ML18153B727

LER 89-014-00:on 890417,main Control Room Ventilation Isolated Due to High Voltage Output on B Chlorine Gas Detector.Caused by Increased Flow Past Sensor in Duct. Use of Chlorine discontinued.W/890512 Ltr

ML18153B727
Person / Time
Site:	Surry
Issue date:	05/12/1989
From:	KANSLER M R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
89-015, 89-15, LER-89-014, LER-89-14, NUDOCS 8905240217
Download: ML18153B727 (4)

Text

NRC Form :l66 ~-1-83)

• LICENSEE EVENT REPORT (LERJ POW 28-06-01 U.S. NUCLEAR REGULATORY COMMISSION APPROVED 0MB NO. 316Q.0104 EXPIRES: 8/31/88 FACILITY NAME (1) I DOCKET NUMBER (2) I PAGE 131 Surry Power Station, Units 1 and 2 O 16 I O I o I O I 2, 8 ,o 1 I OF O I 3 TITLE (4) Main Control Room Ventilation Isolation (Unplanned Due to a Spurious Chlorine Gas Detector Alarm EVENT DATE (5) I.ER NUMBER (6) REPORT DATE (7) ESF Actuation)

OTHER FACILITIES INVOLVED (8) MONTH DAV VEAR VEAR Itt SEQUENTIAL

}!(\ REVISION MONTH DAY VEAR FACILITY NAMES DOCKET NUMBER(SJ

• NUMBER NUMBER 01s1010101 014 11 7 8 9 s1 9-01 114 -010 o 1s 1 I 2 s19 o Is Io Io Io I* I I I I OPERATING MODE (8) THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Chsck ono or more of rho fol/aoying)

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........ --------1 20.402(b) 20,405(c) ,lL 60,73(1)(2J(iv) 73.71(b) --20.406(1)(1

)(I) 6Q.311(c)(11 50.73(1)(21M 73.71(c) ---20.406(1)(1

)(II) 50.38(cl(21 50.73(11(2J(vill OTHER (Sp*cifV in Abstract LEVEL O O Q ----b*law *nd In Texr, NRC Farm POWER I 1101 I I 111111= 20.405(1)(11(1111 60.73(11(21(11 60,73(1H2Hvlll)(AI 366A) --20.405(1)(11 (lvl 50,73(11(2)(11) 60.73(1H2llv111HBI

--20.40&(1)(1 JM 50.73(11(2)(1111 50.73(1H2Hxl LICENSEE CONTACT FOR THIS I.ER (12) NAME TELEPHONE NUMBER AREA CODE M. R. Kansle*r, Station Manager 8 I O I 4 31 5 I 7 I -1 3 1 l I 81 4 CAUSE SYSTEM COMPONENT I I I I I I I I COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (131 TURER I I I I I I CAUSE SYSTEM I I COMPONENT MANUFAC-TURER I I I I I I I I I I I I SUPPLEMENTAi.

REPORT EXPECTED (141 MONTH DAY YEAR EXPECTED SUBMISSION n YES /If vo1, camp/oro EXPECTED SUBMl~/ON DATE) DATE 1151 I ABSTRACT /Llmir to 1400 SPIJCOI, i.* .. spproximarstv fift**n singl***P"c*

tvP*Writron fine,) (181 NRC Form 388 19-831 On April 17, 1989 at 1150 hours0.0133 days <br />0.319 hours <br />0.0019 weeks <br />4.37575e-4 months <br />, with both units at cold shutdown, the main control room (MCR) ventilation automatically isolated due to a high voltage output on the "B" chlorine gas detector.

The voltage increase generated a spurious high chlorine gas alarm and the control room exhaust fan tripped and the supply and exhaust dampers closed. This is being reported as an unplanned engineered safety feature actuation.

The detector was removed from service, and the MCR ventilation was realigned.

The voltage increase was due to increased flow pas; the detector's sensor in the ventilation duct. The use of chlorine at the plant's sewage treatment system has been discontinued, and the Technical Specification requiring the chlorine detectors has been deleted. Consequently, the control room ~hlorine detectors are no longer required and have been removed from service . .,40.,17 890512 8905~ ' 05000280 PDR ADOCK PNU s I I -.

NRC form .. A (11-1131 FACILITY NAME (1 I LICENSEE EV-REPORT (LER) TEXT CONTINUATI-POW 28-06-01--

U.S. NUCLEAR REGULATORY COMMISSION , APPROVED 0MB NO. 3150-010<

EXPIRES: 8/31/88 DOCKET NUMBER 121 LER NUMBER 161 PAGE 13* *Surry Power Station, Units 1 and 2 VEAR ::*:*:*:*:*

SEQUENTIAL.

• • • • • • • • !REVISION

• • • .*.*.*.

NUM9ER ***.:*** NUMl!IER NRC FORM :lellA 19,83, 0 15 IO IO IO 12 I 81 0 81 9 -011 I 4 -010 012 OF O I 3 1.0 Description of the Event On April 17, 1989 at 1150 hours0.0133 days <br />0.319 hours <br />0.0019 weeks <br />4.37575e-4 months <br />, with Units 1 and 2 at cold shutdown, the main control room ventilation (EIIS-VI) automatically isolated due to a high voltage output on the chlorine gas detector, CLA-VS-lOOB (EIIS-DET).

The voltage increase generated a spurious high chlorine gas alarm and the control room exhaust fan, l-VS-F-15 (EIIS-FAN), tripped and the supply and exhaust dampers, l-M0D-VS-l03B and l-M0D-VS-l03C (EIIS-DMP), closed. Use of chlorine at the plant's sewage treatment system, which necessitated the Technical Specification (T.S.) requirement for the chlorine detectors, had been discontinued prior to this event. The T.S. requirement had also been deleted. However, the detectors had not yet been removed from servic~ at the time of the event. This is being reported as an unplanned actuation of an engineered safety features component.

2.0 Safety

Consequences and Implications The chlorine gas detection system (EIIS-VI) consists of two chlorine detectors, "A" & "B", installed in the main control room. Each detector 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 trip the fan and close the dampers. The high chlorine gas signal was spurious and, consequently, there was no need for control room isolation.

In addition, chlorine gas is no longer utilized at the station sewage treatment facility.

Therefore, 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 previously performed by the detector vendor determined that the detector sensor operation*

-.

NRC Farm aaA 19-831 FACILITY NAME 111 LICENSEE E~T REPORT (LER) TEXT CONTINUAT-DOCKET NUMBER 121 POW 28-06-01 U.S. NUCLEAR REGULATORY COMMl'sslON APPROVED OM9 NO. 3150--0104 EXPIRES: 8/31 /88 LEA NUMBER 161 PAGE 131

• Surry Power Station, Units 1 and 2 o 1s10*1010121810 819 -01114 -010 013 oFo 13 TEXT Ill ,.,,.,,. -;. ,.,,,..,,.

u* HditiaMI NRC Fotm .JllliA*sJ 1171 NRC FORM 31111A 19,83i is airflow dependent due to mounting of the ~ensor in the ventilation duct. The airflow has a cooling effect on the sensor which increases the voltage output, thus inducing a spurious signal. 4.0 Immediate Corrective Action(s)

The detector was reset and operators verified the chlorine gas detector system was operable.

5.0 Additional

Corrective Action(s)

The "B" detector was hours in preparation design change, and the was realigned.

The removed from service. removed from service at 1510 for removal of the system per a main control room ventilation "A" detector was subsequently 6.0 Action(s)

Taken to Prevent Recurrence The chlorine gas treatment system at the sewage treatment plant has been replaced by an ultraviolet system. The requirement for a chlorine gas detector system has been deleted from the Technical cations, and the system has been removed from service. 7.0 Similar Events See Unit 1 LERs: 87-016 87-0.20 87-022 87-026 87-029 8.0 Manufacturer/Model Number(s)

Capital Controls Company, INC/MPP3045.

-' .. May 12, 1989 U.S. Nuclear Regulatory Commi.ssion Document Control Desk 016 Phillips Building Washington, D.C. 20555 Gentlemen:

e VIRGINIA ELECTRIC ANO POWER COMPANY Surrv P_, Station P.O. Box 3115 Surrv, Viroinie 23883 Serial Ro.: Docket Ro.: License Ro. : 89-015 50-280 50-281 DPR-32 DPR-37 Pursuant to Surry Power Station Technical Specifications, Virginia Electric and Power Company hereby submits the following Licensee Event Report for Units 1 & 2. REPORT NUMBER 89-014-00 This report has been reviewed by the Station Nuclear Safety and Operating Commi.ttee and will be reviewed by Safety Evaluation and Control. Enclosure cc: Regional Administrator Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323 -.