ML20024F745

LER 90-017-00:on 901104,discovered That Train a of Class IE 120-volt Distribution Panel DP001 Energized from Alternate Power Supply.Caused by Less than Adequate Administrative Controls.Log Will Be utilized.W/901212 Ltr

ML20024F745
Person / Time
Site:	South Texas
Issue date:	12/12/1990
From:	Ayala C, Mcburnett M HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-017-01, LER-90-17-1, ST-HL-AE-3645, NUDOCS 9012170176
Download: ML20024F745 (6)

Text

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4 The Light company P.O. Box 1700 llouston, "Icxas 77001 (713) 228,9211 llouston 1.ighting & Power .

December 12, 1990 ST-ilL- AE- 364 5 File No.: C26 10CFR50.73 U. S. Nuclear Regulatory Commission Attentio..: Document Control Desk Washington, DC 20555 South Texas Project Electric Generating Station Unit 2 Docket No. STN 50-499 Licensee Event Report 90 017 Regarding Class 1E 120 Volt AC Distribution Panel Energized by Alternate Power Source in y_Lplation of Technical Snecification Pursuant to 10CFR50.73, llouston Lighting 'n Power Company (H14P) submits the attached Licensee Event Report (LER 90 017) regarding a Class 1E 120 volt AC distribution panci energized by alternate power source during coro alterations in violation of Technical Specifications. This event did not have any adverse impert on thn health and safety of the public.

On December 3, 1V10, an extension of the due date of this letter to December 14, 1990 was requested of, and granted by, Mr. Art flowell of NRC Region IV.

If you should have any questions on ".h!.s matter,1 lease contact

.Mr. C. A. Ayala at (512) 972 8628 or myself ac (512) 972 8530.

h 8/

M. A. McBurnett Manager, Nuclear Licensing RAD /sgs

Attachment:

LER 90-017 (South Texas, Unit 2) 90121701'/6 901212 PDR ADOCK 05000499 S PDR A1/LER017U2.L01 A Subsidiary of Ilouston Industries incorporated 7gQQ

$ r*r t._' n. ~y , Ell

J ST HL-AE 3645 Ilouston Lightlag & Power Cornpan)

South Texas Project Electric Generat ng St.:on File No.: G26 pag, .2 cc:

Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission Associate General Counsel 611 Ryan Plaza Drive, Suite 1000 Houston Lighting & Power Company Arlington, TX 76011 P. O. Box 61867 Houston, TX 77208 George Dick, Project Manager U.S. Nuclear Regulatory Commission INPO Washington, DC 20555 Records Center 1100 Circle 75 Parkway J. I. Tapia Atlanta, CA 30339 3064 Senior Resident Inspector c/o U. S. Nuclear Regulatory Dr. Joseph M. Hendrie Commission 50 Be11 port Lane P. O. Box 910 Be11 port, NY 11713 Bay City. TX 77414 D. K. Lacker J. R. Newman, Esquire Bureau of Radiation Control Newman & Holtzinger, P.C. Texas Department of Health 1615 L Street, N.W. 1100 West 49th Street Washington, DC 20036 Austin, TX 78756 3189 R. P. Verret/D. E. Ward

-Central Power & Light Company P. 0. Box 2121 Corpus Christi, TX 78403 J. C. Lanier/M. B. Lee City of Austin Electric Utility Department

.P.O.' Box 1088 Aus tin,1DC 78767 R. J. Costello/M. T. Hardt City Public Service Board L Pc 0. Box 1771' San Antonio, TX 78296

(

t l Revised 10/08/v0 l

l U /NRC/

NitC FORM k6 U S. NUCLfAR REOULATORY COMMzS$lON APPROVED OMB NO. 3150 4104 EXPIRES: 0'30S2 ESTIMATED BURDEN PER RESF/ NM TO COMrLY WTH TH!S lNFORMATION COLLLCTION REO' JEST 50.0 HR0 FORWARD COMVENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REFORTS MANAGEMENT BRANCH LICENSEE EVENT REPORT (LER) (P-530). U.S. N'JCLE AR REGULATORY COMM;SSION. WASHINGTON. DC 20555.

AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104). OFFICE OF MANAGEMENT AND BUDGET WASHINGTON. DC 20503.

rACIUTY NAME (1) Brunswick Steam Electric Plant Unit 1 DOCKET NUMBE R (2) PAGE O) 05000325 010F 03 TITLE (4) Group 6 Isolation and SBGT Auto-Start Due to Scan Overload on the VRGM Microprocessor EVENT DATE ($) Lf R NUMBER (6) REFORT DATE (7) OTHER FACIUTIES INVDLVED (B)

MONTH DAY YEAR YEAR SEO NO. REV.NO. MONTH DAY YEAR FACluTY NAME DOCVIT NUMBER 11 17 90 90 -

020 -

00 l 12 13 90 BSEP Unit 2 05000324 THIS REPORT IS SUOMITTED PURSUANT TO THE REQUIREMENTS OF 10 Cr A t (Oneck or,e or more of the following) (11)

OIT RATING MODE (9) 5 20 c2m 20 e5<c) x Sa73n2)ov) 73.71 ct )

NWE R 20 40$(a)(110) 50.36(c )< 1) 50.73(a)(2iM 73.71(c)

LEVEL (10) 000 20 05m(1MM 50$cM2)

• TD(aK2MMO OTHER (Specify In Abstract and Ted) 1p , 9 .

20.405(a)(1100 50=73(a)(2X0 50.73(a)(2)(WMA) 3 , w.

20.405(a)(110v) 50.73(aM2)(ll) 50.73tsW2)(wwB) 1;W%Dn

' ' "3 G 20 405(aW1)M 50.73(aH2Who 50.73(aH2Hz) tjcENSEE CONTACT FOR THIS LER (12)

NAME TONY HARRIS, REGULATORY COMPLIANCE SPECIALIST TELCPHONE NUMBER (910) 457-2038 COMPLETE ONE UNE FOR EACH (VMFONENT FAILURE DESCRIBED IN THIS REPOPT (13)

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE A CAUSE SYSTEM COMPONENT MANUFACTURER REFORTABLE TO NPRDS TO NPROS B IL CPU S637 N SUPPLE MENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR SU6V!SSION YES (if yes, complete EXPECTED SUBMISSION DATE) X NO DATE (15)

ADSTRACT (Umit to 1400 spaces. Le. appronimately Afteen single space typewntten lines) (16)

Unit I was in a refuel outage with the reactor defueled. Unit 2 was operating at 100%

power. On 11/17/90, at 0718, a Group 6A and 6B Primary Containment Isolation System (PCIS) and Secondary Containment isolations were received, along with SBGT system auto-start. The event was the result of an isolation signal generated from the Wide Range Gas Monitor (WRGM) microprocessor, and was not a valid isolation on high radiation. No abnormal release was indicated prior to or following the isolation.

The event was due to a scan overload on the microprocessor. A technician performing a daily check of historical release data on the stack keyed in an incorrect information code on the microprocessor keypad. The caused a scan overload on the system, and caus9d relays in the microprocessor isolation logic to drop out, resulting in the Group 6 signal. The scan overload is a design problem with the microprocessor. The vendor has been contacted for replacement of this part of the system. Other WRGMs have in the Turbine Building have the same overload concern, but do not initiate isolation: however, replacement of these components is being evaluated. This event had minimal safety significance. Valves and systems in the isolation logic performed as designed.

~._ _ _ _ - . _ _ _ _ . . _ - . - . . . . - - . - - . . _ _ . _ _ ._ _ __m. - _ _ - _ _ ~ , _ _ _

'hAC F08C 366A U.5, NUCLEAR REoVLATORY COMMIS540N APPROWD oMB NO 31.A0104 '

EXPIRES: d/30/92 ESTIMA1TD BURDEN PER RE$9oNSE TO COMPLY wtTH THl$ INFORMATION LICENSEE EVENT REPORT (LER)- '$"uss" NEE $fURE'EIEs"EMAiE TO'HE RECORDS AND RE TEXT CONTINUATION -

Sa^Nc" 7530). u.s. NuCa4R nEoutAToRY CouwssioN.

u^N^ot", DC WASHINGTON 20555. AND TO THE PAPERWORK REDUCTION PROJE ,

(31540104) OFFICE OF MANAGEMENT ANO DVDGET, WASHINGTON.DC 20503 FACldTY NAME (1) - DOCKET LIR NUMBER (6) PAGE (3)

NUMBER (7)

Brunswick Steam Electric Plant Unit 1 3 05000325 YEAR HUMBER

• NUMBER 90 -

020 - 00 TEXT (tr MORE $ PACE t$ REQUIRED. USE A0olTIONAL NRC FORM 365A'S)(17)

EVENT Group)6 (WRGM _ isolation microprocessor.due to a scan overload on the Main Stack Wide Range Gas Monitor

-INITIAL CONpITIONS Unit 1 was in the refuel mode with no fuel in the vessel. Secondary containment was not in affect. Unit 2 was at 100% power.

-EVENT DESCRIPTION On 11/17/90, at approximately 0718,-a Group 6A and 6B Containment Atmospheric Control System and Secondary Containment Isolation from the Stack Radiation

' Monitor signal occurred on Unit 1 and Unit 2. The isolation resulted in closure of Group 6 valves on both Unit 1 and Unit 2 with exception of the 1 CAC-V5 (Torus Nitrogen Inlet) and 1-CAC-V6 (Drywell- Nitrogen Inlet) . valves. These valves-received a closed signal, but did not fully close due to the short duration of the isolation signal (approximately 450 milliseconds). The Unit 1 and Unit 2 Reactor Building ventilation dampers isolated and both Unit 2 Standby Gas Treatment (SBCT) system trains and Unit 1 "A" SBGT system train - started as required. .The Unit 1 "B" SBGT system train was out of- service for maintenance. ,

The Main Stack Radiation Monitor readings were verified prior to the event to be normal. Elfluent release rate calculations were performed and did not indicate

- an abnortal release. The Main Stack Radiation Monitor was declared inoperable, l and Technical Specification required sampling begun. Work Request / Job Order (WR/J0) 90-AUQD1 was initiated to investigate the reason for the isolation. L EVENT' INVESTIGATION / ROOT CAUSE i

~

Troubleshooting was begun on-tho' Main-Stack Radiation Monitor to determine the origin of the momentary high radiation signal. Environmental and Radiation Control (E&RC) technicians were taking daily readings at the Stack Monitor keypad (RM 23) in the back panels of the Control Room for 24-hour stack release rate at the time of: the event. This reading is not required by FSAR or' Technical- -

Specifications, but assists the count room in their release tracking. An-information code-for historical data is keyed into the RM-23 unit, which in turn

' extracts the data from the historical files in the'RM 80 microprocessor.

The information code used to call-up this program (201) was incorrectly keyed in (by the technician as 200. This- initiated closure: of the relays in the high radiation logic, due to a problem in the RM-80 microprocessor computer program.

The - momentary - (approximately 450 millisecond) relay reset generated by ' the - -

microprocessor initiated the Group 6 isolation-logic for both Unit 1 and Unit 2.

'On 11/18/90, investigators attempted to recreate the isolation signal with no success, On 11/20/90, the incorrect information retrieval code was entered eight times before duplicating the signal. Eleven additional attempts were made later that day,-.with four isolation signals generated.

The vendor for the WRGM (Sorrento Electronics) was contacted concerning this problem. The vendor stated that he was aware of similar program problems at other utilities. Channel item requests that end in "00" (e.g. ,100, 200, etc.)

L d

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e - - - - - . , - - - < . - ~ ~

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• NDc FORM 3CSA U.$. NUCLEAR REoVLATORY COMMISSON APPROVED oMB NO. 31504104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RES89NSE TO COMPLY WITH THl$ INFORMATION LICENSEE EVENT REPORT (LER) pu@ nbug'gluM37,^313101g, necono3 3,o nopoy73 TEXT CONTINUATION MANAGEM BRANCH F54 U.S. NUCLEAR REOULATORY CoMM:SSON.

WASHINGTON, DC 20555. AND TO THE PAPERWORK REDUCTION PfCJECT (31504104) OFrlCE oF MANAGEMENT AND BUDGET. WASHINGTON.DC 20$03 F ACIUTY NAME (1) DOCITT LER NUMBER (6) PAGE (3)

NUMBER (2)

Brunswick Steam Electric Plant Unit 1 05000325 YEAR NUMBER NUMBER 90 - 020 - 00 TEXT llf MORE SPACE IS REQUIRED. USE ADDIT 1oNAL NRC FORM 366A'S) (17) ,

result in a scan overload. Channel items which end in "00" are not associated with valid data base parameters, and are normally not requested. Requesting these channel items causes the RM 80 microprocessor to search for data that does not exist - = When the search time exceeds the time frame allowed, the resulting >

monitor status is scan overlt d. A scan overload signal will trigger several relays to reset. These relays are the same relays that give the DOWN SCALE /INOP and MIGH RAD alarms:in the control room, and initiate the Group 6 isolation, secondary containment and the SBCT system auto start.

The root cause of this event is therefore a design problem with the computer program for the Stack Wide Range Gas Monitor (WRCM) RM-80 microprocessor, which may initiate an intermittent high radiation signal to the Group 6 isolation logic whenever e command function is keyed in which ends in "00" CORRECTIVE ACTIONS An update to the WRCM microprocessor will be -obtained frw the vendor to eliminate this problem. As an interim measure, the non-essential daily readings

= will not be -taken. In addition, personnel in the E6RC counting room, who have daily interface with the WRGM computer, have been made aware of the concern for a potential isolation when keying in information codes to the WRGM computer.

Other Sorrento RM 80 microprocessors are located at the Turbine Building exhaust WRCMs. These RM-80s are similar microprocessors, but do not initiate an isolation signal. These units initiate a high radiation alarm only. Replacement of the microprocessor boards for these units is being evaluated. >

EVENT ASSESSMENT

-This event had minimal safety significance for both units. Unit 1 was in a ,

refuel outage,.with no fuel in the vessel. Secondary containment was not in -

- affect at the time of the event. Unit 2 was in Mode 1 (RUN), at 100% -power, The mitigating function of the WRGM isolation logic . is to initiate - a Group 6

. isolation and SBGT auto start signal. The SBGT system, isolation signals and isolation valves functioned as designed during-this event.

- The WRGM microprocessor unit involved in this event was originally installed in

-June, 1983. Although other isolations have occurred due to problems-with the WRGM, none have been the result of this microprocessor problem. One-LER in the-past three years involved a Group 6 isolation initiated by an isolation signal from the Stack WRGM. LER 1 88 022 involved a Group 6 isolation signal received during E&RG sampling; however, no conclusive reason could be determined for this event.

SYSTEM / COMPONENT EIIS CODE Wide Range Gas Monitor (WRCM) IL RM 80 Microprocessor IL/GPU Standby Gas Treatment System (SBGT) BH Containment Atmospheric Control (CAC) BB Drywell Nitrogen Inlet Valve BB/ISV Torus Nitrogen-Inlet Valve BB/ISV

'