ML20044F585

LER 93-004-00:on 930419,isolation Valve Unexpectedly Closed While Trip Unit Was Tested.Cause for Valve Closing Undetermined.Logic of Trip Unit Correctly Configured to Prevent Closing.No Corrective Actions taken.W/930518 Ltr

ML20044F585
Person / Time
Site:	Hatch
Issue date:	05/18/1993
From:	Beckham J, Tipps S GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HL-3307, LER-93-004-02, LER-93-4-2, NUDOCS 9305280281
Download: ML20044F585 (5)

Text

- Goorgia Power Company

• 40 invemess Centerr Parkway Post Cnfice Box 129s Bermngham, Alabama 35201 Telephone 205 877-7279 m

' a. T. s, sw. a. Georgia Power Vce PrA Sent f4acisar "C:M' C" t +: N*,

Hatch Pro;ect May 18, 1993 Docket No. 50-366 HL-3307 005456 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Edwin I. Hatch Nuclear Plant - Unit 2 Licensee Event Report Group 2 Primary Containment Isolation System Valve Closes Durina Procedure Performance Gentlemen:

In accordance with the requirements of 10 CFR 50.73(a)(2)(iv), Georgia Power Company is submitting the enclosed Licensee Event Report (LER) concerning a Primary Containment Isolation System valve which closed during performance of a surveillance procedure. This event occurred at Plant Hatch - Unit 2.

Sincerely,

/ J. T. Beckham, Jr OCV/cr

Enclosure:

LER 50-366/1993-004 cc: Georcia Power Company Mr. H. L. Sumner, General Manager - Nuclear Plant NORMS U.S. Nuclear Reaulatory Commission. Washinoton. D.C.

Mr. K. Jabbour, Licensing Project Manager - Hatch U.S. Nuclear Reculatory Commission. Reaion II Mr. S. D. Ebneter, Regional Administrator Mr. L. D. k'ert, Senior Resident Inspector - Hatch 9 R O O f Ii d 9305280281 930518 PDR ADOCK 05000366 /

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u.5.uuAndaAw mih5ix w g g g -OiO4 LICENSEE EVENT REPORT (LER)

FAciti;) hart (i) us.Ati herbtk (2) . -. -

PLANT 1RTCH, LWIT 2 05000366 1 lcrl4 TlILE (4)

GROUP 2 PRIMAPY ONUA1!EENT IS01ATION SYSTEM VALVE CIDSES IUAING PROCEDUPI PERFDPJ%NCE T hT LATE (5) EER huMBEk (6J REFORT LATE (7) diner FACILITIE5 1hv0tviD (6) m;hle LAY TEAK tiAs 5EQ hum REW M;hlr LAY TEAK FALILITt hAME5 DOCLEI humbEk(5) 05000 04 19 93 93 004 00 05 18 93 05000 CPERATIkG inI5 WU BkcH E M5W EMWWMM MW (H)

MODE (9) 1 20.402(b) 20.405(c) ^ 50.73(a)(2)(iv) 73.71(b)

P0BER ~

20.405(a)(1)(1) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

LEVEL 056 20.405(a)(1)(ii) 20.405(a)(1)(iii)

[ 50.73(a)(2)(t) 50.36(c)(2) _

50.73(a)(2)(vii) _

CINER (Specify in 50.73(a)(2)(viii)(A) Abstract below)

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20.405(a)(1)(iv) -

50.73(a)(2)(ii) ~

50.73(a)(2)(viii)(B) 20.405(a)(1)(v) 50.73(alt 2)(iii) 50.73(alt?)(x)

LICEh5EE CChiACT FDa Inl5 LEA (12)

AAME iELEin;ht huPEER GEA CCLE STEVEN B. TIPPS, MMMGER NUCIIAR SAFEIY AND COMPLIANCE, IRTCH 912 367-7851 CCMPLETE CAE LlhE iGR EALn FAILL.kE DE5ChiEED lh Tnl5 kEF0kT (13)

AUSE SYSTEN'CCFPChENT CAUSE 5YSTEN CCMPChEhT PD T QFAC- PO\T CS NhkFAC-T R h Sufi L E ME hi At REPOAI EAFECIED (14; *Lhin CAV YEAR SUEMISSION

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On 4/19/93 at 1305 CDT. Unit 2 was in the Run mode at a power level of 1370 CMWT (56.2% rated thermal power). At that time, Group 2 Primary Containment Isolation System valve 2E51-F008, Reactor Core Isolation Cooling (RCIC) System Steam Supply Line Isolation Valve, unexpectedly closed. Instrument and Controls (16C) personnel were performing a functional test on Analog Transmitter and Trip System (ATTS) trip unit 2E51-N657A, RCIC Steam Line Differential Pressure Instrument, per surveillance procedure 57SV-SUV-011-25, "ATTS Panel 2H11-P925 Channel FT&C," at the time the valve closed. This trip unit provides an isolation signal to valve 2E51-F008 on steam supply line high differential pressure, A functional test of this isolation function was in progress at the time the valve closed; however, Operations and I&C personnel verified the logic had been configured as required by the surveillance procedure to prevent the isolation signal from actually closing the valve. With no other reason for the closing of valve 2E51-F008 apparent, licensed Operations personnel reopened the valve at 1318 CDT.

The cause of this event could not be determined. The logic was confirmed to be configured as required by the procedure to prevent the valve from closing, the logic drawings were reviewed to ensure the procedure was technically correct, and the actions of the I&C technicians performing the functional test were reviewed to ensure they correctly followed the procedure. No problems were found in any of these areas. Finally, the test was performed again with no changes having been made to the procedure; the test was run successfully and the event did not recur. No corrective actions were taken because the cause of the event could not be determined.  ;

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. LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION i rACILITY KAME (1) DDCKET WUMBER (2) LER NUMBER [5) PAGE (3) l YEAR '5EQ hum iiE V r PIANT HA701, UNIT 2 05000366' 93 004 00 2 0F 4 (

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PLANT AND SYSTEM IDENTIFICATION  !

Ceneral Electric - Boiling Water Reactor

-Energy Industry Identification System codes are identified in the text as (EIIS jl Code XX). I i

DESCRIPTION OF EVENT On 4/19/93 at 1305 CDT, Unit 2 was in the Run mode at a power level of 1370 CMWT i (56.2% rated thermal power). At that time, Group 2 Primary Containment l Isolation System (EIIS Code JM) valve 2E51-F008, Reactor Core Isolation Cooling j (RCIC, EIIS Code BN) System Steam Supply Line Isolation Valve, unexpectedly  ;

closed. Instrument and Controls (160) personnel were performing a functional  ;

test on Analog Transmitter and Trip System (ATTS, EIIS Code JF) trip unit . I 2E51-N657A RCIC Steam Line Differential Pressure Instrument, per surveillance .l procedure 57SV-SUV-Oll-2S, "ATTS Panel 2H11-P925 Channel FT&C," at the time the {

valve closed, j I

ATTS trip unit 2E51-N657A sends an isolation signal to valve 2E51-F008 in the 'l event of a RCIC steam line high differential pressure signal. A high I differential pressure signal is indicative of a possible break in the steam j supply line; therefore, an isolation signal-is generated to close valve  !

2E51-F008 to isolate any line break which might exist. Unit 2 Technical  !

Specifications Table 4.3.2-1, item 5.a, requires that trip unit 2E51-N657A be l functionally tested at least once per month to ensure it is operable. This l functional test is performed per the instructions contained in surveillance j procedure 57SV-SUV-Oll-2S. j i

This procedure had been revised recently and, as allowed by plant administrative l control procedure 10AC-MGR-003-0S, " Preparation and Control of Procedures," the  !

changes were being validated by performance of the procedure. As part of the l' functional test of trip unit 2E51-N657A, the isolation logic to valve 2E51-F008 '

is configured so that the isolation signal generated when testing the trip unit j will not result in actual closure of the valve. This is done simply by opening j a single link (Link JJ-6) in the logic downstream of the trip unit's output l relay. The link required to be opened to defeat the valve isolation logic was  !

different than the one used in previous revisions; therefore, it was part of the {

procedure changes being validated. j i

I&C technicians set up the ATTS trip unit test signal generator and opened Link JJ-6 as required by procedure 57SV-SUV-011-2S. They then increased the test  ;

signal to trip unit 2E51-N657A toward the high trip setpoint for the unit. At 6 that point, Operations personnel received the "RCIC Steam Line High Diff Press  !

Stm Line Break" annunciator and noted that valve 2E51-F008 had closed. They ,

halted the functional test and began an investigation of the event. As part of their investigation, Operations personnel confirmed that Link JJ-6 was opened as .[

4 required by procedure 575V-SUV-011-2S. j l

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LICENSEE EVENT REPORT (LER) l TEXT CONTINUATION j FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (5) PAGE (3)

TEAR SEQ hum REW PUNr HA H, UNIT 2 05000366 93 004 00 3 DF 4 TEXT Since the surveillance procedure had been revised recently, it was suspected it i may have been technically incorrect (e.g., specified the wrong link to be l opened) thereby causing this event. Therefore, performance of-the procedure was suspended and the trip unit and logic restored to normal. With no other reason for the closing of valve 2E51-F008 apparent, licensed Operatiens personnel-reopened the valve at 1318 CDT.

An extensive review of the procedure and associated logic drawings was performed, including a field walk down of the wiring to ensure it matched the drawings. This review verified that procedure 57SV-SUV-011-2S was written correctly. On 4/20/93, the functional test of trip unit 2E51-N657A was performed successfully, without valve 2E51-F008 closing.

CAUSE OF THE EVENT The cause of this event could not be determined. The logic was confirmed to be configured as required by the procedure to prevent the valve from closing, the-logic drawings were reviewed to ensure the procedure was technically correct,-

and the actions of the I&C technicians performing the functional test were reviewed to ensure they correctly followed the procedure. No problems were found in any of these areas. Finally, the test was performed again with no changes having been made to the procedure; the test was run successfully and the event did not recur.

REPORTABILITY ANALYSIS AND SAFETY ASSESSMENT This report is required by 10 CFR 50.73(a)(2)(iv) because an unplanned actuation of an Engineered Safety Feature (ESF) system occurred. Specifically, Croup 2 Primary Containment Isolation System valve 2E51-F008 unexpectedly closed during the performance of a surveillance procedure in which isolation of the valve was to have been prevented. This valve is a component in the Primary Containment Isolation System.

The Primary Containment Isolation System provides timely protection against the onset and consequences of accidents involving the release of radioactive j materials from the fuel and nuclear system process barriers. To accomplish this, the Primary Containment Isolation System initiates automatic isolation of appropriate lines which penetrate the Primary Containment whenever monitored variables exceed preselected operational limits. In particular, the RCIC system steam supply line contains two isolation valves, an inboard and an outboard, which are part of the Croup 2 Primary Containment Isolation System. One of the signals which will cause isolation of this line, i.e., closure of the isolation valves, is a RCIC steam line high differential pressure signal. A high differential pressure signal is indicative of a possible break in the steam supply line; therefore, an isolation signal is generated to close the valves to isolate any line break which might exist. This action limits inventory loss, j contamination spread, and equipment damage resulting from the escaping steam.  !

ATTS trip unit 2E51-N657A sends an isolatica signal to valve 2E51-F008, the j outboard isolation valve.  !

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TEXT CONTINUATION FACIL]TV NAME (1) DOCKET NUMBER (2) LeR NUMBER (5) PAGE (3)

TEAR SEQ hum sEv FI/6T IMTCH, UNIT 2 05000366 93 004 00 4 0F 4 Tio In this event, outboard isolation valve 2E51-F008 unexpectedly closed during the functional test of ATTS trip unit 2E51-N657A. No actual condition existed which would have required this valve to close. Review of the surveillance procedure being performed at the time of the isolation and the logic itself revealed no problems which would have caused the valve to close. Testing of the logic on 4/20/93 confirmed it was functioning as expected. Therefore, it is concluded that the isolation logic was operable and capable of performing its intended function, and that the unexpected closure of valve 2E51-F008 was not Indicative of a problem with the logic or the valve. Consequently, this event had no adverse impact on nuclear safety. Tnis analysis is applicable to all power levels and operating modes. ,

CORRECTIVE ACTIONS 4

As described previously, a review of the procedure, logic drawings, logic wiring, and I6C technician actions while performing the procedure did not reveal the causes of this event. Consequently, no corrective actions could be taken. >

ADDITIONAL INFORMATION No system' .ther than those mentioned in this report were affected by this event.

, No failed components caused or resulted from this event.

Previous similar events in the last two years in which an unplanned ESF system actuation occurred for unknown reasons were reported in the following Licensee Event Reports:

50-321/1992-005, dated 3/18/92, 50-321/1992-012, dated 6/11/92, 50-321/1992-018, dated 7/30/92, 50-321/1992-022, dated 9/25/92, 50-321/1993-005, dated 5/14/93.

None of these events involved the isolation logic for valve 2E51-F008 or resulted dcring the performance of procedure 57SV-SUV-011-2S nor did they involve the corresponding Unit I valve or surveillance procedure. Therefore, investigation into the causes of the previous events could not have predicted ,

^

the occurrence of this event nor resulted in actions to prevent it.

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