05000261/LER-1981-016-03, /03L-0:on 810611,during Startup,Motor Driven Auxiliary Feedwater Pump a Tripped Due to Low Discharge Pressure While Feeding Steam Generators.Event Reoccurred on 810716.Caused by Backleakage Through Discharge Valve AFW-40

/03L-0:on 810611,during Startup,Motor Driven Auxiliary Feedwater Pump a Tripped Due to Low Discharge Pressure While Feeding Steam Generators.Event Reoccurred on 810716.Caused by Backleakage Through Discharge Valve AFW-40

ML20009G118
Person / Time
Site:	Robinson
Issue date:	07/10/1981
From:	Cox H CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009G110	List: 05000261/LER-1981-016, Forwards LER 81-016/03L-0 05000261/LER-1981-016-03, /03L-0:on 810611,during Startup,Motor Driven Auxiliary Feedwater Pump a Tripped Due to Low Discharge Pressure While Feeding Steam Generators.Event Reoccurred on 810716.Caused by Backleakage Through Discharge Valve AFW-40
References
LER-81-016-03L, LER-81-16-3L, NUDOCS 8108030344
Download: ML20009G118 (2)

LER-1981-016, /03L-0:on 810611,during Startup,Motor Driven Auxiliary Feedwater Pump a Tripped Due to Low Discharge Pressure While Feeding Steam Generators.Event Reoccurred on 810716.Caused by Backleakage Through Discharge Valve AFW-40

Event date:
Report date:
2611981016R03 - NRC Website

text

FORM 366 m S. NC6 EAR REGUMcTORY COMMIS$iGN 7

(7-77) #

LICENSEE EVENT REPORT e

CONTROL BLOCX: l l

l l

l l lh (PLEASE PRINT OA TYPE ALL REQUIRED INFORMATION) i 6

l0 l1l l Sl Cl H] B l Rl 2 l@l 0 l 0 l - l 0 l 0 l 0 l 0 l 0 l-l 0 l 0 l@l 4 l 1 l1 l 1 ' 1]@l l

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7 8 9 LICENSEE CODE 14 15 eCENSE NUMBER 25 26 LICENSE Ty 30 57 CAT 50 CON'T

(.0 l I l 3$n"CE l L }@l 0 l 5 l 0 l 0 l 0 l 2 l 6 l 1 @l 0 l 6 l 1 l ' l 8 l 1 @l 0 17 l 1 l 0 l 8 l 1 l 7

8 60 61 DOCKET NUM8ER 68 69 EVENT DATE 74 75 REPORT D ATE 80 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h io l2l l On June 11, 1981, at 1145 hours0.0133 days <br />0.318 hours <br />0.00189 weeks <br />4.356725e-4 months <br />, during plant startup, "A" Motor Driven A W Pump was l

Iol3l l noted to be tripped due to low discharge pressure while feeding the steam generators. I lol4l l On June 16, 1981, at 2115 hours0.0245 days <br />0.588 hours <br />0.0035 weeks <br />8.047575e-4 months <br />, with unit at 93% power, "A" AW pump tripped durine I

lo Isl l performance of Periodic Test 22.1C.

The remaining operable AW pump provides 100%

l l 0 l6 l l feedwater capacity and so there was no threat to public health and safety.

Since the l l o l 7 l l Steam Driven AW Pump was inoperable, this resulted in operation in a degraded mode l

I o Is l l permitted by Tech. Spec. 3.4.3 which is reportable pursuant to 6.9.2.b.2.

I 80 7

8 9 SYSTEM

CAUSE

CAUSE COYP.

VALVE CODE CODE SU8 CODE CO*jPONENT CODE SUSCODE SU8 CODE l0l91 l Hj H]h Wh l B lh lP lU lM lP lX lX lh lBl@ lZlh 7

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10 11 12 13 18 19 20 SEQUENTIAL OCCURRENCE REPORT REVISION LE R RO EVENT YEAR R EPORT NO.

CODE TYPE N O.

@ REPORT l8 l1 l l-l l0 l1 l6 l

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_ 21 22 2J 24 26 27 28 29 30 31 32 TAKEN A TO ON PLANT T

HOURS S 8 i FO 1 8.

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40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l i j o l l Af ter the fitst pump trip, the discharge valve was readjus ted.

Af ter the second l

li li j l pump trip, the cause of both trips was determined to be backleakage throuch motor 1

l operated discharge valve V2-16A and check valve AW-40 which created steam binding l

i,,,i lil3l l with u the pump casing.

These valves were reworked which reduced the backleakage.

l [i i4 ; j Additionally, as a precautionary measure, the pump casing is being vented hourly.

I 80 7

8 9 ST S

% POWER OTHER STATUS IS OV RY DISCOVERY DESCRIPTION NA l

l A l@l Operator Observation l

l1 l5 l dh l 0 l 0 l 0 lh' A TiVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE NA l

l NA l

li 161 I 21 @ l Z l@l 7

8 9 10 11 44 45 80 PERSONNEL EXPOSURES NUV8ER TYPE

DESCRIPTION

l Ii I 7 I l 0l ol Ol@l Zl@l NA w

2 a

Pe RSONN E L,Nau'R,,,

NUv8ER

DESCRIPTION

l 11 1a 1 l 0l 0l Ol@l NA 80 7

8 9 11 12 LOSS OF OR DAVAGE TO FACILITY TYPE

DESCRIPTION

NA l

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8 9 10

[ 8108030344 810710 NRc uSE ONLY PDR NA l llllllllll l l l :1 PDR ADOCK 05000261 68 69 80 5 i

7 iu (803) 383-4524

{

Howard T. Cox psoyg NAME OF PR3 PARER

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e Supplemental Information for Licensee Event Report 81-16 1.

Cause Description and Analysis:

On June 11, 1981, at 1143 hours0.0132 days <br />0.318 hours <br />0.00189 weeks <br />4.349115e-4 months <br />, during plant startup and the reactor critical, "A" Main Feedwater Pump was secured for repair of a drain valve leak on "6B" Feedwater Heater.

Both Motor Driven Auxiliary Feedwater Pumps started automatically as a resu.:.

"B" Auxiliary Feedwater (AFW) pump was secured and "A" AFW Pump alone was used to feed the steam generators. At 1145 hours0.0133 days <br />0.318 hours <br />0.00189 weeks <br />4.356725e-4 months <br />, it was noted that "A" AFW pump had tripped on low discharge pressure. The operators immediately went to the pump room, readjus ted ths cischarge valve throttled to prevent pump runout, and restarted the pump satisfactorily at 1215 hours0.0141 days <br />0.338 hours <br />0.00201 weeks <br />4.623075e-4 months <br />. The trip was thought to have been caused by an improperly positioned discharge valve. On June 16, 1981, at 2115 hours0.0245 days <br />0.588 hours <br />0.0035 weeks <br />8.047575e-4 months <br />, with the unit at 93% power, "A" AFW pump tripped during the performance of Periodic Test 22.1C.

Since the pump was ho t (indicating possible backleakage and pump casing vapor binding) the casing was vented., the pump was restarted, and the test was satisfactorily completed at 2132 hours0.0247 days <br />0.592 hours <br />0.00353 weeks <br />8.11226e-4 months <br />. After a review, it was determined that both pump trips were due to cavitation caused by steam as a result of backleakage through motor operated discharge valve V2-16A and check valve AFW-40.

During both events, "B" AFW pump was operatienal and capable of supplying the necessary feedwater. For this reason there was no threat to the public health and safety.

Since the Steam Driven AW pump was inoperable during this time, the failure of "A" AFW pump resulted in cperation in a degraded mode permitted by Technical Specification 3.4.3 which is reportable pursuant to 6.9.2.b.2.

2.

Corrective Action

Af ter the first pump trip, the discharge valve was readjusted.

Af ter the second pump trip, th'e pump casing was vented.

In bo th cases, the pump was successfully restarted.

i 3.

Corrective Action to Prevent Recurrence:

The motor operated discharge valve (V2-16A) and check valve (AFW-40) were repaired in an ef fort to stop the backleakage.

The backleakage, as indicated by pump casing temperature, was reduced low enough to preclude steam binding of the pump.

However, as an added precaution, the auxiliary operators were instructed to vent the pump casing as necessary on an hourly basis. This will continue until the next outage of sufficient length for a thorough investigation and the resolution of the backleakage problem.

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