ML20087P748
| ML20087P748 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 04/02/1984 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8404090334 | |
| Download: ML20087P748 (2) | |
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g-TENN ESSEE VALLE AUTHORITY CHATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II
', ' ' ; [' 4 A 0Ip 2, 1984 BLRD-50-438/83-45
-BLRD-50-439/83-38 U.S. Nuclear Regulatory Coinnission Region II Attn Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Cecrgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - DESION OF AUXILIARY FEEDWATER PUMP TRIP AND THROTTLE VALVE ELECTRICAL CIRCUITS - BLRD-50-438/83-45, BLRD-50-439/83 FINAL REPOR_T The subject deficiency was initially reported to NRC-0IE Inspector L. Watson on July 19,1983 in accordance with 10 CFR 50.55(e) as NCR BLN EEB 8316. This was followed by our interim reports dated August 18 and December 27, 1983 Enclosed is our final report.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Janager Nuclear Licensing Enclosuro oc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Records Center (Enclosure)
Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite ~1500 Atlanta, Oeorgia 30339-
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ENCLOSURE s*
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 DESIGN OF AUXILIARY. FEEDWATER PUMP TRIP. AND THROTTLE VALVE ELECTRICAL CIRCUITS 10 CFR 50.55(e)
BLRD-50-438/83-45, BLRD-50-439/83-38 N P BLN EEB 8316
REPORT Description of Deficiency
' 1 The. electrical circuitry for the Auxiliary Feedwater Pump Turbine controls receives power through a manual transfer switch (1/2CA-43-003-S) from channel G
-s (normal) and. channel F (alternate) of the 125V DC Class 1E power system (EU) and the -120V Class '1E AC Vital Power Distribution System (EJ). The transfer switch is designated and labeled S.(special) for sepr. ration purposes; however, the cables, conduit, and equipment are ~ designated and labeled G (channel G). The
' design criteria " Physical Independence of Electrical Systems," M4-50-D786, stipulates that. circuits which can receive power from two divisions shall be
. identified as S and separated from all other wiring. Therefore, this circuit violates the requirements of the design' criteria.
1 The root cause of this deficiency was determined to be.mtsinterpretation of
' design criteria (" Physical Independence of Electrical Systems," N4-50-D786).
Design criteria N4-CA-D740, " Auxiliary Feedwater Systems," paragraph 6.9, states that the turbine controls shall:be powered from channel G with the capability'to n
- manually transfer -to channel F power.. The only guidance provided by N4-50-D766 -
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L to meet this'mquirement is not within the body of the criterion, but in a note associated with Table 5.4.1 of this document.
~ Safety Implications The incorrect identification and. labeling of the conduits, cables, instruments, Jand controls associated with the auxiliary feedwater pump turbine peroides false information to the operator and the maintenance staff. The identification tags indicate diannel G, but the system will at times be powered from channel F.
In
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this situation, the operator could authorize maintenance on the channel F power
. system or alignment of the auxiliary feedwater (AFW) system such that redundancy is lost. l A single failure could then degrade the AFW system so that it could not maintain adequate ' water level in the steam generators during all design base
' events.
At some future date, another channel G circuit could be routed with the AFW turbine control-circuits. This is possible since there are no specia notes,
' designations, or restrictions on the conduit and cable schedules to indicate the d-
.special natum of the AFW turbine control. circuits. If the routing of 1 additional channel G circuits in ~these raceways eventuates, both channels F and
- G control power sources could be lost due to a common failure.
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~ Corre*tive Artien I
The affected AFW pump turbine control cables, conduit, and equipment were revised to S. separation category on engineering change notice (ECN) 2372. The main control room instrumentation was mvised to S by ECN 2833. These revisions will result in the relabelling of the Effected cables, conduit, and equipment and onsure compliance with N!4-50-D786. All construction rework associated with these ECNs will be completed by January 15, 1985.
TVA considers this an isolated occurrence not requiring action to prevent recurrence.
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