ML16341C645
| ML16341C645 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 09/12/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 7909270279 | |
| Download: ML16341C645 (12) | |
Text
UNITE 0 STATES NUCLEAR REGULATORY COMMISSION REGION V 1990 N. CALIFORNIABOULEVARD SUITE 202, ItVALNUTCREEK PLAZA IVALNUTCREEK, CALIFORNIA94596 September 12, 1979 C. F~dcS Docket Nos.
50-275 50-323 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94106 Attention:
ter. Philip A. Crane, Jr.
Assistant General Counsel Gentlemen:
Enclosed is IE Bulletin 79-23 which requires action by you with regard to your power reactor facility(ies) with an operating license or a construction permit.'hould you have questions regarding this Bulletin or the actions required of you, please contact this office.
Sincerely, R. H. Engelken Director
Enclosures:
l.
List of IE Bulletins Issued in the Last Six t1onths cc w/enclosures:
J. Worthington, PG&E W. Raymond.
PGSE R; Ramsay,
- PGSE, Diablo Canyon
0 0
I
ssion No. 790S220104
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.S iNS No.:
6820 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT l'JASHINGTON, D.C.
20555 September 12, 1979 IE Bulletin No.,79-23 POTENTIAL FAILURE OF EMERGENCY DIESEL GENERATOR FIELD EXCITER TRANSFORMER Descri tion of Circumstances:
Florida Power and Light Company recen ly reported a problem encountered during a 24-hour full load test of the emergency diesel generators (EDG) at their Turkey Point facility.
Approximately 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> into the test, the A-EDG tripped due to a differential-relay lockout on B and C phases; the B-EDG was manually
- stopped, thus interrupting the test at that point in time.
Subsequent investigation and testing by the licensee revealed a design error on both the A and 8
EDGs which resulted in overheating of the Exciter Power Transformers (EPTs) at sustained high load operation.
The following nameplate data applies to the equipment installed at Turkey Point:
Emer enc Diesel Generator General Motors (Electro-Motive Division)
Model EMD-999-20 Engine-turbocharged, 2 cycle, EMD design 20-645E4 Generator-END-design Model A-20 Exciter Power Transformer GE-single phase Model -9T24Y1004 Seri a 1 -I 1D Cycles-60 KVA 15 Insulation-4160 V
The manufacturer's findings and recommendations regarding the above problem are described below:
"A potential problem can exist if the neutral of the generator and the neutral of the primary windings of the excitation power transformer (EPT)
(sometimes referred to as the control power transformer (CPT)) are connected.
A direct connection between the neutrals, or a connection through common grounding of both neutrals, are equally undesirable conditions.
Whenever ei ther of these undesirable con-ditionss
- exist, high circulating currents can be induced by harmonics.
These currents may exceed transformer ratings and result in transformer damage or failure.
IE Bulletin No. 79-23 Sember 12, 1979 Page 2 of 2 The connection between the neutrals, ei ther direct or through common grounding, may have been designated in the original wiring design, or may have been subsequently added by a contractor or by power plant personnel to balance excitation transformer voltages relative to the generator.
Ho significant benefi t is obtained by balancing the primary voltage of the exci tation trans-former by means of these connections."
According to the manufacturer, "to avoid this potential transformer damage or failure, the circuitry of each installation should be examined to determine if a circuit exists between the neutral of the primary windings of the EPT or CPT and the generator neutral.
If the condition exists, the neutral circuit should be disconnected, and the transformer primary neutral allowed to float."
Licensees may utilize Regulatory Guide
- 1. 108, Revision I, as a reference for the periodic testing of diesel generator units used as on-site electric power systems at nuclear power plants.
Action to be Taken by Licensees:
For all power reactor facilities with an operating license or a construction permit:
l.
Determine whether or not connections have been made between low KVA rated transformers and high KVA rated EDGs without adequate limitations on the flow of.circulating currents.
If applicable, provide a description of the corrective action being taken to address this problem.
2.
Provide a schedule for the completion of a sustained full-load operation test of the EDGs for a duration of not less than 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> s, or provide the results of the similar long duration, full-load test which has already been completed on the EDGs installed at your facility.
The test should demonstrate full-load carrying capability for an interval of not less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, of which 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> should be at a load equivalent to the continuous rating of the diesel generator and 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at a load equivalent to the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> rating of the diesel generator.
The test should also verify that voltage and frequency requirements are maintained and that the cooling system functions within design limits.
3.
Provide a written report of the above actions within 45 days of the receipt of this Bulletin.
Reports should be submitted to the Director of the appropriate NRC Regional Office.
A copy of your report should be sent to the U. S. Nuclear Regulatory Commission, Office of Inspection and Enforcement, Division of Reactor Opera-tions Inspection, IJashington, D.C 20555.
Approved by GAO, 8180225 (R0072); clearance expires 7/31/80.
Approval was given under a blanket clearance specifically for identified generic problems.
s
CE Bulletin No. 79-23 Sep'tember 12, 1979 LISTING OF IE BULLETINS ISSUED IN LAST SIX MONTHS Enclosure Page 1 of 3 Bulletin No.
79-14 (Supplement 2) 79 Subject Seismic Analyses For As-Built Safety-Pelated Piping Systems Possible Leakage of Tubes of. Tritium Gas in Time-pieces for Luminosity Date Issued 9/7/79 9/5/79 Issued To All Power Reactor Facilities with an OL or a CP To Each Licensee who Receives Tubes of Tritium Gas Used in Timepieces for Luminosity 79-13 (Rev.
1)
Cracking in Feedwater System Piping 79-02 Pipe Support Base Plate Rev. 1)
Designs Using Concrete Supplement
- 1) Expansion Anchor. Bolts 8/30/79 8/20/79 All Designated Applicants for OLs All power Reactor Facilities with an OL or a
CP 79-14 (Supplement) 79-21 79-20
.79-19 79-18 79-05C506C 79-17 Seismic Analyses For As-Built Safety-Rel ated Piping Systems Temperature Effects on Level t'leasurements Packaging Low-Level Radioactive Haste for Transport and Burial Packaging Low-Level Radioactive Haste for Transport and Burial Audibility Problems Encountered on Evacuation Nuclear'ncident at Three Nile Island - Supplement Pipe Cracks in Stagnant Borated Hater Systems at PHR Plants 8/15/79 8/13/79 8/10/79 8/10/79 8/7/79 7/26/79 7/26/79 All Power Reactor Facilities with an OL or a CP All PHRs with an operating. license All tlaterials Licensees who did not receive Bulletin No. 79-19 All Power and Research Reactors with OLs, fuel facilities except uranium mills, and certain materials licensees All Power Reactor Facilities with an Operating License To all PHR Power Reactor Facilities with an OL All PHR's with cooperating license
'I
'IEBulletin No. 79-23 September 12, 1979 Enclosure Page 2 of 3 Bulletin No.
Subject LISTING OF IE BULLETINS ISSUED IN LAST SIX HONTHS Date Issued Issued To 79-16 Vital Area Access Controls 7/26/79 All Holders of and applicants for Power Reactor Operating Licenses who anticipate loading fuel prior to 1981
~ 79-14 (Revision 1) 79-15 79-14 79-13 79-02 (Rev. 1)79-01A 79-12 79-11 79-10 Seismic Analyses For As-Bui 1t Safety-Related Piping System Deep Draft Pump Deficiencies Seismic Analyses for As-Built Safety-Related Piping System Cracking In Feedwater System Piping Pipe Support Base Plate Designs Using Concrete Expansion Anchor Bolts Environmental equal if ication of Class 1E Equipment (Deficiencies in the Envi-ronmental qualification of ASCO Solenoid Valves)
Short Period Scrams at BMR Facilities Faulty Overcurrent Trip Device in Circuit Breakers for Engineered Safety Systems Pequalification Training Program Statistics 7/18/79 7/11/79 7/2/79 6/25/79 6/21/79 6/6/79 5/31/79 5/22/79 5/11/79 All Power Reactor Facilities with an OL or a CP All Power Reactor Licensees with a CP and/or OL All Power Reactor facilities with an OL or a CP All PMRs with an OL for action. All BllRs with a CP for information.
All Power Reactor Facilities with an OL or a CP All Power Reactor Facilities with an OL or CP All GE B1JR Facilities with an OL All Power Reactor Facilities with an OL or a CP All Power Reactor Facilities with an OL
'September 12, 1979 LISTING OF IE BULLETINS ISSUED IH LAST SIX MONTHS Encl os ure Page 3 of 3 Bulletin No.
'79-09 79-08 79-07
- 79-06B 79-06A (Rev 1)79-06A 79-06 79-05B 79-05A 79-05 Subject Failures of GE Type AK-2 Circuit Breaker in Safety Related Systems Events Relevant to BWR Reactors Identified During Three Mile Island Incident Seismic Stress Analysis of Safety-Related Piping Review of Operational Errors and System Mis-alignments Identified During the Three Mile Island Incident Review of Operational Errors and System f1is-alignments Identified During the Three Mile Island Incident Review of Operational Errors and System Mis-alignments Identified During the Three Mile Island Incident Review of Operational Errors and System Mis-alignments Identified During the Three Mile Island Incident Nuclear Incident at Three Mile.Island Nuclear Incident at Three Mile Island Nuclear Incident at Three Mile Island Date Issued 4/17/79 4/14/79 4/14/79 4/14/79 4/18/79 4/14/79 4/11/79 4/21/79 4/5/79 4/2/79 Issued To All Power Reactor Facilities with an OL or'P All BWR Power Reactor Facilities with an OL All Power Reactor Facilities with an OL or CP All. Combustion Engineer-ing Designed Pressurized Water Power Reactor Facilities with an Operating License All Pressurized Water Power Reactor Facilities of Westinghouse Design with an OL
- All Pressurized Water Power 'Reactor Facilities of Westinghouse Design
. with an OL All Pressurized Water Power Reactors with an OL except BQl facilities All BMl Power Reactor Faci 1 ities with an OL All BQJ Power Reactor Facilities with an OL All Power Reactor Facilities with an OL and CP