ML20134B538

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Event Tracking Sheet Re 941023 Event Concerning Potential Containment Bypass Path Thru Lpsi/Naoh Addition Sys.Caused by Design or Installation Error
ML20134B538
Person / Time
Site: Saint Lucie NextEra Energy icon.png
Issue date: 11/10/1994
From: John Tappert
Office of Nuclear Reactor Regulation
To:
Shared Package
ML20134B255 List:
References
FOIA-96-485 27940, NUDOCS 9501300174
Download: ML20134B538 (4)
v • d • e


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c os OEAR EVENT TRACHING SREET SORT > Assignment Date l QUERY > *TAPPERT" $ Assigned To & Assir.ned Date >- 10/01/94 i

Plcnt: SAINT IECIE Unitt 1 Engineers TAPPERT J j Ev nt: 10/23/94 Norning Report: Briefing:

50.72#: 27440 LER#2 050000009400000 PN#:

Cther Notification: ,

Cycten: Components l l \

OPERATING NODE SIGNIFICANCE l bl' Operation A Reactor Protection System 7 - Se=rtop B Safety Related Cooling System i Hot Standby C - Fuel Cladding

. Hot Shutdown D Reactor Coolant Pressure Boundarv 5

6 Cold Shutdown Refueling

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Containment Plant Power dther C - Unexpected Plant Performance H - Other-CAUSE EVENT TYPE Equipment Failure SIC Significant Event Design or Installation Error x E01 - Event of Interest Operating Error TBD To Be Determined

. Maintenance Error OTH Other 5 External 6 Other POTENTIAL AO: Criterion:  ;

Proposed By: TAPPERT 3.

Engineer pI /1/p[q Approved: d -

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Sec t ion Leader ,

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EVENTS ASSESSMENT PANEL First Screening: 11/08/94 sYr significance

Description:

POTENTIAL CONTAINMENT BYPASS PATH THRU LPSI/NAOH ADDITION SYSTEM.

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ASSIGmENT DATE: October 24. 1994 ASSIGNED TO: TAPPERT l l l PLANT & UNIT: ST. LUCIE 1 l EVENT DATE: October 23. 1994 S0.72 REPORT NO: 27940 DAILY REPORT DATE/NO:

OTHER REPORT: LER 94-06 EVENT Sum ARY AND SPECIFIC FOLLOW-UP ASSIG MENT POTENTIAL CONTAINNENT BYPASS PATH THRU LPS!/NADH ADDITION SYSTEM EXAMINE FOR SAFETY AND GENERIC SIGNIFICANCE AND FOR TECHNICAL DETAIL.

CIRCLE THE APPLICABLE CASE:

SAFETY SIGNIFICANCE CLASSIFICATION: OTH E01 X SIG A0 GENERIC CONCERN STATUS: YES IN # BUL f GL#

OR BRIEF: YES

  • CLOSEOUT On October 20, 1994, while performing GL 89-10 differential pressure testing of MOVs, the Itcensee discovered a potential containment bypass flow path at St Lucie Unit I. Specifically, the, plant has two trains of Containment Spray.

The Containment Spray system uses a Sodi'.s Hydroxide Spray Additive system to cor. trol PH and maximize radiotodine removal from the containment atmosphere.

The NA0H is added using eductors that take a suction from the pump discharge and discharge to the pump suction. The design flaw discovered is that the flow paths for both trains of NA0H addition share a common leg of piping.

. Therefore, if one containment spray pump was running and the other was idle.

l the suction piping of the idle train would be pressurized from the running l train and lift the idle train's suction relief valve.

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In the event of a postulated loss of Coolant Accident concurrent with a failure of one containment spray pump failure (from Loss of Offsite Power and failure of one emergency Diesel Generator or direct failure of the pump), the suction reitef valve could open on the idle train, and after a Recirculation Actuation Signal would release containment sump inventory outside of

, containment. The reitef could also lift on a small break LOCA which did not

! require containment spray when a containment spray pump is procedurally aligned to the High Pressure Safety injection system for NPSH enhancement. The actual flow out of the relief would be limited by the NA0H Spray Additive system eductor to 128 gallons per minute. The FSAR assumes an Engineered Safeguards equipment external leakage rate of 2 liters per hour.

The relief valve is in the Reactor Auxiliary building and is served by the ECCS area filtered ventilation system. Despite the tremendous increase in leakage, the licensee concluded that, using WREG 1465 source terms and operational particulate efficiencies, offsite and onsite doses would not exceed regulatory limits. The Itcensee has also performed a modification to make the trains physically independent. This event has been classified as an Event of Interest.

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