ML18153A128

LER 97-004-00:on 970317,main Steam Safety Valve Was Outside as Found Setpoint Tolerance.Specific Cause Unknown,However, Minor Setpoint Drift Can Be Expected.No Immediate Corrective Actions performed.W/970415 Ltr

ML18153A128
Person / Time
Site:	Surry
Issue date:	04/15/1997
From:	Christian D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
97-210, LER-97-004, LER-97-4, NUDOCS 9704220103
Download: ML18153A128 (4)

Text

e *e 10CFR50.73 I

Virginia Electric and Power Company Surry Power Station

• 5570 Hog Island Road*

Surry, Virginia 23883 April 15,1997

• U. S .. 1\luqlear Regulatory Commission Serial No.: 97-210 D0cument COntrol Desk SPS:JDK Washington, D.C. 20555 Docket No.: 50-280 License No.:DPR-32

Dear Sirs:

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

REPORT NUMBER 50-280/97-004-00 This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be forwarded to the Management Safety Revi.ew Committee.

for its review.

Very truly yours, D. A. Christian Station Manager Enclosure Commitments contained in this letter: None cc: Flegional Administrator 101 Marietta Street' NW Suite 2900 Atlanta, Georgia 30323 2 2 0 0 0 3

• FLA. Musser NRC Senior Resident Inspector Surry Power Station 9704220103 970415 PDR ADOCK 05000280 S

• PDR Illllll lllll lllll lllll llllll 111111111111

• I I I 1 D f *

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/1 NRC r"ORM 366 (4-95)

LICENSEE EVENT REPORT {LER)

~UCLEAR REGULATORY COMMISSION

• APPROVED BY 0MB NO. 3150-0104 EXPIRES 4/30/98 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST: 50.0 HRS REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE LICENSING PROCESS AND FED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (T*6 F33).

U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC (See reverse for required number of digits/characters for each block) 20555*0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150*0104), OFFICE OF MANAGEMENT. AND BUDGET, WASHINGTON. DC 20503.

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

SURRY POWER STATION, Unif 1 05000 - 280 1 OF3 TITLE 141 Main Steam Safety Valve As Found Setpoint Out Of Tolerance EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

SEQUENTIAL REVISION FACILITY NAME DOCUMENT NUMBER MONTH DAY YEAR YEAR MONTH DAY YEAR.

NUMBER NUMBER 05000~

FACILITY NAME DOCUMENT NUMBER 03 17 97 97 -- 004 -- 00 04 15 97 05000-OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more) (11)

MODE (9) N 20.2201(b) 20.2203(a)(2)(v) X S0.73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.22D3(a)(3)(i) so. 73(a)(2)(ii) 50.73(a)(2)(x)

LEVEL (10) 0% 2D.2203(a)(2)(i) 20.2203(a)(3)(ii) .50.73(a}(2)(iii) 73.71 2D.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv) OTHER 2D.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v) Specify in Abstract below 2D.2203(a)(2)(iv) 5D.36(c)(2) 50.73(a)(2)(vii) or in NRC Form 366A LICENSEE CONTACT FOR THIS LER (12)

NAME I TELEPHONE NUMBER (Include Area Code)

D. A. Christian, Station Manager (757) 365-2000 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS

• TONPRDS X SB RV D243 YES SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR I YF:S . I NO SUBMISSION DATE (If yes, complete EXPECTED SUBMISSION DATE). I ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On March 17, 1997, with Unit 1 in Cold Shutdown, setpoint testing of Unit 1 Main Steam Safety (MSSVs) revealed that the lift setting for one MSSV was outside the As Found setpoint tolerance (+/- 3%) that is allowed by Technical Specific'ation (TS) 3.6.A.

This event is reportable pursuant to 10CFR50.73(a)(2)(i)(B) for conditions prohibited by TS 3.6.A, 3.6.B.3.

The safety valves were sent to Wyle Laboratories for testing to ensure conformance with TS requirements. The As Found. setpoint for one MSSV was. found to be outside TS tolerance'.

The safety valve was repaired, adjusted~ a_nd tested to be within the correct As Left setpoint tolerance (+/- 1%) allowed by TS.

This event posed no significant safety implications because the safety valves would have performed their safety function in the event of an overpressure condition. The health and safety of the public were not affected at any time durinq this event.

NRG FORM 366 (4-95)

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91

... r.=_=NR=C=i==-:)=R=M=3=66=A============e~==============e==_=S.=N=U=C=LE=A=R=R=E=G=U=LA=T=O=RY=CO=M=M=l=SS=l=ON 4 95

, ~ .( - - l - _ =======L=IC=E=N=S=E=E=E==V=E=N=T=R===E=P=O===R=T======(L=E=n=R=)==========,r=======tt TEXT CONTINUATION FACILITY NAME (1) DOCKET LER NUMBER (6) *PAGE (3)

YEAR I SEQUENTIAL NUMBER I REVISION NUMBER Sunv Power Station Unit 1 05000 - 280 97 -- 004 -- 00 20F 3 TEXT (If more space is required, use additional copies of NRG Form 366A} (17)

1.0 DESCRIPTION

OF THE EVENT On March 6, 1997, Unit 1 was shut down to start a Refueling Outage. As part of the outage scope, the fifteen Main Steam Safety Valves (MSSVs) [EIIS-SB,RV] were removed and *sent to Wyle Laboratories in Huntsville, Alabama for setpoint testing. The MSSVs were tested in accordance with station testing procedures developed pursuant to the Surry Power Station ASME Section XI Testing Program for Pumps and Valves.

On March 17, 1997, with Unit 1 in Cold Shutdown, ~etpoint testing of the Unit 1 MSSVs revealed that the initial lift setting for one valve (1-MS-sv~ 104C) was outside the As Found setpoint tolerance (+/- 3%, 1087 to 1153 psig) that is allowed by Technical Specification (TS) 3.6.A. The*

valve exhibited a lift setting of 3.7% above its nominal value of 1120 psig. The next lift exhibited a lift setting of 1151 psig which* is within the As Fou*nd setpoint tolerance.

This event is reportable pursuant to 1OCPR50.73(a)(2)(i)(B) for conditions prohibited by TS 3:6.A, 3.6.B.3.

2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS The MSSVs provide overpressure protection for the Main Steam Supply System piping upstream of the main steam trip valves. The As Found lift pressure settings for the MSSVs are bounded by the safety analyses for overpressure transients that are part of the current licensing basis.

The peak steam line pre.ssure reached in this transient is 1159 psig assuming that all MSSVs open at their maximum allowable TS lift setpoint. This maintains a 36 psi margin to the design limit of 1195 psig. The maximum impact of failure of 1-MS-SV-104C to open at its tolerance limit could be an increase of the peak. pressure by 6 psi. This is well within the available margin.

Using the As Found Lift pressures for the MSSVs associated* with the "C" main steam line, it is expected that the peak pressure would remain below the current analysis value.

-Since the acceptance criteria for overpressure events were met, the health and safety of the

• public were not affected.

3.0 CAUSE OF THE EVENT The MSSV experienced minor setpoint drift which can be expected under normal operating conditions. Although the specific cause of such setpoint drift is not known, its occurrence is weli.

documented in the industry.

• 4.0 IMMEDIATE CORRECTIVE ACTION(S)

Unit condition at the time of discovery did not require any immediate corrective actions to be performed. A Deviation Report was l;,Ubmitted tq document this condition.

• NRC FORM 366A (4-95)

__ - -----~----

\' i N.RC F"')RM 366A (4-95) e .S. NUCLEAR REGULATORY COMMISSION

,, LICENSEE EVENT REPORT (LER)

~ ll=================T=E=X=T=C=O=N=T=l~N~U=A=T=IO~N~===rr============rr======tt FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3)

YEAR I SEQUENTIAL NUMBER I REVISION NUMBER Surrv Power Station Unit 1 05000 - 280 97 -- 004 -- 00 3 OF 3 TEXT.(lf more space is required, use additional copies of NRC Form 366A) (17) 5.0 ADDITIONAL CORRECTIVE ACTION(S)

Engineering reviewed the "Loss of External Electrical Load Event" analysis, which is the limiting transient for main steam line pressurization, to ensure the As Found lift settings were within the bounds of existing analyses.

The MSSV with the As Found lift pressure outside the setpoint ailowed. by Technical Specification _3.6.A was inspected and ov.erhauled by the manufacturer, Dresser Industries, at the Wyle Testing Laboratory Site in Huntsville, Alabama. The MSSV was As Left tested in accordance with procedure 1-MPT-0427-02, Main Steam Safety Setpoint Verification, to verify that the+/- 1% requirement of TS 3.6.A was met. . .

A Maintenance Rule evaluatio.n is ongoing. If it is determined that a .Maintenance Rule Fun_ctional Failure occurred, it will be addressed in accordance with the req~ireinents of the Maintenance Rule Program ...

6.0 ACTIONS TO PREVENT RECURRENCE Safety valve setpoint drift is a recognized phenomenon. Periodic testing and maintenance will continue to be performed in accordance with Virginia Power ASME Section XI Testing Program for Pumps and Valves to ensure that the valves are maintained as required by TS. Additionally, to ensure the MSSVs* are tested_ under their operating condition, a change was made in 1996 to 1(2}-MPT-0427-02, Main. Steam *safety Setpoint Verification, to require thermal stabilization of the spring and upper body of the MSSV prior to setpoint testing.

VPAP-0804, Safety and Relief Valve Program, requires a comprehensive database be maintained. The information contained in the database is used to . monitor safety valve performance.

7.0 SIMILAR EVENTS Unit 1 LER 90-011-00, Main Steam Safety Valves Out of Tolerance Due to Minor Setpoint Drift

. Unit 2 LER 91-002-00, Main Steam Safety Valves Out of Tolerance Due to Minor Setpoint Drift Unit 1 LER 94-002-00, Main Steam Safety Valves Out of Tolerance Due to Minor Setpoint Drif.t Unit 2 LER 95-002, Main .Steam &* Pressurizer Safety Valve As Found Lift Setting Out of Tolerance 8.0 ADDITIONAL INFORMATION Unit 2 was operating at 100% and was not affected by this event.

NRC FORM 366A (4-95)