ML19309B237
| ML19309B237 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 02/26/1980 |
| From: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-79-27, NUDOCS 8004030311 | |
| Download: ML19309B237 (3) | |
Text
',T BALTIMORE GAS AND ELECTRIC COMPANY P. O. B OX 1475 B A LTI M O R E. M ARYt.AN D 21203 February 26, 1980 Antwun C.LuMo'aLL.Ja.
v.cc mess.oa ve Swmv Mr. Boyce E. Grier, Director Regioni. One, Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 1?h06
Subject:
Calvert Cliffs Nuclear Power Plant Units Nos.1 & 2, Dockets Nos. 50-317 & 50-318 IE Bulletin 79-27
Reference:
NRC letter dated 11/30/79 from B. H. Grier to A. E. Lundvall, Jr., same subject.
Dear Mr. Grier:
IE Bulletin No. 79-27, which was forwarded to us by the referenced letter, requested certain infor=ation concerning the potential vulnerability of Calvert Cliffs to a loss of a non-Class 1E instrumentation and control power bus during operation.
The fonoving information is provided in response to the Bunetin and fonovs the format of the Bulletin:
Response to la.
Equipment required to achieve a cold shutdown derives power from k kV unit buses, k80 Volt unit buses, k80 Volt motor control centers, 120 VAC instrument buses and 125 VDC battery buses. Voltmeters, potential indicators and alarms exist in the control room to alert the operator to the loss of power to any bus.
Resnonse to ib.
Each piece of equipment (instrument, valve or motor) required to achieve a cold shutdovu vas reviewed in order to identify sources of power f - control, operation and indication. Except as noted in the response to belov, loss of any one bus or facility vin not irptir the ability to
.ieve cold shutdown.
Reseonse to le.
As a result of this review, the folleving =odifications win be made:
i i
avoo o 30 s
Mr. B. H. Grier Psbruary 26, 1980 Two hot leg and three cold leg reactor coolant system temperature indicators are provided for each loop on the control panels. Three additional hot leg and three additional cold "eg te=perature channels are available at a remote location in the control room. Loss of a single inverter causes failure of panel indicators on loop 11 cold leg temperature and loop 22 cold leg temperature, however, remote control room indications are unaffected. Modifications vill be made on these loops such that a single inverter loss vill leave at least one panel indicator available for each loop temperature. Engineering has been initiated and it is anticipated that installation vill be complete by May 30, 1980.
Law pressure safety injection control valve CV-306 must be closed during shutdown cooling. Loss of 120 VAC to this valve causes the valve to open. This is the required position during accident conditions.
Provisions vill be made for non-electrical operation of the valve during shutdown operations. Engineering has been initiated and installation vill be completed during the first cold shutdown on each unit after receipt of equipment.
Shutdown cooling temperature control valve C7-657 sast be open to provide a shutdown cooling flow path. ksa of 120 VAC to this valve causes the valve to close. This is the required position during accident conditions. Provisions vill be made for non-electrical operation of this valve during shutdown operations. Engineering has been initiated and installation vill be completed during the first cold shutdown on each unit after receipt of equipment.
Reseense to 2.a, b, and e.
Operating instructions and abnor=al and emergency procedures have been reviewed for adequacy, which would be used by operators in the event of a loss of power to a class 1-E or non-class 1-E distribution buses.
The review has determined that a new procedure is needed. This procedure, which vill be implemented by May 30, 1980 vill address loss of power symptoms, equipment that is requirad for the safe shutdevn of the plant that vould be affacted, alternate indication / equipment that say be used, and methods for restoring power.
Resnonse to 3.
I Vital 120 VAC is supplied by four inverter buses on each unit.
No automatic change-over is employed. Change-over to an alternate scurce can be accomplished by a nanual switch only. kss of a single i=verter vill not impair the ability to achieve a cold shutdown. Each 120 VAC vital bus has a volt meter and a Mange-over switch position indicator in the control room. Additionany, loss of an inverter results in an alars to alert the operators. No t*me delay relays are employed in the inverters, and based on favorable operating experience, no modificati.ss are proposed.
If you require any additional infor=ation on this natter, please l
contact us.
Very truly vours 7
/
f afu
Mr. B. E. Grier February 26, 1980 cc:
J. A. Biddison, Esquire G. F. Trowbridge, Esquire Mr. E. L. Conner, Jr.
Division of Reactor Opersticas Inspection Office of Inspection and Enforcement Washington, D. c.
20555 f
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