ML20072P908
| ML20072P908 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 03/09/1983 |
| From: | Warembourg D PUBLIC SERVICE CO. OF COLORADO |
| To: | Wagner P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| P-83098, NUDOCS 8304040412 | |
| Download: ML20072P908 (2) | |
Text
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public senice company *e Cenomde
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16805 Road 19 1/2, Platteville, Colorado 80651-9298 qv-M}
March 9, 1983 TG
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- U) E Fort St. Vrain Unit No. 1 p
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L Mr. Philip C. Wagner, Project Manager Region IV Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011
Dear Mr. Wagner:
As you are aware, Fort St.
Vrain experienced an incident at approximately 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on March 9, 1983, which caused the loss of use of the Unit Auxiliary Transformer.
Technical Specification LCO 4.6.1(a) requires that both the Unit Auxiliary Transformer and the Reserve Auxiliary Transformer be operable for unrestricted reactor operation at power. A 24-hour period is allowed for either transformer to be out of service provided that both diesel generator sets are tested and are operable. Since the duration for which the Unit Auxiliary Transformer will not be available is not known at this time, but will in any event exceed the 24-hour limitation imposed by LCO 4.6.1(a), we propose to operate the reactor at up to 30% power i
for the purposes of primary coolant clean-up.
Sources of electrical power available at Fort St. Vrain other than the Unit Auxiliary Transformer include:
1.
The Reserve Auxiliary Transformer (RAT) - this transformer is i
used for plant startup and normally supplies plant shutdown auxiliary electrical requirements.
It also functions as a backup to the Unit Auxiliary Transformer.
2.
Emergency Diesel Generator Sets - two standby diesel generator sets provide an alternate on-site electrical power supply, either of which has adequate capacity to power all electrical auxiliaries that are essential for shutdown cooling.
3.
Five 230 KV Transmission Lines - these transmission lines are capable of supplying independent, redundant off-site power to either or _both of two switchyard busses which, in turn, can L
supply all on-site power.
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Mr. Philip C. Wagner P-83098 4.
Alternate Cooling Method Diesel Generator - this diesel generator unit is capable of supplying electrical power to load centers and motor control centers which are completely independent of the remainder of the plant electrical distribution system.
Rased upon the availability of electrical power as outlined above, the objectives of LCO 4.6.1 to assure that an adequate source of power is available to operate the plant during normal operation, for cooling during shutdown, and for operation of engineered safeguards in emergency situations is met.
We anticipate that it will require approximately ten days to complete performance of tests on the Unit Auxiliary Transformer and to repair associated bus ducts.
During the period from March 10 through March 20, 1983, we would propose to operate utilizing the intent of LC0 4.6.1 with the Unit Auxiliary Transformer out of service and with the following compensatory actions:
1.
Reactor operation at less than 30% thermal power.
2.
Once each 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, start both diesel generator sets to verify operability, shut the units down, and leave controls in the automatic mode.
3.
Continued operability of all three 480V a-c essential busses.
This mode of operation has been reviewed by the Plant Operations Review Committee with the finding that the change is safety significant because it involves a change to the Technical Specifications, but that the change is not an unreviewed safety question since loss of the Unit Auxiliary Transformer has been analyzed in the FSAR.
A formal Technical Specification change and attendent 10CFR170 Class III fees will be submitted under separate correspondence.
Ve truly yours, v/
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Don Warembourg Manager, Nuclear Produc ion DW/cls
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