05000260/LER-1979-013-03, /03L-1:on 790530,reactor Core Isolation Cooling Sys Tripped on Overspeed During Flow Test.Caused by Improper Assembly Which Allowed Turbine Wheel Nut to Loosen,Causing Axial Loading of Bearings

/03L-1:on 790530,reactor Core Isolation Cooling Sys Tripped on Overspeed During Flow Test.Caused by Improper Assembly Which Allowed Turbine Wheel Nut to Loosen,Causing Axial Loading of Bearings

ML18024B031
Person / Time
Site:	Browns Ferry
Issue date:	09/24/1979
From:	TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18024B030	List: 05000260/LER-1979-013, Forwards LER 79-013/03L-1 05000260/LER-1979-013-03, /03L-1:on 790530,reactor Core Isolation Cooling Sys Tripped on Overspeed During Flow Test.Caused by Improper Assembly Which Allowed Turbine Wheel Nut to Loosen,Causing Axial Loading of Bearings
References
LER-79-013-03L, LER-79-13-3L, NUDOCS 7909280531
Download: ML18024B031 (5)

LER-1979-013, /03L-1:on 790530,reactor Core Isolation Cooling Sys Tripped on Overspeed During Flow Test.Caused by Improper Assembly Which Allowed Turbine Wheel Nut to Loosen,Causing Axial Loading of Bearings

Event date:
Report date:
2601979013R03 - NRC Website

text

lt t'L'UCLI;ARfII:I3197 lad j)f)IYUoh Mlosllttjt I7-71)

I ICENSEE EVENT REPORT IPI.EASE PRINT OR TYPE ALL REQUIRED INFOfltVIATION) t sj

'~jr>"wTROL CLoca:

I I

]Qi I

6 o Qj A

L g

RJ ~FZIOT o

o

o o

o o o

.,O' I I 0" ~0' 8

io LICENSEE COI)I 14

'lb LILLt,SE Nuh!OLII 2b JG LICENSE TYPL J0 br C>>f bjl COIJ'T

[@pe iij>oiji ~LC 0

5 0

0 0

2 6

0 7

0 5

3 0

I 7

9 jOs 0

9 2

4 7

~9 Qo DOCKET NUMBER G8 05 EVEoJT DATE 74 7s nEI on1 o>>1E No EVFNT DESCRIPTION AND PROIIAOLE CONSEQUENCES QIO

~o 2

( With reactor at rated temperature and pressure,.the RCIC tripped on overspeed during ~

~oz I flow 7:est.

> Coring tha investigation, there was a loss of sPeed signal in the control ezc~

the public.

Previous occurrences

BFRO 50-296/7832, BFRO 50-259/7615

~

Technical i Specification 3.5.F was involved.

~QS 7

8 9

SYSTEM

CAUSE

CAUSE Cohip.

VALVE CODE CODE SVOCODE COMPONENT CODE suocoDE suocoDE

[~CE Qi'+4 Gz

~x Oiz N

E 0

F

.0 IN Ojj

~z Oj" L~J Os 7

8 9

10 11 12 13 18 19 20 SEOUEN11>>l.

OCCURRENCE REPORT REVISION Lfnino EVEtiT YEAR R EPOR T NO.

CODE TYPE NQ.

Q!7 Ri>oe'79

~

~01 3

~m

~03

~L

~

~1 2'I 22 23 24 20 27 28 29 30 31 32 ACTION FUTURE EFFECT SHUT DO)VN ATTACHh'IFtiT NPRDP PRIME CohiP, CQAIPONfjnjl1 TAKEtl ACTIOtt ON PLANT METHOD

'HOURS Q22 suoMITTED FURM buO.

suf PLiER 'IANurAL'tu>>I'tl QAOj+20jn

+20zo QEQzj 0

0

+YQzz

+Q4 jJLj07'JLL ZIQQ(

'3 34 3b 38 37 40 41 42 43 44 CAUSE DFSCRIPTION AND CORRECTIVE ACTIONS 27 o

In> ro er initial assenbl allowed tnrbine wheal nut to loosen des~tr JdZE tgjERTs~nd A causin axial loadin of bearin s.

Bearin wear allowed shaft to gt~~p~~p causing speed control malfunction, thus throttle valve remained open.

Wheel nut,bear~

ings, and actuator replaced.

Woodward Governor, SN 968510.

Terry Turbine, Model A825~0 Type GS-l.

hiE THDD OF OISCOVfRY DISCOVEIIYOESCRIPfiON Q32 Qzi Operator Observation 4b 48i LOL~TION QF RELEASE NA 4 Ta

>17 i Pit 7 80

'/EI099805 't NRC LISE Oi'4L Y LLLLLI:

ii8 fi!I 7

8 5

FACILITY STATUS RL PQ'jNEII OTIIEflSTATU" E

Qzi, $0~01 Ooj NA 7

8 9

13 12 I'I 4 'I ACTIVITY COII IENI RELEr!SEU QP HEI EASI ALIOUNI'OFACTIVIfY

~Z 1~$

3 I~ZO34 NA 7

8 Ti 44 NI.RSUNt!EL fXP!JSUHES "II7,' 7l'H 1YPL OfScfliPI ION

~!7 j ~00 OJQ!7 ~ZQj[

NA 7

8 11 12 ii PEIISONtio L ftlJVflits 7

8 9

I I 12 LOSS Of On DAMAGETo FACILI1 Y TYPE DESCAIPTIQN o

ZQ77j NA 7 '

9 10 PU 8 L IC I 1 Y issuto ocscnip7iQN 4s o

LN 0!!

NA V.

9 Ii)

Nr)ME Oi PIIEPAIILf1 PIIONE'

4 1vb

~e Tennessee Valley Authority Fjrowns Ferry Nuclear Flarrt s

I'or'm I3F-17 BF I,").2 1/l0/79 LI!R SUPPLEMENTAL INFORMATION BFRO-.'>0-260 /

7913 Technical Specificatior. Involved Reported Under Technical Specification T.

S. 6.7.2.b.2 Date of Occurrence 5/'30/79 Time of Occurrence Unit Ederrrification and E)escr~ition of Ocrurr'ence:

RCIC would trip on overspeed when flow test was attempted.

Speed indicati'on was lost in control room during investigation.

(.rir><lition'rior'o O rcurr i rr< c Unit was at 1% power with rated temperature and pressure after refueling outage.

Action specified in the Technical Specific~sticn Surveillance Requirements met duo t~oino orebie eceu~imonc.

Describe.

HPCI operability SI's run.

~Ay)ar'ent Cause

<if Occurr'ence:

Initial malfunction of EG-R actuator caused throttle valve to remain open when RCIC was run resulting in an overspeed trip. During opera-bility tests 'to return RCIC to service, unusual bearing wear allowed shaft to strike magnetic pick-up and caused loss of speed indication.

Bearing wear may have caused initial malfunction of the EG-R. Cracks in bearings were found during disassembly.

The apparent cause of bearing failure was improper initial assembly allowing a turbine (OVER)

An:i~isis of Occrrrr e>>ce:

There was no damage to plant equipment, no activity released, no personnel exposure or injury, no hazard to health or safety of the public.

Cor r'ective Action:

Actuator and bearings replaced; ball and tappet overspeed trip mechanism was replaced; wheel nut was replaced and staked.

The bearings of other units will be inspected during next refueling outage.

I:ailure Data:

Previous occurrences

BFRO 50-296/7832, BFRO 50-259/7615.

":lletention:

eriod - Lifetune; Responsibility -,Administrative Supervisor

• Re rision:

'Se) s t

A arent Cause of Occurrence (Continued) wheel nut to unthread destroying its threads and causing axial loading cracking the bearings.

During bearing replacement, it was discovered that mechanical overspeed trip reset mechanism needed ad)ustment.

The ball and tappet trip mechanism was also inspected and the ball was found binding in its socket.

A arent Cause of Occurrence (Continued) wheel nut to unthread destroying its threads and causing axial loading cracking the bearings.

During bearing replacement, it was discovered that mechanical overspeed trip reset mechanism needed ad)ustment.

The ball and tappet trip mechanism was also inspected and the ball was found binding in its socket.