ML20063L283
| ML20063L283 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 02/18/1994 |
| From: | Denton R BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9403040171 | |
| Download: ML20063L283 (5) | |
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BALTIMORE GAS AND ELECTRIC 1650 CALVERT CtJFFS PARKWAY. LUSBY, MARYLAND 20657-4702 l
ROBERT E. DENTON VICE PRE $1 DENT NUCLE AR cNERGY (4:0) MO-44SS l
February 18,1994 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Correction of Erroneous Information Supplied in a License Amendment Reauest i
REFERENCES:
(a)
Letter from Mr. R.: E. Denton (BG&E) to NRC Document Control Desk, dated April 1,1993, License Amendment Request; Onsite Power Distribution Systems, AC Distributien - Operating (b)
Letter from Mr. R. E. Denton (BG&E) to NRC Document Control Desk, dated February 9,1994,10 CFR 50.9 Notification Concerning Erroneous Information Supplied in a License Amendment Request We have discovered an error in a License Amendment Request l Reference a]. This error was not identified until after the Nuclear Regulatory Commission (NRC) issued a corresponding License Amendment and Safety Evaluation Report. Since this information was used by the NRC during the technical review process in approving the License Amendment, we reported the information under the requirements of 10 CFR 50.9(b) [ Reference b].
Attachment (1) of this submittal provides corrected information to allow the Commission to reevaluate their approval of the license amendment. Baltimore Gas and Electric Company has administratively prohibited the use of the license amendment and invoked the more restrictive controls which previously existed. We will maintain this prohibition until we are informed by the Commission whether approval of the amendment was appropriate.
We consider the accuracy ofinformation which we provide to NRC a matter of extreme gravity. We have therefore commenced a root cause analysis to fully examine the causes of this error, and we will l
take appropriate corrective actions to prevent its recurrence.
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9403040171 940218 PDR ADOCK 05000317 P
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Document Control Desk -
February 18,1994 Page 2 Should you have any further questions regarding this matter, we will be pleased to discuss them with I
you.
V N ery truly yours, N
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STATE OF MARYLAND TO WIT :
COUNTY OF CALVERT I hereby certify that on the
/klN day of k htut1/4
,1994,befo me, the subscriber, a Notary Public of the State of Maryland in and fot Dal0(rl (A n 4t /
personally appeared Robert E. Denton, being duly sworn, and states that he is Vice Prrfident of the Baltimore Gas and Electric Company, a corporation of the State of Maryland; that he provides the foregoing response for the purposes thuein set forth; that the statements made are true and correct to the best of his knowledge, information, and belief; and that he was authorized to provide the response on behalf of said Corporation.
WITNESS my liand and Notarial Seal:
Le Notary Public c2 hb My Commission Expires:
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<un.u/
/ Date' l
RED /DDM/dtm Attachments: (1)
Correction of Erroneous Information Supplied in a License Amendment Request l
(2) 120 VAC Vital Electrical Power Distribution System Functional Diagram cc:
D. A. Brune, Esquire J. E. Silberg, Esquire R. A. Capra, NRC L
D. G. Mcdonald, Jr.. NRC T. T. M attin, NRC P. R. Wilson, NRC R. I. McLean, DNR J.11. Walter, PSC
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A'ITACIIN1ENT (1) q COllRECTION OF ERRONEOUS INFOR51ATION SUPPLIED IN A LICENSE A51END51ENT REQUEST IIACKGROUND On April 1,1993, Baltimore Gas and Electric Company (BG&E) submitted a license amendment which proposed to revise the Actions of Technical Specification ' 3.8.2.1, "A.C. Distribution -
r Operating." Under the proposed amendment, we would be allowed to power a 120 Volt A.C. (VAC) -
vital bus from the inverter backup bus for up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> instead of the previous 8-hour limit. In order to make our proposed technical specifications adhere more closely 'to NUREG-1432,
" Standard Technical Specifications for Combustion Engineering Plants," we submitted two modifications to the proposed changes (References 2 and 3). These changes reduced the proposed allowed outage time from 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and reduced the allowed time to place a 120 VAC vital bus on the inverter backup bus from 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
1 On October 29,1993, the requested changes were approved as License Amendments 183 (Unit 1) and 160 (Unit 2). Since approval, the amended provisions of Specification 3.8.2.1 have been used once. De 24-hour allowance for operation with one 120 VAC vital bus powered by the inverter -
backup bus was used by Unit 1 on January 24 - 25,1994. Unit 1 was in hiode 3 during the entire period.
CORRECTION OF ERRONEOUS INFOltN1ATION In the April 1,1993 license amendment request (Reference 1), we made the following statement, "The inverter backup bus is fed from a Class 1E 480/120 VAC regulated transformer (diesel backed)"
(" Background" section, fourth paragraph). No other explicit statements regarding the qualifications of the inverter backup bus were made in Reference (1) or the subsequent submittals. In the " Safety Analysis" and " Determination of Significant Ilazards" sections of Reference (1), we stated that the 120 VAC bus would be capable of performing its safety function when powered by the inverter backup bus for all events except those which included a loss of offsite power.
The Safety Evaluation Report (SER) which accompanied the approved license amendment contained the following statements, "Each unit has an inverter backup bus which can be used as a source of power for the vital busses and can be manually connected to one vital bus _at a time.
Although the inverter backup bus is fed from a Class 1E regulated transformer that, in turn, is backed by an emergency diesel generator, it is not capable of providing uninterruptible power to the vital busses during design basis events such as a loss of offsite power. Therefore, it is not considered an emergency source of power."
Our submittal was incorrect in that the regulating transformer which feeds the 120 VAC inverter backup bus is not classified as Class 1E. A correct wording of the sentence in Reference (1) would be, "The inverter backup bus is fed from a 480/120 VAC regulating transformer (Class IE diesel backed)."
Attachment (2) is a drawing of the relevant portions of the Calvert Cliffs electrical system. The i
drawing clearly delineates which portions of the electrical r. stem are Class 1E. The 4 Kv electrical system, including the diesel generators and the Afotor Centrol Center (h1CC) which powers the-inverter backup bus are Class 1E qualified. The electrical inverters for the 120 VAC vital busses which are fed from :ither the 125 VDC busses or the inverter backup bus are also qualified as Class 1E. The inve*cter backup bus, (e.g., the cables, regulating transformers, and bus) from the electrical breaker which isolates it from the Class 1E SiCC to the inputs of the inverters, is not Class IE.
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ATTACilMENT m CORREC110N OF ERRONEOUS INFORMATION SUPPLIED IN A LICENSE AMENDMENT REQUEST
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i The MCC, which provides power for Class 1E and non-Class 1E loads including the inverter backup bus, contains branch circuit breakers which are coordinated to ensure that any postulated fault on the non-Class 1E circuits will not degrade the Class 1E qualified circuits. The MCC feeds a regulating transformer which supplies the inverter backup bus. The inverter back"o bus provides four fused disconnects each of which rupplies one vital inverter. A transfer switch ln each inverter allows the inverter backup bus to :av A power directly to the 120 VAC vital bus. The transfer switches are
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key interlocked such tha? ont one 120 VAC vital bus may be supplied by the inverter backup bus at j
any time.
We have reviewed the qualifications of the components used in the inverter backup bus. All components of the inverter backup bus were purchased and qualified to Class 1E during original plant construction except for the regulating transformer. The regulating transformer is standard electrical equipment (Sola brand Type CVS Constant Voltage Transformer). The transformer and the inverter backup bus are located in the cable spreading room which is a mild environment. The transformer has been verified as seismically adequate according to the Seismic Qualification Utility Group (SQUG) Generic Implementation Procedure (GIP). The inverter backup bus has also been evaluated under the SQUG GIP. There are some minor issues (i.e., adequacy of anchorage) that will be repaired before it fully meets the SQUG GIP criteria. However, the inverter backup bus is capable of supplying power to a 120 VAC vital bus during and following a Calvert Cliffs Design Basis Earthquake.
In summary, the regulating transformer, the cables, and the inverter backup bus are not Class 1E.
Ilowever, we believe that the conclusions made in the " Safety Analysis" and " Determination of Significant Hazards" sections of our license amendment request and those made in the NRC Safety Evaluation Report are correct. Specifically, a 120 VAC vital bus is capable of performing its safety i
function when powered by the inverter backup bus for all events except those which include a loss of offsite power. Therefore, we believe that the allowed outage times approved by the amendment are justified.
REOUESTED ACTION 1
We request that the NRC review this corrected information and determine if approval of the amendment was appropriate. Until we are notified, we will continue to administratively prohibit use of the license amendment.
HEFERENCES (1)
Letter from Mr. R. E. Denton (BG&E) to NRC Document Control Desk, dated April 1,1993, License Amendment Request; Onsite Power Distribution Systems, AC Distribution - Operating (2)
Letter from Mr. R. E. Denton (BG&E) to NRC Document Control Desk, dated July 22,1993, Revision to License Amendment Request; Onsite Power Distribution Systems, AC Distribution - Operating (3)
Letter from Mr. R. E. Denton (BG&E) to NRC Document Control Desk, dated September 8,1993, Revision to License Amendment Request; Onsite Power Distribution Systems, AC Distribution - Operating 2
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120 VAC VIT AL ELECTRICAL POWER DISTRIBUTION SYSTEM FUNCTIONAL DIAGRAM EDG ATTACHMENT (2) i 1
4KV DUS 14 ww (Y T
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480V BUS 14 A
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MCC 104R o g
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REGUL ATING TRN4SFORMER T
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120 VAC NVERTER BACKUP BUS NO 11 (lY11)
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- NOTE' THIS DRAWING DEPICTS TIE UNIT 1 120 VAC VITN. ELECTRICAL POWER DISTRIBUTION SYSTEus.
THE UNIT 2 SYSTEM 15 SIMILAR 2
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Z "NON x NVERTER NVERTER NVERTER NVERTER NO.11 NO.13
. NO.14 NO.12 9E t't$ VDC QS WDC US VOC 125 VDC SUS NO.11 SU5 880.12 EM5 NO. 72 EUS MO. 21 00VAC vlTA 120VAC MTA 120VAC MTA 120VM MTA M5T. BUS MST. BUS MST. BUS M5T. BUS HQ.11tJ A)
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NO.12(2tp
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