ML18057A414

Application for Amend to License DPR-20,changing Tech Specs to Revise Wording for Reactor Protective Sys Trip Setting Limits for Steam Generator Low Water Level

ML18057A414
Person / Time
Site:	Palisades
Issue date:	08/21/1990
From:	Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML18057A413	List: ML18057A412 ML18057A414 ML18057A416
References
NUDOCS 9008300148
Download: ML18057A414 (3)

Text

1 CONSUMERS POWER COMPANY Docket 50-255 Request for Change to the Technical Specifications License DPR-20 For reasons hereinafter set forth, it is requested that the Technical ,

Specifications contained in the Provisional Operating License DPR-20, Docket 50-255, issued to Consumers Power Company on October 16, 1972, for the Palisades Plant be changed as described in Section I below:

I. Change Item 5 in Table 2.3.1 to read:

Four Primary Coolant Three Primary Coolant Pumps Operating Pumps Operating

5. Steam Generator Not lower than the Not lower than the LowWater Level Center Line of Feed- Center Line of Feed-Water Ring Water Ring II. Discussion The above proposed Technical Specifications change is requested to modify the description of the low water level trip which will be not lower than the center line of feed-water ring. The description in the present Technical Specifications describes this trip setpoint not lower than the center line of the feedwater ring, which is located 6'-0" below normal water level (NWL). For the currently installed steam generators, there will be no change in the trip setpoint. For the replacement steam generators, the center line of the feedwater ring is approximately 5'-8" below NWL. Normal water level is nominally two feet below the can deck.

The can deck supports the steam separators (cans). This Technical Specification change will make the Technical Specification equally applicable to the original and the replacement steam generators.

The low steam generator level reactor trip protects against loss of feedwater flow accidents and assures that the design pressure of the primary coolant system is not exceeded. Because the main feedwater system supplies subcooled water to the steam generator, the loss of main feedwater flow will result in a reduction of the secondary system heat removal capability. The decrease in energy removal rate from the primary system causes the primary system fluid temperature to increase. The resulting primary system fluid expansion results in an insurge into the pressurizer, compressing the steam space and causing the primary system pressure to increase.

As stated in the Technical Specifications Basis, the specified setpoint assures that there is sufficient water inventory in the steam generator at the time of trip to allow a safe and orderly plant shutdown, thus preventing steam generator dryout when assuming minimum auxiliary feedwater capacity. Our evaluation of the Loss of Feedwater Flow OC0890-0389-NL02 9008300148 900821 PDR ADOCK 05000255 I )'

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2 transient has assumed water inventory at 6'-0" below NWL. NWL is assumed to be at two-feet below the can deck. NWL, however, is not a specified level in the Technical Specifications and could conceivably be changed to optimize steam generator operation. At the same assumed water level (6'-0" below NWL) for the replacement steam generators, the water inventory at the time of trip is significantly greater than in the original steam generators. Therefore, the effect on the loss of feedwater event with the trip setpoint at 6'-0" below NWL is bounded by the FSAR analysis for the original steam generators.

The proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated. The change only affects the description of the low level steam generator reactor trip setpoint. The steam generator secondary water inventory below the trip setpoint is larger for the new steam generators, assuring adequate time for a safe and orderly plant shutdown and preventing steam generator dryout. The plant response to a loss of feedwater event has not been altered. Therefore, the probability or consequences of an accident have not been affected.

The proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated. The loss of feedwater flow events have not been affected. The low level trip setpoint will still assure proper system response to prevent PCS overpressurization. Therefore, no new or different kind of accident is created.

The proposed change does not involve a significant reduction in the margin of safety. The trip setpoint for the new steam generators will provide for a larger secondary inventory, therefore providing greater greater time to preventing steam generator dryout in a loss of f eedwater event and assuring that the PCS design pressure will not be exceeded.

The margin of safety is, therefore, not affected.

OC0890-0389-NL02

3 III. Conclusion The Palisades Plant Review Committee has reviewed this Technical Specification Change Request and has determined that this change does not involve an unreviewed safety question and, therefore, involves no significant hazards consideration. This change has been reviewed by the Nuclear Safety Services Department. A copy of this Technical Specification Change Request has been sent to the State of Michigan official designated to receive such Amendments to the Operating License.

CONSUMERS POWER COMPANY By ~C?

• David P Hoffman, Nuclear Operations Sworn and subscribed to before me this 21st day of August 1990.

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Elaine E Buehrer,-Notary Public

[SEAL]

Jackson County, Michigan My commission expires October 11, 1993 OC0890-0389-NL02