ML19350F087

LER 81-061/03L-0:on 810522,RHR Loop a Miniflow Valve, 1-FCV-74-12,declared Inoperable.Caused by Geared Limit Drive Hypoid Gear Cocked on Drive Sleeve,Out of Step W/Geared Limit Switch.Gear Realigned & Properly Installed on 810523

ML19350F087
Person / Time
Site:	Sequoyah
Issue date:	06/18/1981
From:	Harding M, Kirk G TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19350F086	List: ML19350F085 ML19350F087
References
LER-81-061-03L, LER-81-61-3L, NUDOCS 8106240200
Download: ML19350F087 (5)

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' EVEf47 DESCRIPTION AND PROSA8LE CONSECUENCES h .

o 2 [ Unit 1 in Mode 1 at 99% RTP. Residual Heat Renoval Loop A miniflov valve,1-FCV-74-12, [

o a I was declared inocerable. This event resulted in entry inlo LCO 3.5.2. There was no I o a l effect upon oublic' health or safety. Previous occurrences - none. 1 o s l 6

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p i Thf geared limit drive hvooid eear was discovered cocked on the drive sleeve.

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istilI caused the hypoid gear to set out of steo with the ceared limit switch. The hvooid i g i gear was realigned and installed properly on 5/23/81.

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LER SUPPLEMENTAL INFORMATION SQRO-50-327/81061- Technical. Specification Involved: 3.7.8.1 Reported Under Technical Specification: 6.9.1.13.b Date of Occurrence: ~ 5/22/81 Time of Occurrence: 1520 CDT Identification and Description of Occurrence:

_ . , t' Residual heat removal loop A miniflow valve,1-FCV-74-12, was declared inoperable. This event required entry into LCO 3.5.2.

Conditions Prior to Occurrence:

Unit 1 in' Mode 1 at 99% RTP.

Apparent Cause of Occurrence:

Removal of valve operator (Linit Torque SN3-00) housing cover found he cover cracked, the geared limit drive hypoid gear cocked on drive sleeve, and the pin which locates the hypoid gear on the sleeve . improperly installed. The

hypoid gear being cocked caused it to get out of step with the limit switch.

Analysis of Occurrence:

The following are possible causes of failure of the valve.

1. The housing cover was cracked either prior to or during operation. This may have caused the stack up of bearing and hypoid gear to move upward during operation.

2. Misassembly of hypoid ' gear onto sleeve at original assembly or by TVA d

Construction.

3. Improper installation of pin which locates hypoid gear on sleeve during origin'al assembly or by TVA Construction.

Because there is no clear TVA record that the failure is due to 1$ proper maintenance or operation, we have assumed it was a manufacturing defect.

Corrective Action:

The pin was removed, hole deburred, hypoid gear realigne'd, and pin installed properly on'5/23/81.

This event has been reported under 10 CFR 21.

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, i, LER SUPPLDiENTAL INFORMATION i

Corrective Action, Continued This event is conaidered as an isolated case, but the following additional

-actier, will be taken.

1. The applicable maintenance instruction (MI-11.2) will be revised to require that when maintenance is performed on any SMB-00 operator, that the hypoid gear be inspected for proper installation. ,

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2. ME?ntenance Requests will,be written to stroke each safety-related valve

.w ith a SMB-00 operator to observe operation of the valve and inspect outer housing cover ,for cracks and proper installation.

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o PART 21 REPORT LER 81061 Originating Document No. PRO-1-81-137 Plant: Sequoyah Nuclear Plant Component or System Identification: RER loop A miniflow valve 1-FCV-74-12

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Supplier of Co=ponent: Wastinghouse .

Nature of Defect or Noncompliance:

s Removal of valve operator (Limit Torque SMB-00) housing cover found the cover cracked, the geared limit drive hypoid gear cocked on drive -sleeve, and the pin which locates the hypoid gear on the sleeve improperly installed. The hypoid gear being cocked caused it to get out of step with the limit switch.

The following are possible causes of failure of the valve.

1. The housing cover was cracked either prior to or during operation. This may

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have caused the stack up of bearing and hypoid gear to move upward during operation.

2. Misasse=bly of hypoid gear onto sleeve at original asse=bly or by TVA Const ruction.

3. Improper installation of pin which locates hypoid gear on sleeve during original assembly or by TVA Construction.

Because there is no clear TVA record that the failure is due to improper maintenance or operation, we have assumed it was a manufacturing defect.

Extent of Safety Hazard:

A possibility of RHR pump burnout under certain conditions.

Date Which Defect or Noncompliance Was Discovered:- May 22, 1981 Number'of Identical Components in Us'e: h

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Location of Components: Various locations and systems Corrective Action Taken or To Be Taken:

The pin was re=cved, hole deburred, hypoid gear realigned, and pin installed properly on 5/23/81.

This event is considered as an isolated case, but the following additional action will be taken.

1. The applicable maintenance instruction (MI-11.2) will b'e revised to require that when maintenance is perfor=ed en any SM3-00 operator, that the hypoid i

gear be inspected for proper installation.

2. Maintenance Requests will be written to stroke each safety-related valve with a SMB-00 operator to observe operation of the valve and inspect outer housing cover for cracks and proper installatien.

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_,, .PART 21 REPORT

>. I Length of Time Required to Complete Action:

The valve was returned to service on May.23, 1981. The additional corrective actions will be ongoing.. .

!!as defect or noncompliance been reported previously? Yes No X 0

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