ML20091J359

Final Deficiency & Part 21 Repts U-64 Re Limitorque Operator Motor Pinion/Worm Shaft Clutch Gear Failure.Initially Reported on 831017.Caused by Improperly Installed Motor Pinion Gears.Gear Failures May Also Impact Wolf Creek

ML20091J359
Person / Time
Site:	Wolf Creek, Callaway, 05000000
Issue date:	05/17/1984
From:	Schnell D UNION ELECTRIC CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
REF-PT21-84 U-64, ULNRC-828, NUDOCS 8406050486
Download: ML20091J359 (6)

Text

N y(b UNION ELECTRIC COM PANY 1908 G R ATIO1 STREET ST. LOUIS, M ISSOU RI May 17, 1984 OONALD P. SCHNELL O so 149 voce passeosNT ST. LOUIS, MISSOU R0 63 5 86 Mr. James G. Keppler

. Regional Administrator LU.S. Nuclear Regulatory Commission Region'III

'799 Roosevelt Road Glen Ellyn, IL 60137.

Dear Mr. Keppler:

ULNRC-828 FINAL 10CFR50.55 (e)/PART 21 REPORT:

LIMITORQUE OPERNrOR MOTOR PINION / WORM SHAFT CLUTCH GEAR FAILURE, U-64 l Ref: ULNRC-769 dated March 20, 1984 Enc: Examination Findings l

On October 17, 1983, Union Electric informed the NRC Region III office of a potential 10CFR50.55 (e)/10CFR21 regarding Limitorque operators for valves BN-EV-8812 A&B. On March 20, 1984, a final report, ULNRC-769, was written, concluding that the gear failures experienced were due to improperly installed motor pinion gears. This improper installation was attributed to site i maintenance activities. After the report was issued, various '

activities were initiated to implement the corrective action.

Included in these activities was a review of past maintenance records and inspection of previously damaged operators. One of these inspections revealed motor pinion / worm shaft clutch gear damage in a SB-2-80 type operator with a properly installed and oriented motor pinion gear, thus invalidating the conclusions reached in the referenced report. Therefore, on April 10, 1984, Union Electric notified the NRC that ULNRC-769 should be considered an interim report and that further investigations were underway to determine and.fix the problem.

Union Electric contacted Westinghouse requesting further

, assistance in assessing the situation and resolving the problem.

On April 12, 1984, with representatives from both Westinghouse Electro-Mechanical Division (EMD) and Limitorque on site, seven operators of the SB-2-80 type were examined. .The results of the examination are described in the-enclosure, " Examination Findings". Additional gear failures were found including the failure of a Unit 2 spare operator which was received from Westinghouse and had not been installed in the plant. This information indicated that the SB-2-80 actuators on valves EJ-HV-8811 A and B needed to be evaluated. Because of the failure of the spare operator, Union Electric contacted the NRC on April 18, 17 g84060504868h483 DR ADOCK 05 PDR

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'[Mr'lJamns G. Keppler.

.May.17,;1984 Paged 2

1984-informing them that' Union Electric considered the above failure a 10CFR Part 21 issue.

. Westinghouse and Limitorque. mobilized' additional resources

'to' address this issue. This effort consisted of tests and reviewsLof past operating history.. Tests were run at the Limitorque shop and Callaway site from April 120 until April 28,

'1984. Limitorque, working in their shop using a test stand, ran

a series-of tests and was not able to duplicate the failures Lwhich were occurring on site. After these inconclusive shop

. . tests, Union Electric, Limitorque,1and Westinghouse decided additional tests were needed.in the field. Westinghouse ran a series of tests in the field to evaluate alternate key material and obtained failures similar to.the ones previously encountered.

While the testing was going on, Westinghouse and Limitorque reviewed their records of the operating histories of the SB-2-80 type-operators.and data concerning other failures similar to the ones at the Callawayfsite. It was their opinion that this problem was' limited to SB-2-80 type operators at the Callaway

' site. .This information suggested-a.second course of action.

Concurrent.with the testing' program, Union Electric and Westinghouse pursued: acquisition of a replacement for the SB-2-80 typefoperator. SB-1-60. operators.wereiselected based on their use in similar applications. The'SB-1-60 type operator also provided direct.interchangeability-with the-SB-2-80 type operator

-and met all the valve design requirements. After the additional site testing of the SB-2-80 proved inconclusive, the decision was made to install and. test a SB-1-60 type' operator at.the'BN-HV-

8812A location. .If this, test proved successful, all-SB-2-80 type actuators would be, replaced with-SB-1-60_ type actuators.

Pr'ior to installation of the new operators on valve BN-HV-8812A, the. valve internals, seat,_and disk were inspected

-by Union Electric and Westinghouse EMDfpersonnel. The valve was found to'be in good condition with no' unusual wear. The first LSB-1-60. type operator was then' installed and tested at the.

BN-RV-8812A location on May 4,:1984.- The test, which was developed-by Westinghouse'SMD and is consistent ~in scope with

~

. earlier. tests 1that had induced gear. failure,. consisted of stroking the valve twenty-five times and then disassembling the actuator'to inspect the-motor pinion and worm shaft clutch gear.

LAfter completion of the test and disassembly, the gears were

found to be undamaged,_the keyways exhibited normal wear,

, ' setscrews were tight,-and there were'noisigns of stress. Based on:these facts, Westinghouse _and Union Electric declared the test.

successful'.

Based upon the successful-test, replacement of all remaining SB-2-80 taq?e actuators with SB-1-60 type - actuators -commenced. A total of four valve operators were affected, those at the BN-HV-8812A&B and EJ-HV-8811A&B. locations. It should be noted that.after installation each operator was subjected to a generic

. test to assure correct. installation and set-up. No problems were

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Mr. Jam s G..Keppler

, May 17, 1984' Page 3

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encountered. Based on the replacement of SB-2-80 actuators, the valve inspection program discussed in ULNRC-769 will not be implemented.

Union Electric considers this our final report on this item since we have replaced all SB-2-80' type operators on site.

Although this closes out Union Electric's action regarding this

-problem, these failures may impact other facilities, including the SNUPPS unit'at Wolf Creek. Therefore, SNUPPS will follow-up with a formal response to the' generic implications of this problem in regard to the Wolf Creek site. Included in this-report will be further discussions of the ongoing test program being conducted by Westinghouse.

Very truly yours,

~

Donald F. Schnell WBB/glp cc: -W. L. Forney, NRC Region III Richard DeYoung, Director I&E NRC Resident Inspectors, Callaway Plant (2)

Missouri Public Service Commission

9 STATE OF MISSOURI )

) SS CITY OF ST. ' LOUIS )

Donald F. Schnell, of lawful age, being first duly sworn upon oath says that he is Vice President-Nuclear and an officer of Union' Electric Company; that he has read the foregoing document and knows.the content thereof; that he has executed the same for and on behalf of.said company with full power and authority to do.so; and that the' facts therein stated are true and correct to the best of his

' knowledge, information and belief.

By c _ . _

5/ (

Donald F. Schnell Vice President Nuclear SUBSCRIBED and sworn to be' fore me this o?/# day of , 198M BARBkA e/gF PF[

NOTARY PUBUC, STATE OF MISSOURf NY COMMISSION EXPIRES APRIL 2L 1985

!= ST. LOUIS COUNTY d

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EXAMINATION FINDINGS ,

OPERATOR LOCATION- FINDINGS SERIAL NUMBER

1. 244650 Installed in the plant 1. No gear damage .

at BN-HV-8812A 2. Kcj for motor pinion gear deformed at center

3. Motor pinion setscrew bent (See Note 3)

2. 244651 Installed in the plant 1. Extensive motor pinion / worn shaft clutch at BN-HV-8812B gear damage-

2. Key sheared-

3. Setscrew sheared

3. 244653 Warehouse (See Note 1) 1. Broken teeth on motor pinion and worn shaft Previously installed clutch gear.

in the plant at 2. Key deformed at center BN-HV-8812A 3. Setscrew sheared

4. 247211 Warehouse (See Note 1) 1. No gear damage Previously installed 2. Key deformed at center in the plant 3. Setscrew loose at BN-HV-8812B

5. 208987 Installed in the plant 1. No gear damage at EJ-HV-8811B 2. Extensive key deformation at center

3. Setscrew loose

6. 249009 Warehouse (See Note 2) 1. Slight motor pinion / worn shaft clutch gear damage

2. Key deformed at center

3. Setscrew loose

7. 249010 Warehouse (See Note 2) 1. No gear damage

2. Key deformed at center

3. Setscrew tight

Notes

1. Operator previously installed in the plant as a temporary alteration and is in the process of being sent off-site

for refurbishment and requalification.

2. Unit 2 spare. No previous history of operation at Callaway.

3. Westinghouse conducted a series of additional tests on this valve operator with various key materials (see below) but using the same gear train. However, Westinghouse failed to perform a surface examination of the gear train prior to the second test making it uncertain whether the gear damage found after the second test can be attributed to the key material or some other mechanism for gear damage.

-Test 1 - 1018 (Certifi'ed) Key

l. No gear damage

2. Key deformed at center-

3. Setscrew loose

. Test 2 - 4140 Key

1. Motor pinion / worm shaft clutch gear damage

2. No key damage

3. Setscrew tight

_. _ __ - _ _ - - . - .