ML19330B663
| ML19330B663 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 07/30/1980 |
| From: | Clayton F ALABAMA POWER CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8008050346 | |
| Download: ML19330B663 (4) | |
Text
Alabama Power Cr.mpany 600 North 18th Street Fest Office Box 2641 Birmingnam. Aiaeama 35291 Telegnone 205 323 5341 L
hkjWe',"dtt Alabama Power July 30, 1980 Docket No. 50-348 No. 50-364 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Attention: Mr. A. Schwencer JOSEPH M. FARLEY NUCLEAR PLANT - UNITS 1 AND 2 DEGRADED ELECTRICAL POWER GRID CONDITIONS Gentlemen:
Enclosed is the information you requested by telephone on July 21, 1980, concerning the additional testing to be performed on Unit 2 to satisfy the NRC Staff Position 4 on this subject. This response super-cedes the Position 4 response included with the F. L. Clayton to A. Schwencer letter dated July 17, 1980.
Should you have any further questions, please advise.
Yours very truly, F~ L. Clayton, Jr.
TLC /rt Enclosures cc:
Mr. R. A. Thomas Mr. G. F. Trowbridge Mr. L. L. Kintner Mr. E. Reeves Mr. W. H. Bradford ol5 5
/!/
80 0 3 0 5 0 3f[f
ENCLOSURE POSITION 4' The voltage levels at the safety-related buses should be optimized for the full load and minimum load conditions that are expected throughout the anticipated range of voltage variations of the offsite power source by appropriate adjustment of the voltage tap settings of the intervening transformers. We require that the adequacy of the design in this regard be verified by actual measurement and be correlation of measured values with analysis results.
Provide a description of the method for making this verification; before initial reactor power operation, provide the documen-tation required to establish that this verification has been accomplished.
l
RESPONSE
In response.to IE Information Notice 79-04, Alabama Power Company submitted additional infomation to the NRC concerning.the adequacy of station electrical distribution system voltages by letters dated December 11, 1979, and May 1, 1980.
The December 11, 1979, letter contained voltage profiles which demonstrated that the voltage tap settings of the distribution j
system transformers have been optimized for the full load and minimum load conditions that are expected throughout the anticipated range of voltage variations of the offsite power source. A computer analysis was performed to obtain the optimum tap settings for the distribution system transformers, 4
and the optimum tap settings for each transformer are shown on the single line diagram which is contained in the December 11, 1979, letter.
Farley Unit 1 is currently operating with the transfomer taps set as indicated on the referenced single line, and Farley Unit 2 will utilize the same tap 1
settings.
i A test was perfomed at Farley Unit 1 to verify that the analytical method used for calculating the worst case voltage drop and to optimize the trans-former voltage tap settings is valid. A 7,000 hp Circulating Water Pump fiotor connected to 4.16 KV Bus 1B was started, and the voltage on the high voltage side of Startup Auxiliary Transfomer 1B and the voltage on 4.16 KV i
Bus IB were recorded for the motor starting condition.
The transformer j
low voltage winding which supplies the 7,000 hp motor was unloaded prior to the motor starting test. This test case was modeled on the voltage drop computer program, and the calculated voltage on 4.16 KV Bus 18 at the instant of motor starting was within 0.3% of the measured bus voltage for
~
this condition.
It should be~ pointed out tmtt the starting load of this motor represented approximately 50% of the total load that would occur due to an SI and a simultaneous reactor trip, which would be the worst case condition as described in the referenced December 11, 1979, letter. This demonstrates that the cable and transformer impedances used from the 230 KV system through'the startup transfomer and to the 4.16 KV bus are extremely
. accurate.
However, after several telephone discussions with the NRC Staff and their consultant, it was stated that further testing was required to demonstrate the. accuracy of:the circuit constants down to the 208V distribution level and to demonstrate the adequacy of the analytical model for performing
' accurate voltage drop studies. Therefore, the following additional test will
- be performed on Unit 2....
The purpose of the~ additional testing is to verify the accuracy of the transformer and cable impedances used in the computer analysis and to confirm that the methodology of the computer program for calculating the bus voltages is correct, given the 230 KV system voltage and the plant distribution system loadings. The test will be conducted as follows for the string of. buses.which were determined by the analysis to exhibit the largest voltage drops during the worst case analysis (refer to the attached figure for this discussion):
The electrical parameters (V, KW, KVAR) will be measured at the points shown with the loads indicated running at steady state.
These loads represent nearly 100% of the train 8 safeguards equipment which would be required under an actual safety injection conditica. Because this test will be performed during the Unit 2 Integrated Safeguards Test and since the non-1E loads will not be running, the total load on Startup Transformer 2B will be approximately 17% of the total load due to an SI and a simultaneous unit trip.
The test results will be recorded and the 230 KV system voltage and bus load parameters (KW, KVAR) recorded in the test will be input into the computer.
The bus voltages will be calculated using the same analytical model that was used in the worst case analysis. The analytical results will then be compared with the test results to demonstrate the adequacy of the calculational constants.
Some allowance must be made for error in the measurement of the electrical parameters due to tolerances of the bus instrument transformers and the test equipment (these tolerances will be specified in the submittal of the results to the NRC). Justification for differences between the analytical and test results, including these measurement errors, will be provided.
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