ML18100A847

LER 93-014-00:on 931228,ESF Actuation & Resultant & Pressurizer Overpressure Protection Sys Channel 1 Actuation Occurred.Caused by Defective Procedure.Slave Relay Surveillance Procedures revised.W/940128 Ltr

ML18100A847
Person / Time
Site:	Salem
Issue date:	01/27/1994
From:	Pastva M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-014-01, LER-93-14-1, NUDOCS 9402030067
Download: ML18100A847 (6)

Text

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• Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station January 27, 1994 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 LICENSEE EVENT REPORT 93-014-00 This Licensee Event Report is being submitted pursuant to the requirements of Code of Federal Regulation 10CFR50.73(a) (2) (iv).

Issuance of this report is required within thirty (30) days of event discovery.

Sincerely yours,

// ~{f,~~

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1' ndra General Manager -

Salem Operations MJPJ:pc Distribution 3100~9 9402030067 940127 r PDR ADOCK 05000311 i' S PDR f*

The power is in )Our hands.

95-2189 REV 7-92

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION 16-891 - APPROVED OMB NO. 3150-0104

- EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LERI COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH IP-530). U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20555. AND TO THE PAPERWORK REDUCTION PROJECT 13150-0104). OFFICE OF MANAGEMENT AND BUDGET. WASHINGTON. DC 20503.

FACILITY NAME 11) DOCKET NUMBER 12) I PAGE (3)

Salem Generating Station - Unit 2 TITLE C~I I o 15 Io Io Io 13 I l 1l I , loF 01 S ESF Actuation & Resultant Pressurizer Overpressure.Protection System Channel I Actuation.

EVENT DATE ISi LER NUMBER 161 REPORT DATE 17) OTHER FACILITIES INVOLVED (81 MONTH DAY YEAR YEAR  :}% SE~~~~~~AL tt ~~~~~ MONTH DAY YEAR FACILITY NAMES DOCKET NUMBERISI OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE R~OUIREMENTS OF 10 CFR §:(Chock an* or ma,. of th* fallawlnfl/ (11) l-~~~~~-L---1--1 POWER L~~~L l

MODE (9) 5 20.402lbl 20.4051all1llil 20.405lcl 60.3Slcll11 I-X 60.73(all2llM 60.731all21M -

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50.73111 (2llviil)(AI 60.73111121 lvlilllBI 366AI 50.73(1l12lliiil 60.731all211xl LICENSEE CONTACT FOR THIS LER 1121 NAME TELEPHONE NUMBER AREA CODE M. J. Pastva, Jr. - LER Coordinator 6 10 I 9 3 13 f 9 1- 1 SI 1 16 I S COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (131 MANUFAC* MANUFAC*

CAUSE SYSTEM COMPONENT TUR ER TUR ER I I I I I I I I I I I I I I I I I I I I I I I I.I I I I SUPPLEMENTAL REPORT EXPECTED 1141 MONTH DAY YEAR EXPECTED n YES (If Y*S. complot* EXPECTED SUBMISSION DATE/ hci NO ABSTRACT (Umir ro 1400 spaces. i.~.. 11ppr0Kimac111v fifrtum sing/e.space rypewritrtJn lintJs} (161 SUBMISSION DATE 1151 I I I On 12/28/93, at 0850 hours0.00984 days <br />0.236 hours <br />0.00141 weeks <br />3.23425e-4 months <br />, Reactor Coolant System (RCS) 22 Accumulator .

outlet valve 22SJ54 unexpectedly opened and injected an estimated volume of 1735 to 2640 gallons (2200 ppm boric acid) into-the RCS. The resultant RCS pressure transient'actuated Pressurizer Overpr~ssure Protection System (POPS) Channel I, causing Pressurizer Reli~f Valve 2PR1 to open at 375 psig. Highest indicated RCS pressure was approximately 372 psig. RCS pressure decreased to approximately 280 psig prior to being rec*overed by the Pressurizer heaters. This event occurred when test switch TS-603 was operated, per procedure S2.0P-ST.SSP-0010(Q),

Solid State Protection System .(SSPS) Train B Slave Relays Testing. Plant equipment responded properly to this event and TS-603 was reset to allow reclosure of 22SJ54. The root cause of this event is Defective Procedure, per NUREG-1022. S2.0P-ST.SSP-0010(Q) did not indicate that operation of TS-603 would result in opening of 22SJ54. Proc"edures have been revised to identify test switches which affect SJ54 valves and require that the appropriate SJ54 breaker be cleared and tagged.

Integrated Operating Procedure IOP-6 (Hot Standby to Cold Shutdown) has been revised (both Units) to tag all SJ54 valve breakers when RCS pressure is less than or equal to 1000 psig. A detailed technical review of all SSPS slave relay testing procedures will be performed. Procedural inadequacy identified with IOP-6 and S2.0P-ST.SSP-0010(Q) and the procedure identified in LER 311/92-005-00, will be examined to determine if any generic implications exist.

NRC Form 366 (6-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-014-00 2 of 5 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification system (EIIS) codes are identified in the text as {xx}

IDENTIFICATION OF OCCURRENCE: .,

Engineered Safety Featqres Actuation (22 Reactor Coolant System Accumulator Discharge) and Resultant Pressurizer Overpressure Protection System (POPS) Channel I Actuation Event Date: 12/28/93 Report Date: 1/27/94 This report was initiated by Incident Report No.93-529 CONDITIONS PRIOR TO OCCURRENCE:

Mode 5, due to forced outage - Reactor Coolant system (RCS) Pressure approximately 320 psig - RCS Temperature between 170-l80°F Solid State Protection System (SSPS) Train B Slave Relays Testing in progress in accordance with procedure S2.0P-ST.SSP-0010(Q).

DESCRIPTION OF OCCURRENCE:

On December 28, 1993, at 0850 hours0.00984 days <br />0.236 hours <br />0.00141 weeks <br />3.23425e-4 months <br />, Reactor Coolant System {AB} 22 Accumulator outlet valve 22SJ54 unexpectedly opened and injected an estimated volume of 1735 to 2640 gallons (2200 ppm boric acid) into the RCS. The resultant RCS pressure transient actuated POPS Channel I, causing Pressurizer Relief Valve 2PR1 to open at 375 psig. Highest indicated RCS pressure was approximately 372 psig. RCS pressure decreased to approximately 280 psig prior to being recovered by the Pressurizer heaters. This event occurred when test switch TS-603 was operated, per S2.0P-ST.SSP-0010(Q). Plant equipment responded properly to this event and TS-603 was reset to allow reclosure of 22SJ54. The NRC was notified of this event pursuant to 10 CFR5 0

• 7 2 ( b) ( 2 ) ( ii)

• ANALYSIS OF OCCURRENCE:

Availability of RCS accumulators ensures a sufficient volume of borated water will be immediately forced into the reactor core through each reactor cold leg in the event RCS pressure decreases below the pressure of the accumulators. This initial surge water into the reactor core provides the initial cooling mechanism during postulatedlarge RCS pipe ruptures. RCS accumulators are required Operable during Modes 1, 2, and 3 when the RCS pressure is greater

Salem Generating Station DOCKET NUMBER LICENSEE EVENT REPORT (LER) TEXT CONTINUATION LER NUMBER PAGE Unit 2 5000311 93-014-00 3 of 5 ANALYSIS OF OCCURRENCE: (cont_' d) than 1000 psig. An operable RCS accumulator requires its discharge valve be opened and its associated power lockout switch be in the "LOCKED OUT" position. When RCS pressure is less than 1000 psig operating procedures require the RCS discharge valves be closed.

This prevents an accumulator from injecting its contents during normal RCS depressurization and cooldown.

Operability of the twq POPSs or an RCS vent opening ensures protection of the RCS f~om pressure* transients which could exceed the limits of Appendix G to 10CFR Part 50 when one or more the RCS cold legs are less than or equal to 312°F. Either POPS has adequate relieving capability to protect the RCS from overpressurization when the transient is limited to either 1) the start of an idle Reactor Coolant Pump with the secondary water temperature to the steam generator less than or equal to 50°F above the RCS cold leg temperatures, or 2) the start of a safety injection pump and its injection into a water solid RCS.

While performing SSPS Train B Slave Relays Testing, RCS 22 Accumulator outlet valve 22SJ54 unexpectedly opened and injected an estimated volume in the range of 1735 to 2640 gallons (2200 ppm boric acid) into the RCS. The resultant RCS pressure transient actuated POPS Channel I, causing Pressurizer Relief Valve 2PR1 to open at 375 psig. 2PR1 open indications included overhead annunciation and Pressurizer Relief Tank (PRT) pressure and temperature indication.

In addition, indications of decreasing accumulator level and pressure were received. Highest indicated RCS pressure was approximately 372 psig, as recorded by PT-403 (RCS 11 hot leg pressure transmitter).

Accumulator pressure decreased to approximately RCS pressure which terminated the injection. RCS pressure decreased to approximately 280 psig prior to being recovered by the Pressurizer heaters. This event occurred when test switch TS-603 was operated, as specified by the involved test procedure, S2.0P-ST.SSP-0010(Q). Plant equipment responded properly to this event and TS-603 was reset to reclose 22SJ54. .

APPARENT CAUSE OF OCCURRENCE:

The root cause of this event is Defective Procedure, per NUREG-1022.

S2.0P-ST.SSP-0010(Q) did not indicate that operation of TS-603 would result in opening of 22SJ54.

During January 1993, the Procedures Upgrade Program (PUP) completed the technical review of slave relay test procedures, which included S2.0P-ST.SSP-0010(Q). However, this review did not identify that SSPS Train "B" Test switch (TS603) would send an open signal to 22SJ54 when placed in the "operate output" position. As a result, the surveillance test procedure omitted relevant information. This procedural inadequacy had not been identified during prior performances of the procedure since the procedure is normally

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-014-00 4 of 5 APPARENT CAUSE OF OCCURRENCE: {cont'd) performed at RCS pressures above 1000 psig. At RCS pressures above 1000 psig, the accumulator is required to be operable with its discharge valve open. Therefore, the test signal would be applied to an already open valve. Performance of this procedure is required once per 62 days and is applicable in Modes 1-4. This event occurred while performing the procedure in Mode 5 with RCS pressure less than 1000 psig. At the time of this event, the procedure was being performed to allow entry. into Mode 4.

A contributor to this procedural inadequacy resulting in an ESF actuation (during prior Mode 5 performance of the procedure) was a procedural change to Integrated Operating Procedure IOP-6 (Hot Standby to Cold Shutdown) made in November 1991. This change was initiated due to Technical Specification (TS) Amendments 130 and 109, for Units 1 and 2, respectively, which appropriately removed the TS requirement to clear and tag the SJ54 valve breakers when greater than 1000 psig. However, the procedure change also removed a requirement to administratively clear and tag the breaker when less than 1000 psig, which subsequent review following this event showed to be inappropriate.

PREVIOUS SIMILAR OCCURRENCES:

LER 311/92-005-00 reported a prior occurrence, caused by procedure inadequacy involving SSPS Procedure S2.0P-ST.SSP-OOOl(Q), Manual Safety Injection, and the concurrent replacement of Rosemount steam flow transmitters. Corrective action to this event consisted of revising the procedure to identify the consequence of moving the Mode Select Switch to TEST as well as the review and appropriate revision of other station procedures involving use of this switch.

SAFETY SIGNIFICANCE:

This event did not affect the health and safety of the public.. It is reportable as an Engineered Safety Features Actuation pursuant to 10CFR50.73(a) (2) (iv). In addition, this event is reportable in accordance with Technical Specification (TS) Action Statement 3.4.10.3.c. and pursuant to the requirements of TS 6.9.2.

Two concerns associated with this event were the possibilities of nitrogen injection into the RCS and pressurized thermal shock (PTS):

Nitrogen was not injected into the RCS. A fully charged accumulator will discharge nitrogen into the RCS if pressurizer pressure is less than 162 psig. Since pressurizer pressure was 320 psig, a minimum of 3785 gallons boric acid volume and all nitrogen remained inside the accumulator.

The reactor was not subjected to PTS. The increase in

e

• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-014-00 5 of 5 SAFETY SIGNIFICANCE: (cont'd) pressurizer pressure was maintained at a small value (55 psid) due to relief valve 2PR1 opening and the pressurizer operable with a steam bubble. If the pressurizer had been solid, the relief valve(s) would have passed water instead of steam and a much larger increase in pressure would have occurred. Also, the reactor was exposed to the water surge for a short time period and in such a manner that the reactor vessel wall temperature change was insign*ificant.

Following this event, Engineering performed calculations to determine the potential consequences of a single accumulator and of all four accumulators discharging into the RCS with a .solid pressurizer.

Results from these calculations show that under worst case conditions (solid pressurizer) operation would not have occurred outside of acceptable temperature/pressure relationships as defined by TS. Due to the recognized significance of this concern, corrective action involving the SJ54 valves, as described below, has been taken to mitigate this concern.

CORRECTIVE ACTION:

SSPS slave relay surveillance procedures have been revised to identify test switches which affect SJ54 valves and require that the appropriate SJ54 breaker be cleared and tagged.

1(2)-IOP-6 has been revised to tag all SJ54 valve breakers when RCS pressure is less than or equal to 1000 psig.

Engineering performed calculations to determine the impact of a single Accumulator and of all four Accumulators discharging into the RCS during a solid plant condition.

A detailed technical review of all SSPS slave relay testing procedures will be performed.

Procedural inadequacy identified with IOP-6 and S2.0P-ST.SSP-0010(Q) and the procedure identified in LER 311/92-005-00, will be examined to determine if any generic implications~~

neral Manager -

Salem Operations MJPJ:pc SORC Mtg.94-008