ML20207K748
| ML20207K748 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/18/1986 |
| From: | Meers B TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20207K578 | List: |
| References | |
| 302.02-SQN, 302.02-SQN-R03, 302.02-SQN-R3, NUDOCS 8701090508 | |
| Download: ML20207K748 (25) | |
Text
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-s TVA EMPI4YEE CONCERNS REPORT NUMBER: 302.02 SQN SPECIAL PROGRAM REPORT TYPE: Sequoyah Nuclear Plant Element REVISION NUMBER: 3
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REASON FOR REVISION:
To Incorporate SRP and TAS conuments Revision 1 To Include one additional concern Revision 2 To Incorporate SRP conuments and SQN Corrective Action Plan Revision 3 PREPARATION PREPARED BY:
B. Meers, Jr.
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DATE APPROVED BY-Yb l$~l$'f6 N/A ECSP MAN 4GER DATE MANAGER OF NUCLEAR POWER DATE CONCURRENCE (FINAL REPORT ONLY)
- SRP Secretary's signature denotes SRP concurrences are in files.
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TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT EMPLOYEE CONCERNS TASK GROUP OPERATIONS CEG i
Subcategory: Cable and Conduit Element:
Five Percent Low Voltage Problems Report Number: 302.02 SQN (Revision 3)
Concern Number: XX-85-122-004 H-85-122-005 MAS-86-004 Evaluator:
B. Meers. Jr.
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B.
eers, Jr.
Date 4*
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@' 'i, Reviewed by: ' OPS 'CEG Member Date Approved by:
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12.-3-1 /o n-W. R. Lagdedren Date 1324T
Revision 3
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FIVE-PERCENT LOW VOLTAGE starting of the Emergency Diesel Generators and of compensating for the five percent low voltage by operating the safety-related buses at higher
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than normal voltage levels. The concern of Diesel Generator starts is alleged to cause unnecessary plant shutdowns and place undue stress and wear on the Diesel Generators thereby reducing their reliability. Ihe concern of higher than normal voltage supplied to safety-related equipment is alleged to have overstressed and reduced the life and reliability of plant equipment.
The scope of this report is limited to evaluation of alleged Diesel Generator starts, plant shutdowns due to five percent low voltage, and the presence of higher than normal voltages on che safety-related 6.9-kV & 480-volts Shutdown Boards. The issue of Diesel Generi. tor reliability will be addressed in a report titled "D/G Reliability" (Reference 1).
This specific report will address diesel starts only to the extent that they did or did not occur.
II.
SPECIFIC EVALUATION METHODOLOGY This element is made up of two K-Forms and one concern identified to the Sequoyah Employee Concerns Program:
"II-85-122-004 - Sequoyah - a 5% voltage drop at each plant causes problems by cycling diesel generators unnecessarily (which degrades reliability) and causes too many plant
. shutdowns. TVA compensates by operating busses at higher than normal voltage ratings, anticipating voltage reductions, stressing equipment and components unnecessarily, and reducing component life and reliability. CI stated that there was inadequate voltage regulations for busses. CI has no further information. Anonymous concern via letter."
11-85-122-005 - Brown's Ferry - is worded identical to the above concern but specifically for Brown's Ferry and was transmitted as generic to other plants.
NAS-86-004 - Sequoyah - Potential equipment damage as a result of lR2 station over voltage.
l The K-forms were reviewed to determine the areas of concern. The referenced documents were reviewed to determine the requirements, archived copies of weekly Sequoyah Nuclear Plant Surveillance Instruction, SI-3 were reviewed to determine the past voltage conditions (Reference 14), and interviews were held with cognizant individuals Page 1 of 22
Revision 3
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in SQN Division of Power System Operations, operations, the operations
. procedures group, SQN Design Services (DNE), plant modifications group, and with a former supervisor of SQN electrical maintenance.
This report was completed in accordance with the " Evaluation Plan for the Operations Category Evaluation Group (CEG)" and the " Operations Subcategory Evaluation Plant (SEP)."
III. FINDINGS The Emergency Diesel Generators will start and assume the Shutdown Board load five minutes following the beginning of a sustained degraded voltage (95% normal voltage) if a Safety Injection Signal is not initiated or in ten seconds with a SI (Reference 2 and 3).
Either one of these events is reportable to the NRC and will result in a LER (License Event Report) being generated - any inadvertent Emergency Diesel Generator start is reportable by a LER (Reference 43). A search of LER's generated at SQN during the period 1980 to 1986 revealed no l
D/G starts because of degraded voltage. The correct operation and lR1 calibration of the degraded voltage relays was confirmed by interviews with cognizant engineers working in SQN DPSO.
A review of the documents governing SQN AC Auxiliary Power System voltage limits was conducted. These included:
- 1) The SQN Area Plan (Reference 12)
- 2) SQN Standard Practice SQO 39 (Reference 6)
- 3) SQN General Operating Instruction GOI-6G (Reference 5)
- 4) ANSI Standard C84.1 (Reference 7)
- 5) Nemoranda from Protection and Analysis Group (References 15 through 27)
- 6) Nemoranda from Engineering Design (References 28, 29, 31, and 34 through 36)
- 8) The SQN Technical Specifications for units 1 and 2 l
, (References 41 and 42) lR1 The industry standard that assigns recommended and safe limits on voltages for power system operation is ANSI C84.1.
The specific voltage limits regarding this concern are 6.73-kV to 7.24-kV and 440 volts to 504 volts (Range A service voltages that shall be met based on design);
6.56-kV to 7.26-kV and 440 volts to 508 volts (Range B service voltages that shall be met on an emergency basis, excursions from which shall be limited in extent, frequency, and duration), Reference 7.
These limits are defined in SQN Area Plan, SQO 39, and GOI-6G. The FSAR specifies the same voltage limits, but neither commits to or takes exception to ANSI C84.1.
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'~ 'DPN N7701 in the SQN Area Plan identifies C84.1 Range A voltages (in Table 1 of DPN N7701) as " Normal Voltage Range" and C84.1 Range B l
voltages (in Table 2 of DPN N7701) as "Ninimum Limits for Safe lR1 Operation." Footnote 2 to Table 1 states "The maximum voltage on the 6.9-kV unit board at Sequoyah Nuclear Plant must be maintained at 7,240 volts when fed from offsite power and 7,100 volts when fed from unit generator." Footnote 1 to Table 2 states "The minimum voltage limit on the 6.9-kV shutdown board at Sequoyah Nuclear Plant must be maintained at 6,700 volts until all the identified valve operators and pump motors are certified by the vendor or tested to operate at a reduced starting voltage." (Reference 12)
[R1 The DPN describes the transfer to alternate power sources as initiated by " loss-of-voltage type relays with an effective trip setpoint of 0 volts." No mention is made of the automatic transfer to an alternate source on degraded voltage as described in SQN FSAR Table 8.2.1-1.
DPN N7701 specifically addresses relays that monitor safety-related voltages for the purpose of automatic transfer to alternate sources, degraded voltage relays are not mentioned. The description of transfer to alternate power sources is not in accordance with the SQN FSAR (Reference 4).
The DPN N7701 reference to ANSI Standard C84.1 is out of date, although the subject voltage limits are the same.
SQN Standard Practice SQO 39 references DPN N7701 and requires that during " Units 1 and 2 Full-Load Operation" the Shutdown Boards are
" required to maintain a minimum of 6560 volts... for design basis trips" - this has not been observed in all cases (R.terence 37).
SQN General Operating Instruction G01-6G references both DPN N7701 and
)
SQO 39 and restates the maximum and minimum voltage limits cited in I
these documents. The GOI-6G Table 1 entry of 6560 volts is incorrect l
and should be 6730 volts to agree with the references cited. The GOI-6G Table 2 entry of 6,700 volts is incorrect and should be 6560 volts to agree with cited references. These errors were identified by comparison of GOI-6G with DPMN7701 and ANSI C84.1.
GOI-6G gives detailed instructions as to what immediate action short of tap changes is negessary should the safety-related board voltages exceed the voltage limits defined in Tables 1 & 2 - the action is to switch to alternate onsite power supplies until the voltages are restored to the table limits. This action has not been taken on numerous occasions and for prolonged periods of time when these limits were exceeded (References 37 through 40). No actions have been taken on these occasions due to lack of acceptance criteria on voltage limits or corrective action requirements in Surveillance Instruction SI-3.
Memoranda from the Protection and Analysis Group authorize transformer tap settings for SQN (References 15 through 27) that are consistent with ANSI C84.1.
Some other memoranda authorize grid voltages that are higher than these l
allowed by ANSI C84.1 based on the transformer tap setting i
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Revision 3 i
l authorizations (References 30, 31 and 34). At least three memoranda
,specifically state that grid voltages should be within the voltage limits of ANSI C84.1 through DPM N7701 (References 32, 33, and 45). No SQN instruction was located that defines and identifies the transformer tap assignment responsibility.
The SQN FSAR describes automatic transfer to alternate onsite ac voltage sources in case of loss of Shutdown Board voltage or degraded voltage (951 normal), but does not reference ANSI C84.1.
Specific instructions are also given for the case where the unit board voltage is 7260 volts or greater:
"The operator will. tate the action necessary to reduce the voltage" (Reference 4).
Numerous instances of voltages in excess of 7260 for extended periods of time are found recorded on SI-3 weekly data sheets. No evidence was found to indicate that attempts were made to reduce the voltages as required (Reference 40). The FSAR does not discuss voltages on the 480 volt Shutdown Boards that are in excess of the limits set by ANSI C84.1 and TVA (References 7, 5, 6, and 12).
Numerous instances of excessive voltages on the 480 volt Shutdown Boards were found which were both of relatively short and long duration (Reference 38). Voltages recorded from SI-3 were between 540 volts and 590 volts (Reference 39).
Cognizant engineers stated that motors at SQN have overheated and failed l
as a result of the high shutdown board voltages.
[R1 No undervoltage problems with the 480-volt buses have been identified by l
review of historical conduct of weekly performances of SI-3.
lR1 The SQN Technical Specifications specify only that the Shutdown Boards are required to be operable and that a given number are available. No definition or voltage requirements for operability range are specified (References 41 and 42).
The possibility of design problems associated with the AC Auxiliary Power System prompted a review of a Design Basis Analysis titled "AC APS Voltage and Loading Analysis - Sequoyah UI & 2."
(Reference 47).
In this analysis the statement is made that the Auxiliary Power System cable sizing is correct as identified by the plant cable pull cards.
This report was completed in accordance with ANSI C84.1 and did not identify any voltage drops that would explain the wide range of voltages read from the SQN Shutdown Boards as indicated by of SI-3 weekly / data.
Voltage readings from the 6.9-kV Shutdown Boards indicate that undervoltages were of such magnitude to have prompted Diesel Generator starts as described in the SQN FSAR (References 37, 3, and 4).
The FSAR describes Diesel Generator starts on degraded voltage as automatic.
This automatic start sequence is initiated by degraded voltage relays that have setpoints of 6560 volts. If any two phases of the Shutdown Boards drop below 6560 volts for more than 5 minutes, the Diesel 1
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Generators will be automatically started and the Shutdown Boards transferred to the diesel bus to correct the degraded voltage condition (Reference 3).
Cognizant individuals in DPS0 and operations stated that the degraded voltage relays that initiate the referenced Diesel Generator starts and Shutdown Board transfer were operational by October 1983. Before October 1983, the unit operator was responsible for starting the diesel generators and transferring the shutdown boards when observing degraded voltage conditions (Reference 4 and 37) lR1 because the shutdown board degraded voltage logic to start the generators l
was not a design installed feature. Since the October 1983 lR3 modification, three voltage readings from the 6.9-kV shutdown boards indicated that the diesel generators should have started automatically and shutdown boards transferred as described in the SQN FSAR (References 37, 3, and 4).
No records of Diesel Generator starts due to degraded i
voltage conditions on 6.9-kV Shutdown Boards could be located (Reference lR1 43). No reason for this failure could be identified.
lR3 Transformers tap settings in service at the present time were not field verifiable due to safety imposed access limitations (it is necessary to climb on top of the transformers to verify the high voltage-tap settings).
SQN Surveillance Instruction SI-3 (weekly conduct) documents a variety of data including Start Bus and Shutdown Board voltage readings. In addition to documented voltages outside the acceptable limits, the SI was found inadequate or weak in these areas:
The Shutdown Boards nomenclature is not specified (page 8 of SI).
Procedural errors were noted that included blank data sheets, entries of poor legibility, check marks or initials substituted for data, missing data sheets, and missing dates on data sheets (Reference 44).
The second page of the SI does not identify the location of the meters used to take the voltage readings.
The second page of the SI does not provide for the recording of the date.
l The acceptance criteria do not define the acceptable voltage l
limits.
lR1 No action is defined for failure to meet acceptance criteria as l
defined in GOI-6G.
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Conclusions:==
Several TVA procedures need to be updated and corrected.
As evidenced by analysis of weekly conduct of SI-3, several rather severe voltage deviations from normal have occurred on both the 6.9-kV and the 480 volt Shutdown Boards. Some of these deviations have been of 4
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such magnitude and duration as to possibly cause equipment degradation.
The wording of DPN N7701, SQO 39, and GOI-6G is such that effective instruction in controlling excessive overvoltages is lacking and the 4
instructions may be read such that inaction is incorrectly justified.
Acceptance criteria on voltage limits are lacking in the Shutdown Board l
voltage section of SI-3 (weekly).
[R1 Lack of adequate voltage acceptance criteria in the Shutdown Board section SI-3 (weekly) endangers safety-related equipment and may i
compromise safe shutdown capability, SQN FSAR lacks reference to ANSI C84.1 as it relates to Shutdown Board l
voltage limits.
IR1 SQN Technical Specifications for both Units 1 and 2 lack acceptance I
criteria on the limits for Shutdown Board voltage.
i As regards the instant concern:
"II-85-122-004 - Sequoyah - a 5-percent voltage drop at each plant causes problems by cycling diesel generators unnecessarily (which degrades reliability) and causes too many plant shutdowns. TVA compensates by operating busses at higher than normal voltage ratings, anticipating voltage reductions, stressing equipment and components unnecessarily, and reducing component life and reliability. CI stated that there was inadequate voltage regulations for busses. CI has no l
further information. Anonymous concern via letter."
l Based on the findings:
The issue of cycling Diesel Generators unnecessarily is not valid 1
because no evidence of such starts could be located in the LER history (Reference 43).
The issue of degraded Diesel Generator reliability is not evaluated I
in this report - this will be evaluated in SQN ECTG Report 301.02, i
" Diesel Generator Reliability Problems."
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buses at higher than normal voltage ratings cannot be verified.
Ample evidence exists to demonstrate that Shutdown Boards have been operated at low and high voltages (based on ANSI C84.1 and TVA requirements). Anticipation cannot be demonstrated, but inadequate requirements and procedures allowed the adverse voltage conditions to develop and be sustained in some cases. The concern of high voltage on buses is found to be valid.
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The issue of overstressing and degrading the reliability of I
i equipment is found to be valid. Corrective action response IR1 should include an assessment of potential future equipment l
1 reliability.
l The issue of inadequate bus voltage regulation is found to be valid because of the excessive voltage swings on the Start Buses and the Shutdown Boards when they are connected to either the grid or to the SQN turbine generators.
NAS-86-004 - Sequoyah - Potential equipment damage as a result of IR2 station over voltage.
l The issue of potential equipment damage as a result of station bus I
overvoltage at SNP is found to be valid because of numerous instances l
of voltages on both the 6.9-KV and 480 volt shutdown boards in excess IR2 of the maximum limit recommended in ANSI C84.1.
These repeated l
excessive voltages are the potential for degradation of energized l
electric motors and other equipment through the mechanism of l
overheating and eventual insulation breakdown.
IV.
200T CAUSE Based on the findings, the root cause is determined to be the failure I
to include adequate operational requirements in SI-3 and in the plant IR1 technical specifications for plant shutdown board voltage limits in l
aggordance with the SQN FSAR and ANSI C84.1 l
Y.
GENERIC APPLICABILITY This concern has been determined to be applicable to all TVA nuclear plants. Due to the findings cited, these conditions could exist at other plants possibly causing degradation of safety-related equipment.
lR1 Page 7 of 22
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e e- - - VI.
REFERENCES
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2.
SQN FSAR Section 8.2.1.6, "6.9 kV Start Board Control and Relaying," (Including Amendment 1).
3.
SQN FSAR Table 8.2.1-1, " Auxiliary Power Supplies and Bus Transfer Schemes," sheets 4 and 5. (Including Amendment 1).
4.
SQN FSAR Section 8.3, "Onsite Power System " (Including Amendment 1).
5.
SQN General Operating Instruction GOI-6G, " Apparatus Operations,"
Revision 27, dated May 31, 1986.
6.
SQN Standard Practice SQO 39, "Sequoyah Nuclear Plant - AC Auxiliary Power System Operating Instructions and Transformer Voltage Tap Settings," Revision 2 dated February 7, 1985.
7.
ANSI Standard C84.1 - 1982 (Revision of ANSI Std. C84.1 1977 and C84.la - 1980), "American Natior.a1 Standard for Riectric Fower Systems and Equipment - Voltage Ratings (60Hz)," Approved October 15, 1982 8.
SQN SWYD 3. " Operations of Sequoyah Nuclear Plant 500-kV and 161-kV Switchyards " dated April 9, 1975.
9.
SQN SWYD 13. " General for Generating Plants (as edited for SNP),"
. dated July 13, 1973.
10.
SQN SWYD15. " General for Generating Plants," dated July 9, 1981.
i 11.
SQN SWYD18 "Sequoyah Nuclear Plant Switchyard Operations -
l Sequoyah Nuclear Plant Voltage Schedule," dated December 7, 1084.
1%. SQN Area Plan 1403 TS 02.57.01, "DPN N7701."
13.
SQN Surveillance Instruction SI-3, " Daily Weekly, and Monthly Logs," Revision 49, dated June 27, 1986.
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April 20, 1986 on NPDCS Microfilm:
DATE MICROROLE NO.
DATE MICROROLE NO.
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800304 121-0244 800310 121-0181 800401 115-4783 800414 115-4648 800421 115-4533 800428 115-4470 800505 115-4391 800512 115-4313 800519 115-4198 800527 115-4123 800609 115-3997 800708 122-2919 800617 115-3894 800901 122-1460 800623 115-3822 800915 122-1273 800629 115-3759 800929 122-1100 800714 122-2831 801013 122-1868 800722 122-2718 801110 122-2139 800804 122-3374 801124 121-2412 800811 122-3279 801208 122-2499 800818 122-3191 801215 122-2390 800826 122-3102 801229 122-2253 800908 122-1361 810112 135-3496 j
800922 122-1185 810126 135-3319 801006 122-1703 810209 135-3842 I
801020 122-1629 810223 135-3664 l
801103 122-2171 810309 136-0075 i
801117 122-2027 810323 135-4119 Y
801201 122-2578 810406 145-2051 801215 122-2390 810420 145-1852 801222 122-2351 810504 163-0504 810105 135-3565 810518 162-4118 t
810119 135-3407 810601 185-2198 f
810202 135-3932 810615 185-1999 e
810216 135-3753 810629 185-1817 810302 136-0164 810316 135-4030 i
810330 135-3991 l
810413 145-1911 810427 145-1757 810510 163-0430 810525 162-3982 810608 185-2098 810622 185-1919 r
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DATE MICR0 ROLE NO.
DATE MICR0 ROLE NO.
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810706 196-2772 810713 196-2580 810720 196-2391 810727 196-2239 810803 218-2284 810810 218-2525 810817 218-2713 810824 218-2903 810831 218-3130 810902 240-2716 810907 240-2565 810914 240-2309
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810921 240-3034 810928 240-2857 811005 252-3673 811012 252-3460 811019 252-3918 811026 252-3161 811102 266-3164 811109 266-2960 811116 266-2685 811123 266-2409 811130 266-2176 811207 293-2506 811214 293-2799 811221 293-3079 811228 293-3255 820104 318-2243 820111 318-2485 820118 318-2666 820125 318-2870 820201 331-1943 820215 331-2332 820222 331-2496 820301 343-2404 820308 343-2592 820315 343-2798 820322 343-2994 820329 343-3204 820405 353-2310 820412 353-2501 820419 353-2689 820426 353-2892 820503 366-2393 820510 366-2598 820517 366-2794 820524 366-2953 820531 366-3111
.820607 371-2315 820614 371-2570 820621 371-2689 820628 371-2877 820705 385-2308 820712 385-2497 820719 385-2646 820726 385-2824 820802 395-2332 820809 395-2529 820816 395-2707 820823 395-2886 820830 395-3101 820906 405-2134 820913 405-2333 820920 405-2482 820927 405-2749 821004 418-2243 821011 418-2411 821018 418-2599 821025 418-2761 821101 426-1993 821108 426-2171 821115 426-2358 821122 426-2555 821129 426-2745 821206 438-3685 821213 438-3884 821220 438-4061 821227 438-4283 830103 449-3732 830110 449-3891 830117 449-4096 830124 449-4275 830131 449-4490 830207 461-2012 830214 461-2222 830221 461-2419 830228 461-2597 830307 468-2177 830314 468-2375 830321 468-2600 830328 468-2778 830404 476-2060 830411 476-2246 830418 476-2452 830425 476-2620 830502 487-1870 Page 10 of 22
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DATE MICROROLE NO.
DATE MICR0 ROLE NO.
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830509 487-2057 830516 487-2209 830523 487-2332 830530 487-2464
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830605 494-1865 830613 494-1997
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830620 494-2124 830627 494-2291 830704 508-1926 830711 508-2158 830718 508-2404 830725 508-2582 830801 531-3249 830808 531-3509 830815 531-3683 830822 531-3862
( p 8 of 20 missing) 830829 531-4103 830905 535-0310
( p 8 of 20 missing) 830912 535-0521 830919 535-0668 830926 535-0849 831003 543-1862 831010 543-2040 831018 543-2266 831024 543-2390 831031 543-2633 831107 554-2189 831114 554-2359 831121 554-2488 831128 554-2698 831205 567-2338 831212 567-2470 831219 567-2726 831226 567-2928 840102 586-0887 840109 586-1065 840116 586-1235 840123 586-1443 840130 586-1625 840206 595-2013 840213 595-2193 840220 595-2364 840227 595-2532 840314 610-2649 840319 610-2818 840326 610-2968 840402 619-2359 840408 619-2535 840416 619-2806 840423 619-2981 840430 619-3169 840507 630-2538 840514 630-2751 840521 630-2947 840528 630-3136 840604 643-3046 840611 643-3222 840618 643-3428 840625 643-3624 840702 655-4211 840709 656-0196 840716 656-0343 840723 656-0493 840730 656-0706 840806 665-2041 840812 665-2198 840820 665-2416 840827 665-2614 840903 676-2191 840910 676-2341 840917 676-2530 840924 676-2721 841001 682-1650 841008 682-1818 841015 682-1978 841022 682-2179 841029 682-2352
}
841105 687-2972 841112 687-3111 841119 687-3314 841126 687-3515 841203 701-0364 841210 701-0516 841217 701-0672 841224 701-0877 841231 701-1045 850107 713-1805 1
850114 713-1993 850121 713-2189 i
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Revision 3 DATE MICR0 ROLE NO.
DATE MICR0 ROLE NO.
850128 713-2356 850204 720-0269 850211 720-0461 850218 720-0709 850225 720-0879 850304 732-1830
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850311 732-1974 850318 732-2231 850325 732-2440 850401 749-3475 850408 749-3718 850415 749-3924 850422 749-4111 850429 750-0052 850506 778-1798 850512 778-2009 850520 778-2182 850527 778-2393 850603 792-3304 850610 792-3519 850617 792-3749 850624 792-3920 850701 805-1662 850708 805-1861 850715 805-2033 850722 805-2209 850729 805-2415 850805 816-2029 850812 816-2216 850819 816-2391 850826 816-2577 850902 846-1788 850910 846-1986 850916 846-2138 850923 846-2357 850930 846-2542 851007 862-2296 851014 862-2445 851021 862-2662 851028 862-2887 851104 886-2237 851111 886-2400 851118 886-2584 851125 886-2791 851202 909-2159 851209 909-2336 851216 909-2586 851223 909-2769 851230 909-2973 860107 935-0455 860113 935-0661 860120 935-0864 860127 935-1049 860203 953-1676
. 860210 953-1871 860217 953-2057 860224 953-2207 860302 972-0556 860310 972-0769 860317 972-0931 860324 972-1006 860331 972-1132 860406 979-3120 860414 979-3352 860420 979-3483 IJ. Namorandum from Alfred A. Surzese, Head, Protection and Analysis Group to Hugh Gardner, Area Manager, "Sequoyah Nuclear Plant -
Transformer Tap Settings," dated October 23, 1985, RINS E31 851023 200.
16.
Memorandum (TVA Form 45) from Ray A. Robinson to Hector DeSouza, Jr., "Sequoyah Nuclear Plant - Transformer Tap Settings," dated August 7, 1984, RIMS L23 840820 278.
17.
Memorandum from William A. Doyle, Supervisor, Protection and Analysis Group to Edward L. Eichelberger, Area Superintendent, "Sequoyah Nuclear Plant - Transformer Tap Settings," dated January 13, 1983, RIMS E07 830113 001.
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Memorandum from William A. Doyle. Supervisor, Protection and Analysis Group to Edward L. Eichelberger, Area Superintendent,
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"Sequoyah Nuclear Plant - Transformer Tap Settings " dated February 1, 1983, RIMS E07 830201 004.
19.
Nemorandum from William A. Doyle, Supervisor, Protection and Analysis Group to Edward L. Eichelberger, Area Superintendent, "Sequoyah Nuclear Plant - Transformer No., 1 Tap Settings," dated November 15, 1982 RIMS E07 821116 001.
20.
Memorandum from Protection and Analysis Group to Edward L. Eichelberger Area. Superintendent, "Sequoyah Nuclear Plant - Transformer No., 1 Tap Settings," dated November 4, 1981, (No RIMS No., assigned).
21.
Nemorandum from Protection and Analysis Group to Edward L. Eichelberger, Area Superintendent, "Sequoyah Nuclear Plant - Transformer No., 2 Tap Settings," dated November 4, 1981, (No RINS No. assigned).
22.
Memorandum from Protection and Analysis Group to William H. Morgan, Area Superintendent "Sequoyah Nuclear Plant -
6,900-480-Volt Transformer Tap Settings," dated March 6, 1981, RINS E07 810318 002.
23.
Nemorandum from Protection and Analysis group to William H. Norgan, Area Superintendent, "Sequoyah Nuclear Plant -
Common Station - Service Transformer A and B Tap Settings," dated October 17, 1980 RIMS E07 801029 001.
24.
Memorandum from William A. Doyle, Supervisor, Protection and Analysis Group to William H. Norgan, Area Superintendent.
"Sequoyah Nuclear Plant - Transformer Bank No. 1 Tap Settings,"
dated July 30, 1980, RINS E07 800730 003.
25.
Memorandum from Protection and Analysis Group to William H. Norgan, Area Superintendent, "Sequoyah Nuclear Plant -
Transformer Bank No. 1 Tap Settings," dated June 20, 1980, RIMS E07 800620 003.
26.
Memorandum from Protection and Analysis Group to William H. Norgan, Area Superintendent, "Sequoyah Nuclear Plant -
Common Station - Service Transformers A and B Tap Settings," dated March 3, 1980, RIMS E07 800303 001.
27.
Memorandum from Protection and Analysis Group to William H. Norgan, Area Superintendent, "Sequoyah Nuclear Plant -
480 Shutdown and Unit Boards - 6,900-480-Volt Transformers - Tap Setting," dated March 3, 1980 RIMS E07 800303 002.
Page 13 of 22
7 Revision 3
~~
28.
Memorandum from Roy H. Dunham, Nanager of Engineering Design to C.
E. Winn, Manager of P$wer Engineering, "Sequoyah Nuclear Plant -
Units 1 and 2 Auxiliary Power System Transformer Voltage Tap Settings," dated January 11, 1980, RINS EEB 800114 914.
29.
Memorandum from J. A. Coffey, Director of Nuclear Power, to R. W. Cantrell, Acting Manager of Engineering Design "Sequoyah Nuclear Plant Units 1 and 2 - Auxiliary Power System - Plant / Grid Interface Restrictions After Installation of Common Station -
Service Transformer (CSST) C-Quality Information " dated March 8, 1984, RINS?.
30.
Memorandum from H. L. Abercrombie Acting Nanager, Nuclear Production to C. C. Mason, Power Plant Superintendent, Sequoyah Nuclear Plant "Sequoyah Nuclear Plant Units 1 and 2 - AC Auxiliary Power System Plant / Grid Interface Restrictions After Installation of Common Station - Service Transformer (CSST)
C,"
dated July 19, 1983 RINS L23 830707 821.
31.
Nemorandum from H. N. Sprouse, Manager of Engineering Design to H.
J. Green, Director of Nuclear Power '"Sequoyah Nuclear Plant Units 1 and 2 - Auxiliary Power System - Plant / Grid Interface Restrictions After Installation of Common Station - Service Transformer (CSST) C - Quality Information," dated i
February 16, 1983, RINS EEB 830218 915.
32.
Memorandum from J. G. Dew 3ase. Assistant Director of Nuclear Power (Operations) to J. M. Ballentine, Power Plant Superintendent, NUC PR, Sequoyah Nuclear Plant, "Sequoyah Nuclear Plant - AC Auxiliary Power System - Plant / Grid Interface Operational Matrix," dated June 23, 1981, L22 810318 951.
33.
Memorandum from J. G. Dewease Assistant Director of Nuclear Power (Operations) to J. M. Ballentine, Power Plant Superintendent, NUC PR Sequoyah Nuclear Plant, "Sequoyah Nuclear Plant - AC Auxiliary Power System - Operating Instructions and Transformer Voltage Tap Settings - Sequoyah Nuclear Plant Standard Practice SQO 39," dated March 31, 1981, RINS L23 810329 876.
i 34.
Memorandum from M. N. Sprouse, Manager of Engineering Design to H.
I J. Green, Director of Nuclear Power "Sequoyah Nuclear Plant Units 1 and 2 - AC Auxiliary Power System - 161-kV Grid Operating Restrictions," dated June 1, 1981, RINS EEB 810602 925.
35.
Memorandum from Roy H. Dunham, Manager of Engineering Design to C.
E. Winn, Manger of Power Engineering, "Sequoyah Nuclear Plant -
l Units 1 and 2 AC Auxiliary Power System - Plant / Grid Interface "
dated February 1, 1980, (RINS No. not known).
1 1
l
)
i Page 14 of 22
=.
t Revision 3
~ ~ ~ -
~ ~ ~ ~
36.
Memorandum from M. N. Sprouse, Manager of Engineering Design to J.
R. Calhoun, Director of Nuclear Power, "Sequoyah Nuclear Plant
~ ~ ~ ~ ~ ~ ~
Units 1 and 2 - AC Auxiliary Power System - Plant / Grid Interface,"
dated October 17, 1980 RIMS EEB 801017 920.
37.
SQN SI-3, " Weekly Log Sheets" for the time period 1980 to
~"
April 28, 1986 on NPDCS Microfilm - LOW VOLTAGE PROBLEMS ON 6.9-kV SHUTDOWN BOARDS:
DATE MICROROLE NO.
DATE MICROROLE NO.
800311 121-0181 800325 115-4875 800505 115-4391 800623 115-3822 800629 115-3759 800708 122-2919 801103 122-2171 801222 122-2351 801229 122-2253 810105 135-3565 810223 135-3664 810302 136-0164 810309 136-0075 810323 135-4119
~
810504 163-0504 810608 185-2098 810706 196-2772 820705 385-2308 830425 476-2620 840220 595-2364 840528 630-3136 850225 720-0879 I
l I
Page 15 of 22
e Revision 3
~~~
~ - ~ = -
38.
~
SQN SI-3, " Weekly Log Sheets," for the time period 1980 to
_. -.~
~~
April 28, 1986 on NPDCS Microfilm - HIGH VOLTAGE PROBLEMS ON 480 VOLT SHUTDOWN BOARDS:
DATE MICR0 ROLE NO.
DATE MICR0 ROLE NO.
~~
800310 121-0181 800519 115-4198 800527 115-4123 800609 115-3997 800804 122-3374 800811 122-3279 800818 122-3191 800915 122-1273 800908 122-1361 800901 122-1460 800922 122-1185 800929 122-1100 801006 122-1703 801020 122-1629 801013 122-1868 801110 122-2139 801117 122-2027 801124 121-2412 801201 122-2578 801208 122-2499 801215 122-2390 801222 122-2351
~~
801229 122-2253 810105 135-3565 810112 135-3496 810119 135-3407 810126 135-3319 810202 135-3932 810209 135-3835 810302 136-0164 810309 136-0075 810316 135-4030 810427 145-1757 810511 163-0430 810518 162-4118 810601 185-2198 810622 185-1919 810706 196-2772 810713 196-2S80 810720 196-2391 810810 218-2525 810817 218-2713 810824 218-2903 810907 240-2565 810921 240-3034 810928 240-2857 811005 252-3673 811012 252-3460 811116 266-2685 811130 266-2176 811207 293-2506 811214 293-2792 820104 318-2243 820111 318-2485 820118 318-2666 820125 318-2870 820201 331-1943 820215 331-2332 820222 331-2496 820301 343-2404 820308 343-2592 820322 343-2994 820517 366-2794 820524 366-2953 820913 405-2333 820920 405-2482 820927 405-2749 821004 418-2243 821011 418-2411 821115 426-2358 821206 438-3685 821213 438-3884 821220 438-4061 821227 438-4275 830103 449-3732 820110 449-3891 830117 449-4096 830725 508-2582 830801 531-3249 830808 531-3509 830815 531-3683 830905 535-0310 830919 535-0668 831205 567-2338 831212 567-2470 831219 567-2726 831226 567-2928 840102 586-0887 840130 586-1625 Page 16 of 22
Revision 3
~~
'E
'DATE MICROROLE NO.
DATE MICROROLE NO.
'C 840430 619-3169 840514 630-2751 840604 643-3046 840924 676-2721 841008 682-1818 841022 682-2179 850121 713-2189 850415 749-3924 850422 749-4111 850429 750-0052
- - - ~
850506 778-1798 850610 792-3519 850624 792-3920 850902 846-1788 850916 846-2138 850930 846-2542 851007 862-2296 851104 886-2237 851111 886-2400 851118 886-2584 851125 886-2791 851209 909-2336 851216 909-2594 860120 935-0864 860331 972-1132 39.
SQN SI-3, " Weekly Los Sheets," for the time period $980 to April 28, 1986 on NPDCS Microfilm - HIGH VOLTAGE PROBLENS ON 480 VOLT SHUTDOWN BOARDS (VOLTAGES IN EXCESS OF 540 VOLTS):
DATE NICROROLE NO.
DATE NICROROLE NO.
800922 122-1185 801201 122-2578 801208 122-2499 801222 122-2351 801229 122-2253 810112 135-3496 810126 135-3319 810316 135-4030 810427 145-1757 810622 185-1919 810706 196-2772 810720 196-2391 810810 218-2525 810824 218-2903 810928 240-2857 811207 293-2506 820920 405-2482 821213 438-3884 830110 449-3891 830801 531-3249 830808 531-3509 830919 535-0668 840416 619-2806 840423 619-2981 840514 630-2751 850121 713-2189 850429 750-0052 851209 909-2336 860331 972-1132 40.
SQN SI-3, " Weekly Log Sheets" for the time period 1980 to April 28, 1986 on NPDCS Microfilm - HIGH VOLTAGE PROBLENS ON 6.9 Kv SHUTDOWN BOARDS:
DATE MICROROLE NO.
DATE MICROROLE NO.
800818 122-3191 801020 122-1629 801201 122-2578 801208 122-2499 801215 122-2390 801222 122-2351 801229 122-2253 810105 135-3565 810112 135-3496 810119 135-3407 810126 135-3319 810202 135-3932 810209 135-3842 810427 145-1757 810518 162-4118 810525 162-3982 Page 17 of 22
Revision 3 U ' ~ " ' ~ '
~
DATE MICROROLE NO.
DATE MICR0 ROLE NO.
810713 196-2580 810720 196-2391 810810 218-2525 810817 218-2713
~_
810824 218-2903 810921 240-3034 810928 240-2857 811005 252-3673 811012 252-3460 811116 266-2685 811130 266-2176 811207 293-2506 811214 293-2799 820104 318-2243 820125 318-2870 820201 331-1943 820215 331-2332 820301 343-2404 820322 343-2994 820329 343-3204 820517 366-2794 820524 366-2953 820614 371-2570 820913 405-2333 820920 405-2482 820927 405-2749 821011 418-2411 821213 438-3884 821220 438-4061 821227 438-4275 830110 449-3891 830725 508-2582 830801 531-3249 831205 567-2338 831212 567-2470 831219 567-2726 831226 567-2928 840423 619-2981 840430 619-3169 850422 749-4111 850624 792-3920 850701 805-1662 850902 846-1788 851007 862-2296 851125 886-2791 851216 909-2586 860120 935-0864
-41.
SQN Technical Specifications Section 3/4.8.1, "AC Sources,"
(Including Amendment 37) for Unit 1.
42.
SQN Technical Specifications Section 3/4.8.1, "AC Sources,"
(Including Amendment 29) for Unit 2.
43.
SQN Reportable Occurrence Log.
4,4. SQN SI-3, " Weekly Log Sheets" for the time period 1980 to April 28, 1986 on NPDCS Microfilm - PROCEDURE PROBLEMS:
DATE NICROROLE NO.
DATE NICROROLE NO.
810316 135-4030 810330 135-3991 811102 266-3164 811221 293-3079 820118 318-2666 820315 343-2798 820426 353-2892 820802 395-2332 820816 395-2707 830605 494-1865 830704 508-1926 840123 586-1443 840702 655-4211 841217 701-0672 850318 732-2231 850701 805-1662 850722 805-2209 851021 862-2662 851230 909-2973 860113 935-0661 860210 953-1871 860310 972-0769 Page 18 of 22
Revision 3
__7 _
- ~~" ~~ " ~
'45.
Memorandum from Roy H. Dunham, Manager of Engineering Design to C.
'~
^
~- ~~
~
E. Winn, Manager of Power Engineering, "Sequoyah Nuclear Plant Units 1 and 2 - AC Auxiliary Power System - Operating Restrictions," dated January 21, 1980, RIMS EEB 800121 901.
46.
~
Memorandum from M. N. Sprouse, Manager of Engineering Design to H.
J. Green, Director of Nuclear Power, "Sequoyah Nuclear Plant Units 1 and 2 - AC Auxiliary Power System - Plant / Grid Interface," dated
_l' February 19, 1981 RINS EEB 810219 907.
3 47.
"AC APS Voltage and Loading Analysis - Sequoyah UI E U2, OE2-EEBCAL00I," dated January 31, 1986, RIMS 860213F0048, MICROROLE 6105 860716F.
48.
Memorandum (form TVA 45) from G. T. Hall, SQN Engineering Design to Roy C. Denney, "High Voltage Potential - Employee Concern "
l dated January 29, 1986, (no RIMS number assigned).
i VII.
INNEDIATE OR LONG-TERM CORRECTIVE ACTION Sequoyah Nuclear Plant Line Management was notified of this
[
j report's findings during the conduct of this evaluation and has l
J initiated action to determine the extent of adverse consequences l
l to plant equipment and components attributable to higher lR1 than normal voltages.
Significant Condition Report (SCR) SQN
[R3
?
EEB86147 RO was initiated on November 21, 1986 to address this l
condition.The safety significance of subjecting plant equipment l
to higher than normal voltages cannot be made until that evaluation l
i is complete.
l The Sequoyah Corrective Action Plan (CATD 30202-SQN-01) is outlined in a memorandum from D. W. Wilson to R. C. Denney, dated November 10, 1986 (B25861114009) which reads as follows:
The purpose of this memorandum is to transmit the attached CAP 1
Tracking Checklist and to provide the revised CAP that will be usea l
to determine what corrective action is required for Employee lR3 Concerns Task Group Element Report 302 '_ SQN (S03 860815 852) l titled: -5 Percent Low Voltage Problems. This haemorandum supersedes l
j my memorandum to you dated September 18, 1986 (B25 860930 028).
l b
r, j
Page 19 of 22 i
--- _,--- ~ --_,
.-------n
Kevision 3
- w g& m~
- geop, The subject report concludes that : 1) voltage deviations with the i
potential to damage or degrade the reliability of equipment have i
occurred on both the 6.9kV and 480V Shutdown boards, 2) the 1
procedures lack effective instructions on controlling voltages, IR3 and 3) although the surveillance record of voltages indicates i
that undervoltage starts of the diesel generator should have l
occurred, there hcVe been no diesel generator starts due to 1
l This CAP addresses the three concerns of the subject report and I
determines what actions are required to prevent recurrence.
IR3 Action Plan A. To determine if equipment has really been unacceptably degraded the following steps will be taken:
I
'n IR3
- 1. Determine the maximum voltages that could have occurred in the i
auxiliary power system. This effort will pinpoint the boards IR3 that have seen the highest voltages and determine if equipment I
rated 8kV or 600 V ac will need any further consideration.
I OES will review the recorded voltages for the 161kV a.
i switchyard for the past year tc determine the maximum i
voltage that has occurred. This will establish the (R3 highest voltages for a two-unit shutdown.
EEB and i
OES will review historical data to determine highest i
voltages for a one-unit shutdown.
I b.
EEB will use the maximum switchyard voltage to determine I
maximum voltages in the auxiliary power system. REB will 1
develop an impedance diagram based on the minimum board I
loading, and, by using the maximum switchyard voltages I
as the source voltages, will calculate the maximum (R3 voltages of the boards. Operations will provide EEB l
with a history of tap changes for the Common Station i
Service transformers and 6900/480V Shutdown I
transformers and the existing tap settings.
I 2.
Review all Class 1E ac electrical equipment for susceptibility l to overvoltage. This will narrow the scope of the lR3 investigation to only the devices that are susceptable to I
overvoltage.
I SQEP will provide a list of types of equipment that have a.
(R3 been subjected to overvoltage.
l, Page 20 of 22 L
. =.
s Revision 3 pc m.
~
b.
EEB technical specialist will determine which devices I
are most susceptible to overvoltage and also which lR3
~ ~ ~~~~ ~ ~
devices may have been degraded.
l 3.
Sequoyah Electrical Maintenance will determine if there is l
evidence of overvoltage induced failures in the maintenance lR3
- record, i
Once the most susceptible equipment has been identified, the 1
= - - ~ -
maintenance record will be reviewed to determine if an lR3 excessive number of these components has required maintenance.
l 4.
Sequoyah Electrical Maintenance will field test the equipment
[R3 that is most likely to have been degraded.
l In addition to reviewing the maintenance record, a l
representative sample of susceptible components will be lR3 tested to determine if their insulation has been unacceptably l
degraded.
l B.
To correct and update the procedures the following steps will l
be taken:
l l
1.
Operations will immediately revise SI-3 by a temporary l
change to reflect acceptance criteria of ANSI C84.1, and to l
notify lead electrical engineer, DNE, if voltage cannot be l
maintained within these limits. Previously voltage readings l
were only taken to demonstrate board operability.
l 4
lR3 2.
EEB will perform load flow studies and coordinate with PSO to l determine the optimum transformer taps and switchyard l
voltages. Minimum load conditions (modes 5 and 6), in I
conjunction with maximum grid voltages will be used to I
establish transformer tap settings for maximum voltages.
l Maximum load conditions (LOCA and full load rejection) in l
j conjunction with minimum grid voltages will be used to I
i establish trsnsformer tap settings for minimum voltages.
l The minimum and maximum voltages and the transformer l
tap settings will be given to SQEP to release on a drawing.
l Revisions to procedures will be based on the information l
provided by the drawing.
l l
C.
To determine why undervoltage starts of the diesel generator have l not occurred the following steps will be followed:
I l
1.
SQEP will perform a comprehensive review of the voltage l
relaying and indication circuits. Relay and potentiel l
transformer accuracy, burden, human factors, and calibration I
will be considered to determine if the circuits have the l'
required accuracy.
I l
Page 21 of 22 i
i
e
/
Revision 3
'~"'[" ~' ~
" * ~
2.
If no problems are found in the design then SQEP will l
determine if testing or tracing the circuits is needed to I
ensure the circuits are performing as intended.
l I
.D.
If no problems are found in the voltage indicating circuits, then I
operations will determine why some of the voltage readings do not l
meet QA requirements.
l lR3 E.
Action to Prevent Recurrence l
l The root cause of this employee concern was determined to be I
inadequate procedures. The actions outlined in section B will l
prevent recurrence of this problem.
I I
The scheduled completion date for the above items is l*
December 22, 1986.
l Page 22 of 22
"R lil 4
RI I L Ri nc t.
- ECPS120J-ECPS121C
~
TENNESSEE VALLEY AUTHORITY PA%E FRLQULHCY
- REQUEST OFFICE OF NUCLEAR P0HER RUN TIME - IIn e
ONP - ISSS - R1'M EMPLOYEE CONCERN PROGRAM SYSTEM (ECPS)
RUN DATE - 10/l LIST OF EMPLOYEE CONCERN INFORMATION CATEGORY: OP PLANT OPER. SUPPORT SUBCATEGORY: 30202 LOH LINE Vr' T AGE g
S GENERIC KEYHORD A H
APPL QTC/NSRS P
KEYHORD B CONCERT:
SUB R PLT BBSH INVESTIGATION S
CONCERN KEYHORD C NUMB L':
CAT CAT D LOC FLQB REPORT R
DESCRIPTION KEYHORD D MAS-86-004 OP 30202 N SQN YYYY SS POTENTIAL EQUPMENT DAMAGE AS A RESUL REPORT T OF STATION OVER VOLTAGE n
XX 122-004 DP 30202 N SQN YYYY I-85-924-SQN SS SEdUOYAH - A 5% VOLTAGE DROP AT EACH NONCONFORMANCE T50217 K-FORM PLANT CAUSES PROBLEMS BY CYCLING DI CORRECTIVE ACTIOS ESEL GENERATORS UNNECESSARILY (HHICH GENERAL g
DEGRADES RELIABILITY) AND CAUSES TO EQUIPMENT 0 MANY PLANT SHUTDOHNS. TVA COMPENS ATES BY OPERATING BUSSES AT HIGHER T HAN NORMAL VOLTAGE RATINGS,ANTICIPAT g
ING VOLTAGE REDUCTIONS, STRESSING EQ UIPMENT AND COMPONENTS UNNECESSARILY
, AND REDUCING COMPONENT LIFE AND RE LIABILITY. CI STATED THAT THERE HAS y
INADEQUATE VOLTAGE REGULATIONS FOR BUSSES. CI HAS NO FURTHER INFORMATI ON.
ANONYMOUS CONCERN VIA LETTE XX 122-005 OP 30202 N BFN YYYY I-85-923-BFN NS BROHN'S FERRY - A 5% VOLTAGE DROP AT NONCONFORMANCE T50217 K-FORM EACH PLANT CAUSES PROBLEMS BY CYCLI CORRECTIVE ACTIO' NG DIESEL GENERATORS UNNECESSARILY (
GENERAL HHICH DEGRADES RELIABILITY) AND CAUS EQUIPMENT 3
ES TOO MANY PLANT SHUTDOHNS. TVA C0 MPENSATES BY OPERATING BUSSES AT HIG HER THAN NORMAL VOLTAGE RATINGS. AN TICIPATING VOLTAGE REDUCTIONS, STRES a
SING EQUIPMENT AND COMPONENTS UNNECE SSARILY, AND REDUCING COMPONENT LIFE AND RELIABILITY. CI STATED THAT TH ERE HAS INADEQUATE VOLTAGE REGULATIO 3
N FOR BUSSES. CI HAS NO FURTHER INF ORMATION. ANONYMOUS CONCERN VIA n
3 CONCERNS FOR CATEGORY OP SUBCATEGORY 30202 O
n 4
1 l
3
,