ML20214U951
| ML20214U951 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 05/28/1987 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Russell W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 2NRC-7-147, 87-08, 87-8, NUDOCS 8706110386 | |
| Download: ML20214U951 (4) | |
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2NRC-7-147 Beaver V No. 2 Unit Project Organization Telecopy 8
P.O. Box 328 May 28, 1987 Shippingport, PA 15077 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 ATTENTION: Mr. William T. Russell Administrator
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 CIB - Initiated Timers for Control Room Emergency Pressurization Fans Potential Significant Deficiency Report 87-08
REFERENCE:
Letter 2NRC-7-105, dated May 4, 1987, J. J. Carey to Dr. T. E.
Murley Gentlemen:
This final report is a revision to the report submitted via the referenced letter for potentially reportable Significant Deficiency 87-08 relating to "CIB-Initiated Timers for Control Room Emergency Pressurization Fans."
Due to a clerical error the date of corrective action completion was incorrectly reported as April 11, 1987.
The correct date is May 4, 1987 for the completion of the installation, with retest being completed on May 7,1987.
Pursuant to the requirements of 10CFR50.55(e), the attached final report substantiates that the initially reported condition has been evalu-ated as not reportable.
No additional information or reports on this item are, therefore, anticipated.
DUQUESNE LIGHT OMPANY
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By
_J. J.'darey Sr. Vice President MMk$o l
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United States Nuclear Regulatory Commission Mr. William T. Russell, Administrator Potential Significant Deficiency Report 87-08 Page 2 DLC/ijr NRC/DLC/SDR/8708 Att ent AR NAR cc: Mr. P. Tam, Project Manager (w/a)
Mr. J. M. Taylor, Director (3) (w/a)
Mr. J. Beall, Sr. Resident Inspector (w/a)
Mr. L. Prividy, NRC Resident Inspector (w/a)
INP0 Records Center (w/a)
NRC Document Control Desk (w/a)
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ATTACHMENT 1.
Summary Timers initiated by Containment Isolation Phase B (CIB) signals which divert the Control-Room Emergency pressurization system one hour after a CIB initiation, were powered from the respective fan control circuit. The circuitry was revised (ACN-C-174) to supply power to the timers from an uninterruptible source to insure that the timer would not reset if a loss of power occurred at ame point after a CIB.
Loss of power would cause the timer to reset to beginning of the timing cycle and would not begin its cycle until power had been restored to the emergency AC buses.
This would prevent the fans from starting after one hour.
When the change was implemented on the drawings, the power source assigned was not uninter-ruptible as had been stated in the-ACN.
2.
Immediate Action Taken i
E&DCR D-5169-S06 was issued to revise the circuitry and power the CIB timers from the CAT IE 125VDC battery system.
Mr. L. M. Rabenau, Lead Compliance Engineer, Beaver Valley Power Station Unit No. 2, contacted Mr. Dave Limroth, NRC Region I, of this concern on March 27,1987.
On April 24, 1987, Mr. Rabenau contacted Mr. L. Tripp, NRC Region I, to request a one week extension on the filing date for the report for SDR 87-08.
This extension was to allow for further evaluation of reoortability, and was granted by Mr. Tripp.
3.
_ Description of Deficiency i
CIB timers which require uninterruptible power to prevent resetting the timers on a loss of offsite power subsequent to a CIB are powered from an emergency AC distribution panel which is fed from an emergency MCC.
Loss of power will interrupt power to the MCC and the distribution panels.
4.
Analysis of Safety Implication The Loss of Offsite Power (LOOP) design basis for BVPS-2 is consistently t
identified throughtout the BVPS-2 FSAR as LOOP coincident with any postu-i lated event.
This assumption is a design requirement consistent with NRC regulations.
It defines the set of equipment which can be credited for accident mitigation.
It is not used to define a dynamic transient concur-rent with or following an accident. Loss of offsite power events at times t > 0 are not universally evaluated or assumed. Within this design basis, the emergency diesel generators start on either a safety injection signal (SIS), or a loss of preferred power to the emergency buses and thus pro-vide a backup power source to safety-related loads.
Given the original design and a LOOP coincident witn an SIS, the referenced timers would receive power from the emergency diesel generators upon receipt of the CIB signal.
Since the design basis did not assume an intermediate loss of l
power to these buses, the timers would cause the start of the emergency pressurization fans 60 minutes after receipt of the CIB signal.
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Because the postulated sequence of events is beyond the design basis for BVPS-2 and the design as originally provided would function correctly within the parameters defined by design basis assumptions and events, there is no deficiency in plant design and the modification of the timer power source to a DC power supply is an enhancement to safety system reli-ability.
5.
Corrective Action The power supplies were changed to a DC source as described in E&DCR D-5169-506. Work was completed on May 4,1987 and retest completed on May 7, 1987.
6.
Additional Report No Additional Reports are expected.
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