ML20210R828

Revised Bases Page B.3/4.9-6 to TS Section 3/4.9,providing Clarity & Consistency with Sys Design Description in UFSAR Sections 8.3.2.1 & 8.3.2.2

ML20210R828
Person / Time
Site:	Quad Cities
Issue date:	08/13/1999
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20210R824	List: ML20210R828 SVP-99-147, Notifies of Change to Bases of TS to Licenses DPR-29 & DPR- DPR-30.Change to TS Section 3/4.9 Provides Clarity & Consistency with Sys Design Description in Ufsar,Sections 8.3.2.1 & 8.3.2.2.TS Bases Page,Encl
References
NUDOCS 9908170227
Download: ML20210R828 (2)

Text

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4 ATTACHMENT A.

REVISED BASES PAGE B.3/4.9-6 l

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9908170227 990013 PDR ADOCK 05000254 P PDR t ._

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..- i ELECTRICAL POWER SYSTEMS B 3/4.9 I BASES '

Each battery of the D.C. electrical power systems is sized to start and carry the normal D.C. loads plus all D.C. loads required for safe shutdown on one unit and operations required to limit the consequences of a design basis event on the other unit for a period of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> following loss of offsite power plus a single active failure without taking credit for the battery charger. The battery chargers are sized to restore the battery to full charge under normal (non-emergency) load conditions. A normally disconnected alternate 125 volt battery is also provided as a backup for each normal battery, if both units are operating , the normal 125 volt battery must be returned to service within the specified time frame since the design configuration of the alternate battery circuit is )

susceptible to single failure and, hence, is not as reliable as the normal station circuit. During times {

when the other unit is in a Cold Shutdown or Refuel condition, an alternate 125 volt battery is l available to replace a normal station 125 volt battery on a continuous basis to provide a second I available power source.

With one of the required D.C. electrical power subsystems inoperable the remaining system has the I capacity to support a safe shutdown and to mitigate an accident condition. However, a subsequent worst-case single failure would result in complete loss of ESF functions. Therefore, an allowed outage time is provided based on a reasonable time to assess plant status as a function of the inoperable D.C. electrical power subsystem and, if the D.C. electrical power subsystem is not restored to OPERABLE status, prepare to effect an orderly and safe plant shutdown.

Inoperable chargers do not necessarily indicate that the D.C. systems are not capable of performing i their post-accident functions as long as the batteries are within their specified parameter limits. With both the required charger inoperable and the battery degraded, prompt action is required to assure an adequate D.C. powr supply.

ACTION (s) are provided to delineate the measurements and time frames needed to continue to assure OPERABILITY of the Station batteries when battery parameters are outside their identified limits.

Battery surveillance requirements are based on the defined battery cell parameter values. Category A defines the normal parameter limit for each designated pilot cell in each battery. The pilot cells are the average cells in the battery based on previous test results. These cells are monitored closely as an indication of battery performance. Category B defines the normal parameter limits for each connected cell. The term " connected cell" excludes any battery cell that may be jumpered out because of a degraded condition or for any other reason. Category B also defines allowable values for each connected cell. These values, although reduced, provide assurance that sufficient capacity exists to perform the intended function and maintain a margin of safety. When any battery parameter is outside the Category B allowable value, the assurance of sufficient capacity as described above no longer exists and the battery must be declared inoperable.

Verifying battery termina! voltage while on float charge for the batteries helps to ensure the effectiveness of the charging system and the ability of the batteries to perform their intended function. The voltage requirements are based on the nominal design voltage of the battery and are consistent with the initial voltages assumed in the battery sizing calculations.

QUAD CITIES - UNITS 1 & 2 Amendment Nos.

(Issued By Comed Letter Dated August 13,1999)

B 3/4.9-6