ML20009H279
| ML20009H279 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 07/31/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8108070138 | |
| Download: ML20009H279 (9) | |
Text
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TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 374ot 400 Chestnut Street Tower II l
CA h s
July 31, 1981 1
Mr. Harold R. Denton, Director Isu 0 G 198W 73 Office of Nuclear Reactor Regulation u.s. man uouuussa i' g ""
U.S. Nuclear Regulatory Commission 7
Washington, DC 20555 N/
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Dear Mr. Denton:
0) i i
In the Matter of the
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Docket Nos. 50-259 Tennessee Valley Authority
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50-260 In response to a letter from T. A. Ippolito to H. G. Parris dated July 20, 1981, enclosed is additional information regarding the electrical system modifications for the Browns Ferry Nuclear Plant in support of requested license amendment TVA BFNP TS 156 submitted to you by my letter dated April 9, 1981 and supplemented by letters dated June 8 and July 2, 1981. The enclosed consists of information regarding generator circuit breaker vendor testing, preoperational and periodic testing, and planned maintenance frequency.
l We hope that this will resolve all of the NRC staff's concerns regarding i
license amendment request TVA BFNP TS 156. Because of a delay in unit 1 restart date we now need NRC approval of TS 156 by August '14,1981.
As stated in my July 2, 1981 letter to you, the technical specifications proposed in TS 156 are to be implemented on Browns Ferry units 1 and 2 4
when unit 1 is returned to operation following completion of the current unit 1 refueling outage.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, nager Nuclear Regulation and Safety Subsce d nd swo to efore me this day of 1981.
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An Equal Opportunity Employer
6 ENCLOSURE RESPONSE TO NRC REQUEST FOR INFORMATION REGARDING TVA BFNP TS 156 BROWNS FERRY NUCLEAR PLANT
(
REFERENCE:
T. A. Ippolito 1etter to H. G. Parris dated July 20, 1981)
Question 1 7
Provide a table showing generator circuit breaker design specifications, testing required, tests performed, and test results.
Response
The requested data is tabulated in Table 1.
Question 2
/
In the GBB/TVA minutes of meeting of November 18, 1980 you discussed 4
testing for out-of-phase switching. Have these tests been performed? If so, provide the results.
Response
4 Out-of-phase switching was not included in the specification for the fr generator breaker'but was a later contract addition.- Brown Boveri Corporation (BBC) is completing their 200-kA breaker developmental l
testing program including out-of-phase' switching.^ The out-of-phase l
switching test will be performed for TVA observation after the developmental tests are complete. The breaker, as installed l
l with 165-kA rating, was tested for out-of-phase switching. These tests are listed in KEMA Report of Performance No. 2366-74 as the tests in 1
which the recovery voltage on opening is approximately 29-kV. See sheets 6 and 7 of Report 2366-74. A copy of the test report summary has been previously sent to NRC. 1The breaker'made' currents.as high as 251-kA peak
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and interrupted as high as 103 kA symmetrical and 133 kA asymmetrical at t
29-kV.
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4 Question 3 4
In your June 8, 1981 submittal you' state that the maximum fault requiring interruption is 145-kA and that the breakers are currently rated at 165-kA and will be upgraded to 212-kA.
In reference to the above provide
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the following:
a.
What is the basis for the above ratings?
b.
Provide a time table for completion of the modifications to upgrade the breakers to 212-kA.
Response-(a)
TVA has performed short circuit studies to determine possible fault l
currents. The rating of 165-kA is a specification of the generator
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breaker established by the breaker manufacturer. This rating is adequate for the foreseeable future.
A system change which could result in fault currents above 165-kA is the temporary use of a lower impedance generator step-up transformer.
This would be done only in the very unlikely event of a failure of more
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- m To account for this possible situation TVA plans to increase the interrupting rating to 200-kA.- (Previous references to 212-kA were i
incorrect. The breakers will be uprated to 200-kA). Long range short circuit studies do not indicate that the fault current will rise above 200-kA.
Response-(b)
Although the 165-kA interruptng rating will be adequate for a number of
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years, plans 'are to uprate the breaker.tx) 200-kA during the next refueling outage of unit 2.
This outage is presently scheduled for the g,,
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Question 4 7n the GBB minutes of November 14, 1980 youreferenceteststhatbave been' completed. You state these tests are listeo in table II of ANSI C37.09-1978. Are these tests the same as in table II of ANSI /IEEE C37.09-1979?
Response
The reference to ANSI c37.09 in the meeting minutes of November 13-14, 1980 was in error. The correct reference is ANSI C37.09-1971 which was the standard in effect during 1978. The TVA specification E6.7.01 for Browns Ferry generator breakers refers to ANSI Standard C37.09-1971 for testing and requires TVA approval for the omission of and 3nort-circuit test duty listed in Table II therein. At the present time, the applicable ANSI standard for generator brea'<ers is still under
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development in IEEE. Because of the absence of appropriate published standard, the peculiarities of generator breaker application, and the
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fact that manufacturers, particularly European manufacturers, prefer to
" package" their test shots (breaker operations) somewhat differently from the ANSI.C37.09 test duties, this is a reasonable approach to test
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specifications.
It should be noted that generator breakers of this high
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rating are only available from European manufacturers. The minutes of the meeting between Gould-Brown Boveri and TVA representatives of November 12 and 13, i980 records TVA's acceptance of test reports of previous applicable tests, both for the breaker uprated to 200-kA and with its initial 165-kA rating, and also recognizes certain listed test duties as not applying or as being enveloped by other tests which were performed. The short-circuit test report accepted for the 165-kA rated breaker is the report of tests performed for generator breakers for TVA's Raccoon Mountain Pumped-Storage Plant witnessed by TVA.
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As a result of IEEE breaker standards consolidation program during the 1970's, C37.09-1979 does include some test duties which are not listed in c37.09-1971, but none of these apply to generator breakerJ.
The minutes of the November 13-14, 1980 meeting relate acceptable test
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reports for the 200-kA breaker to ANSI test duties primarily for contract technicality purposes. However, we prefer to discuss only the 165-kA rating until the testing program is complete for the 200-kA rating. We anticipate this program will be completed by December 31, 1981.
Question 5 What onsite testing will be accomplished on the generatoa circuit breakers?
a.
preoperational test b.
periodic tests c.
maintenance frequency
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Response
The following is an outline of the preoperational testing, periodic testing, and maintenance frequency of the Browns Ferry Nuclear Plant 20.7-kV generator breakers.
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Preoperational Testing I.
Air Compressor Plant 1.
Calibration of pressure switches 2.
Functional check of controis circuit II.
Water Cooling Plant
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1.
Functional check of controls circuit 2.
Checkout of conductivity meter 3
Verification of flow sensors III.
Generator Breaker 1.
Calibration of pressure switches and gauges 2.
Tic ng S'sts on main, arcing, and resistor contacts of each phass f
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3 Doble tests (power factor) of each phase of the generator breaker 4.
Air consumption tests for breaker operation i
5.
Functional checkout of controls circuit (blocking, annunciation, etc.), includes protective relay calibration 6.
Main generator, main transformers, unit station-service transformers, and associated bus work protective relays selectivity testing b.
Periodic Testing NOTE:
The scheduling of periodic testing and maintenance I
frequency is based on an 18-month refueling cycle and is an estimate only.
Reevaluation will be done as experience is gained with the generator breakers. The testing and maintenance will be adjusted accordingly.
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Generator Breaker 1.
Every operating cycle a.
Calibrate protective relays 2.__..Every other operating cycle r
a.
Timing tests on main, arcing, and resistor contacts of each phase b.
Doble tests of each phase of the generator breaker c.
Air consumption tests for breaker operation c.
Maintenance Frequency I.
Air Compressor Plant
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1.
Once each operating cycle, check out compressor system 2.
Every,other operating cycle, service compressor plants completely l
II.
Cooling Water Piant 1
1.
Once each operating cycle, celubricate pump bearings and perform general inspection of water plant 2.
Every other operating cycle, celubricate motor bearings III.
Generator Breaker 1.
Once each operating cycle, perform visual inspection of breaker operating parts for wear 2.
Every third operating cycle, perform major overhaul on breaker l
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e Question 6 When will changes to the FSAR which incorporate the generator breakers be submitted?
Response
Submittal of an updated FSAR is required by July 22, 1982 pursuant to 10 CFR 50.71(e). The updated Browns Ferry FSAR will be submitted in the late spring-early summary 1982 time frame consistent with the above regulation.
It will contain a brief description of the Browns Ferry generator breakers consistent with the level of detail required by 10 CFR 50.71(e).
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ATTACHMSNT 1 BROWNS FERRY SPECIFICD RArl;fGS AND TESTS FOR GENERATOR BREAKERS Parameter Rating Tests 1.
Voltage kV-rms 24 Dielectric withstand 60 kV-rms, 1 minute, passed (routine test).
2.
Load current 36 Heat run BBC Rpt No.
(continuous) kA HAQ-2611E (on Bellefonte generator contract 72C2-85500), 40.8 kA 50 Hz = 38.51 kA 60 Hz, breaker within acceptable temperature rise.
3 Insulation level 150 kV BIL Withstood 1.2 x 50 microseconds 195 kV crest, positive and
~ negative waves, BBC test 1-352780-041-900 (Bellefonte).
4.
Interruptin$
165 capacity, kA-rms A.
Symmetrical 176 kA @ 15.5 kV. '(See Raccoon Mountain DEMA test No. - 2366-74.
Passed.
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B.
Asymmetrical 230 kA @ 15.5 kV.
(See KEMA 2366-74)." Passed. ~
5 Close and latch, 446 558 kA @ 20.5 kV.
(See kA-peak KEMA test report 624-80).
Passed.
6.
Short time, kA 3 sec @-
4 seconds @ 461 kA. '(See 165 kA KEMA 2366-74). Passed.
7.
Maximum rate of
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Not specified 3 kV/ microseconds.
(see
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rise of recovery KEMA 2366-74). Adequate, voltage 8.
Out-of-phase 29.5 kV, 29.5 kV @ 98 kA 90 kA asymmetrical.
(See KEMA
, 2366-74). Passed._
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