ML17328A326

LER 90-004-00:on 900611,reactor Tripped from Power Range, Neutron Flux,High Negative Rate Signal.Probably Caused by Drop of Two or More Control Rods.Preventive Maint Program for Rod Control Sys Will Be enhanced.W/900711 Ltr

ML17328A326
Person / Time
Site:	Cook
Issue date:	07/11/1990
From:	Blind A, Carteaux P AMERICAN ELECTRIC POWER CO., INC., INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-004-01, LER-90-4-1, NUDOCS 9007200197
Download: ML17328A326 (8)

Text

ACCELERATED DI~OBUTION DEMONST]TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9007200197 DOC.DATE: 90/07/11 NOTARIZED: NO DOCKET FACIL:50-316 Donald C. Cook Nuclear Power Plant, Unit 2, Indiana & 05000316 AUTH. NAME AUTHOR AFFILIATION 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 AFFILIATION LER 90-004-00:on 900611,reactor protection sys actuation caused by power range & neutron flux.

W/9 ltr.

NOTES'UBJECT:

DISTRIBUTION CODE. IE22T COPIES RECEIVED..LTR I ENCL TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

2 SIZE:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD3-1 LA 1 1 .PD3-1 PD 1 1 GIITTER,J. 1 1 INTERNAL: ACNW 2 2 AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DS P 2 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB9H3 1 1 NRR/DLPQ/LHFB11 1 1 NRR/DLPQ/LPEB10 1 1 v,~NRR/DOEA/OEAB11

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v N /-DST/I= B8Dl NRR/DST/SRXB" 8E EG~j 02 1 RES/DSIR/EIB 1 1 GN3 FILE 01 1 1 EXTERNAL: EG&G BRYCE,J.H 3 3 L ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHY,G.A 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HEI.P US TO REDUCE iVASTE! CONTACT THE DOCUMENT CONTROL DF5K, ROOiiI Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUb'IENTS YOU DON'T NEEDi FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 32 ENCL 32

Indiana Michigan Power Company Cook Nuclear Plant P.O. Box 458 Bridgman, Ml 49106 616 465 5901 lNDlAHA NlCHIGAN POMfFR July 11, 1990 United States Nuclear Regulatory Commission Document Control Desk Rockville, Maryland 20852 Operating Licenses DPR-75 Docket No. 50-316 Document Control Manager:

In accordance with the criteria established by 10 CFR 50.73 entitled Licensee Event Re ortin S stem, the following report is being submitted:

90-004-00 lg I'>> %L 9 -,I ~,

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'Sincerely,' ~ .','a ~, ., ~g,s 'p i Blind lant Manager AAB:clj Attachment cc: D.H. Williams, Jr.

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A.B. Davis, Region M.P. Alexich III P.A. Barrett J.E. Borggren R.F. Kroeger B. Walters Ft. Wayne NRC Resident Inspector J.G. Giitter, NRC J.G. Keppler M.R. Padgett, G. Charnoff, Esq.

Dottie Sherman, ANI Library D. Hahn INPO S.J. Brewer/B.P. Lauzau PDP 9007200k cpj '$007 4QOCK 0 0003 i

'p( 1 I

NRC FORM 366 V.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31504104 (64)9) E X PI A E S. 4/30/92 ESTIMATED BUADEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LERl COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (PE)30), V.S, NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PRD)ECT (31504)104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503i PA E 31 050003]6 DOCKET NUMBER l21 FACILITY NAME lll D.C. Cook'Nuclear Plant Unit 2 10F0

eactor Protection System Actuation Caused By A Power Range, Nuetron Flux, High Negative Rate Signal EVENT DATE (5) LER NUMBER I6) REPORT DATE (7) OTHER FACILITIES INVOLVED (SI SEQUENT)AI REVS~ MONTH DAY YEAR FACILITYNAMES DOCKET NUMBER(6)

MONTH OAY YEAR YEAR y~lcg NVMSER NUMB ~ R 0 5 0 0 0 0 5 0 0 0 0 0 4 THIS AEPORT IS SUBMITTED PURSUANT T 0 THE REQUIREMENTS OF 10 CFR ()t IC)rece one oi more ol the Io)tom'np/ (11 OPERATING MODE (9) 20.402(e) 20.405(cl X 50.73(el(2) liv) 73.71(el 20A05( ~ )ill)i) 50.36(cll'll S0.7 3( ~ ) 121(v) 73.71(cl POWER LEVEL OTHER ISpecily rn AO)trect (101 20.405 le ) llI (6 I 50.36(cl(21 50.73(el(2)(vi) I tN)ow end in Tent, NRC Form 20.40S( ~ l(11(iii) 50.73( ~ I (2) (I) 50.73(el(2) (viii)(AI 366A/

20A05(el(1) (4) 50.73( ~ l(2) Ie) 50.7 3( ~ ) (2) (v) ii ) (6) 20A05 le)Ill(vl 50.734) (21 (IB) 50.73( ~ )(2)lel r .3$AxrrFPF RCW/A ',Egc LICENSEE CONTACT FOR THIS LER (12)

TELEPHONE NUMBER NAME AREA CODE P.F. Carteaux Safet and Assessment Su erintendent 616 465 -5 901 COMPLETE ONE LINE FOR EACH COMPONENT fAILURE OESCRIBEO IN THIS REPORT (13)

MANVFAC. REPORTABLE MANUFAC EPORTABLE CAUSE SYSTEM COMPONENT CAUSE SYSTEM COMPONENT TURER TO NPRDS TURER TO NPADS n %he X" SN*' LS M*'0 4 0

'" N"'%PL.Q5@'~4'9 i X A"':ARvno IL Ivl r 1 "2 0 e e < t .'I ~ 'Cnrn t/r nIu ,I~, 4 reiver I/rr X J B TF 180 Y X A A H S MONTH DAY YEAR SUPPL'EMENTAL REPORT EXPECTED lie) EXPECTED SU HAMI SS ION DATE (15)

YE'S Illyn, complete EXPECTED SUBSIISSION DATE/ NO ASSTAACT ILimit to 1400 )peen, I e., operon)merely /i/teen rinp)e )pere typewritten linn/ Ilel On June ll, 1990 at 1417 hours0.0164 days <br />0.394 hours <br />0.00234 weeks <br />5.391685e-4 months <br />, the Unit power range, neutron flux, high negative 2 reactor tripped from a rate signal. This signal requires a 2 out of 4 (2/4) logic to initiate a trip.

Although the cause of the trip is not conclusively known, believed that a drop of more than one (1) control rod caused the it is reactor to trip. At the time of the reactor trip, a technician was walking on top of the rod control system power cabinets. It could not be determined whether the presence of the technician contributed to the postulated rod control system failure. No hardware failure that would have resulted in the dropping of control rods was identified. Prior to Unit restart, all control rods were successfully exercised.

Following the reactor trip, no malfunctions of safety-related systems or components occurred. In addition, all safety equipment responded as designed. The NRC was notified via the Emergency Notification System (ENS) at approximately 1537 hours0.0178 days <br />0.427 hours <br />0.00254 weeks <br />5.848285e-4 months <br /> on June 11, 1990.

NRC Form 366 (64)91

NRC FORM 366A US. NUCLEAR REGULATORY COMMISSION APPROVEO 0MB NO.31500(04 (689)

E XP IR E 6; 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILERI INFORMATION COLLECTION REQUEST: 50A) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P4I30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500(04). OFFICE OF MANAGEMENTANO BUDGET. WASHINGTON, OC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEQUENTIAL (.~g 4EVISION Y EAR h~@ NUMSE4 'UMSE4 D. C. Cook Nuclear Plant Uni.t 2 0 5 0 0 0 3 ] 9 0 004 0 0 02 0" 0:>

TEXT ///rrroro 4/Nre /4 ror)rr(rod, Ir(o oddrdorrol HRC Form 3664'4/ ((2)

Conditions Prior to Occurrence Unit 2 reactor (EIIS/AB-RCT) in Mode 1 (Power Operation) at 86 percent rated thermal power.

On June (EIIS/JE) ll, 1990 at actuation 1417 hours, a reactor protection system (reactor trip) occurred due to a power range (EIIS/IG-CH), neutron flux, high negative rate signal. This signal requires a time-compensated 2/4 logic to initiate a reactor trip.

During the day of the reactor trip, at 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br />, Maintenance personnel had initiated surveillance testing of ionization and infrared detectors (EIIS/IC-DET). At the time of the reactor 'r-

'1".trip; 'a technician was on- top-of-.cont ol" rod.(EIIS/AA-ROD) ~ -~

while..working'.'on overhead,'.fir'e,c.etectors; ~power';,.:4:.;..cabinets.{EIIS/AA-.CAB).

Although the technician was aware of his proximity to sensitive equipment, and no bumping of any components was reported, his possible contribution to a spurious rod control system failure cannot be discounted.

Following the reactor trip sequence [opening of the reactor trip breakers (EIIS/JE-BKR), turbine (EIIS/TA-TRB) trip, insertion of reactor control rods, feedwater isolation (EIIS/JB), and automatic starting of the motor-driven auxiliary feedwater pumps (EIIS/BA-P)], Operations Department personnel immediately performed Emergency Operating Procedures (EOPs) to verify proper response of the automatic protection system and to assess plant conditions for indicated appropriate recovery actions. Minor failures of components were reported following the trip. These included: North heater drain pump (EIIS/SN-P) failed to trip, rod bottom light (EIIS/AA-IL) for control rod C-7 failed, and steam generator (EIIS/SB-SG) No. 21 Channel 3 low level bistable (EIIS/JB-LT) failed.

Cause of the Event Although the cause of the trip is not conclusively known, believed that a drop of two (2) or more control rods caused the it is reactor to trip on a high negative rate signal. Other possible causes considered included the simultaneous failure of two (2) power range channels, and a reactor protection system logic failure. The coincidental failure of two power range channels is considered highly unlikely. Subsequent testing showed no nuclear NRC Form 366A (64)9)

NRC FORM 366A e U.S, NUCLEAR REGULATORY COMMISSION APPROVED OMB NO,31504)104 (689)

EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUESTI 504) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP4)30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31504H04). OFFICE OF MANAGEMENTAND BUDGETI WASHINGTON. DC 20503.

FACILITY NAME (I I DOCKET NUMBER LT) LER NUMBER (6) PAGE (3)

SEQUENTIAL REVISION NVMSSR NVMSSR D.C. Cook Nuclear Plant Unit 2 0 s 0 0 0 316 90 004 0 0 0 3 oF 0 5 TEXT /I/more 4/Neo /4 required, oeo oddioooorrr/IC form 3664'4/ (17) instrumentation abnormalities. Similarly, post trip testing of the reactor protection system (RPS) logic failed to identify a cause for the reactor trip. Historically, RPS logic failures have resulted in a significant delay when opposite RPS train response times are compared. In this case, both trains of reactor protection processed the negative rate signal simultaneously. This RPS response is indicative of an actual negative rate condition.

Following the trip, phase B of the stationary gripper power supply (EIIS/AA-JX) to control rod power cabinet 2AC was found with a high resistance across its disconnect switch (EIIS/AA-HS).

However, the failure of one phase of the stationary gripper power supply alone is not sufficient to cause a control rod to drop.

At least two phase failures are needed. Recommendations for rod

"", -control system:.preventi've.maintenance" had not'"previously /I "V 8 identified a-need-'for plower. supply "disconnect"and as'sociated inspections. The lack of preventive maintenance may have '"uswork increased the component's sensitivity to external forces. This, coupled with the presence of the technician on top of the power cabinets, may have resulted in a momentary failure and subsequent multiple rod drop event.

A~nal sis of Event This event is being reported in accordance with 10 CFR 50.73 (2) (iv) as an event that resulted in an unplanned automatic (a) actuation of the engineered safety features, including the reactor protection system.

The automatic protection responses, including reactor trip and its associated actuations, were verified to have functioned properly as a result of the reactor trip signal. Based on the above, it is concluded that. the event did not constitute an unreviewed safety question as defined in 10 CFR 50.59 (a) (2),

nor did it adversely impact the health and safety of the public.

Corrective Action All rod control power cabinet disconnect switches and fuses (EIIS/AA-FU) were inspected. Phase B of the power supply to control rod power cabinet 2AC was found with a high resistance across its disconnect switch. The questionable disconnect box was removed from its bus duct (EIIS/AA-BDUC), inspected, NRC ForIR 366A (64)9)

NAC FORM)SEA US. NUCLEAR AEGULATORY COMMISSION e APPROVED OM 8 NO. 31500'I 04 I609)

EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST: 600 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND AEPOATS MANAGEMENT BRANCH IP4)30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PAO/ECT (31504104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (11 DOCKET NUMBER (2I LER NUMBER (8) PAGE (3)

/4(A SEQUENTIAL 31'< 4EvrsK>N YEAR NUMSE4 A NUMEE4 D.C. Cook Nuclear Plant Unit 2 o s o o o 31 690 004 00 04 OF 0 5 TExT /// moro 4/>>oo /4 roorrirorL Pro odchriorro/ N/I c Form 36643! I IT) disconnect switches exercised, and proper operation verified.

Fuses were also replaced as a precaution. All other power cabinet disconnect boxes were also inspected; however, no abnormalities were discovered.

The buswork that transfers power from the reactor trip breakers to the power cabinet disconnect switches was inspected for proper tightness at each of the junctions. Each joint was found clean and tight.

Each control rod power cabinet was inspected for blown fuses, loose fuse clips, and wire tightness. No problems were found in any of the cabinets.

Control Rod Drive Mechanism (CRDM) (EIIS/AA-DRIV) resistance '

checks were'erformed on, rods,'in the.,2AC power cabinet. "The

.resistances were found-'wi'th'in a'cceptable limits".

After extensive checks of the rod control system (EIIS/AA) failed to uncover evidence of failure, all control rods were exercised in and out using a special procedure. All control rods performed normally during the performance of the special procedure.

Although the presence of the technician on top of the power cabinets could not be confirmed as a contributor to the reactor trip, the policy to utilize tools, equipment, and components only for their intended function was reinforced to affected personnel.

The preventive maintenance for the rod control system will be enhanced to include program periodic inspection of power supply buswork, disconnects and fuse clips.

Repairs to the North heater drain pump, rod bottom light for control rod C-7, and steam generator No. 21 - Channel 3 low level bistable were completed prior to Unit restart on June 14, 1990.

Plant I.D. No: 2-HLS-403 (Condensate heater shell side extreme low level switch)

Manufacturer: Magnetrol International Inc.

Model No: 249-C-MP EIIS Code: EIIS/SN-LS NRC Form 366A (669)

NRC FORM 366A V.S. NUCLEAR REGULATORY COMMISSION APPROVED 0 M 6 NO. 31500104 (669) ~

EXPIRES l 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LERI INFORMATION COLLECTION REOUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT 131500104). OFFICE'F MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1I DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEQUE NTIAL 4'49 REVISION NUMSE R ER r NUMSER D.C. Cook Nuclear Plant Unit-2 o s o o o 31 6 9 0 0 4 OF 0 5 TEXT P! mort (po(O /4 r(quit(r/ u(O odCh5orho/NRC Form 3%43/(12)

Plant I.D. No: 2-BLP-112 (Steam generator reactor protection input narrow range level transmitter)

Manufacturer: Foxboro Co.

Model No: N-E13DM-HIM2-BL EIIS Code: EIS/JB-LT Plant

Description:

Control Rod C-7 Bottom Light Bistable Manufacturer: Westinghouse Model No: HD2E-E2784 EIIS Code: EIIS/AA-IL I h hI, ~,h 'I R, ~,r h ur E~ ~ h r

r Plant- De"'cr'iption: "Powe'r) Supply to Cont ol-"Rod Power

~ F ~

r Cabinet 2AC Disconnect Switch Manufacturer: Westinghouse Model No: 44E3058 EIIS Code: EIIS/AA-HS Previous Similar Events None.

N R C Form 366A (6I)9)