ML18152A618

LER 87-029-00:on 871108,main Control Room Ventilation Isolated Due to High Voltage Output on Chlorine Detector. Caused by Increased Voltage Output Inducing Spurious Signal.Ventilation Sys realigned.W/871204 Ltr

ML18152A618
Person / Time
Site:	Surry
Issue date:	12/04/1987
From:	Benson D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
87-034, 87-34, LER-87-029, LER-87-29, NUDOCS 8712160035
Download: ML18152A618 (4)

Text

POW 28-06-01

, NRC Form 36e U.S. NUCLEAR REGULATORY COMMISSION (9-831 APPROVED 0MB NO. 3160-0104 EXPIRES: 8/31/88 LICENSEE EVENT REPORT (LER) .

FACILITY NAME (1) DOCKET NUMBER (2) I PAGE 131 TITLE (4)

Surry Power Station. Units 1 & 2  ! OJSJOJOJOl?l~ln 1joF rl ~

Main Control Room Ventilation Isolation Due To High Voltage Output on Chlorine Gas Detector *

• EVENT DATE (51 LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (81 MONTH DAY YEAR YEAR tit SEQUENTIAL

• NUMBER /:)~ REVISION NUMBER MONTH DAY YEAR FACILITY NAMES DOCKET NUMBER(Sl g

11 1 ol,s 8 7 sl1 012 I 9 - olo 1 I2 ol4 sl 7 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Ch*ck on* or mar* of th* fol/O'flng/ (11)

MODE (91

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- 73.71(bl 50.38(0)(11 50.38(cll21 50.73(a)(ZlM 50.73(11(21(vlil - 73.71(cl OTHER (Sp*clfy in 4bsrract b*low 1nd In Text NRC Form

- 50.73(1)(2J(i) 50 .73(1 I(ZJ(vllll (Al 366A)

- 150.73(1JIZl(li1 50.73(11(21(111) 50.73(11 (2)(viiil (Bl

. 50.73(1H2Hxl LICENSEE CONTACT FOR THIS LER (121 NAME **-TELEPHONE NUMBER AREA CODE D. L. Benson, Station Manager 81 014 3 I SI 71- I 31 118 I 4 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (131 CAUSE SYSTEM COMPONENT MANUFAC- SYSTEM COMPONENT MANUFAC*

TURER TURER R~o~i~gkE ilili!ili!ilili!l!i!i!ili!l!l!i!i!ilillli!iiililllill CAUSE I I I I I I I I I I I *I I I 'i.*.*.*.:.*.*.:.:,;,:_:.....U..Jlt...:'

I I I I I I° I li!llill!i!ili!l!l!lll!i!i!l!i!i!i!i!ili!i!i!:!iii!il I I I I I I I SUPPLEMENTAL REPORT EXPECTED (141 MONTH DAY YEAR EXPECTED

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SUBMISSION DATE (151 j YES (If yo,, comp/et* EXPECTED SUBMISSION DATE/ NO l l I ABSTRACT (Limit to 1400 spac**, i.a., approxlmat*ly flfteon slng/o,speco typ*writton lines/ 1161 On November 8, 1987 at 1608 hours0.0186 days <br />0.447 hours <br />0.00266 weeks <br />6.11844e-4 months <br />, the Main Control Room (MCR) ventilation was isolated due to a high voltage output on Chlorine Gas Detector, CLA-VS-lOOA {EIIS-DET}. As a result of the voltage spike, the Control Room Exhaust Fan, 1-VS-F-15

{EIIS-FAN} tripped and supply damper, 1-MOD-VS-103A {EIIS-DMP}

and exhaust damper, l-MOD-VS-103D {EIIS-DMP} closed. The Chemistry Department verified that there was no detectable chlorine gas present in the control room . . The Chlorine Detector was reset and the Main Control Room ventilation

{EIIS-VI} was realigned. At the time of these occurrences, both Unit 1 and Unit 2 were operating at 100% power. The Main Control Room ventilation isolated due to high sensor voltage on the Chlorine Gas Detector. An investigation performed by the detector vendor determined that the detector sensor operation*,

is air flow dependent due to mounting of the sensor in the ventilation duct. The air flow has a cooling effect on the sensor which increases the voltage output, thus inducing a spurious signal. The Chlorine Gas Treatment System at the Sewage Treatment Plant will be replaced~by an ultraviolet system. At that time, a Technical Specification revision will be submitted to remove the Chlorine Gas Detectors.

~712160035 871204 F.~,R ADOCK 05000280 /

S1. DCD T~'E ;2-Q l I NRC Form 366

POW 28-06-01

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NAC Fo,m 388A e U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LERI TEXT CONTINUATION APPROVED OMS NO. 3150-0104 EXPIRES: 8/31 /811 FACILITY NAME (1) DOCKET NUMBER 121 LER NUMBER (61 PAGE (31 Surry Power Station, Units 1 & 2 o 15 Io Io Io 12 18 I O 81 7 - o I ii 9 - o In n I , OF n I~

TEXT /If - - i.,.,...,. 11* <<ltllrloMI NRC Fonn 31111A~I !171 1.0 Description of the Event On November 8, 1987 at 1608 hours0.0186 days <br />0.447 hours <br />0.00266 weeks <br />6.11844e-4 months <br />, the Main Control Room (MCR) ventilation was isolated due to a high voltage output on Chlorine Gas Detector, CLA-VS-lOOA {EIIS-DET}. As a result of the voltage spike, the Control Room Exhaust Fan, 1-VS-F-15

{EIIS-FAN} tripped and supply damper, 1-MOD-VS-103A

{EIIS-DMP} and exhaust damper, 1-MOD-VS-103D {EIIS-DMP}

closed. The Chemistry Department verified that there was no detectable chlorine gas present in the control room. The Chlorine Detector was reset and the Main Control Room ventilation {EIIS-VI} was realigned. At the time of these occurrences, both Unit 1 and Unit 2 were operating at 100% power.

2.0 Safety Consequences and Implications The Chlorine Gas Detection System {EIIS-VI}

consists of two chlorine monitors installed in the Main

.Control Room * . Each monitor has sensors located in the Main Control Room ventilation supply duct. Each detector operates one train of two series supply and exhaust dampers. When either one of the detectors senses chlorine in excess of 5 ppm, its associated supply and exhaust dampers close and the Control Room exhaust fan trips. Initiation of Safety Injection

{EIIS-BQ} will also cause the closure of the supply and exhaust dampers and trip the MCR exhaust fan. Although the initiating signal was spurious, the Chlorine Gas Detection System functioned as designed. The Chemistry Department verified that there was no chlorine gas present in the control room, the health and safety of the public were not affected.

3.0 Cause The Main Control Room ventilation isolated due to high sensor voltage on the Chlorine Gas Detector. An investigation performed by the detecto~ vendor determined that the detector sensor operation is ai~-

flow dependent due to mounting of the sensor in the ventilation duct. The air flow has a cooling effect on the sensor which increases the voltage output, thus inducing a spurious signal.

NRC FORM 386A

• U.S.GPO: 1986*0*624*638/465 19.all

POW 28-06-01 NRC Form 3MA U.S. NUCLEAR REGULATORY COMMISSION (9-831 LICENSEE EVENT REPORT ILEA) TEXT CONTINUATION APPROVED 0MB NO. 3150-0104 EXPIRES: B/31 /88 FACILITY NAME 111 DOCKET NUMBER (21 LER NUMBER (61 PAGE 131 Surry Power Station 1 Units 1 & 2 o Is Io f o Io I 21 81 o al 7 - ol 2 I g - nIn n I ~ OF nI ~

TEXT /If,,,,,,._ ii ,equitwl, ua Mid- NRC Fonn .m.l'*J (171 4.0 Immediate Corrective Action Chemistry verified that there was no chlorine gas present in the MCR. The ventilation system was realigned.

5.0 Additional Corrective Actions None.

6.0 Actions Taken To Prevent Recurrence The chlorine gas treatment system at the Sewage Treatment Plant will be replaced by an ultraviolet system. At that time, a Technical Specification revision will be submitted to remove the Chlorine Gas Detectors.

7.0 Similar Events See Unit 1 LERs: 87-016 87-020 87-022 87-026 *~

8.0 Manufacturer/Model Number Capital Controls Company, INC/MPP3045.

NRC FORM 366A *U.S.GP0:1986*0*824*538/465 19-831

• VIRGINIA ELECTRIC ANO POWER CO~PANV Surry Power Station P. 0. Box 316 Surry, Virginia 23883 December 4, 1987 U.S. Nuclear Regulatory Commission Serial No.: 87-034 Document Control Desk Docket No.: 50-280 016 Phillips Building Licensee No.: DPR-32 Washington, D.C. 20555 Gentlemen:

Pursuant to Surry Power Station Technical Specifications, Virginia Electric and Power Company hereby submits the following Licensee Event Report for Surry Unit 1.

REPORT NUMBER 87-029-00 This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be reviewed by Safety Evaluation and Control.

Very truly yours, David L. Benson Station Manager Enclosure cc: Dr. J. Nelson Grace Regional Administrator Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323

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