ML18096A962

LER 92-019-00:on 920805,main Steam Line Isolation Occurred Due to Design,Manufacturing,Construction/Installation Inadequacy.Design Mod in Progress to Correct Main Streamline Flow Sensing line.W/920903 Ltr

ML18096A962
Person / Time
Site:	Salem
Issue date:	09/03/1992
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-019, LER-92-19, NUDOCS 9209090395
Download: ML18096A962 (5)

Text

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• Public Serv!ce Electric and Gas Company P.O. Box 236 Hancock$ Bridge, New Jersey 08038 Salem Generating Station September 3, 1992 U. s. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

pear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-70 DOCKET NO. 50-272 UNIT NO. 1 LICENSEE EVENT REPORT 92-019-00 This Licensee Event Report is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR 50.73(a) (2) (iv). This report is required to be issued within thirty (30) days of event discovery.

Sincerely yours,

c. A Vondra*

General Manag.er -

Salem Operations MJP:pc -

Distribution 080133 The Energy People 5 920903 920909 039CK 05000272 95-2189 (10M) 12-89 PDR .ADO PDR

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (6-89) 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 PAG 1:1)

Salem Generating station - Unit 1 Trl"LE 14)

!01s101010121112 1loFOJ4 ESF Signal Acuuatmon: Main Steamline Isolation Due To Design EVENT DATE 15) LEA NUMBER 16) REPORT DATE 171 OTHER FACILITIES INVOLVED Ill)

MONTH DAY YEAR YEAR tr: SE~~~~~~AL }) ~~~~~~ MONTH DAY YEAR FACILITY NAMES DOCKET NUMBERISI 010019013 912 THIS REPORT IS SUBMITTED PURSUANT TO THE R~QUIREMENTS OF 10 CFR §: (Ch*ck on* or moro of th* following) 111 I OPERATING x

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LICENSEE CONTACT FOR THIS LEA (12)

NAME TELEPHONE NUMBER AREA CODE M. J. Pollack - LER Coordinator 6 1° I 9 31 3 I 9 1- I 2 I 0 I I 2 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (131 MANUFAC* MANUFAC*

CAUSE SYSTEM COMPONENT TUR ER TUR ER B BIA 615 I I WP2 19 I 0 y 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 VEAR EXPECTED l YES (If yos, comp/et* EXPECTED SUBMISSION DATE) lxl ABSTRACT (Umit to 1400 spactJs, i.e., tJpproximatBly fifteen sing/e.spactJ typewritten lines) 116)

NO SUBMISSION DATE {151 I I I On August 5, 1992, at 2129 hours0.0246 days <br />0.591 hours <br />0.00352 weeks <br />8.100845e-4 months <br />, a main steamline isolation (MSI) occurred on low T (< 543°F) coincident with a high steamline flow signal. MSI is a~vEngineered Safety Feature (ESF). At the time, the* 13 Auxiliary Feedwater Pump was being started .to support post maintenance testing. Upon starting the pump, speed control was erratic (oscillating by as much as 1000 rpm) which led to the pump tripping on mechanical overspeed. Since Reactor Coolant System (RCS) T was 535°F, at the time of the event, the respective bistables were trippea providing half the logic required for MSI. The high steamline flow logic requires high flow indication in one (1) of two (2) channels per Steam Generator (S/G) in two (2) of four (4) S/Gs. The MSI occurred when the 11 and 13 Steam Generator's (S/Gs) steamline flow channel bistables tripped. The root cause of this event is "Design, Manufacturing, Construction/Installation" inadequacy. The No. 13 Auxiliary Feedwater Pump is a turbine driven pump with the turbine supplied steam by the 11 and 13 S/Gs. Due to the design of the steam flow instrumentation, at 535°F steam generator pressure has caused flashing in the steamline flow reference legs during start of the 13 Auxiliary Feedwater Pump. In this event, the start and subsequent erratic speed control of the* 13 Auxiliary Feedwater Pump resulted in channel spikes in the 11 and 13 S/G channels satisfying the logic for MSI. The false signals cleared, on their own. Design modifications are being developed to correct main steamline flow sensing line concerns.

The 13 Auxiliary Feedwater Pump Woodward governor has been replaced.

NRC Form 366 (6-891

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 so*oo212 92-019-00 2 of 4 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 Feature signal actuation: Main Steamline Isolation due to qesign Event Date: 8/5/92 Report Date: 9/3/92 This report was initiated by Incident Report No. 9.2-491.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 3 (Hot Standby)

DESCRIPTION OF OCCURRENCE:

On August 5, 1992, at 2129 hours0.0246 days <br />0.591 hours <br />0.00352 weeks <br />8.100845e-4 months <br />, a main steamline isolation (MSI) occurred on low T (< 543°F) coincident with a high steamline flow signal. At the tlfu~; the 13 Auxiliary Feedwater Pump was being started to support post maintenance testing. Upon starting the pump, speed control was erratic (oscillating by as much as 1000 rpm) which led to the pump tripping on mechanical overspeed.

Since Reactor Coolant System (RCS) {AB} T was 535°F, at the time of the event, the respective bistables were l}lpped providing half the logic required for MSI. The high steamline flow logic requires high flow indication in one (1) of two (2) channels per Steam Generator (S/G) in two (2).of four (4) S/Gs. The MSI occurred when the li and 13 Steam Generator's (S/Gs) steamline flow channel bistables tripped.

MSI is an Engineered Safety Feature (ESF). Therefore, on August 5, 1992, at 2221 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.450905e-4 months <br />, this event was reported to the Nuclear Regulatory Commission (NRC) in accordance with Code of Federal Regulations 10CFR 50.72(b) (2) (ii).

APPARENT CAUSE OF OCCURRENCE:

The root cause of this event is "Design, Manufacturing, Construction/

Installation" inadequacy.

The No. 13 Auxiliary Feedwater Pump is a turbine driven pump with the turbine supplied steam by the 11 and 13 S/Gs. Due to the design of the steam flow instrumentation, at 535°F steam generator pressure

LICENSEE EVEN'!' REPORT (LER) TEXT CONTINUATION Salem Generating station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-019-00 3 of 4 APPARENT CAUSE OF OCCURRENCE: (cont'd) has caused flashing in the steamline flow reference legs during start of the 13 Auxiliary Feedwater Pump. In this event, the start and subsequent erratic speed control of the 13 Auxiliary Feedwater Pump resulted in channel spikes in the 11 and 13 S/G channels satisfying the logic for MSI.* Salem Units 1 and 2 have experienced similar MSI actuations in the past (e.g., reference LERs 272/92-017-00 and

• 311/92-008-01) * : The false signals cleared,* on their own. Design modifications are being developed to correct main steamline flow sensing line concerns.

The Salem design arrangement for main steamline flow differential pressure measurement includes two (2) taps (to provide redundancy) on the high and low pressure side of the main steamline venturi.

Attached to the taps are 1" manual globe valves. Steam is directed through 1 11 pipe to condensate pots located near the high pressure tap. Condensate is then directed *to a Rosemount differential pressure transmitter.

ANALYSIS OF OCCURRENCE:

MSI protection is applicable in Mode 1 (Power Operation), Mode 2 (Startup), and Mode 3 (Hot Standby). It is provided to mitigate the consequences of various design base accidents including main steamline rupture and a S/G primary to secondary tµbe rupture.

The Auxiliary Feedwater System consists of two (2) motor driven auxiliary feedwater (MDAFW) pumps, one ("1) steam driven auxiliary feedwater pump and associated valves and piping. It is required to be operable in Modes 1, 2, and 3. The system is designed to cooldown the RCS to less than 350°F from normal operating conditions in the event of a total loss of off-site power~ At less than 350°F,. the* *.

Residual Heat Removal (RHR) System would be used to remove excess RCS heat.

At the time of this event, the MDAFW pumps were operable and supplying feedwater to the S/Gs. As identified previously, the steam driven auxiliary f eedwater pump was being tested following maintenance activities.

All valves which close on an MSI signal.were already closed. Since the actuation did not result from an actual plant need for MSI, this event did not affect the health or safety Of the public. However, since Main Steam Isolation is an ESF system, this event is.reportable to the Nuclear Regulatory Commission in accordance with Code of Federal Regulations 10CFR50.73{a) (2) (iv).

The erratic operation of the steam driven Auxiliary Feedwater Pump was investigated. The cause of the erratic operation was attributed to entrained air in the governor's oil system (Woodward is the manufacturer). The air was bled out and the pump was successfully

LICENS.EE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-019-00 4 of 4 ANALYSIS OF OCCURRENCE: {cont'd) tested and returned to service. Since returning it to service, pump erratic operation occurred twice (without a subsequent MSI). After the first recurrence, entrained air in the governor's oil system was again bled out. After the second recurrence, the governor was replaced. It was sent to the distribution/service representative for testing. Investigation revealed that this governor (installed circa 1990) had been rebuilt to incorrect specifications. A 10 lb buffer spring had been used instead of a 26 lb buffer spring causing the .

observed erratic operation. According to the service company, the manufacturer had provided an outdated component specification list~

The service representative has checked his records and has determined this event to be an isolated occurrence. The other rebuilt turbine driven auxiliary feedwater pump governors, supplied to PSE&G, have been validated (through records) to contain the correct buffer spring.

CORRECTIVE ACTION:

As identified in Salem Unit 1 LER 272/92-017-00, an in-depth study was completed of main steamline flow instrumentation. Engineering is developing design modifications to correct the main steamline flow sensing line concerns.

As discussed in the Analysis of Occurrence section, the 13 Auxiliary Feedwater Pump Woodward governor has been replaced.

PSE&G_will conduct an investigation of other safety related governors rebuilt for PSE&G to look for similar problems as experienced with I

the 13 Auxiliary Feedwater Pump's governor. .j 1

~~

General Manager -

Salem Operations MJP:pc SORC Mtg.92-097