ML19296D308
| ML19296D308 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 02/27/1980 |
| From: | Ray J YANKEE ATOMIC ELECTRIC CO. |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19296D309 | List: |
| References | |
| WYR-80-23, NUDOCS 8003030415 | |
| Download: ML19296D308 (2) | |
Text
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4l Telephone 617 366-9011 TWX 710 390-0739 YANKEE ATOMIC ELECTRIC COMPANY
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B.3.2.1 Lc WYR 80-23 l[=L, 4,)
20 Turnpoke Road Westborough, Massachusetts 01581 KNKEE
,ss February 27, 1980 United States Nuclear Regulatory Ccmmission Washington, DC 20555 Attention:
Mr. Dennis L. Ziemann, Chief Division of Operating Reactors
References:
(1)
License No. DPR-3 (Docket.No. 50-29)
(2)
USNRC Letter to All Power Reactors dated August 8, 1979 (3)
YAEC Letter to USNRC, LER 50-29/79-26, dated October 27, 1979 (4)
YAEC Letter to USNRC dated November 1,1979, WYR 79-128 (5)
YAEC Letter to USNRC dated November 16, 1979, WYR 79-140
Subject:
Adequacy of Station Electric Distribution Systems Voltages
Dear Sir:
As required in Reference (2), we have reviewed the electric power systems at Yankee Rohe to determine if the offsite power systems and the onsite dintribution systems are of srfficient capacity and capability to automatically start and operate all safety loads if all onsite power sources are not available.
In developing this response, he discovered a potential problem existed when Yankee Rowe was off line, certain bus tie breakers were closed, and the grid voltage was at the minimum expected value. This potential problem hos reported in References (3) and (4).
Reference (5) proposed the installation of voltage regulators on the secondary side of the 115/2.4 kV station service transformers as the solution to this potential problem. The voltage regulators were installed and energized in January 1980.
Our analysis is based on the auxiliary power system with voltage regulators in service and the gufielines of Enclosure 2 of Reference (2).
Our analysis demonstrates that the onsite power system and offsite power system is of sufficient capacity and capability to start and operate all safety loads if all onsite power sources are not available. The analysis is contained in the attached report, YAEC 11206 " Auxiliary Poker System Study for Yankee Nuclear Power Station."
Reference (b) also required that the adequacy of the onsite and offsite power distribution systems be verified by test to assure that the analysis results are valid.
Because of the difficulty of simulating high and low f
8003030 N6 1
4 United States Nuclear Regulatory Commission February 27, 1980 Attn:
Mr. Dennis L. Ziemann, Chief Page 2 voltage conditions in the transmission system together with various conditions in the plant, we have chosen to verify the analysis using our computer program and our model of the station auxiliary power system to predict bus voltages for actual plant conditions. The verification is also contained in the attached report. Comparison of bus voltages predicted by the computer program to actual bus voltages reveal that the computer model is valid.
In addition, because voltage regulators are installed in the auxiliary power system at Yankee Rohe, adequacy of the station electric distribution system is assured by the proper operation of the voltage regulators.
We have reviewed the electric pover system at Yankee Rowe to assure that the intent of GDC-17 is met.
We have determined that, to the extent practicable, there are no events or conditions which could result in the simultaneous or consequential loss of both circuits to the offsite net 6crk.
We trust that this information ir satisfactory; however, should you desire additional information, please contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY
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d2L J. A. Kay Senior Engineer - Licensing JAK/jgh