ML20199L774

Proposed Tech Specs Bases for Sections 3/4.10.K & 3/4.10.L, Provides Description of Design & Operation of RHR SD Cooling Subsystem

ML20199L774
Person / Time
Site:	Quad Cities
Issue date:	01/21/1999
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20199L759	List: ML20199L774 SVP-99-004, Informs That Comed Has Changed Bases of FOLs DPR-29 & DPR-30 App a TS Bases for Sections 3/4.10.K & 3/4.10.L.Changed Tss, Encl
References
NUDOCS 9901280144
Download: ML20199L774 (2)

Text

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.n REFUELING OPERATIONS B 3/4.10 BASES 3/4.10.1 Sinole Control Rod Removal 3/4.10.J Multiole Control Rod Removal 1

These specifications ensure that maintenance or repair of control rods or control rod drives will be performed under conditions that limit the probability of inadvertent criticality. The requirements for l

simultaneous removal of more than one control rod are more stringent since the SHUTDOWN MARGIN specification provides for the core to remain subcritical with only one control rod fully.

withdrawn.

Refueling interlocks restrict the movement of control rods and the operation of the refueling equipment to reinforce operational procedures that prevent the re. actor from becoming critical.

These interlocks prevent the withdrawal of more than one control rod. Under these conditions, since only one control rod can be withdrawn, the reactor core will always be shut down even with the highest worth control rod withdrawn if adequate SHUTDOWN MARGIN exists. Verification that all the other control rods are fully inserted is required to assure the SHUTDOWN MARGIN is within the limits. Verification that the five by-five array of control rods are inserted and disarmed while the scram function for the withdrawn control rod is not available is required to ensure that the possibility of criticality remains precluded. '

During refueling operations, no more than one control rod is permitted to be withdrawn from a core cell containing one or more fuel assemblies. When all four fuel assemblies are removed from a core cell, the control rod may be withdrawn with no restrictions. With no fuel assemblies in the core cell, the associated control rod has no reactivity control function and is not required to remain inserted. Prior to reloading fuel into the core cell, the associated control rod must be inserted to j ensure that an inadvertent criticality does not occur. i 3/4.10.K Residual Heat Removal and Coolant Circulation - Hioh Water Level 3/4.10.L Residual Heat Removal and Coolant Circulation - Low Water Level The requirement that at least one shutdown cooling mode loop of the residual heat removal (RHR) I system be OPERABLE or that an altamate method capable of decay heat removal be demonstrated ensures that sufficient cooling capacity is available to remove decay heat and maintain the water in l the reactor pressure vessel below 140*F as required during REFUELING.

ms e n.T T The requirement to have two shutdown cooling mode loops of the RHR system OPERABLE when there is less than 23 feet of water above the reactor pressure vessel flange ensures that a single failure of the operating loop will not result in a complete loss of shutdown cooling capability. With

. the reactor vessel head removed and 23 feet of water above the reactor pressure vessel flange a large heat sink is available for core cooling. Thus, in the event of a failure of the operating shutdown cooling loop, adequate time is provided to initiate attemate methods capable of decay heat removal or emergency procedures to cool the core.

9 OUAD CITIES - UNITS 1 & 2 B 3/4.10-3 Amendment Nos. 171 a 167

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9901290144 990121 PDR ADOCK 05000254 P PDR ,.

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t ATTACHMENT TECHNICAL SPECIFICATION HASES

• SVP-99-004 Page 3 of 3 Insert A:

The RiiR Shutdown Cooling subsystem configuration was not designed to be throttled to sufficiently maintain constant reactor '

coolant temperature. Continuous or intermittent operation of one subsystem can maintain and reduce the reactor coolant temperature as required. Each RIIR shutdown cooling subsystem is considered OPERABLE ifit can be manually aligned either remotely or locally in the shutdown cooling mode.

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