ML18093A281

Special Rept 87-2:on 870709 & 10,two Overpressure Protection Sys (Pops) Actuations Occurred.Caused by Close Tolerance Between Pops Actuation Setpoint & RCS Pressure Required to Start Reactor Coolant Pump

ML18093A281
Person / Time
Site:	Salem
Issue date:	08/03/1987
From:	Zupko J Public Service Enterprise Group
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
87-2, NUDOCS 8708100384
Download: ML18093A281 (3)

Text

e PS~G Public Service Electric and Gas Company. P.O. Box E Hancocks Bridge, New Jersey 08038 Salem Generating Station August 3, 1987

u. s. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-75 DOCKET NO. 50-311 UNIT NO. 2 SPECIAL REPORT '87-2 This Special Report describes two (2) pressurizer overpressure protection system (POPS) actuations *occurring on July 9, 1987, and July 10, 1987. This report is being submitted pursuant to the requirements of Technical Specification Action Statement 3.4.10.3.c within 30 days.

Sincerely yours,

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J. M. q~p~o*:-<<.

General Manager-Salem Operations MJP:pc Distribution I'::~

8708100384 870803 PDR ADOCK 05000311 S PDR The Energy People 5" '

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- e SPECIAL REPORT NUMBER 87-2 PLANT IDENTIFICATION:

Salem Generating Station - Uriit 2 Public Service Electric & Gas Company Hancock's Bridge, New Jersey 08038 IDENTIFICATION OF OCCURRENCE:

Pressurizer Overpressure Protection System Channel I Actuation Event Date(s): 7/09/87 Report Date: 8/03/87 This report was initiated by Incident Report No.87-269 CONDITIONS PRIOR TO OCCURRENCE:

Mode 4 - Reactor Power Level 0% - Unit Load 0 MWe DESCRIPTION OF OCCURRENCE:

This Special Report describes two (2) Pressurizer Overpressure Protection System (POPS) actuations. The first actuation occurred on July 09, 1987 at 2342 hours0.0271 days <br />0.651 hours <br />0.00387 weeks <br />8.91131e-4 months <br /> and the second actuation on July 10, 1987 at 0231 hours0.00267 days <br />0.0642 hours <br />3.819444e-4 weeks <br />8.78955e-5 months <br />. This report is submitted for information in accordance with the requirements of Technical Specification Action Statement 3.4.10~3.c. which states:

In the event that either the POPS's or the RCS vents are used to mitigate an RCS pressure transient, a Special Report shall be prepared and submitted to the Commission pursuant to Specification 6.9.2 within thiity (30) days. The ~eport shall describe the circumstances initiating th~ transient, the effect of the POPS's or vents on the transient and any corrective action necessary to prevent recurrence.

On July 09, 1987, with the Unit in Mode 4 (Hot Shutdown), No. 23 Reactor Coolant Pump (RCP) was started in support of heatup operations. The Reactor Coolant System (RCS) pressure was 325 psig.

The start of the pump caused a sufficient pressure transient spike to actuate POPS Channel No. I. The highest indicated pressure was approximately 360 ~sig * . on July 10, 1987, during investigation of the setpoint setting, POPS Channel I again actuated.

APPARENT CAUSE OF OCCURRENCE:

The root cause of this event is the close tolerance between the POPS actuation setpoint and the RCS pressure required to start an RCP.

When an RCP is started it causes a pressure spike. This rise in pressure was sufficient to cause the first actuation of POPS Channel I. Initial Channel I POPS alarm and actuation setpoints revealed them to be low; 350 psig and 355 psig, respectively. Technical Specifications require the actuation setpoint to be below 375 psig.

With RCP operations requiring RCS pressure to be at a m1nimum value

SPECIAL REPORT 87-2 APPARENT CAUSE OF OCCURRENCE: (cont'd) of approximately 325 psig the pressure transient caused by the start of the No. 23 RCP was enough to increase the RCS pressure above the POPS actuation setpoint.

All equipment was found to be within calib~ation. The pressure transmitters were electronically indicating approximately 3 psig low, the comparator actuation setpoint was set at 369 psig, the Control Room bezel indication was approximately 5 psig low, and the P250 computer indication was 12 psig low.

ANALYSIS OF OCCURRENCE:

The RCP operations were performed in accor~ance with the respective procedures. The maximum indicated pressure was approximately 355 psig. Valve 2PR1 remained open for approximately 20 seconds following the first actuation and 10. seconds following 'the second actuation. Had the valve failed to close either time, the operator would have responded by closing blocking valve 2PR6. All systems and indications functioned as designed. There was no undue risk to the health or safety of the public due to this event. In accordance with Technical Specification Action Statement 3.4.10.3.c, because the POPS was actuated to mitigate a RCS pressure transient, this Special Report is being submitted pursuant to the requirements of Technical Specification 6.9.2.

CORRECTIVE ACTION:

Because the allowable instrument and channel tolerances can reduce the margin between the minimum required pressure for RCP operation and POPS channel setpoints (the indicated error), the pressure transient resulting from starting a RCP may cause actuation of either or both POPS channels. A review of the Operations procedures involved shows that sufficient operator guidance is given. No procedure modifications are required. The NSSS Supplier will be contacted regarding these events soliciting recommendations to preclude recurrence. Additionally, a review of different types of pressure transmitters will be conducted to determine the availability of more accurate sensing devices to preclude recurrence.

• This event will be reviewed by the Nuclear Training Department for applicability in the licensed operator training progr~ms.

Ge£t=~

Salem Operations MJP:pc SORC Mtgg 87-055