ML20079C922

Corrected Tech Spec Page 3.1-4 Re Setpoint for Low Condenser Vacuum Scram

ML20079C922
Person / Time
Site:	Oyster Creek
Issue date:	06/18/1991
From:	GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML20079C881	List: ML20079C880 ML20079C922
References
NUDOCS 9106260327
Download: ML20079C922 (1)

Text

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particular protection instrument to not requirsd; or ths plant is placsd in the protection or safe condition that the instrument initiates. This is accomplished in a normal manner without subjecting the plant to abnormal operatione conditions.

The action and out-of-service requirements apply to all instrumentation within a particular function, e.g., if the requirements on any one of the ten scram functions cannot be met then control rods shall be inserted.  ;

1 The trip level settings not specified in Specification 2.3 have been included in this specification. The bases for these settings are discussed below.

The high drywell pressure trip setting is 5 3.5 peig. This trip will scram the reactor, initiate containment spray in conjunction with low low reactor water l level, initiate core spray, initiate primary containment isolation, initiate automatic depressurization in conjunction with low-low-low-reactor water level, i initiate the standby gas treatment system and isolate the reactor building. The scram function shute the core down during the loss-of-coolant accidents. A steam leak of about 15 gpm and a liquid leak of about 35 gpm from the primary system will cause drywell pressure to reach the scram point; and, therefore, the scram provides protection for breaks greater than the above.

High drywell pressure provides a second means of initiating the core spray to mitigate the consequences of loss-of-coolant accident. Its trip setting of $3.5 psig initiates the core spray in time to provide adequate core cooling. The break size coverage of high drywall pressure was discussed above. Low-low water level and high drywell pressure in addition to initiating core spray also causes isolation valve closure. These settings are adequate to cause isolation to minLmize the offsite dose within required limits.

It is parmissible to make the drywell pressure instrument channels inoperable during performance of the integrated primary containment leakage rate test provided the reactor is in the cold shutdown condition. The reason for this is that the Engineered Safety Features, which are ef fective in case of a LOCA under these conditions, will still be effective because they will be activated (when the Engineered Safety Featuren system is required as identified in the technical specification of the system) by low-low reactor water level.*

The scram discharge volume has.two separate instrument volumes utilized to detect water accumulation. The high water level is based on the design that the water in the SDIV's, as detected by either set of level instruments, shall not be allowed to exceed 29.0 gallone; thereby, permitting 137 control rods to scram. To provide further margin, an accumulation of not more than 14.0 gallons of water, as detected by either instrument volume, will result in a rod block and an alarm. The accumulation of not more than 7.0 gallone of water, as detected in either instrument volume will result in an alarm.

Detailed analyses of transients have shown that sufficient protection is provided by other scrams below 45% power to permit bypassing of the turbine trip and generator load rejection scrams. However, for operational convenience, 40% of rated power has been chosen as the setpoint below which these trips are bypassed.

This setpoint is coincident with bypass valve capacity.

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Alowcondenservacuumscramtripof20inchesHghasbeenprovidedtoprotectthel149 main condenser in the event that vacuum is lost. A loss of condenser vacuum would cause the turbine stop valvas to close, resulting in a turbine trip Oyster Creek 3.1-4 Amendment No 20, 73, 79, 112, 149, 152

• Correction: 11/30/87, 6/18/91 9106260327 910618 fR ADO M 05000M 9 PDR

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