ML20091J235
| ML20091J235 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 05/31/1984 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8406050443 | |
| Download: ML20091J235 (2) | |
Text
,,
e Duxe POWER GOMPANY P.O. HOX 33180 CHARLOTTE, N.C. 28242 HALH. TUCKER TELEPHOME vue runsasser (704) Oh4531 May 31, 1984 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Ms. E. G. Adensam, Chief Licensing Branch No. 4 Re: Catawba Nuclear Station Docket Nos. 50-413 and 50-414
Dear Mr. Denton:
Section 8.4.10 of the Catawba Safety Evaluation Report discusses Confirmatory Item 38, 100% Load Reduction Capability.
In response to this item, please find attached a revised response to Question 430.110.
Very truly yours, kb-lfjg Hal B. Tucker ROS/php Attachment cc: Mr. James P. O'Reilly, Regional Administrator U. S.
Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 NRC Resident Inspector Catawba Nuclear Station l
Mr. Robert Guild, Esq.
Attorney-at-Law P. O. Box 12097 Charleston, South Carolina 29412 Palmetto Alliance 2135) Devine Street Columbia, South Carolina 29205 Mr. _ Jesse L. Riley Carolina Environmental Study Group 854 Henley Place gd Charlotte, North Carolina 28207
- I B406050443 840531 PDR ADOCK 05000413
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CNS 430.110 Section 10.4.4.1 of the FSAR indicates Catawba can accept up to 100% turbogenerator load reduction without tripping the reactor or main steam relief valve actuation. Since this allows the turbine generator to remain on line powering station loads following a loss of the offsite power system, describe the magnitude and effect of the transient and. steady state voltage and frequency output of the main generator on the station loads (especially on Class lE loads) starting with and following load reduction.
Response':
.If the turbine generator is subjected to a 100% load reduction, the maximum voltage on the output of the generator is estimated to be approximately 129% of rated with the period of the excursion where voltage is above 110% of rated being approximately 3.2 seconds. The maximum frequency is estimated to be approximately 107.5% of rated.
The maximum values of voltage and frequency do not exceed nomal equipment ratings.
Per industry standards, power equipment such as 4 KV switchgear, 4160/600 V transformers, and 600 V switchgear is designed to with-stand voltages in excess of 1.4 per unit for a duration of 60 seconds.
Motors are typically subjected to hi-pot tests at 2150 volts for 575 volt motors, and 9000 volts for 4 KV motors for a duration of 60 seconds.
Based on vendor information and test results, electronic equipment and control components are also capable of withstanding the transient following a 100% load rejection. The frequency excursion would result in a motor speed increase of 71%; however, NEMA standards require that motors be designed to withstand overspeeds of 20% for short durations without damage.
The value above for maximum voltage is very conservative as it is based on initial conditions where the generator is operating 5%
above rated voltage with a power factor of 0.9.
Since the Catawba generators have a rated voltage approximately 5% higher than the connected transformers, the generators are not likely to be operated above rated voltage.
It is also unlikely that the unit would be operating with a power factor below 0.95.
Based on actual operating conditions, the maximum voltage should not exceed 122%.
Although the turbine generator is designed to accept a 100% load rejection, it is extremely unlikely that the unit will be subjected to a 100% load reduction while remaining on line powering station loads. This is especially the case since the unit is tied to the switchyard through two separate circuits which terminate in separate bays of a breaker-and-a-half arrangement.
430-53 Rev. 11 t