05000395/LER-1988-006, Special Rept Spr 88-05:on 880512,safety Injection/Reactor Trip Occurred When MSIV a Shut During Testing.Details Described in Encl LER 88-06.Accumulative Usage Factor for Affected Safety Injection Nozzle Did Not Exceed 0.70

Special Rept Spr 88-05:on 880512,safety Injection/Reactor Trip Occurred When MSIV a Shut During Testing.Details Described in Encl LER 88-06.Accumulative Usage Factor for Affected Safety Injection Nozzle Did Not Exceed 0.70

ML20153A969
Person / Time
Site:	Summer
Issue date:	07/08/1988
From:	Bradham O SOUTH CAROLINA ELECTRIC & GAS CO.
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
SPR-88-05, SPR-88-5, NUDOCS 8807120671
Download: ML20153A969 (2)

LER-2088-006, Special Rept Spr 88-05:on 880512,safety Injection/Reactor Trip Occurred When MSIV a Shut During Testing.Details Described in Encl LER 88-06.Accumulative Usage Factor for Affected Safety Injection Nozzle Did Not Exceed 0.70

Event date:
Report date:
3952088006R00 - NRC Website

text

C

.' Gs mpany l g Jeckinsville. SC 29065 SCE&G {$$$??

July 8, 1988 Or J. Nelson Grace Regional Administration s V. S. Nuclear Regulatory Commission Region II, Suite 2900 101 Marietta Street, N.W.

Atlanta. Georgia 30323

Subject:

Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Special Report (SPR 88-05)

Dear Dr. Grace:

This Special Report is being submitted pursuant to the requirements of Technical Specificatior. 3.5.2 "ECCS Subsystems - Tave t 350*F". On May 12, 1988, a Safety Injection (SI)/ Reactor Trip occurred when "A" Main Steam Isolation Valve shut during testing. Details of this event are described in LER 88-06 provided as Enclosure 1. This event represents the seventh actuation cycle to date for the Virgil. C. Summer Nuclear Station. The accumulative usage factor for the affected safety injection nozzle did not exceed 0.70.

Should there be any questions, please call at your convenience.

Very truly yours,

9

0. S. Bradham Vice President, Nuclear Operstions RJB/0SB:bh Enclosure 1: LER 88-06 (6 pages) c: See page 2 8807120671 080708 Y- @

PDR S

ADOCK 05000395 PNU 1(

Dr. Nelson Grace July 8, 1988 Page 2

-c: J. G. Connelly, Jr./0. W. Dixon, Jr./T. C. Nichols, Jr.

D. A. Nauman E. C. Roberts c J. L. Skolds W. A. Williams, Jr.

General Managers L. A. Blue C. A. Price S. R. hunt R. B. Clary W. R. Higgins J. R. Proper ,

R. M. Campbell, Jr. {

K. E. Nodland l J. C. Snelson G. O. Percival R. L. Prevatte J.-B. Knotts, Jr. '

Marsh & McLennan. ~

Occument Management 8 ranch _ .~ _]

INPO~ Records Center ANI Library NSRC RTS (SPR 880005)

NPCF File (818.07)

10CFR50.73 So t Ca oline Electric & Gas Company an A. n Jenkmsvuie. SC 23065 Nuclear Operations SCE&G <an 3454c41

, a --

June 10, 1988 Document Control Oesk U. S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Virgil C. Summer Nuclear Sta ion Docket No. 50/395 Operating License No. NPF-12 LER 88-006 Gentlemen:

Attached is Licensee Event Report No.88-006 for the Virgil C. Summer Nuclear Station.

10CFR50.73(a)(2)(iv).This report is submitted pursuant to the requirenants of Should there be any questions, please call us at your convenience.

Ie ul ours, N A.

3 auman RJB/0AN: led Attachment pc:

J.G.Connelly, Jr./0. W. Dixon, Jr./T. C. Nichols, Jr.

E. C. Roberts

0. S. Bradham W. A. Willi 6ms, Jr. K. E. Hodland J. N. Grace J. C. Snelson J. J. Hayes, Jr. G. O. Percival General Managers R. L. Prevatte C. A. Price J. B. Knotts, Jr.

G. G. Soult INP0 Records Center J. R. Proper ANI Library R. B. Clary Marsh & McLennan NSRC W. R. Higgins T. L. Matlosz RTS (ON0 880027)

NPCF R. M. Campbell, Jr.

File (818.07)

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,,, vtAn H] vis ni,.e e srrectro sue.ussioN u rri 7 No 'n"W?i A=v = ACr w ,. , . .- .# .e.,.. e .= m m .~., o .i l l l At 0446 hours0.00516 days <br />0.124 hours <br />7.374339e-4 weeks <br />1.69703e-4 months <br />, May 12, 1988, a Safety Injection (SI)/ Reactor Trip occurrea when 'A" Main Steam Isolation Valve IMSIV) shut during testing. When the test switch was released following the testing of "A" MSIV, the valve went fully shut decreasing the steam flow from its associated steam ganerator. This decrease of steam flow on "A" steam header caused a corresponding increu e in steam flow and a decrease in steam pressure on B and C steam headers. As part of the "Reactor Protection System," this rapid decrease in steam pressure on two headers causd a Safety Injection (SI)/ Reactor Trip.

A Notification of an Unusual Event (NUE) was declared at 0510 hours0.0059 days <br />0.142 hours <br />8.43254e-4 weeks <br />1.94055e-4 months <br /> as the result of the SI and was downgraded to normal plant cono! tion at 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br />.

On May 16, 1988, during a review of the post tr!o data by the Independent Safety Engineering Group (ISEG), it was identified that ervice Water flow to the Reactor Building Cooling Units (RBCU) decreased below the Technical Specifications limit during the event.

On May 17, 1988, a Management Review Board meeting, chaired by the acting Vice President, Nuclear Operations, was convened to review this event. As a result of this meeting, the following action is to be taken:

Engineering is to review the design requirements of the MSIV circuitry, identify what is common in both the normal and test circuit, and what can be monitored during the next test. With respect to the reviewing of post trip data, Computer Services is to evaluate the feasibility of displaying various carameters in graphic form for higher visibility.

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Containment Fan Cooling System - EIIS (BK)

Essential Service Water System - EIIS (BI)

IDENTIFICATI_0N OF EVENTS Safety Injection and Reactor Trip w.ien testing. "A" Main Steamline Isolation Valve shut during Post trip review identified that Service Water flow to the Reactor Building Coc> ling Units deteriorated below the Technical Specifications minimum value durina the event.

EVENT DATE May 12, 1988 OISCOVERY DATE May 12, 1988 and May 16, 1988 REPORT OATE June 7, 1988 This .eport was initiated by Off-Normal Occurrrice Report 88027.

CONDITION PRIOR TO EVENT

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0l0 Cl3 oF 0 l5 DESCRIPTION OF EVENT On May 12, 1988, at approximately 0446 hours0.00516 days <br />0.124 hours <br />7.374339e-4 weeks <br />1.69703e-4 months <br />, Surveillance Test Procedure (STP) 121.002, "Main Steam Line Operabili+y Test,"'was being performed on (MSIV). "A" Main Steam Isolation Valve to 90% and The back subject to 100% test open.verifies operability of the valve by stroking it from 100% open The and wastest observed was being byperformed at a local control test switch by a Reactor Operator (RO) the Shift Supervisor.

The movement of the valve is confirmed by observing the valve indication on the Main Control Board and therefore, communications had been established with the Control Room.

The R0tonotified switch the testthe ControlNOTE:

position. Room of his action and placed the two position (Normal / Test)

The switch has a spring return to the normal position. When the Control Room notified the R0 that movement of the valve was-

, satisfactory, he released the switch and it spring returned to normal. At this time, the

, valve went shut instead of returning to 'he full open position.

D Shutting of "A" MSIV isolated steam from a steam generator which resulted in an increased steam flow (SG) B and C.

and a rapid decrease in steam pressure from the remaining steam generators Low steam line pressure is "rate sensitive" and the rapid decrease in steam line pressaire resulted in initiating a Safety Injectiv., (SI)/ Reactor Trip. As a result of the valid SI, the Shift Supervisor declared the plant to be in a Notification of an Unusual Event (NUE) at 0510 hours0.0059 days <br />0.142 hours <br />8.43254e-4 weeks <br />1.94055e-4 months <br /> on May 12, 1988. Approximately five .ainutes later (0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br />), the condition of the plant was dowr. graded to normal.

Following the replacement of the test switch, restart was authorized and criticality was established at 2104 hours0.0244 days <br />0.584 hours <br />0.00348 weeks <br />8.00572e-4 months <br />, May 12, 1988.

On May 16, 1988, during a review of the post trip data by the Independent Safety Engineering Group (ISEG), it was identified that Service Water flow to the Reactor Building during the Cooling sub;ectUnits event. (RBCU) detericrated below the Technical Specifications limit CAUSE OF EVENT The cause of the closure of "A" MSIV is believed to be attributed to the operation of the test switch.

The R0 stated that on completion of the test, he may have "relaxed" holding the normal. switch in the test position prior to releasing it and allowing it to spring return to The Licensee has tested similar switches and found that continuity could be "broken" if it is slowly moved from the "Test" to "Normal" position. No interruption in continuity normal.

has been witnessed when allowing the switch to spring return from test to

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rorwn. ,-. . n.a .,, ,-c m,n m 8l8 0lq6 -j 0l 0 Oj 4 OF 0l5 The cause of low Service Water flow to the RBCU's during the event is believed to be due to an unidentified (at present) aquatic growth and/or silt deposits. The operations personnel could not specifically state that they saw or acknowledged the low Service Water flow alarm prior to securing the Service Water Booster Pumps (SW8P). Within five minutes of the initiation of this combined (SI/ Reactor Trip) event, 're were approximate 1/ 84 alarms which had to be acknowledged by control roorr 'sonnel which contributed to their uncertainty with respect to the low flow condit ..

The reviewers, performing the initial post trip review, verified the starting of the SWBP's and the initial flow rate of a minimum 4000 gpm, but failed to notice the flow deterioratica below the minimum value as required by the Technical Specifications.

ANALYSIS OF EVENT The consequences due to these events were minimal. The Redctor Protection System responded to the abnormal conditions by initiating the SI/ Reactor Trip. The computer printout verifies proper starting of the Service Water Sooster Pumps and the initial flow of a minimum 4000 gpm to the RBCU's. In addition, both trains of Reactor Building Spray System remained operable and are redundant to the RBCU's as stated in the Bases of the Technical Specifications.

Due to a previous steam generator tube leak, the steam exhausted to atmosphere from the Turbine Driven Emergency Feedwater Pump resulted in an unmonitored radioactive release.

The icrelease and hasconsequences.

cf minimal been calculated to be a small fraction of the allowable release limits IMMEDIATE CORRECTIVE ACTION On receipt of the Safety Injection and Reactor Trip, the Control Room Supervisor initiated action as required by the appropriate Emergency Operating Procedure (E0P).

Action, in part, required the verification of equipment starting such as Service Water Booster Pumps, Motor Driven Emergency Feedwater Pump, Turbine Driven Emergency Feedwater 1 Pumps, and Diesel Generators.

1 At approximately 0510 hours0.0059 days <br />0.142 hours <br />8.43254e-4 weeks <br />1.94055e-4 months <br />, the Shift Supervisor declared a Noti'ication of an Unusual Event (NUE) as a result of the SI which was downgraded to normal plant condition at 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br />.

Upon replacement of the HSIV switch, restart was authorized and criticality was established at 2104 hours0.0244 days <br />0.584 hours <br />0.00348 weeks <br />8.00572e-4 months <br /> on May 12, 1988.

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0l 0;6 _ 0;0 0;5 op 0 ;5 When identified on May 16, 1988 by ISEG that Service Water flow to the RBCU's had been below the Technical Specifications limit, both trains of R8CU's were declared inoperable.

Service Water flow balance was conducted and flow adjusted, as required, to other heat exchangers which increased the flow to "A" RBCU above the minimum required and the unit was declared operable after twenty-five hours and thirty minutes.

ADDITIONAL CORRECTIVE ACTION On May 17, 1988, Nuclear Operations was convened to review these events.a Management Review Board The following corrective action is to be taken:

Engineering is to review the design requirements of the MSIV circuitry, evaluate what is common any futuretotest. the "Normal" and "Test" circuitry, and identify what can be monitored during In addition, the circuitry is being evaluated to determire if-the "Test" circuitry can be segregated from the."Normal" circuitry.

A sign hasofbeen

operation posted on the test panels that instructs the test performer on the proper the switch.

- In addition, Operations personnel have been instructed not to operate the MSIV or test switch if another failure occurs until a complete inspection of the switch and associated solenoid valves has been performed.

With respect to the failure to identify the low flow condition, the following action is planned. Computer Services is to cxpedite the feasibility of displaying post trip parameters in graphical form to enhance review. Shift Engineers will be required to review this Licensee Event Report to increase awareness of the requirements for an indepth review of post trip data.

The A and B Train RBCU's have been acid cleaned and flow established to above the min required by Technical Specifications. Service Water flow to the R8CU's will be monitored periodically start in September to verify 1988. flow until the forthcoming refueling outage which is scheduled to A modification to the Service Water system is scheduled for this cutage. This modification will install qualified valves which w111 allow the isolation of one RBCU per 1 train and therefore reducing the flow requirement to 2,000 gpm.

PRIOR OCCURRENCES LER 85-005, April 16, 1985