ML18004B885

LER 87-038-00:on 870622,high Steam Generator Water Level Turbine Trip & Main Feedwater Isolation Actuated Automatic Reactor Trip on Interlock.Caused by Sudden Increase in Electrical Load.Precautionary Measures taken.W/870722 Ltr

ML18004B885
Person / Time
Site:	Harris
Issue date:	07/22/1987
From:	Howe A, Watson R CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
HO-870470-(O), LER-87-038, LER-87-38, NUDOCS 8707270238
Download: ML18004B885 (7)

Text

ACCESSION NBR: 8707270238 DOC. DATE: 87/07/22 NQTARIZED: NQ DOCKET FACIL: 50-400 Shearon Harris Nuclear Pomer Planti Unit ii Carolina 05000400 AUTH. NAME AUTHOR AFFILIATION HOWEi A. Carolina Pomer 5 Light Co.

WATSON. R. A. Ca. olina Pomer 5 Light Co.

RECIP. NAME RECIPIENT AFFILIATION

SUBJECT:

LER 87-038-00: on 870622 reactor trip on turbine tT ip during sgnchroni zation. Cause could not be pT eciselg determined.

Precautionarg measures taken to reduce effects of future similar transient 4 plant returned to svc. W/870722 ltr.

DISTRIBUTION CODF: IE22D COPIES RECEIVED: LTR 1 ENCL g SIZE:

TITLE: 50. 73 Licensee Event Report (LER>i Incident Rpti etc.

NOTES: Application for permit renewal filed. 05000400 RECIPIENT COP IES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-1 L* 1 1 PD2-1 PD 1 1 BUCKLEYi B 1 1 INTERNAL: ACRS MICHELSON 1 1' ACRS MOELLER 2 '

2 AEOD/DQA AEOD/DSP/NAS 1 AEOD/DSP/RQAB 2 2 AEOD/DSP/TPAB 1 1 DEDRO 1 NRR/DEST/ADE 1 0 NRR/DEST/*DS 1 0 NRR/DEST/CEB 1 1 NRR/DEST/ELB 1 1 NRR/DEBT/I CSB 1 1 NRR/DEST/MEB 1 NRR/DEBT/MTB 1 1 NRR/DEBT/PSB 1 NRR/DEBT/RSB 1 1 NRR/DEBT/SC-'B 1 1 NRR/DLPG/HFB 1 1 NRR/DLPG/GAB 1 NRR/DOEA/E*B 1 1 NRR/DREP/R*B 1 NRR/DREP/RPB 2 2 AS/ILRB 1 1 NRR/PMAS/PTSB 1 1 REG FIL 02 1 1 RES DEP Y G I 1 1 1ELFORDi J 1 RES/DE/EIB 1 RGN2 FILE 01 1 1 E X TER NAL: EGGG GROHi Mi H ST LOBBY WARD LPDR 1 1 NRC PDR NSIC HARRYSi J 1 NSIC MAYSi G TOTAL NUMBER OF CQP IES REGUIRED: LTTR 45 ENCL 43

NRC Fosm 355 I) ~ UA. NUCLEAR AEOULATOAYCOMMISSION (943)

APPROVED OMB NO. 31500)BC LICENSEE EVENT REPORT (LER) EXPIRES: 5/31/SS FACILITY NAME (I) DOCKET NUMBER (2) PA E 3 Shearon Harris, Unit 1 0 5 0 0 0 1 OF TITLE (Cl Reactor Trip on Turbine Trip During Syn'chronization.

EVENT DATE IS) LER NUMBER (6) REPOAT DATE (7) OTHER FACILITIES INVOLVED (SI MONTH DAY YEAR YEAR cpc% SFOUENTIAL REVISION MONTH DAY YEAR FACILITYNAMES DOCKET NUMBER(SI NUMBER NUMBER 0 5 0 0 0 0 6 28 787 0 3 0 0 22 87 0 5 0 0 0 OPERATINO THIS REPORT IS SUBMITTED PURSUANT TO THE REOUIREMENTS OF 10 CFR (): (Check one or more of the folios((npl (11)

MODE (0) 20AOS(c) 50.734)(2)(iv) 73.71(B)

POWER 10AOS(e)(1) (I) SOM(c) (1) 50.734)(2)4)(vill) 73.71(c)

LEVEL 20.405( ~ )(I)IS) SOM(c) (2) 50.734)(2)(rB) OTHER (Specify In Abstrect

@gky(3I'0A02(B)

(10) 20AOS(e l(1) (III) 50.73(e) (2((l) 50.734)(2)(rill)(A)

(N/ow end In Tent HRC Form SSSAI 20AOS(e I (1 I (lv) 50.73(el(2) (5) 50.73 (es2) (B) 20.405 (~I (I I (vl 50.73(eH2) (III) 50,73(e) (1)(e)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE Andrew Howe, En ineer Regulator Com liance 91 936 2- 271 9 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

'ceyy vr CAUSE SYSTEM COMPONENT MANUFAC TUAEA EPOATABLE TO NPROS R4 CAUSE SYSTEM COMPONENT MANUFAC.

TURER EPORTABL TO NPRDS

%MS SUPPLEMENTAL REPORT EXPECTED (IC) MONTH DAY YEAR EXPECTED SUBMISSION DATE (15 I YES (lf yet, Cemplete EXPECTED SUBMISSION DA TEI NO ABSTRACT (Limit to le00 speces, I e., epproelmetely fifteen slnplecpece typewritten linesl (IS)

On June 22, 1987, at 0307, with the plant at 6X thermal power level, the turbine generator was synchronized to the power grid during a plant startup.

The turbine control system picked up excessive electrical load immediately upon tie in to the grid. The resulting transient caused a high steam generator water level turbine trip and main feedwater isolation, and the turbine trip actuated an automatic reactor trip on interlock.

The plant response to the reactor trip was as expected. Auxiliary Feedwater started automatically when the main feedwater pumps tripped on the high steam generator water level. The plant was stabilized in Mode 3.

The cause of the sudden increase in electrical load could not be precisely determined. Specific precautionary measures were taken to reduce the effects of any future similar transient, and the plant was returned to service without repeat of this event.

7Q7Q70238 87~OOyoo PDR ADOCK OSOOO4DORO S

NRC Fotsn 355 (903)

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NRC Forth 3EBA U.S. NUCLEAR REOUI.ATORY COMMISSION

((M)3)

LI SEE EVENT REPORT (LER) TEXT CONTINUATION APPROVED OMB NO. 3(60-0104 EXPIRES: B/31/BB FACILITYNAME (ll DOCKET NUMBER (1) LER NUMBER (B) PAGE (3) yEAR ~ EEOUENTIAL )I(PI REVISION NUMSER Yrr: NUMSER Shearon Harris Unit 1 o s o o o 40 87 , 038 00 02 oF 0 3 TEXT ///mors E/toes /E /tt/tstd, Itos ~ //Otto/HRC Frtrm 3EKAB/ ((7)

DESCRIPTION:

On June 22, 1987, the plant was being started up following a reactor trip the previous day (Refer to LER-87-037-00). At 0307, the reactor was in Mode 1 at 6X thermal power level, and the turbine-generator was ready for synchronization onto the grid. One of the two parallel generator output breakers was then closed.

Upon closure of either generator, output breaker, the turbine control system (hereafter referred to as the DEHCS for Digital"Electrohydraulic Control System) is programmed to automatically load to a minimum value, approximately 50MWe. However, at least 200 MWe was assumed by the generator upon synchronization, as determined by the recorders.

The sudden load increase and excessive steam demand caused steam generator water level to increase. The swell in steam generator "C" level reached the hi-hi setpoint of 82.4X narrow range level, which automatically actuates a turbine trip and main feedwater isolation, and trips the main feedwater pumps. The load on the turbine prior to trip was sufficient to pick up protective interlock P-7; this is the "at-power" interlock which inputs to the Reactor Protection System that the plant is at or above 10X power level (thermal or turbine power). With interlock P-7 actuated, the turbine trip also caused the reactor to automatically trip. Auxiliary Feedwater automatically started when the main feedwater pumps tripped.

The plant response to the reactor trip was as expected. The reactor was stabilized in hot standby Mode 3, with heat removal via steam dump and auxiliary feedwater flow.

CAUSE:

An investigation of the DEHCS did not reveal a particular problem which would explain the sudden load increase. Prior to this event, a number of modifications and adjustments had been made to the DEHCS to improve the efficiency of the turbine. The vendor representative evaluated these changes and concluded that they did not cause the transient. He noted that similar events had occurred at other plants and were somewhat sporadic in nature in that a specific cause could not be determined It was determined to make certain adjustments to the DEHCS settings and to the steam admission valves limiting control settings to reduce the impact of any future similar transient. Specifically, an adjustment was made to the turbine speed input to increase the deadband constant, and a.valve limit circuit was used during restart= which limits the valve travel to a selected value.

r/Rc FCRM SEEA *U.S.OPO:I OB/HHQ4 BSB/4BB r .

(BEL3)

'RC Form

'983) 3$ 8A US. NUCLEAR REOULATORY COMMISSION Cr LI SEE EVENT REPORT (LER) TEXT CONTINUATION APPROVED OMB NO. 3150-0104 EXPIRES: 8/31/88 NIj FACILITY NAME I'l DOCKET NUMBER (2) LER NUMBER (8) PAGE (3)

YEAR SEQUENTIAL REVSION NUMBER NUM ER Shearon Harris, Unit 1 o s o o o 40 087 0 3 0 0 3 oF 0 TEXT ///moro E/>>co/F //r/rorL I>>o o(E/or>>/KRC Form 3854'E/ ((7)

ANALYSIS:

This event is reportable as an actuation of the Reactor Protection System and the Engineered Safeguards Features Actuation System, as per 10CFR50.73(a)(2)(iv).

There were no safety consequences as a result of this event. The plant was operated within the bounds of the Technical Specifications and the FSAR.

Following the reactor trip, the plant was stable in Mode 3.

CORRECTIVE ACTION:

The adjustments to the DEHCS were implemented prior to reactor startup. The plant was synchronized onto the grid without further problems of this nature.

Evaluation of the DEHCS is ongoing.

NRC FORM SSEA *U.B.GPO:(98(L0424.538/455 (9'B3)

~ ~ e o 0 ~

C~E Carolina Power & Light Company I

HARRIS NUCLEAR PROJECT P.O. Box 165 New Hill, NC 27562 JUL 2 2 1987 File Number.'HF/10-13510C Letter Number: HO-870470 (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 87-038-00 Gentlemen:

In 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:lmj Enclosure cc.'Dr. J. Nelson Grace (NRC RII)

Mr. B. Buckley (NRR)

Mr. G. Maxwell (NRC SHNPP)