ML20116L512
| ML20116L512 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 10/09/1992 |
| From: | Recasha Mitchell GENERAL ELECTRIC CO. |
| To: | Cwalina G Office of Nuclear Reactor Regulation |
| References | |
| REF-PT21-92 MFN-189-92, NUDOCS 9211180372 | |
| Download: ML20116L512 (5) | |
Text
I, October 4,1992 ELS92 04NRC.WP h1FN 189 92 Director of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Station 9 D4 Washington, D. C. 205S5 Attentior :
G, C. Cwalina Vendor inspection Branch
Subject:
Germane to Safety Safety Related RilR Pump Motor Fan Failure at a BWR/4 Plant Please fiad the attached memo of my telephone call to you of November 9,1992. The call provided information atx3ut the subject failure.
Very truly yours, Q -(
MG., Cd'L R. C. Mitchell, Project Manager Safety, Environmental A Quality Assurance Attachment ec:
L S. Gifford (GE Rockville)
P. W. Marriott (GE)
(USNRC)
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MEMO OF TELEPfiONE CALL DATE:
November 9,1992 TIMli:
10:10 A M PERSON CALLINO: R. C. Mitchell Pl!RSON CALLED:
G. C. Cwalina (NRC NRR/RVIB, El 501 D88)
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SUlHECT:
Safety Related RilR Pump Motor Fan Failure at a BWR/4 &nt Greg Cwalina was called in order to inform the NRC of a condition deten;ined to not be repos table but considered to be Germane to Safety, nis conclusion 's based upon GE compiding its evaluation as to reportability undar 10 CFR Part 21.
Background
.. BWR/4 utility recently informed riE NE that a safety related GE pump motor for the Residual lieat Removal (RiiR) system failed. During operation of the motor, a blade in the lower fan came
!oose and impacted the motor stator coils which caused an electrical fault. This motor was not original equipment. The utility had purchased this mctor from a canceled nuclear project. In addition to this recent failure, in 1980, the same BWR/4 utility had experienced a similar fan failure on one of the plant's original RHR pump motois. At that tim,it was concluded that the failure was due to fracturing of the single fdlet welds which attach the fan blades to the fan discs.
The utility subsequently fabricated a new fan for the failed motor and re-configured the current single fillet welds to include double fillet welds. In addition, to improve the reliability of other motors with this same fan weld design, the utility applied this new weld configuration to those motors, nis information was aup?ht;d to the NRC by this utility in June of 1980. Since that time, no further problems occurred until the recent fallere of the motor purchased from the canceled project.
The BWR/4 utility requested that GE NS determine the root cause of this recent motor fan failure. GE NE's evaluation concluded that the root cause of failure was a lack of weld penetration between the fan blades and discs.
Safety Basis GE NB has concluded that for the BWR/4 mility, this was a random single failure because in 1980 y
the utility applied the new weld configuration to all of their RHR motor fans. nerefore, only the motor obtamed from the canceled project had the potential for failure. This single failure is within t
the safety design basis of the plant and additional single failures do not have to be considered for this evaluation.
OE has no knowledge of any other BWR plants which have experienced this same kind of fan weld failure in the history of these motors, nese motors were built in the early 1960s by the GE San Jose Motor Plant, which is no longer in operation. Tne GE Motor plant applied this particular fan p.
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f weld nnfigurction (single weld) on thi-ty different motor models. GE NE does not have complete -
records of how many of these motor models are in o )erating nuclear pl:nts. Ilowever,it c:n be conservatively estimated that since 1972, there have en more than one hundred of these motors i
applied in safety related BWR applications, e.
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various Core Spray (CS) systems. In addition,g., Residuallleat Removal (RI since the early 1960s, many more motors have been used m non safety related and commercial applications. It is therefore reasonable to assume that all of these motors have seen many hours of service through BWR plant start up testing, plant operatloa (in the case of the RilR), surveillar/e (or other testing for the Emergency Core Cooling System motors), non safety related applications and commercial i
applications with no known fan weld failure other than the two failures reported by the BWR/4 utility, which were 12 years apart. His history 3rovides a basis forjudging the potential for fan weld failure on these motors to be a low proba 3ility event.
Corrective Actions and Preventive Measures GE has not issued a Service Advice Letter (SAL) because the GE facility that originally manufactured the GE motors ceases to exist. Ilowever, as a precautionary measure, on October 29,1992 GE NE issued a Germane to Safety communication to inform their BWR utility customers of this condition. GE NE recommended that all BWR utilities inspect the fan blade weld on all suspect motor models (attached) for proper weld penetration at the earliest possible time. PWR plants may also be affected by this condition.
New duplicate GE motors are manufactureAy GE Canada, Motors and Drive Department. As part of a design improvement, all new surph., motors (except for SK6337XCl24A and 5K6338XC89A) have the double fillet weld incorporated in the weld design.
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ATTACllMENT Siuspect Motor Model Numbers SK6346XC74A SK6346XC83A SK6348XC23A SK6348XC29A SK6346XC73A SK6346XC95A SK6346XC97A SK6346XC94A SK6347XCl22A SK6347XC100A SK6347XC109A
.5K6348XC94A
$K6348XC109A SK6348XC77A 5K6348XC98A SK6348XC84A 5K6348XC102A SK6348XC90A
$K6348XC107A SK6348XC47A SK6346XC102A 5K6348XC52A SK6347XC65A SK634'/XC59A SK6348XC39A
$K6346XC97B SK6348XC106A 5K6348X133A SK6348XCl32 SK6348XC110A SK6337XCl24A SK6348XCl27A 5K6338XC125A SK6339XCl49A
$K6338XC89A 5K6358XC3A 5K6326XC234A 5K6336XC295A
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f DISTRillUTION e
liig Rock Point J. W. Smith Ilrowns Ferry 1,2&3 J. E. Jones Brunwick 1&2 M. L. Ilurstell Caorso W. J. Zarella Chinshan 1&2 T.P. Lung Clinton J. W. Smith CNV1&2 R. B. Simons Cofrentes J. Montes Cooper B. J. Erbes Dresden 2&3
- 11. K.11erzog Duane Arnold R. E. Brown Fermi 2 J. E. Morrison Fitzpatrick R. J. Nicholls Fukushima 1,2&6 M. Yamaguchi OMN A. C. Steiner Grand Gulf R.O.Furgeson llatch 1&2 W. E. Grimrne l{ ope Creek P. C. Ray KKM_
P. F. Riner Kuo Sheng 1&2 T.P. Lung Laguna Wrde 1&2 R. R. Shepperd LaSalle 1&2
- 11. K.11erzog Leibstadt J. Villarreal Limerick 1&2 J. D. Decker Millstone 1 J. P. Riley Monticello C. N. Oallt Nine Mile Point l&2 P. Robles /H. R. Peffer Oyster Creek J. L Miller Peach Bottom 2&3 J. D. Decker Perry O. A. Watford Pilgrim A D. Ilimle Quad Cities 1&2
- 11. K. liervog River Bend W. D. Arndt Santa Maria de Garona J. Montes Shoreham R. W. Skrotsky Susquehanna 1&2 M. M. Urioste Tarapur 1&2 J. E. Morrissey Tokai 2 J.T Tanaka Tsuruga 1 J.T.Tanaka Vermont Yankee A. D. Himle WNP2 J. Armenta Affected Plant Contingent Information Plant 1-
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