PY-CEI-NRR-0888, Forwards Summary of MSIV Logic Mod Plans,Per Util 880212 Commitment & Open Item Noted in Insp Rept 50-440/88-03

Forwards Summary of MSIV Logic Mod Plans,Per Util 880212 Commitment & Open Item Noted in Insp Rept 50-440/88-03

ML20151T819
Person / Time
Site:	Perry
Issue date:	08/12/1988
From:	Kaplan A CLEVELAND ELECTRIC ILLUMINATING CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
PY-CEI-NRR-0888, PY-CEI-NRR-888, NUDOCS 8808170346
Download: ML20151T819 (5)

Text

o s ELECTRIC ILLUMIN ATING COMPANY f THE CLEVELAND P.O. DOX 97 s PERAY, OHIO 44081 s TELEPHONE (216) 259 3737 s ADDRESS-Io CENTER ROAD Semng The Best Location in the Nation PERRY NUCLEAR POWER PLANT Al Kaplan ecs msiot8r August 12, 1988 we omua PY-CEI/NRR-0888 L Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Perry Nuclear Power Plant Docket No. 50-440 MSIV Logic Modification Plans Gentlemen:

In a letter dated February 12, 1988 (PY-CEI/NRR-0803 L) CEI committed to performing a design change to the MSIV electrical control circuitry by the end of the first refueling outage. The NRC documented this commitment in NRC Inspection Report 50-440/88-003 dated March 3, 19b8, and left the issue open stating inspector verification of CEI's actions relative to the modification would be required (open item 50-440/88-003-03). By letter dated March 13, 1988 the NRC staff requested that CEI submit detailed design information related to the proposed modification, including logic and wiring diagrams, electrical power schematics, and relay sequencing information.

Attachment 1 is a summary of the proposed codification. The Design Change Package (DCP) is being processed under the requirements of 10 CFR 50.59. A copy of the DCP has been provided to the Perry NRC Senior Resident Inspector for review. If any future revisions are made to the DCP, these will also be given to the Senior Resident Inspector. This DCP contains the detailed information requested in the March 13, 1988 NRC letter.

If you have any questions, please feel free to call.

Very truly ry, d'~ 17 .

, f(L MM  :?n Al Kaplan Vice President Nuclear Group AK:njc ,

cc T. Colburn K. Connaughton USNRC Region III I l 8800170346 080012 DR ADOCK 05000440 PNU Q

.

• Attachnant 1 PY-CEI/NRR-0888 L

. Page 1 of 2 Summary of Event On January 23, 1988 the plant was in Operational Condition 4 (Cold Shutdown)

> vith the HSIV's in the closed position. The "B" RPS bus was deenergized during performance of a surveillance instruction, and it was noted that the inboard MSIV's opened, even though the HSIV control svitch remained in the Closed position. Subsequent investigations, including additional testing and reviews of the elementary drawings verified that this as-built condition was the same for both the RPS A and B busses and was in accordance with the design.

The reviews performed in conjunction with our NSSS vendor, General Electric (GE), determined that the opening of the HSIV's was the result of a characteristic of the design which allows a normally energized relay to change state upon loss of power, resulting in an Open signal to the HSIV's. The evaluation noted that this can occur only under particular circumstances. The HSIV's, if open, vill always close upon loss of both power busses, and upon receipt of an MSIV isolation signal. Furthermore, if an isolation signal is present, the valves vill NOT reopen upon loss of power to either power bus.

Vhen there is no isolation signal present and either the outboard or inboard valves have opened on loss of the A or B bus, the valves vould immediately close upon restoration of power to the bus or upon receipt of an isolation signal. It is only when no isolation signal is present, and power has been lost to only one RPS bus, that the inboard or the outboard MSIV's vill open.

In order to maintain the number of unnecessary valve cycles at a minimum, however, administrative controls were placed into effect to prevent future opening of MSIV's during planned RPS bus deenergizations, and to identify that this was an expected occurrence following unplanned bus losses. The operating instruction for the Reactor Protection System was revised to prevent HSIV opening during a planned RPS bus deenergization or transfer. Also, the 1 instruction utilized to restore plant systems following receipt of an isolation signal was revised to prevent opening of the HSIV's if plant conditions require them to remain closed. The instruction which identifies the automatic actions that occur following a loss of an RPS bus was revised, to identify that this is an expected occurrence if no isolation signals are present when a single bus is lost. Finally, the 18-month surveillance instructions that require bus deenergitation vere revised to prevent HSIV opening upon the bus loss. These administrative controls vill remain in place until completion of the design change described belov vhich vill obviate the need for them. This design change vill be implemented during the first refueling outage.

i

Attachmsnt 1 PY-CEI/NRR-0888 L Page 2 of 2 Summary of Hodification Each MSIV has a MSIV position svitch (8 total). For simplicity the following discussion vill apply only to one of the inboard HSIV's. The other HSIV logics are identical to the logic discussed. In the existing logic, the position of the HSIV position switch (SlA) determines whether two relays are energized or deenergized (see Drawing 1). When the position switch is in the "Closed" position the K74B relay is energized. When the position svitch is in the "Tast" position the K74D relay is energized. This circuit is povered from the "B" RPS bus which means that the K74B and D relays vill both deenergize on loss of RPS bus "B" no matter what position the HSIV position switch is in. Both relays are also deenergized if the HSIV position svitch is in the "Auto" position.

The K74D relay is used in only one application, to slow close test the H51V.

Vith the K74D relay energized (i.e. MSIV position svitch in test), the HSIV test pilot solenoid vill be energized whenever the test push button (S3A) is pushed. Energizing the test pilot solenoid causes the HSIV to slovly close.

The K74B relay is used in four (4) circuits. Two of the relay contacts are used in the B and C MSIV Automatic Isolation Logics to allov the isolation logic to be reset following an isolation signal as long as the four associated HSIV's are shut (i.e. MSIV position switch in test or auto position).

The other two K74B relay contacts being used go into the logic for energizing the A and B pilot solenoids for the "A" mainsteam line inboard MSIV. Vhenever the K74B relay is deenergized (i.e. HSIV position svitch in test or auto position, or RPS bus B loss), these relay contacts are closed permitting the pilot solenoids to be energized. When one or both of the two pilot solenoids associated with an MSIV is energized the HSIV vill open/ stay open. The two pilot solenoids receive power from different RPS busses. This prevents a loss of one RPS bus from causing an MSIV isolation. This arrangement is also what caused the HSIV reopening event discussed in CEI's February 12, 1988 letter.

The loss of the "B" RPS bus with the HSIV position svitch in the closed position caused the K74B relay to deenergize, thereby closing the HSIV pilot solenoid logic contacts. Since one of the two logics was still being povered by an energized RPS bus, this resulted in energization of the associated pilot solenoid and the opening of the respective HSIV.

The proposed modification (Draving 2) vill delete the K74B and K74D relays completely, and instead insert contacts directly off of the HSIV position svitch into the 5 logics affected (1 from K74D and 4 from K74B). Since the HSIV position switch is not affected by loss of electrical pover, it's contacts vill not change state, and the cause of the reopening event vill be eliminated.

It is CEI's understanding from discussions with GE that the modification of inserting the contacts directly off the HSIV position svitch into the isolation logic and pilot solenoid logic is consistent with the other operating BVR-6 plants.

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