ML20207K643
| ML20207K643 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 03/05/1999 |
| From: | Jain S DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 50-334-98-09, 50-334-98-9, 50-412-98-09, 50-412-98-9, L-99-030, L-99-30, NUDOCS 9903170260 | |
| Download: ML20207K643 (5) | |
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Beaver Valley Power Station Shippingport, PA 15077 0004 en r Vi President Fax
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Division March 5, 1999 L-99-030 U. S. Nuclear Regulatory Commission Attention: Document Control Desk
/ Washington, DC '20555-0001
Subject:
Beaver Valley Power Station, Unit No. I and No. 2 BV-1 Docket No. 50-334, License No. DPR-66 BV-2 Docket No. 50-412, License No. NPF-73 Integrated Inspection Report 50-334/98-09 and 50-412/98-09 Reply to Notice of Violation In response to NRC correspondence dated February 5,1999, and in accordance with 10 CFR 2.201, the attached reply addresses the Notice of Violation transmitted with the subject inspection report.
If there are any questions conceming this response, please contact Mr. Mark S.
Ackerman at (412) 393-5203.
//
- Smcerely, hw3& '
Sushil C. Jain Attachment i
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Mr. D. S. Collins, Project Manager Mr. D. M. Kern, Sr. Resident Inspector Mr. W. D. Lanning, Director, Division of Reactor Safety, Region I Mr. H. J. Miller, NRC Region I Administrator DEllVERING 1
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j DUQUESNE LIGHT COMPANY Nuclear Power Division Beaver Valley Power Station, Unit No. I and No. 2 Repiv to Notice of Violation I
1 Integrated Inspection Report 50-334/98-09 and 50-412/98-09 Letter Dated February 5,1999 J
VIOLATION (Severity Level IV, Supplement I)
. Description of Violation (50-412/98-09-01) 10 CFR 50, Appendix B, Criterion III, " Design Control," requires, in part, that:
" Measures be established to assure that applicable regulatory requirements and the design basis... for structures, systems, and components... are correctly translated into l
specifications, drawings, procedures, and instructions.... The design control measures shall provide for verifying or checking the adequacy of design...."
DC voltage drop Calculation No.10080-E-202, Revision 1, dated July 30,1998, is part of the set of calculations that support the design performance criteria specified in i
Section 8.3.2 of the 'UFSAR for the de power system. This calculation stated that, (1)the minimum required (design) voltage at the closing coils of the safety-related j
4160V air circuit breakers was 90Vde, and that, between steps 2 and 6 of the emergency diesel generator loading sequence, the voltage at the DC bus was 129.2Vde; i.e., the same voltage available from the battery charger during normal power plant operation.
Contrary to the above, on and before December 17,1998, design control measures were not established to ensure that the design basis closing voltage requirements of the circuit breakers were met and verified, in that the licensee failed to recognize that, between the specified emergency diesel generator loading steps, the battery charger loading exceeded its rating and, therefore, would not be capable of supplying voltage at the same level as during normal operation. As a result, ten breakers were identified as having calculated voltages below the minimum required by design.
Discussion of the Violation The violation accurately describes an error concerning the incorrect use of the battery charger normal charging or float voltage in Calculations 10080-E-201, Rev.1 Addendum A3 and 10080-E-202, Rev.1 Addendum A3. When the charging voltage was replaced with the station batteries' beginning of duty cycle voltage in the calculations, seven safety related breaker closing coils were found to have calculated voltages less than the vendor recommended value of 90 volts. After further evaluation and ref'mement of the
Reply to Notice of Violation Inspection Report 50-334/98-09 and 50-412/98-09 Page 2 calculations as discussed below, the calculated voltages available at these breaker closing coils were determined to be above 90 volts. Therefore, this equipment met the design requirements and remained operable.
As noted in Inspection Report 50-334/98-09 and 50-412/98-09, there were four other breakers which appeared to be similarly affected. It was determined that these breakers are not required to close during emergency diesel generator (EDG) loading, and that the available voltage to the breaker's closing coils when they are required to operate, is above the vendor recommended minimum value.
Reason for the Violation Several human errors occurred during the initial revision of the calculations which were upgraded from the original A/E supplied direct current (DC) power system voltage calculations. When the calculations were revised, the engineer did not identify that the battery chargers would go into current limit during the EDG sequential loading. The battery chargers normally go into current limit only during short circuit conditions. This error was also not detected by the individuals performing the verification review and approval of the calculations.
Due to this technical error, an incorrect source voltage was used in the calculations of the voltages at the BV-2 480 volt and 4160 volt switchgear. Specifically, equipment loaded on at load step 2 of the EDG sequence, correctly used the calculated beginning of battery duty cycle voltage as an input for determining the voltage at the closing coils for the affected breakers. Equipment loaded on EDG load step 3 and later, used the battery charger float voltage as an input to the calculations since the battery charger is loaded on at EDG load step 2. This would have been acceptable, except that during the first minute load, the battery duty cycle is larger than the current limit value of the battery charger.
When the battery charger goes into current limit, the voltage seen by the loads is based on the battery voltage and not the battery charger voltage.
Corrective Actions Taken and Results Achieved Condition Report (CR) 982188 was written on December 11, 1998, to document the condition in the corrective action program.
The voltages at the affected Unit 2 switchgear breaker closing coils were recalculated using the beginning of the battery duty cycle voltage, while taking into account that the battery charger is supplying the current limit value, in lieu of the battery charger float voltage. Where necessary, the calculations used more realistic electrical cable lengths and operating temperatures to show acceptability.
The results of the calculations demonstrated that the calculated voltages at the affected switchgear breaker closing coils
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l Reply to Notice of Violition l
Inspection Report 50-334/98-09 and 50-412/98-09
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were greater than the vendor recommended minimum operating voltage of 90 volts and remained operable. These results were documented on Electrical Calculation Evaluation Forms98-147 and 98-148 which were approved on December 11, 1998, and December 12,1998, respectively.
Condition Report 982188 also identified that two Unit I calculations similarly used the battery charger float voltage, in lieu of the beginning of battery duty cycle voltage, to j
calculate voltages available at some 480 volt switchgear breaker closing coils. The voltages at these affected switchgear breaker closing coils were recalculated using the beginning of the battery duty cycle voltage.
The results of the recalculations demonstrated that the calculated voltages at the affected switchgear breaker closing coils
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were greater than the vendor reconunended minimum operating voltage of 90 volts.
These results were documented on Electrical Calculation Evaluation Form 98-200 which was approved on December 11,1998.
The engineering administrative procedures were reviewed to ensure that the design analysis process contains adequate controls to ensure compliance with ANSI N45.2.ll -
1974 requirements for design analysis. These procedures, NEAP 2.5, Design Analysis, and NEAP 2.10, Design Verification, include the applicable requirements for design s
inputs and references, design objectives, assumptions, analysis methods, conclusions, design verification, review and approval.
Corrective Actions to Prevent Further Violations The extent of condition review performed for CR 982188 determined that the error regarding the failure to account for the battery charger exceeding its current limit value was limited to the direct current system voltage calculations for Units 1 and 2. These calculations have been evaluated and corrected as described above, and no additional calculations are affected.
A description of the problem identified in CR 982188 was submitted to the INPO Nuclear Network on January 29, 1999, in order to provide the industry with plant operating experience information.
The individuals involved with the preparation of the initial revision of the calculations have been counseled, i
Nuclear Engineering Department (NED) electrical engineers reviewed CR 982188 by February 22,1999, to ensure that they are aware of the concerns identified.
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Reply to Notice of Violation Inspection Report 50-334/98-09 and 50-412/98-09 Page 4 A discussion of this event with emphasis on the use of self-checking and a questioning i
attitude will be included in Module 4 of the 1999 Engineering Support Personnel (ESP)
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retraining cycle.
4 The Engineering Assurance section of NED will investigate why the issue documented in CR 982188 was not previously identified in electrical safety system functional evaluations conducted at Beaver Valley.
This investigation will be completed by September 30,1999.
Date When Full Compliance Will Be Achieved Full compliance was achieved on December 12, 1998, with the completion of the evaluations which confirmed that the calculated voltages at the affected switchgear breaker closing coils were greater than the vendor recommended minimum operating voltage of 90 volts.
The investigation on why the issue documented in CR 982188 was not previously identified in electrical safety system functional evaluations conducted at Beaver Valley will be completed by September 30,1999.
i Module 4 of the 1999 ESP retraining cycle is scheduled to be conducted during the fourth quarter of 1999.