ML17353A614

Part 21 Rept 10CFR21-0073 Re Defect W/Voltage Adjust Potentiometer Mfg by Chicago Telephone Supply Used on NEI Peebles (Portec) Voltage Regulators at Plant.Util Updating Voltage Regulators W/Maury Instrument Corp Potentiometer

ML17353A614
Person / Time
Site:	Turkey Point
Issue date:	02/28/1996
From:	Nuding M MKW POWER SYSTEMS, INC.
To:	Hodge V NRC
References
REF-PT21-96 10CFR21-0073, 10CFR21-73, NUDOCS 9603270295
Download: ML17353A614 (14)

Text

CATEGORY 1 REGULATOR'TNFORMRTION DISTRIBUTION %STEM. (RIDE)

ACt.F;4SIO>'BR:9603270295 DOC.DATE: 96/02/28 NOTARIZED: NO DOCKET ¹ FA('!L.:<," 250 Turkey Point Plant, Unit 3, Florida Power and Light C 05000250 50--251 Turkey Point Plant, Unit 4, Florida Power and Light C 05000251 AU"1'H.NAME AUTHOR AFFILIATION NUDING,M. MKW Power Systems, Inc.

REClk.NAME RECIPIENT AFFILIATION HODGE,V. NRC No Detailed Affiliation Given SUBJECT; Part 21 rept 10CFR21-0073 re defect w/voltage adjust potentiometer mfg by Chicago Telephone Supply used on NEI Peebles (Portec) voltage regulators at plant. Util updating voltage regulators w/Maury Instrument Corp potentiometer.

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DISTRIBUTION CODE: IE19T COPIES RECEIVED:LTR \ ENCL i SIZE:

TITLE: Part 21 Rept (50 DKT)

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QlCI10 NOITrt 28 February, 1996 Vern Hodge USNRC Mail Stop 0-llA1 Washington, DC 20555

Reference:

Report No. 10CFR21-0073

Subject:

Reportable defect. with NEI voltage regulator voltage adjust potentiometer r

Dear Mr. Hodge:

MKW Power Systems'eport 10CFR21-0073 is attached which addzesses a 10CFR21 reportable. defect with the voltage, adjust potentiometer used on the NEI Peebles (Portec) voltage regulators. This was brought to our attention by FP6L - Turkey Point and we immediately began an investigation to determine the impact on other users of the same/similar ecpxipment. Our investigation was completed on 2/26/96.

Yours very truly, MKW POWER SYSTEMS, INC.

~i' Muo~g Michael Nuding General Manager Quality Assurance MN dg Enclosure 9603270295 960228 PDR AOOC(4, OSOOO2SOi S PDR lp('I Post Office Box 1928 ~ Rocky Mount, North Carolina 27802-1928 ~ Phone: (919) 9 -2720 TWX: (510) 929-0725 ~ FAX: (919) 446-3830

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Report No. 10CFR21-0073 FEBRUARY 27~ 1996 10CFR21 REPORTING OF DEFECTS AND NON-COMPLIANCE COMPONENT: Chicago Telephone Supply (CTS), p/n 115R251A Voltage Ad)ust Potentiometer SYSTEM: Diesel Generator control systems with NEI Peebles (Portec) Voltage Regulators CONCLUSION: Defect is Reportable in Accordance with 10CFR21 PREPARED BY: DATE: ~ +/+~

Donald D Galeazzi Engineering Manager REVIENED BY DATE:

Michael Nudi g General Manager, Quality Assurance Post Office Box 1928 ~ Rocky Mount, North Carolina 27802-1928 ~ Phone: (919) 977-2720 TWX: (510) 929-0725 ~ FAX: (919) 446-3830

0 0 REPORT NO. 10CFR21-0073 PAGE 1 OF 5 MKW Power Systems witnessed repair and testing of a voltage regulator foz FPEL Turkey Point at NEI Peebles on 2/10/96 and 2/11/96. NEI manufactured many of the voltage regulators utilized in MKW's safety related diesel generators. Voltage instability was observed and was determined to be caused by foreign material on the stationary wiper portion of the R4 voltage adjust potentiometer. The potentiometer is 250 ohm, 2wg manufactured by Chicago Telephone Supply (CTS), p/n 115R251A and had been used by NEI for over twenty years for this application.

Because of availability problems, NEI replaced the CTS potentiometer with Mauzy Instrument Corporation p/n 50-M123-251 in 8/94). This is an enclosed precision wirewound potentiometer, 250 ohm, 1.5w, with a shaft locking nut. According to NEI, applied burden is 0.06w. When compared to the CTS component, the Mauzy is an upgrade in quality and appears to be less susceptible to contamination on the wiper surface. The FPEL zegulatoz had the R4 potentiometer replaced with the Mauxy part while at NEI and the voltage instability was corrected.

The purpose of the R4 potentiometer is to adjust generator voltage to rated value after installation of the remote voltage adjust motor operated potentiometer. This is normally a one-time adjustment which occurs during initial installation/startup of the EDG and is applicable to the automatic and manual (if used) voltage regulators.

MKW has been supplying NEI voltage regulators foz safety related EDG control systems since 1972. This incident and one prior in 1994 (FPEL EDG 4A and 4B respectively) are the only reported problems of this type; therefore, it is difficult to interpret this occurrence as a defect. In addition, because R4 is normally a one-time adjustment, any foreign material which develops/

accumulates on the wiper surface will not affect voltage regulator operation because it will not interfere with the wiper surface to wiper axm interface. It is recognized that this could cause problems if field adjustment of R4 is required; therefore, MKW Power Systems will notify all customers with NEI voltage regulators about this potential condition.

Chicago Telephone Supply (CTS), p/n 115R251A (NEI p/n 01068).

REPORT NO. 10CFR21-0073 PAGE: 2 OF 5 U.ST Duke Power Oconee ¹72-13000-100 FPRL St. Lucie ¹2 ¹72-05000-100 ¹72-05100-100 FPEL Turkey Point ¹72-13000-100 ¹72-13200-100 Grand Gulf <<72-03200-100 ¹72-03100-100 Knolls Atomic - Kesselring ¹72-05000-100 ¹72-05100-100 Portland G.E. Trogan ¹72-00101-100 PPEL Susquehanna ¹72-08300-100 ¹72-08400-100 SMUD ¹72-05000-100 ¹72-05100-100 TVA - Watts Bar ¹72-06204-100 ¹72>>05100-100 TVA Watts Bar/Sequoyah ¹72-06204-100 ¹72-05100-100 Wisconsin Elec - Pt Beach ¹72-05000-100 ¹72-05100-100 Foreign Almaraz - Spain ¹72-05000-100 ¹72-05100-100 CNV/G.E. Spain ¹72-05000-100 ¹72-05100-100 Cofrentes/G.E. Spain ¹72-05000-100 ¹72-05100-100 Korea Elec Kori II ¹72-05000-100 ¹72-05100-100 KRSKO Slovenia ¹72-05000-100 Kuo Sheng/G.E. ¹72-05000-100 ¹72-05100-100 Laguna Verde (HPCS) ¹72-01200-201S ¹72-01200-101 Laguna Verde Units 1R2 ¹72-05000-100 ¹72-05100<<100 Phillippines ¹72-05000-100 ¹72-05100-100 Zorita - Spain ¹72-05000-100 ¹72-05100-100 DRZ1KT Microscopic examination of the potentiometer showed foreign material on the surface and edge of the stationary slip-ring under the wiper arm collar. The material on the edge was translucent/white-ish and appeared to be a lubricant. The material on the surface was blackish with some white flakes. It is postulated that the lubricate accumulated contaminants and/or dried on the surface. The total amount of foreign material is very small.

REPORT NO. 10CFR21-0073 PAGE 3 OF 5

1) FP&L is in the process of updating their voltage regulators with the Maury potentiometer. Other users should be aware of this possible problem and monitor their EDG output voltage for unstable output during routine testing. Replacement of the potentiometer is dependent upon monitoring/testing.

Immediate response to this notification does not appear to be necessary as the majority of the in-service voltage regulatozs have been operating without incident for approximately 15-20 years.

2) The potentiometer is soldered to a circuit board within the voltage regulator assembly; therefore, field modification is not recommended. For replacement of the potentiometer, recommended that the regulator be returned to NEI (either it is directly or through MKW Power Systems) where proper testing can be performed before the regulator is returned to the customer. Contact. MKW Parts Department for assistance.

If a regulator is to upgraded, we would also recommend replacement of the R5 (stability) potentiometer which is the same type as the R4 potentiometer except it is 100 ohms.

The R5 potentiometer is CTS p/n 115R101A (NEI p/n 01070) and its replacement is Maury p/n 50-M123-101.

REPORT NO. 10CFR21-0073 PAGE: 4 OF 5 EXHIBIT 1 (1 page attached)

VOLTAGE ADJUST POTENTIOMETER "R4" NEI DRAWING A-01068 CHICAGO TELEPHONE COMPANY POTENTIOMETER 4115R251A

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REPORT NO. 10CFR21-0073 PAGE: 5 OF 5 EXHIBIT 2 (1 page attached)

"R4 " REPLACEMENT MAURY f50-M-123-251

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