ML18004B807

LER 87-024-00:on 870421,heater Drain Pumps a & B Tripped Due to Low Differential Pressure & Automatic Turbine Runback Initiated.Caused by Oscillating Feedwater Heater Levels.Pump Low Level Trip Setpoint lowered.W/870521 Ltr

ML18004B807
Person / Time
Site:	Harris
Issue date:	05/21/1987
From:	Schwabenbauer, Watson R CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
HO-870434-(O), LER-87-024, LER-87-24, NUDOCS 8705280172
Download: ML18004B807 (5)

Text

REG TORY INFORMA1 ION DISTRIBU N SYSTEM <R IDS>

I

. 'CCESS'ION NBR: 8705280172 DOC. DAl E: 87/05/2 1 NQTAR IZED: NO DOCKET

"~j FACIL: 50-400 Shearon Harris Nuclear Pouer Planti Unit ji Carolina 05000400 AUTH. NAME AUTHOR AFFILIATIQ;"3 SCHWABENBAUER Carolina Power 5 Li ght Co.

RECIP. NAME RECIPIENT AFFILIATI>N

SUBJECT:

LER 87-024-00: on 87042}i heater drain pumps A 8c 'B tripped due to lots differential pressu> e 0 automatic turbine runbact initiated. Caused bg oscillating feedeater heater levels.

Steam generator water levels restored. W/870521 ltr.

DISTRIBUTION CODE: IE22D COPIES RFCETVED:LTR g ENCL TITLE: 50. 73 Licensee Event Report (LFH)i Incident Rpti etc.

P SIZE:

NOTES:Application for permit renewal filed. 05000400 RECIpIENT COPIES RECIPIENT COP IES ID CODE/NAME LTTR Et~0 L ID CODE/N4ME LTTR E'NCL pD2-1 L* 1 1 PD2-1 PD 1 i BUCKLEYi B 1 1 fp INTERNAL: ACRS MICHELBON 1 ACPS MOELLER AEOD/DOA 1 1 AFOD/DSP/ROAB 2 AEOD/DSP/TPAB 1 1 DEuRO 1 NRR/DEBT/ADE 0 NrtR/DEBT/ADB } 0 NRR/DEBT/CEB 1 N<R/DEBT/ELB 1 NRR/DEBT/ ICSB 1 t~HR/DEBT/MEB 1 NRR/DEST/MTB 1 t~RP/DEBT/PSB 1 NRR/DEST/RSB 1 } N<R/DEBT/BGB 1 NRR/DLPG/HFB 1 VHR/DLPG/GAB 1 NRR/DOEA/EAB 1 NAP/DREP/RAB 1 NRR/DREP/RPB 2 P ILRB NRR/PMAS/PTBB 1 1 REC F 02 1 RES DEPY GI 1 FILE 01 1 EXTERNAL: EGS<G GROH> M 5 5 H ST LOBBY WARD 1 }

LPDR 1 1 tHC PDR 1 1 NSIC HARRIS> J 1 t!SIC MAYS 0 1 TOTAL NUMBER OF COPIES REQUIRED: LTIR 42 ENCL 40

NRC Form 358 U.S. NUCLEAR REOULATORY COMMISSION (94)3) APPROVED OMB NO, 31504104 EXPIRES: 8/31/88 LICENSEE EVENT REPORT ILER)

DOCKET NUMBER (2) PACE 3I FACILITY NAME (I)

SHEARON HARRIS PLANT TITLE lsl UNIT 1 050004001OF03 REACTOR TRIP LOSS OF HEATER DRAIN PUMP B EVENT DATE (5) LER NUMBER (8) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH YEAR YEAR Sgry. SEQUENTIAL .'re'EVISION MONTH DAY YEAR FACILITYNAMES DOCKET NUMBER(S)

DAY )rCig NVMSER:L'CN NUMBER 0 5 0 0 0 0 4 21 87 8 7 0 24 00 05 187 0 5 0 0 0 THIS REPORT IS SUBMITTED PURSUANT T0 THE REQUIREMENTS OF 10 CFR (): (Check onr or morr ol thr Iollovtlnpl (11 OPERATINO ill(ill MODE (8) 20.402(5) 20.405(c) 50.73(s)(2) liv) 73.7((II)

POWER 20,405(s) (I I II) 50M(c) (I) 50.73(s)(2)(v) 73.71(cl LEVEL OTHER ISprclly In Abstrect 20A05(s) 50.38(c) (2) 50.73(s) l2)(vS)

(10) 1 0 below end ln Trit, NRC Form 20.405(sl(1) liii) 50.73(s I (2) (Il 50,73(s) (2) (vli Il (A) 3$ $ A) 20AOSI ~ ) (1)(iv) 50.73( ~ )(2) lii) 50,73 I~ ) (2) (viii)(8 I kev< r.R n,%.. 's .sm'Ps 20A05(sl(1)(v) 50.73(sl(2) liiil 50.73(s) (2)(i)

LICENSEE CONTACT FOR THIS LER l12)

NAME TELEPHONE NUMBER AREA CODE RICHARD SCHWABENBAUER REGULATORY COMPLIANCE 9 19 362 -2 669 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

MANUFAC. EPORTABLE MANUFAC. EPORTABL CAUSE SYSTEM COMPONENT TO NPRDS CAUSE SYSTEM COMPONENT TVRER TVRER TO NPRDS rpp . 45 ......:...SF'~(

I 5)%~~

SUPPLEMENTAL REPORT EXPECTED l14) MONTH DAY YEAR EXPECTED SUBMISSION DATE (15)

YES III yrL completr EXPECTED SUBM/$$ /ON DATEI NO ABSTRACT (Limit to lc00 spscrs, I r., rpproiimrtrly lifteen sinple.spree typrwrittrn linsvl (18)

The plant was operating at approximately 100 percent reactor power and 882 MWe on April 21, 1987 in normal plant line-up, with the Main Feedwater Control Valves in manual control.

At, 0450 hours, 'B'eater Drain Pump tripped due to low differential pressure. The plant operator then started a manual turbine power reduction in order to stabilize plant power. 'A'eater Drain Pump then tripped R(. 0451 hours0.00522 days <br />0.125 hours <br />7.457011e-4 weeks <br />1.716055e-4 months <br />, also due to low differential pressure, which initiated an automatic turbine runback.

During the turbine runback, operators began to manually control feedwater flow, and the plant steam dump system activated due to the large load reduction. While turbine runback was still in progress, 'A'ain Feedwater Pump tripped at 0453 hours0.00524 days <br />0.126 hours <br />7.490079e-4 weeks <br />1.723665e-4 months <br /> due to low suction pressure and was immediately followed by 'B'ain Feedwater Pump tripping for the same reason. With both Main Feedwater Pumps tripped, 'A'nd 'B'ondensate Booster Pumps tripped due to high discharge pressure.

With both feedwater trains tripped and steam generator water levels decreasing, a manual reactor trip was initiated at 0453 hours0.00524 days <br />0.126 hours <br />7.490079e-4 weeks <br />1.723665e-4 months <br />. The plant, was then stabilized in Mode 3 at 557'F (normal no load Tavg) and normal operating pressure with steam generator water levels restored with the Auxiliary Feedwater System.

8705280172 870521 PDR *DOCK 05000400 8 PDR l:E NRC Form 388 (9.83)

NRC Form 388A U.S. NUCLEAR REGULATORY COMMISSION

($ 831 LIC SEE EVENT REPORT {LER) TEXT CON INUATION APPROVEO OMB NO. 3(9)&104 EXPIRES: 8/31/88 FACILITYNAME (1) OOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEQVENTIAL o20 RdvrsloN SHEARON HARRIS PLANT @R NVMSSR NUMBER UNIT 1 o so oo400 024 00 02 OF 0 3 TEXT /S/rrrvo <<>>co k ooqskorE I>>o ////Or>>/I ///(C Forrrr 35//A3/ (IT)

Prior to the event, the plant was operating at approximately 100 percent reactor power. The Main Feedwater Control Valves were in manual control.

Other feedwater system components were in their normal configuration.

At 0450 hours0.00521 days <br />0.125 hours <br />7.440476e-4 weeks <br />1.71225e-4 months <br />, a low pump differential pressure signal tripped the 'B'eater Drain Pump. The trip was caused by erratic and unstable Heater Drain Pump flow and Heater 4 level. Plant operators initiated a manual turbine runback. The operators initiated the runback in response to a partial loss of feed flow and in anticipation of increasing reactor power due to the loss of secondary plant efficiency. At 0451 hours0.00522 days <br />0.125 hours <br />7.457011e-4 weeks <br />1.716055e-4 months <br />, a low pump differential pressure signal tripped the 'A'eater Drain Pump. The loss of both Heater Drain Pumps automatically initiated a turbine runback.

During the turbine runback, operators began to manually control feedwater flow., The turbine runback caused the steam dump system to actuate due to a Tave-Tref mismatch.

As a result, the Main Feedwater Pumps went to run out and low suction pressure tripped both the 'A'nd 'B'ain Feedwater Pumps. The loss of the Main Feedwater Pumps caused the Condensate Booster'umps to go to near shutoff head which tripped both of the Condensate Booster Pumps on high discharge pressure. With both feedwater trains tripped and steam generator water levels decreasing, a manual plant trip was initiated at 0453 hours0.00524 days <br />0.126 hours <br />7.490079e-4 weeks <br />1.723665e-4 months <br />.

The plant was then stabilized in Mode 3 at 557'F (normal no load Tavg) and normal operating pressure. Auxiliary feedwater was actuated automatically on the loss of both Main Feedwater Pumps and was used to restore Steam Generator water levels.

Cause The trips of the Heater Drain Pumps were caused by oscillating Feedwater

• Heater levels and were the initiating event for a turbine runback. The low reactivity worth of Control Bank D and the turbine runback rate resulted in actuation of Condenser dump valves due to Tref-Tave deviation.

A review of archived data indicated erratic and unstable Heater Drain Pump flow and Feedwater Heater g4 level. Both 'A'nd 'B'rains had similar behavior, but the fluctuations in 'B'rain were more severe.

FSAR Figure 10.1.0-5 illustrates the flow paths leading to each Heater Drain Pump. In summary, the suction source for each Heater Drain Pump is the shell side of the respective 84 Feedwater Heater. The maj or flow paths to the (g(4 Feedwater Heater are extraction steam (7th stage), moisture separator drain tank drain, and drains from the shell side of the 85 Feedwater Heater. The major flow paths to the 05 Feedwater Heater are extraction steam (4th stage),

moisture separator reheater drain tank drain, and moisture separator reheater vent. The Heater Drain Pumps discharge to the suction of the respective Main Feedwater Pump.

NRC FORM SddA *U.S.GPO;(988 0.824 538/455 (94)3)

U.S. NUCLEAR REGULATORY COMMISSION N)IC Form 366A (94)3)

LIC >EE EVENT REPORT (LER) TEXT CO NUATION APPROVED OMB NO. 3160&)04 EXPIRES: 8/31/88 FACILITY NAME (ll COCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEQUENTIAL REVSION NVMBER NVM ER SHEARON HARRIS PLANT UNIT 1 o s o o o 4 0 0 7 0 2 4 0 0 0 3 OF 0 TEXT ////rroro Epooo ir /oqo<<m/, rrro /d/dO/M/HRC fe/m 38843/ uT)

Cause (continued)

The data indicates that the Feedwater Heater (I)4 level control system was the source of the problem.

The trip of the Heater Drain Pumps lead to a pressure transient at the Main Feed Pump Suction, a turbine runback, and manual action to adjust feedwater flow. The Condensate Booster Pump has a variable speed coupling which automatically controls the speed based on the pumps discharge pressure. The Condensate Booster Pump automatically compensates for the loss of a Heater Drain Pump, but in this event, the suction pressure of the Main Feedwater Pump was not maintained above the trip setpoint during the transient.

~Anal aia There were no safety consequences resulting from this event. The Reactor Protection System and Auxiliary Feedwater System responded as required.

Normal recovery followed the reactor trip.

This event is reportable under 10CFR50.73(a)(2)(iv) as an actuation of th' Engineered Safeguards Features and Reactor Protection Systems.

Corrective Actions As a result of a previous event associated with the Heater Drain Pumps (LER-87-019-00), the following corrective actions were implemented to improve their reliability: trips on high discharge pressure, delta pressure, and Moisture Separator Reheater pressure were deleted.

Due to this event, further evaluation into the reliability of the Heater Drain System was conducted with the following additional changes being implemented:

1) The low-level trip setpoint for the Heater Drain Pumps in the Number 4 Feedwater Heater was lowered 12 inches to provide a margin for trips on level oscillations;

2) The Main Feeder Pump low suction pressure trip. time delay has been increased from 5 seconds to 15 seconds to provide more time to stabilize after a loss of a Heater Drain pump transient.

NRC FORM 366A <<U.S.GPO.'1988 0.824 538/455 (983)

Carolina Power tt Light Company HARRIS NUCLEAR PROJECT P.O. Box 165 New Hill, NC 27562 MAV Zi 881 File Number'SHF/10-13510C Letter Number.'HO-870434 (0)

U.S. Nuclear Regulatory Commission ATTN: NRC Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT UNIT 1 DOCKET NO. 50-400 LICENSE NO. NPF-63 LICENSEE EVENT REPORT 87-024-00 Gentlemen.'n accordance with Title 10 to the Code of Federal Regulations, the enclosed Licensee Event Report is submitted. This report fulfills the requirement for a written report within thirty (30) days of a reportable occurrence and is in accordance with the format set forth in NUREG-1022, September, 1983.

Very truly yours, R. A. Watson Vice President Harris Nuclear Project RAW:sdg Enclosure cc'Dr. J. Nelson Grace (NRC RII)

Mr. B. Buckley (NRR)

Mr. G. Maxwell (NRC SHNPP)

MEM/HO-8704340/PAGE 1/OS1