ML18052A881

Application for Amend to License DPR-20,reflecting Rev to Recirculation Actuation Sys Logic Removing Single Failure Potential & Deleting Statement Describing Turbine Runback Feature

ML18052A881
Person / Time
Site:	Palisades
Issue date:	02/25/1987
From:	Buckman F CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML18052A880	List: ML18052A878 ML18052A881 ML18052A882
References
NUDOCS 8703040200
Download: ML18052A881 (4)

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l CONSUMERS POWER COMPANY Docket 50-255 Request for Change to the Technical Specifications License DPR-20 For the 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 Octob~r 16, 1972, for the Palisades Plant be changed as describ.ed in Section I below:

I. Changes A. In Section 1.2, under the definition of Degree of Redundancy, add an additional sentence to read:

"This definition does not apply to the 1 oµt of 2 taken twice logic scheme used to initiate the recirculation actuation system."

B. In Section 1.2, under the definition provided for the Engineered Safety Features System Logic, add an additional sentence to read:

"The Recirculation AGtuation System*is initiat;ed by a 1 out of 2 taken twice logic."

CA In the third paragraph of the basis for Section 3.17, delete the phrase related to the turbine runback signal such that the sentence will read:

"If only two channels are operable, the reactor power level is reduced to 70 percent rated power which protects the reactor from possibly exceeding design peaking factors due to undetected flux tilts."

D. Add the following to the basis provided for Section 3.17:

"The Recirculation Actuation System (RAS) initiates on a 1 Ol;lt of 2 taken twice logic scheme. Any one channel declared inoperable shall be placed in a bypass condition to ensure protection from an inadvertent RAS actuation. Since the bypassing of a channel introduces the possibility for a failure to receive an automatic RAS actuation signal, the time period in the bypassed condition is limited."

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E * . . In Table 3.17,4, Item 1, _SIRW Tank Low-Level Switches, change this item to read Minimum Minimum Operable Degree of Permissible Bypass No Functional Unit Channels Redundancy Condition 1 SIRWT Low 4 NA(b) One channel may be Level Switches inoperable for a(b) period of 7 days F. Change Footnote (b) of Table 3.17.4 to read:

"(b) If a channel is declared inoperable, it shall be placed in a bypass condition. Minimum degree of redundancy is not applicable to the SIRWT Low-Level Switches."

II. Discussion A. As a result of the changes to the RAS actuation logic, the degree of redundancy is no longer defined for this system. Therefore, the definition has been clarified by indicating this exception.

B~ The description of the Engineered Safety Features System Logic has been modified to indicate the different format used for the RAS actuation logic.

C. The description of the turbine runback.feature provided in the basis of Section 3.17 is no longer applicable. As provided in Section 14.4.1 of the Palisades Final Safety Analysis Report, the turbine runback feature has been disabled and is no longer used in response to a dropped rod~ Analysis has shown that the turbine runback could have unacceptable effects on reactor performance.

The elimination of the turbine runback is also discussed in a November 3, 1981 letter from D M Crutchfield to D P Hoffman titled

"~alisades - SEP Topics - Design Basis Events". The letter reiterates the fact that the runback has been disabled and, in

• addition, notes that the change was approved when the power increase to 2530 Mwt was granted.

As a result of previous approvals, the statement concerning the turbine runback should be deleted. This change should be considered an editorial correction.

D. Information has been added in the basis of Section 3.17 to describe the change to the RAS actuation logic. This description includes the reason for requiring an inoperable channel to be bypassed and the purpose for the time restrictions provided for a bypassed channel.

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E. As a result of the modification to the RAS actuation logic, a revision was needed for this item to provide appropriate restrictions for an inoperable SIRW Tank low-level switch. This change ensures that certain deficiencies found in the previous actuation logic are not reinstituted as a result of operator action.

The previous deficiencies were described in Licensee Event Report 86-034, dated September 18, 1986.

In the previous Technical Specifications and logic design, single failures were possible in which a premature RAS signal could occur.

The modification of the system to a 1 out of 2 taken twice logic eliminated this concern. To prevent the reinsertion of this possible problem, an inoperable channel will be placed in bypass.

With the new logic and a single channel in bypass, a potential is created for a single failure to occur that would prevent an automatic RAS actuation at the proper time. For this reason, a time limit of 7 days is proposed to restrict the period that this condition can exist. This time period is considered to be needed to complete any potential repairs in the event of a malfunction of a level switch.

The failure to achieve a RAS is not considered to be as significant of a malfunction as an early actuation. It is believed that sufficient time and awareness is available for a failure to actuate to be recognized and any adverse consequences prevented via manual actions. Therefore, an allowable time period in this degraded condition is considered appropriate and necessary.

F. The footnote has been revised to include the bypass requirement for an inoperable channel. This requirement was justified in the description provided for Change E.

The footnote also reiterates that a degree of redundancy is not applicable. This will ensure that a misinterpretation does not occur by restating the exception at its point of application.

Analysis of No Significant Hazards Consideration This Technical Specifications change is required to cause the modif ica-tions provided for the Recirculation Actuation System logic to be reflected in the specifications. The change provides.clarifications to appropriate sections and imposes operability requirements for the SIRW tank low level switches consistent with the modified logic. In addi-tion, an editorial change has been included to delete a reference to a no longer used turbine runback on a dropped rod.

This change results in a more restrictive specification in that the potential for a premature RAS actuation is eliminated and the allowable time in a degraded condition is restricted. Previously, the specifica-tions allowed operation for an unlimited time period with two SIRW tank low level switches inoperable.

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Since this change results in additional controls beyond those currently available, the probability of occurrence or the consequences of an

• accident or malfunction are not increased.

The proposed change provides additional restrictions in the Technical Specifications. These changes are necessary to ensure that appropriate conditions are maintained to prevent a failure of the RAS system.

The change does not create the possibility of a different type of accident or malfunction. The change reduces the potential for a failure as could occur with the current Technical Specifications.

The proposed change results in an increase in the margin of safety from the current specificat~ons. The change adapts the specifications to reflect the modification of the RAS actuation logic. Appropriate restrictions are provided to reduce the chance of the failures previ-ously found in the RAS logic.

III. Conclusion The Palisades Plant Review Committee has reviewed this Technical Speci-fication Change Request and has determined that. this change does not involve an unreviewed safety question and therefore involves no signifi-cant hazards consideration. This change has also been reviewed under the cognizance of the Nuclear Safety Board. 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

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By ~-<:.,..

F W Buckman, Vice Pres~

Nuclear Operations Sworn and subscribed to before me this 25th day of February 1987.

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. Elaine E Bueh~r. Notary Public Jackson County, Michigan My commission expires October 31, 1989 TSP0287-0001-NL02