ML19338F831
| ML19338F831 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 10/20/1980 |
| From: | Swart F PUBLIC SERVICE CO. OF COLORADO |
| To: | Tedesco R Office of Nuclear Reactor Regulation |
| References | |
| P-80369, NUDOCS 8010270361 | |
| Download: ML19338F831 (3) | |
Text
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pubue service company e odewle 12015 East 46th Avenue, Suite 440; Denver, CO 80239 October 20, 1980 Fort St. Vrain Unit No.1 P-80369 Mr. Robert L. Tedesco Assistant Director for Licensing Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Docket No. 50-267
Subject:
Emergency Pcwer Systems
References:
Letter from Tedesco to Warembourg, dated 8/25/80, G-80149 Letter from Warembourg to Tedesco dated 10/15/80, P-80364
Dear Mr. Tedesco:
In the referenced correspondence of August 25, 1980, (G-80149) NRC requested that PSC review i:he current design of the Fort St. Vrain Emergency Power Systems in relation to the Staff Positions.
PSC has now completed the review and we are proposing plant modifications to meet the Staff Positions. The following reiterates the Staff's Positions and provides PSC's reply on a point by point basis:
l NRC Position 1: "Second Level of Under-or-Over Voltace Protection with a Time Delay" "We require that a second level of voltage protection for the onsite power system be provided and that this second level of voltage orotection shall satisfy the following criteria:"
NRC Position la:
"The selection of voltage and time setpoints shall be determined from an analysis of the voltage requirements of the safety related loads at all onsite system distribution levels;"
PSC Reply la:
There are no 4160V safety related loads at Fort St.
Vrain.
All safety related equipment items are powered at the 480 volt level and below.
The largest safety related motor is 150 horsepower.
Voltage and time setpoints have been determined to insure no safety related motor damage occurs at the 480 volt level.
Setpoints will be provided to the NRC in our forthcoming technical specification submittal (Refer to letter from Warembourg to Tedesco dated 10/15/80).
80102703W
[
.o P-80369 October 20, 1980 Page 2 NRC Position Ib:
"The voltage protection shall include coincidence logic to preclude spurious trips of the offsite power source;"
FSC Reply lb:
Coincidence logic will be utilized in the design. (Refer to PSC response to NRC position le for complete details).
NRC Position Ic:
"The time delay selected shall be based on the following conditions:"
(1) The allowable time delay, including margin, shall not exceed the maximum time delay that is assumed in the FSAR accident analysis;"
(2) "The time delay shall minimize the effect of short duration disturbances from reducing the availability of the offsite power source (s); and" (3)
"The allowable time duration of a degraded voltage condition at all distribution system levels shall not result in failure of safety systems or components;"
PSC Reply Ic.
(1) The Fort St. Vrain Station is not a Light. Water Reactor and does not have the critical " timing" concerns of a Light Water Reactor.
There is no need to immediately start reactor coolant or safety injection pumps.
These types of cooling systems do not exist at Fort St. Vrain.
Recognizing this, there was not and is not a need to analyze the aforementioned time delay.
(2) The design has always had this feature.
(3) The design has always had this feature.
NRC Position Id:
"The voltage monitors shall automatically initiate the disconnection of offsite power sources whenever the voltage setpoint and time delay limits have been exceeded;"
PSC Reply id:
This has always been a feature of the Fort St. Vrain design.
NRC Position le:
"The voltage monitors shall be designed to satisfy the requirements of IEEE Std. 279-1971, " Criteria for Protection Systems for Nuclear Power Generating Stations;"
P-80369 October 20, 1980 Page 3 PSC Reply le:
- The " Automatic Backup" connection to offsite power at FSV is made via the 230/4.16 kv reserve auxiliary transformer.
The required second level of undervoltage protection with a time delay has always existad on the FSV 4ky system.
The existing backup relaying will be supplemented by the addition of a third 4ky potential transformer and undervoltage rel ay. This will allow coincidence logic to be utilized and will allow t e intent of IEEE 279 to be met.
As previously stated, the 4kv buses are not safety related, but PSC will make the above mentioned modifications to meet the intent of the staff positions.
NRC Position if:
"The Technical Specifications shall include limiting conditions for operation, surveillance requirements, trip setpoints with minimum and maximum limits, and allowable values for the second level voltage protection monitors."
PSC Reply if:
PSC will provide any necessary Technical Specification chtnges as indicated in our October 15, 1980 letter Warembourg to Tedesco.
NRC Position 2:
" Interaction of Onsite Power Sources with Load Shed Featu re" "We require that the current system designs automatically prevent load shedding of the emergency buses once the onsite sources are supplying power to all sequenced loads on the emergency buses.
The design shall also include the capability of the load shedding feature to be automatically reinstated if the onsite source supply breakers are tripped.
The automatic bypass and reinstatement feature shall be verified during the periedic testing identified in Position 3."
PSC Reply Position 2a: These features are in the existing Fort St.
Vrain Design.
NRC Position 3:
"Onsite Power Testing" PSC Reply 3:
I Complete details of testing provisions will be provided in the aforementioned 4
- Technical Specification submittal.
- If you have any questions on this matter, please contact us.
Very truly yours, 7
/n4;_ f s=,{
Frederic E. Swart Nuclear Project Manager FES/ MEN:pa-
,