIA POWER CC!'PANY SEAVER VALLEY POWER STATION UNIT -
1 COCKET NO. 50-33 Introduction By letter dated November 23, 1977, the Duquesne Light Ccm;any (DLC) submitted a report entitled "Feedwater System Hydraulic Transient Monitoring Program Res ults".
This program.eas conducted in March through July 1977 and was intended to either (1) verify that certain modifications to the feedwater centrol valves have prevented the recurt ence of excessive vibration of the feedwater piping, or (2) to provide data, in the event of excessive vibration of the piping, that would facilitate determination of the stresses imposed on the piping system and that could be analyzed to identify the cause of the vibration.
Discussion During the five months of monitoring the operation of the feedwater system, many plant transients and control system malfunctions were incased on the plant in an effort to reproduce those conditions that may have triggered the excessive vibrations of the feedwater piping that occurred on Novemeer 5, and December 27, 1976, and on January 5, 1977.
During this five months of operation, no such vibration occurred and there were n; indications of piping vibrations, hydraulic transients or feecwater control valv3 instability during the imposed transients and malfunctions.
The Cuques ie Light Company therefore, concluded that the odifications
."e fi f caur : r rel ea!ve has reduced the pr::abilit.: cf a rec;rrer.ce
- f : e ;r t 'ns feed..ater sys tem vibration inciden s to a.ini al level.
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,;e nave reviewed ne licensee's letter dated Nove-ber 23, 1977 and the enclosed report dated November 11, 1977, entitled " Beaver Valley Pcwer Station Unit No.1 Feedwater System Hydraulic Transient Monitoring Program Results" (CUQ-01-19) and the acccmpanying documents : " Beaver Valley Power Statien Feedwater Vibration enitoring Precedure" (0U0-01-05) and "Feedwater System Hydraulic Traisnets Monitoring Program Phase II"
( CU0- 511 -S C). We have also reviewed two Nuclear Services Corporation reports numbered NSC-1-78-012 and NSC-1-73-94 that were also submitted by the licensee on March 17, 1978 and Jan.ary 11, 1979, respectively in response to requests for additiona: i nforma ti on.
In conducting cur review, we found no evidence that hy past modification vibraticn event had occurred and no indication of control valve instab-111ty.
Conclusiun We have, therefore, concluded that the modifications to the feedwater control valves have reduced the probability of recurrence of a vibration event and considering the limited nature of the potential consequences of these feedwater system instabilities (as discussed in our safety evaluation of February 17, 1977) the licensee can continue to operate the Beaver Valley Pcwer Station, Unit No. I without undue risk to the health and safety of the public with respect to feedwater flow instabilities.
Date:
October 17, 1979 LJ)]
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