ML19345D388
| ML19345D388 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 12/02/1980 |
| From: | Wild P STONE & WEBSTER ENGINEERING CORP. |
| To: | Stello V NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| REF-PT21-80-310-001 NUDOCS 8012150033 | |
| Download: ML19345D388 (4) | |
Text
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. PARP 21 IDBUIFICATION NO. fso-wo-coi COPPAth' IWE_Mnemb be-u 9
DATE OF I H IER. W h o D00(ET NO. 6 -3M M DATEDISTRIBUTED s714bo a.m.
ORIGIinL PEPORT SUPPLBENTARY i DISTRIBUTION:
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PRELIMINARY EVALUATION OF THE' ATTACHED REPORT INDICATES LEAD RESPONSIBILITY FOR FOLLOWUP.AS SHOWN BELOW:
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- 4.m ~ on Mr. Victor Stello, Director December 2, 1980 Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Sir:
NOTIFICATION OF DEFECT, 10CFR21 NORTH ANNA UNITS 1 AND 2 VIRGINI'A EIICTRIC AND POWER COMPAhT Stone & Webster Engineering Corporation (S&W), pursuant to the provisions of 10CFR2j, hereby provides notification of a " defect" concerning the North Anna Nuclear Power Station, Units 1 and 2, owned by Virginia Electric and Power Company (VEPCO) and for which S&W provided both engineering and construction services.
In accordance with the rep'orting requirements of Section 21.21(b)(3), the following information is submitted:
(i) Name and address of the individual informing the Commission:
Mr. P. A. Wild, Director of Engineering Stone & Webster Engineering Corporation P.O. Box 2325 Boston, MA 02107 (ii) Identification of the facility, or the basic component supplied for such facility, which contains a defect:
North Anna Nuclear Power Station, Units 1 and 2 Design of Emergency Bus Residual Voltage ius-Transfer (iii) Identification of firm constructing facility or supplying basic component which contains a defect:
Stone & Webster Engineering Corporation
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(iv) Nature of the defect and the safety hazard which could be created:
In the evsnt of a safety injection signal the emergency diesel generators will start automatically. The emergency buses and their safeguard loads will continue to be fed from the preferred (off-site) power source.
Should the preferred source be lost (e.g., undervoltage or sustained degraded voltage) after the diesel has reached rated speed and voltage, the preferred source breaker will trip and the emergency diesel generator breaker will close, transferring certain safeguard loads to the emergency diesel generator.
Since there is no definitive phase relationship between the tripped preferred source and the emergency diesel generator voltages and no time permissive for collapsing of the residual voltage, an out-of-phase transfer is possible. This could result in tevere motor end-turn forces as well as high torsional stresses that could cause motor rotor, coupling, or driven equipment shaft failures.
The out-of phase transfer could result in redundant low head safety injection pumps becoming inoperative. This would represent a major reduction in the protection provided to the public health and safety, and could create a substantial safety hazard.
(v) Date on which information of such defect was obtained:
December 2, 1980.
(vi) In the case of a basic component which contains a defect, the number and location of all such components in use at, supplied for, or being supplied for facilities subject to the regulations:
North Anna Nuclear Power Station, Units 1 and 2.
Our investigation has hown that the only facilities affected are those listed above. Should this information change, this report will be supplemented and appropriate advice will be given to purchasers or licensees.
(vii) Corrective action which has been taken; name of~ individual or organization responsible; and length of time taken to complete the action:
Corrective action consists of the installation of timers that would be set to a value that would allow the residual voltage to decay to an acceptable value for transfer.
Corrective action was completed for North Anna Unit 1 by VEPCO on November 17, 1980.
Corrective action for Unit 2 is in progress.
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(viii) Advice related to the defect that has been given to purchasers or licensees:
The Licensee was informed of the deviation and the corrective action involved.
In addition to actions stated above Surry 1&2 was informed that this problem could exist in their facility.
We have been informed that the NRC has been notified of this problem on NA I&2 by LER Item N 1-80-96.
If you require any further information, please contact Mr. R. B. Bradbury at 617-973-0291.
l Very truly yours, N /~f?./,,-l/(/
P'. A5 WEIT Director Of Engineering JBS:CM h
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