ML20063E797
| ML20063E797 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 08/20/1982 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8208310030 | |
| Download: ML20063E797 (6) | |
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Nuclear Construction Dimion August 20,1982 Robinson Plaza, Building 2, Sutto 210 Pittsburgh, PA 15205 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 ATTENTION:
Mr. R. Haynes Administrator
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Defective Integrated Circuits in Brown Boveri Overcurrent Relays Significant Deficiency Report No. 82-01 Centlemen:
Pursuant to the requirements of 10CFR50.55(e), the " Final Report on Defective Integrated Circuits in Brown Boveri Relays" is attached for your review. If there are any questions concerning this report, please contact the Beaver Valley Unit 2 Project Office.
DUQUESNE LIGHT COMPANY By E. J. (foolever Vice President JMM/wjs Attachment cc:
Mr. R. DeYoung, Director Office of Inspection and Enforcement (w/ attachment)
NRC Document Control Desk (w/ attachment)
Mr. G. Walton, NRC Resident Inspector (w/ attachment)
Ms. E. Doolittle, Project Manager (w/ attachment)
SUBj'CRIBED AND SWORN TO BEFORE ME THIS Mu DAY OF A(/[r-
, 1982.
/MS'W-A$AN B. rad 40TARY PuklC Notary Public ROSitSON TWP., AttEGl*ENT COUNTY My COMWISSION EXPIRES AFRIL 12.1986 Marneer..Penns l.anu Association of Notaries F208310030 820820 fG-PDR ADOCK 05000412 FPVC
United States Nuclear Regulatory Commission page 2 COMMONWEALTH OF PENNSYLVANIA )
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COUNTY OF ALLEGHENY
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On this M 8 day of ll/h
/Th, before me,
/IlAA/ 8 kl./ MC
, a Notary Public in and for said Commonwealth V
and County, personally appeared E. J. Woolever, who being duly sworn, de-posed, and said that (1) he is Vice President of Duquesne Light, (2) he is duly authorized to execute and file the foregoing Submittal on behalf of said Company, and (3) the statements set forth in the Submittal are true and correct to the best of his knowledge, information and belief.
. ' s-(tAs R. mANa$. 90TARY PUBUC Rd);Wv 'f*, AttEGHENT C0UhiY t's C0tc - % [rpdis unit 12.1986 a.,r.et, h:....p..na Assocation of Nctah w
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United States Nuclesr Regulatory Commission page 3 t
JMM/wjs bec:
C. R. Bishop (w/o attachment) i T. D. Jones J. M. Markovich H. M. Siegel i
R. J. Swiderski
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D. H. Williams C. E. Ewing (w'/ attachment)
M. H. Judkis NCD File J. Pedro (NUS)
P. RaySircar (3)
J. Sutton (S&V) j
REFERENCES:
1.
Significant Deficiency Report 82-01 2,
2DLS-12523, dated 2/25/82, " Defective Integrated Circuits in Brown Boveri Overcurrent Relays" 3.
Stone & Webster telecopied letter, dated 8/17/82, "Defec-tive Integrated Circuits in Overcurrent Relays Supplied to Beaver Valley Power Station - Unit No. 2" 1
1
BEAVER VALLEY POWER STATION - UNIT NO. 2 DUQUESNE LIGHT COMPANY Final Report on Defective Integrated Circuits in Overcurrent Relays 1.0
SUMMARY
Solid state overcurrent relays (Type ITE-50H and ITE-50D) manufactured by Brown Boveri Electric, Incorporated (BBE) may malfunction by failing to drop out upon a reduction in current. These relays are designed to pick up when a preset value is exceeded and to drop out when the current falls to a value of approximately 98 percent of the preset vlaue. Failure to drop out might inhibit the operation of a safety-related circuit. BBE attributes the potential problem to an integrated circuit in the above-referenced relays.
2.0 IMMEDIATE ACTION TAKEN On January 3, 1982, a letter was received from BBE identifying the poten-tial problem with the overcurrent relays supplied to BVPS-2.
(This information was previously transmitted to the NRC by BBE on June 16, 1981.) Upon receipt of this letter, two actions were imediately initiatedt i.
the overcurrent relays which BVPS-2 had received from BBE were disassembled to determine whether they did in fact contain the integrated circuits which had been identified as being poten-tially defective, and ii. an evaluation of the potential impact on the safe operation of the plant in the event of the above-referenced relays malfunc-tioning was initiated.
3.0 DEFICIENCY Solid state overcurrent relays (Type ITE-50H and ITE-50D) produced by BBE from 1976 through October 1980 may malfunction.
These relays are designed as "high-dropout" units. This means that they should be self-resetting when the current drops slightly below the pickup setting. BBE published data states that the contacts should drop out when the input current to the relay falls below 98 percent of the pickup setting.
The nature of the potential problem is that the relay may not drop out upon the reduction in current. This is due to an integrated circuit designated as U4 on the drawout printed circuit board of the relay. The integrated circuit is manufactured in two versions designated as the "A" chip and the "B" chip. The relays manufactured with the "A" chip are sus-ceptible to the problem described above. Relays manufactured with the "B" chip version are not susceptible to the problem.
The integrated circuit manufactured by RCA is not defective. The "B" chip is not dependent on rise and fall time for this application. Testing has
demonstrated that not all the "A" chips could successfully duplicate the potential problem.
The integrated circuit may be identified by numbers printed on its body.
The "A" chip is identified with the numbers 4047A and the "B" chip is identified with the numbers 4047B.
The potentially defective relays are component parts of the 4 kV switch-gear (2BVS-304) and diesel generator relay panels (2BVS-731). The 4 kV switchgear has been delivered. The relay panels are yet to be delivered.
4.0 ANALYSIS OF SAFETY IMPLICATIONS A.
BVPS-2 uses only the ITE-50D relays in safety-related circuits. These relays are component part of the 4 kV switchgear units.
Each redundant 4 kV feeder to the redundant 480 V emergency unit sub-stations includes an ITE-50D to trip the 4 kV breaker on overcurrent.
All of the ITE-50D relays supplied to BVPS-2 contain the potentially defective "A" chips.
The 50D includes an internal timer to permit coordination of its trip function with the " downstream" breaker protection. During normal operation, the 50D would be energized for a fault on the secondary of the 480 V unit sub. However, if the fault was cleared by a secondary device, the 50D would drop out prior to operation of its internal timer and subsequent energization of its trip output relay. This action would isolate only the faulted circuit while maintaining power to the remaining 480 V substation loads.
The chip furnished with the BVPS-2 50D relays may prevent the required action and would thus cause the loss of the entire 480 V load center under the above circumstances. Since the relays are used on redundant 4 kV feeders, loss of redundant emergency unit substations is possible and safe plant operation jeopardized.
B.
In the event of a safety injection signal (SIS), selected loads on both safety systems (4160 V and 480 V) receive simultaneous start
' signals. The 4 kV input breakers to the redundant emergency 480 V substations contain ITE-50D relays. The pickup current settings for these relays include the inrush range of the combined starting load for the associated emergency system. As a result, it is possible that a simultaneous malfunction of both relays could occur which would initiate a trip to both emergency 480 V substation breakers af ter their internal timers have timed-out and jeopardize plant safety.
C.
Each incoming supply from the normal 4 kV buses to the redundant 4 kV emergency buses include ITE-50D relays. These relays will sense faults on the normal bus when the emergency diesel generator is in the exercise mode only. (In an accident condition, the diesel is separated for the normal bus.)
In the event that the 50D relays misoperate, as described above, and initiate separation of the emergency 4 kV bus from its normal source i
of power, its safety function will not be impaired. Upon loss of 2
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f normal power to the emergancy bus, all required emergency loads would be step-loaded on the diesel.
5.0 CORRECTIVE ACTION TO REMEDY DEFICIENCY BBE has repaired and returned for installation the above-referenced relays used at BVPS-2 as documented by BBE Certificates of Conformance to the jobsite (dated April 25, 1982, reissued June 7, 1982), and by BBE Trouble-shooting Report sent to Systems Control Incorporated (dated March 18, 1982), and no further action is required.
6.0 ADDITIONAL REPORTS This is the final report on this topic.
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