ML17329A340

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LER 91-010-00:on 911115,reactor Tripped as Result of lo-lo Steam Generator Water Level in Steam Generator 21.Caused by Defective Instrument Isolation Valve.Valve Bonnet Replaced & Cam Disc Repositioned on Valves a & D.W/911216 Ltr
ML17329A340
Person / Time
Site: Cook American Electric Power icon.png
Issue date: 12/16/1991
From: Blind A, Carteaux P
INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-010-01, LER-91-10-1, NUDOCS 9112260303
Download: ML17329A340 (8)


Text

ACCELERATED DI UTION DEMONSTR TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9112260303 DOC.DATE: 91/12/16 NOTARIZED: NO DOCKET FACIL:50-316 Donald C. Cook Nuclear Power Plant, Unit 2, Indiana M 05000316 AUTH. NAME AUTHOR AFFILIATXON CARTEAUX,P.F. Indiana Michigan Power Co. (formerly Indiana & Michigan Ele BLIND,A.A. Indiana Michigan Power Co. (formerly Indiana & Michigan Ele RECIP.NAME RECIPIENT AFFILXATION

SUBJECT:

LER 91-010-00:on 911115,reactor tripped as result of lo-lo steam generator water level in steam generator 21.Caused defective instrument isolation valve. Valve bonnet replacedby & D cam disc repositioned on valves A & D.W/911216 ltr.

S DISTRIBUTION CODE: IE22T COPXES RECEIVED:LTR ) ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER),7Xncident Rpt, etc.

NOTES RECIPIENT COPIES RECIPIENT COPIES D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD3-1 LA 1 1 PD3-1 PD 1 1 COLBURN,T. D 1 1 INTERNAL: ACNW 2 2 AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB8H3 1 1 RR~ST/SPLB8Dl 1 1 NRR/DST/SRXB 8E 1 1 RE~ 02 1 1 RES/DSIR/EIB 1 1 RCH3 F E 01 1 1 EXTERNAL EG&G BRYCE i J ~ H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHYiG A 1 1 NSXC POORE,W. 1 1 NUDOCS FULL TXT 1 1 D

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NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISIS FOR DOCUMENTS YOU DON'T NEEDI FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPXES REQUIRED: LTTR 31 ENCL 31

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indiana Michigan Power Company Cook Nuclear Plant One Cook Place Bridgrnan, Ml 49106 616 465 5901 IIiIQIAItIA NICH!6iAN POWfR December 16, 1991 United States Nuclear Regulatory Commission Document Control Desk Rockville, Maryland 20852 Operating Licenses DPR-74 Docket No. 50-316 Document Control Manager:

In accordance with the criteria established by 10 CFR 50.59 entitled Licensee Event Re ort S stem the following report is being submitted:

91-010-00 Sincerely, A. A. Blind Plant Manager AAB:sb Attachment C~ D. H. Williams, Jr.

A. B. Davis, Region E. E. Fitzpatrick III P. A. Barrett.

B. F. Henderson R. F. Kroeger B. Walters - Ft. Wayne NRC Resident Inspector T. Colburn - NRC J. G. Keppler M. R. Padgett G. Charnoff, Esq.

D. Hahn INPO S. Z. Brewer/B. P. Lauzau B. A.,Svensson

~q 1.2~>,0303 91iiii~ fj,$/)~ l g

PDl~ ADOCK 050003i&

8 PDR

N4C FORM 368 (64)9) APPROVED OMB NO. 3150OI04 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION 4EOUESTI 50.0 HRS. FORWA4D LICENSEE EVENT REPORT (LERI COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGFMENT BRANCH (F830), U.S. NUCLtAR REGULATORY COMMISSION. WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT 131500104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC20503.

FACILITY NAME (I) DOCKET NUMBER (2) PA E 3 Donald C. Cook Nuclear Plant Unit 2 0 5 0 0 0'316 >OFO 3 Reactor Protection System Actuation Due to Low-Low Steam Generator Level When Steam Pressure Increased from Main Turbine Control Valve Closure EVENT DATE (SI LF 4 NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED ISI MONTH DAY YEAR YEAR SEQUENTIAL %ri'EVIQOM MONTH DAY FACILITY NAMES DOCKET NUMBERISI NUMStR NS NUMSER YEAR 0 5 0 0 0 11 15 9 1 9 1 0 10 00 1 21 691 0 5 0 0 0 THIS REPORT IS SUBMITTED PURSUANT T0 THE RtOUIREMENTS OF 10 CFR (i: (Check one or mori of thr followlnp) (11)

OPERATING MODE (9) 20A02(tl 10A05(c) 50,73(el(2) (iv) 73.71(tl POWE 4 20A05( ~ l(1)(B 5036(<<)(I) 50,73(e l(2)(v) 73.'71(c)

LEVEL 1 p p 10A05( ~ I (1)(EI 50.36(c)(2) 50,73(el(2)(vSI OTHER iSprcirl in Ahrtrect hrlow rnd in Fret. HRC Form 20AOS(e) III(iii) 50.73(el(2)(i) 60.73(e) (2) (vr 6) (Al 36b'A) 20A05(e I (1)(Iv) 50.73(e) (2)(il) 50,73(e) (2) (vIE)(B) gj m'...,@g'k 20.405(el(1) (vl 50.73(e)(2) (Iii) 50.73( ~ )(21(el LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER

'x Safety and Assessment AREA CODE P. F. Carteaux Superintendent 6 164 65- 59 01 COhIPLETE ONE LINE FOR tACH COMPONENT FAILU4E DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMI'ONENT MANUFAC. EPORTABLE: MANUFAC EPO4TABL .'

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TG I SV HO 37 SUPPLEMENTAL REPORT EXPECTED (14) MONTH OAY YEAR EXPECTED SUBMISSION DATE (16 I YES iifyrr, complete EXPECTED $ (f64rfSSIOhf fJA TEI NO ABSTRACT ftimit ro lr00 rpecer. fr., epproximrrrly fifrrrn rinclr.epee<< typrvrri rim lined (16)

On November 15, 1991 at 1113 hours0.0129 days <br />0.309 hours <br />0.00184 weeks <br />4.234965e-4 months <br />, the Unit 2 reactor tripped aa a result of a low-low Steam Generator water level in SG 821. Prior instrumentation was being installed on the main turbine tocontrol the reactor (SG) trip, circuit. The purpose of this instrument was to investigate oscillationsfluid control valve A which was scheduled to be tested later that evening. A of pressure i.ndicator which measures the output of the turbine operating device was to be isolated and another tranami.tter was to be installed in parallel to it. However, unknown to personnel involved, worn threads on the stem of the manual isolation valve prevented the pressure indicator from bei.ng completely isolated. As a drain plug waa removed to vent pressure from the instrument isolation valve, pressure on the output of the operating device was also decreased. This effectively lowered the setpoint supplied to the speed governor, which compares actual turbine speed to the operating devi.ce setpoint, and fully closed the high pressure and low pressure turbine control valves. With the steam supply isolated, SG pressure rapidly increased and caused SG level to decrease below the reactor trip setpoint.

The root valve's bonnet was replaced and damaged stem threads were repaired.

During the outage, repairs were also completed to reduce the turbine load swings experienced during valve testing. A review of the work control process will be performed to identi.fy any enhancements that can be added to reduce the probability of an unplanned actuation occurri.ng from similar activities in the future. Any change indicated by the review will be implemented by March 30, 1992.

NRC Form 368 (889)

NRC FORM 366A (6$ 9I t

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION UA. NUCLEAR REGULATORY COMMISSION APPROVED 0MB NO. 31504104 EXPIRES: 4/30/92 ESTI ATED BURDEN PER RESPONSE TO COMPI.Y WTH THIS INFORMATION COLLECTION REOUEST: 50/I HRS. FOAWARD COMMENTS REGARDING BUADEN ESTIMATE TO THE AECORDS AND REPORTS MANAGEMENT BRANCH (P4(301, U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWOAK REDUCTION PROJECT (315041(04I. OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON,OC 20503.

FACII.ITY NAME (1I DOCKET NUMBER (2I LER NUMBER (6I PAGE (31 YEAR Y SEOUENl'IAL REVISION Donald C. Cook Nuclear Plant Unit 2 NUMBER NUMBER 0 5 0 0 0 3 g 6 9 0 1 0 0 0 0 2 " 0 3 TEXT ///mare epeee /4 mr/rr/red, rree eddr'dane///RC Famr 36649/ (171 Conditions Prior to Occurrence Unit 2 in Mode 1 at 100 percent of Rated Thermal Power (RTP).

Descri tion of Event On November 15, 1991 at 1113 hours0.0129 days <br />0.309 hours <br />0.00184 weeks <br />4.234965e-4 months <br />, the Unit 2 reactor (EZZS/JE) tripped as a result of a low-low steam generator water level in SG g21. Prior to the reactor trip, instrumentation was being installed on the main turbine control fluid circuit (EZZS/TA-PC). The purpose of these instruments was to investigate oscillations of control valve A which waa scheduled to be tested later that evening. A pressure indicator (LPZ-15) which measures the output of the turbine operating device was to be isolated and another transmitter was to be installed in parallel to LPZ-15. However, unknown to personnel involved, worn threads on the stem of the manual instrument isolation valve (EXXS/TG-ISV) prevented LPI-15 from being completely isolated. As a drain plug was being removed to vent pressure from the instrument isolation valve of LPZ-15, pressure on the output of the operating device was also decreased.

This effectively lowered, the setpoint supplied to the speed governor, which compares actual turbine speed to the operating device setpoint, and fully closed the high pressure and low pressure turbine control valves.

With the steam supply isolated, SG pressure rapidly increased and caused SG level to rapidly decrease below the reactor trip setpoint. The reactor trip signal was generated approximately 5 seconds after the high pressure control valves were closed.

Following the reactor trip/turbine trip sequence, opening of the reactor trip breakers (EZZS/JE-BKR), insertion of reactor control rods (EIIS/AA-ROD)<

feedwater isolation (EIIS/JB), and automatic starting of the motor<<driven and turbine-driven auxiliary feedwater pumps (EZZS/BA-P), Operations personnel immediately implemented Emergency Operating Procedure 2 OHP 4023.E-O to verify proper response of the Automatic Protection System and to assess plant conditions for appropriate recovery actions.

As seen on previous trips, 3 of 4 main steam isolation valves (EZIS/SB-ZSV) drifted off their open detente. MRV 230 drifted fully closed and MRV 210 and 220 drifted to intermediate positions. All valves were manually reopened.

The highest SG pressure recorded was 1010 psig. An investigation into the cause of this valve drifting problem is ongoing.

A spurious reactor coolant letdown isolation also occurred at the time of the trip. Occasional, spurious letdown isolations have been experienced over the past year and the cause haa not yet been determined. Operators returned letdown to service without incident. Although letdown iaolations have little safety significance, they do provide a distraction to the control Room operations and investigation into the root cause ia ongoing.

Cause of Event The cause of the event was a defective instrument isolation valve failing to provide isolation to a pressure indicator in the main turbine control fluid circuit. The loss of control fluid pressure resulted in closure of all turbine control valves which led to a rapid increase in steam pressure and a resulting decrease in steam generator water levels and the reactor trip.

NRC Farm 366A (64(9)

f NRC FOAM366A (SJIB) t LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION UA. NUCLEAR REGULATORY COMMISSION APP ROY EO OM 6 NO. 3(500(04 EXPIRES: I/30/92 ESTIMATED BURDEN PFA A'ESPONS'E TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50J) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20555, AND TO THE PAPERWOAK REDUCTION PROJECT (3)504(04). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME ()) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEQUENTIAL M REVISION

'Donald C. Cook Nuclear Plant - Unit 2 NUMBER ('?% NUMBER o s o o o 316 91 0 1 0 000 3 QF 0 3 TEXT N mo>> sooce Jt >>BId>>d, u>> oddidoool NRC FomI 366AS I ((7)

Anal sis of Event This report is being submitted in accordance with 10CFR50.73, paragraph (a)(2)(iv), as an event that resulted in an unplanned automatic actuation of the Engineered Safety Features, including the Reactor Protection System.

The automatic protection responses, including reactor trip and i.ts associ.ated actuations were verified to have functioned properly as a result of the reactor trip signal. The reactor coolant letdown isolation valves were reopened, and the Main Steam Isolation Valves which drifted shut were reopened within minutes of the trip. Based on the above, event did not constitute an unreviewed safety question as defined in it is concluded that the 10CFR50.59(a)(2) nor did public.

it adversely impact the health and safety of the Corrective Actions The instrument isolation valve for LPZ-15 was disassembled and i.nspected. The valve bonnet was replaced due to a loose handle on the stem, which may have damaged the threads. After burrs on the threads were removed, the valve stroked freely.

During the outage, the servo cam-disk for turbine control valves A and D was inspected by a vendor representative and found to be out of position. The cam-disk was repositioned on control valves A and D, which changed the opening characteristics of the valves, and decreased the amount of load swings .during control valve testing.

A review of the work control process will be performed to identify any enhancements that can be added to reduce the probability of an unplanned actuation occurring from similar activities in the future. Any change indicated by the review will be implemented by March 30, 1992.

Failed Cpm nent Iden if cation Component descriptions Mai.n Turbine Control Fluid Pressure Setpoint Indi.cator Transmitter Isolation Shutoff Valve Plant designation: 2-ZPZ-15-ZI Manufacturer: Dresser Industries, Inc., Hancock Valve Division Model: 8130W EZZS Code: TG ZSV Previous Similar Events None NRC F onn 366A (649)

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