ML18033B533
| ML18033B533 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/24/1990 |
| From: | Carier P TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9011050279 | |
| Download: ML18033B533 (11) | |
Text
ACCELERATED DISTRIBUTION DEMONSTPWTION SYSTEM
>>S tl REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9011050279 DOC.DATE: 90/10/24 NOTARIZED: NO DOCKET g
FACIL:50-259 Browns Ferry Nuclear Power Station, Unit 1, Tennessee 05000259 50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 AUTH.NAME AUTHOR AFFILIATION CARIER,P.P.
Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
R
SUBJECT:
Discusses Tech Spec Change Request 286 re RPS circuit protection trip level setpoints,per NRC 900922 request.
DISTRIBUTION CODE:
A001D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: OR Submittal:
General Distribution NOTES:1 Copy each to: B.Wilson,S.
BLACK 1 Copy each to: S.Black,B.WILSON 1 Copy each to:
S.
Black,B.WILSON D
/
05000259 05000260 A
05000296 D
RECIPIENT ID CODE/NAME KREBS,M.
ROSS,T.
INTERNAL: ACRS NRR/DOEA/OTSB11 NRR/DST/SELB 8D NRR/DST/SRXB 8E OC/LFMB
~RE~
EXTERNAL: NRC PDR NOTES COPIES LTTR ENCL 1
1 2
2 6
6 1
1 1
1 1
1 1
0 1
1 1
1 5
5 RECIPIENT ID CODE/NAME HEBDON,F NRR/DET/ECMB 9H NRR/DST 8E2 NRR/DST/SICB 7E NUDOCS-ABSTRACT OGC/HDS2 RES/DSIR/EIB NSIC COPIES LTTR ENCL 1
1 1
1 1
1 1
1 1
1 1
0 1
1 1
1 D
R D
NOTE TO ALL"RIDS" RECIPIENTS:
D D
PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 28 ENCL 26
t t
TENNESSEE VALLEY AUTHORITY TVA-BFN-TS-111 P. 0. Box 2000
- Decatur, Alabama 35609-2000 I
GQ ~4 tm~
10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of Tennessee Valley Authority Docket Nos. 50-259 50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) TVA BFN TECHNICAL SPECIFICATION (TS)
NO. 286 REACTOR PROTECTION SYSTEM (RPS)
CIRCUIT PROTECTION TRIP LEVEL SETPOINTS
RESPONSE
TO REQUEST FOR ADDITIONAL INFORMATION By correspondence dated June 4, 1990 TVA submitted a request for TS amendment to revise the RPS circuit protection trip level setpoints for unit 2 and add surveillance requirements section 4.1.B.2 containing the same setpoints for units 1
Ec 3.
By correspondence dated September 22,
- 1990, NRC transmitted a
request for additional information.
Attachment 1 provides the information requested by the NRC staff.
There are no commitments contained in this correspondence.
Xf there are any questions about this response, please telephone Patrick P.
Carier at (205) 729-3570.
Very truly yours, TENNESSEE VALLEY AUTHORITY rick P. Carier, Manager of Site Licensing Enclosures cc:
See page 2
9011050279 901024 PDR ADGCK 05000259 P
PDC An Equal Opportunity Employer
lj
~
~
U.S. Nuclear Regulatory Commission OCT 2~
tc<0 cc (Enclosures):
American Nuclear Insurers Attention:
Librarian The Exchange, Suite 245 270 Farmington Avenue Farmington, Connecticut 06032 Ms.
S.
C. Black, Deputy Director Project Directorate II-4 U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. Charles R. Christopher, Chairman Limestone County Commission P.O.
Box 188
- Athens, Alabama 35611 Dr.
C.
E. Fox State Health Officer State Department of Public Health State Office Building Montgomery, Alabama 36194 Mr. J.
E. Jones General Electric Company 735 Broad Street Suite 1108 James Building Chattanooga, Tennessee 37402 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637
- Athens, Alabama 35609-2000 Thierry M. Ross, Project Manager U. S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
4
ATTACHMENT 1 TS-286 RPS CIRCUIT PROTECTION ADDITIONAL INFORMATION RE/VESTED BY NRC STAFF l.
INFORMATION RE UESTED BY NRC Provide an analysis which determines worst case components for overvoltage, undervoltage or underfrequency.
TVA RESPONS Ana s s for Overvo ta e
The overvoltage protection provided for RPS equipment is a combination of an alarm from the process computer and the tripping capabilities of the RPS circuit protectors.
The voltage regulator at the MG sets normally controls voltage to be less than or equal to 122.4V.
The process computer alarm value for the RPS bus overvoltage is 124.5V.
This alarm provides indication when the MG set is operating outside its regulating band.
The methodology used to determine the limiting components was as follows:
A review of the vendor specifications for the RPS equipment determined that the most limiting components were the power supplies for the Power Range Monitors rated at 115V y10%, 50/60 Hz g10% at 3 amps.
Because this equipment is rated for frequencies of 50 to 60 Hz they are built to handle the temperature increases of operating at lower frequencies
(<60 Hz).
For electromagnetic devices voltage can be defined as:
E = 4 44 x 10 8 AcQfN Where:
E
= 126.5 (2)1/2 V Ac = Square inches cross section (constant) f
= frequency (50 Hz minimum frequency)
N
= Number of turns in winding (constant)
B
= Lines per square inch peak flux density Using this formula, the maximum lines peak flux density for maximum voltage and minimum frequency was calculated.
126.5 (2)1/2
= AcQN = 80,584,691.72V/Hz 4.44 x 10 8 (50 Using this value as an upper limit the maximum voltage for a frequency of 60 Hz was calculated.
V = 80,584,691.72 (4.44 x 10
)(60)/(2)1
= 151.8V
Page 2 of 3 Anal sis for Ove volta e (Cont'd)
Therefore, exposing this equipment to voltage slightly higher than their rating (130.4V at the RPS bus) is not a concern for equipment damage.
Anal sis for Undervolta e
The protection for undervoltage for the RPS equipment is a combination of an alarm from the process computer and the tripping capabilities of the RPS circuit protectors.
The voltage regulator at the MG sets normally controls voltage to be greater than or equal to 117.6V.
The process computer alarm value for the RPS bus undervoltage is 115V.
This alarm provides indication when the MG set is operating outside its regulating band.
The methodology used to determine the limiting components was as follows:
The voltage requirements of the equipment fed from the RPS bus were reviewed against the following criteria:
1.
Equipment that required the highest minimum voltage.
2.
Equipment with maximum voltage drop.
3.
Equipment that could be damaged if subjected to low voltage.
After reviewing the vendor specifications for the RPS equipment it was determined that the most limiting case was the scram solenoids.
The valves will chatter and self destruct if exposed to excessively low voltages.
The analytical limit for undervoltage was selected taking into consideration the voltage drop to the solenoids plus an additional 2V for future load additions.
TVA has performed a calculation which demonstrated that for a required voltage of 102V at the scram solenoids, the voltage at the MG set will be 106.5V.
Therefore, the proposed TS value was selected to be 108.5V.
Anal sis for Underfre uenc The motor generator flywheel set is designed to maintain frequency within 1% from zero to full rated load with normal input to the drive motor.
With a 50% (KVA) step load change the regulator will limit the output frequency to gl5% (51 Ilz) transient.
Recovery to steady state regulation
Page 3 of 3 Anal sis for Underfre uenc (Cont'd) is within one (1) second.
With a three (3) second supply interruption output frequency will not drop more than 5%.
Recovery to steady state regulation after restoration at rated supply voltage occurs within five (5) seconds.
Using the same formula as in the overvoltage analysis, the maximum volt/frequency ratio was calculated:
4.44 x 10-8f
= AcQN If the maximum voltage is equal to 132V and the frequency equal to 60Hz, V/Hz ratio will be equal to:
132 (2)1/2
= 70,073,644.97V/Hz 4.44 x 10 8 (60Hz)
Using this value as the upper limit, the minimum allowable frequency at rated voltage of 120V was calculated.
120 V (2)l/2 55 Hz 4.44 x 10 8 (70,073>644.97)
The proposed TS value for underfrequency is equal to 55Hz plus 1Hz for margin.
2.
INFORMA ON RE UESTED BY NRC Provide the documentation from the mariufacturer which forms the basis for the analysis in Item 1 above.
TVA RESPONSE The documentation requested has been made available for NRC review at the TVA offices in Rockvllle, MD.
3.
INFORMA IO RE UESTED B
RC The staff has previously approved TS 264 on the same subject last year.
Explain and justify the reasons for the new TS change request TS 286.
TVA RESPONSE The conservatism used in the calculations to select the RPS trip setpoint resulted in little margin remaining between the trip setpoint and the normal regulation of the MG set.
As a result of several unplanned ESF actuations, TVA committed to review the existing RPS trip setpoint calculation to determine if excessive conservatism was used.
In
- addition, TVA contracted GE to perform an assessment of the RPS circuit protector and determine if the trip setpoints should be changed.
This resulted in a revision to the calculations to determine new setpoints.
The results of the calculations established new setpoints requiring a
change to the TS to implement.
h