ML18038B319
| ML18038B319 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 06/30/1995 |
| From: | Salas P TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML18038B320 | List: |
| References | |
| NUDOCS 9507070314 | |
| Download: ML18038B319 (6) | |
Text
PR10RZTY 1
(ACCELERATED RZDS PROCESSING)
REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9507070314 DOC.DATE: 95/06/30 NOTARIZED: NO DOCKET g FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 P
50-296'rowns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 AUTH.NAME AUTHOR AFFILIATION SALAS,P.
Tennessee Valley-Authority R
RECIP. NAME RECIPIENT AFFILIATION.
Document Control Branch (Document Control Desk)
SUBJECT:
Provides suppl info recpxested by NRC for review of proposed'S 359 submit.tted on 950511 to reflect interim addition of scram pilot air header low pressure trip function on BFN Unit 3.Revised Units 2
6 3
TS bases page encl.
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TITLE: TVA Facilities Routine Correspondence NOTES RECIPIENT ID CODE/NAME PD2-3 WILLIAMS,J.
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PLEASE HELP US TO REDUCE WASTE!
CONTACT THE DOCUMENT CONTROL
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TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 15 ENCL 14
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Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609 June 30, 1995 U.S. Nuclear Regulatory Commission ATTN:
Document, Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of Tennessee Valley Authority Docket Nos.
50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN)
UNITS 2 AND 3 SUPPLEMENTAL INFORMATION FOR PROPOSED TECHNICAL SPECIFICATION (TS) 359 SCRAM PILOT AIR HEADER LOW PRESSURE TR1P This letter provides supplemental information requested by the NRC Staff for the review of proposed TS 359.
TVA submitted this proposed TS on May 11, 1995, primarily to reflect the interim addition of the scram pilot air header low pressure trip function on Unit 3.
The scram pilot air header low pressure trip function is of Class IE single failure proof design and is composed of seismically and environmentally qualified safety related components.
The actuation logic of the scram pilot air header low pressure trip function employs two channels in a one out of two taken twice configuration.
Functional testing, calibration, and maintenance places the affected channel in the tripped condition.
This places the Reactor Protection System in a half scram condition.
The proposed six month functional test frequency for the scram pilot air header low pressure trip function on Unit 3 is the same as that currently in the Unit 2 TSs for this function.
In general, functional test frequencies are based on industry accepted practices and engineering judgement.
Consideration is given to the conditions required to perform a given test, the ease of performing the test, and the likelihood of a change in the system/component status during 07OO~a 9S07070314 950630 PDR ADOCK 05000260 p
U.S. Nuclear Regulatory Commission Page 2
June 30, 1995 the performance of the test.
Specifically, for the scram pilot air header low pressure trip function, the once per six month functional test frequency is acceptable due to:
1.
The functional reliability previously demonstrated by these switches on Unit 2 during Cycles 6 and 7, 2.
The need for minimizing the radiation exposure associated with the functional testing of these
- switches, and 3.
The increased risk to plant availability while the plant is in a half-scram condition during the performance of the functional testing versus the limited increase in reliability that would be obtained by more frequent functional testing.
A single failure of one of the scram pilot air header low pressure trip switches would not result in the loss of the trip function. It is highly unlikely that two switches in one channel would experience an undetected failure during the period between six month functional tests.
Enclosure 1
contains copies of the appropriate Units 2 and 3 TS Bases page marked-up to show this additional justification for the functional test frequency.
Enclosure 3 forwards the revised Units 2 and 3 TS Bases page that incorporates this "
information.
The proposed 18 month calibration frequency for the scram pilot air header low pressure trip function on Unit 3 is the same as that currently in the Unit 2 TSs for this function.
Setpoint scaling calculations were performed to provide assurance that there is adequate margin. between the required trip setpoint and the limiting safety system settings to account for inaccuracies in the instrument loop.
- The, calculation methodology is based on Regulatory Guide,1.105, Instrument Setpoints for Safety Related Systems.
Regulatory Guide 1.105 endorses Instrument Society of America (ISA)
Standard ISA-S67.04 1982, Setpoints for Nuclear Safety Related Instrumentation Used in Nuclear Power Plants, as an acceptable method for ensuring that setpoints stay within technical specification limits.
The Unit 2 scram pilot air header low pressure trip switches have not shown as found trip values below the minimum acceptable setpoint during the last two cycles of operation.
a1
U.S. Nuclear Regulatory Commission Page 3
.June 30, 1995 The Safety Analysis for this proposed change stated that the scram outlet valves begin to unseat as the air pressure drops below 43 psig.
Additional reviews have determined that this value should be 40 psig.
There are no new commitments contained in this letter. If you have any questions, please contact me at (205) 729-2636.
Sine
- ely, Salas Manager of Site Licensing Enclosures cc (Enclosures):
Regional Administrator U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. Mark S. Lesser, Acting Branch Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637
- Athens, Alabama 35611 Mr. J.
F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852