ML17312A675
| ML17312A675 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 04/05/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17312A674 | List: |
| References | |
| NUDOCS 9604120273 | |
| Download: ML17312A675 (6) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055&0001 SAFET EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.
TO FACILITY OPERAT NG LICENSE NO. NPF-41 M NDMENT NO.
TO FACI ITY OPERAT G
C NSE NO. NPF-51 ND AMENDMENT NO.
TO FACILITY OPERAT NG LICENSE NO. NPF-74 ARIZONA PUBLIC SERVICE COMPANY ET AL.
PALO VERDE NUCLEAR GENERATING STATION UNIT NOS.
1 2
AND 3 DOCKET NOS.
STN 50-528 STN 50-529 AND STN 50-530
- 1. 0 INTRODUCTION By application dated December 20, 1995, the Arizona Public Service Company (APS or the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos.
NPF-41, NPF-51, and NPF-74, respectively) for the Palo Verde Nuclear Generating, Station, Units 1, 2, and 3.
The Arizona Public Service Company submitted this request on behalf of itself, the Salt River Project Agricultural Improvement and Power District, Southern California Edison
- Company, El Paso Electric Company, Public Service Company of New Mexico, Los Angeles Department of Water and Power, and Southern California Public Power Authority.
The proposed amendment would change the instrument setpoint for the reactor trip and main steam isolation signal (MSIS) actuat'ion on low steam generator pressure from a trip setpoint of 2919 psia with an allowable value of 2911 psia to a trip setpoint of >895 psia with an allowable value of ~890 psia.
2.0 BACKGROUND
As part of its setpoint verification program, the licensee recalculated the instrument uncertainties associated with 'the setpoint.
The reduced instrument uncertainty thus obtained justifies a lower instrument setpoint.
The revised calculation uses more realistic (but still conservative) assumptions for accident and post-accident conditions.
To remain conservative, the calculation assumes a worst-case steamline break for containment environment assumptions and'oes not credit the fact that the transmitters are physically located away from the steamlines or that the transmitters are mounted to a very large heat sink.
In addition, the calculation assumes the instrument is required for 30 minutes and, conservatively does not take credit for the high containment pressure trip limiting temperature.
To achieve more realistic
- results, the revised calculation uses the temperature at the instrument, in lieu of the peak containment temperature during the postulated accident.
The revised calculation also assumes a harsh environment only for the period of.
time in which the plant protection system instrument is,required to mitigate the accident.
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The licensee's proposed change provides additional operational margin between steam generator pressure and the HSIS and reactor trip setpoints.
The current trip setpoint is h919 psia with an allowable value of ~911 psia.
Since the recent reduction in hot-leg temperature, normal steam generator pressure at full power is approximately 970 psia.
The licensee's proposed'change would lower the trip setpoint to ~895 psia with an allowable value of h890 psia, which provides an additional 24 psia of margin between normal operation and the trip setpoint.
The increased margin will enhance the safety of operation by decreasing the possibility of a spurious HSIS.
The analytical setpoints used in the safety analysis remain unchanged.
The proposed setpoint change ensures that a reactor trip and HSIS engineered safety feature actuation will occur before the analyzed low steam generator pressure values are reached, even under worst-case accident conditions.
- 3. 0 EVALUATION The proposed technical specification (TS) changes to the instrumentation setpoint for the reactor trip and MSIS actuation on low steam generator pressure are as follows:
TS Table 2.2-1, "Reactor Protective Instrumentation Trip Setpoint Limits,"
Item 1.A.5, "Steam Generator Pressure Low" - change the trip setpoint from h919 psia to ~895 psia and change the allowable values from >911 psia to
~890 psia.
I TS Table 3.3-',
"Engineered Safety Features Actuation System Instrumentation Trip Setpoint Values,"
Item IV.A.1, "Steam Generator Pressure Low" change the trip setpoint" from ~919 psia to >985 psia and change the allowable value from ~911 psia to ~890 psia.
The proposed revised trip setpoint and allowable value ensure that sufficient margin exists below the full load operating value for steam pressure so as not to interfere with normal plant operation, but are still high enough to provide the required protection (reactor trip and main steamline isolation) in the event of an excessive steam demand event.
The setpoint change and the allowable value change was determined in accordance with Instrument Society of America Standard SP67.04 and Revision 2 of Regulatory Guide 1.105, "Instrument Setpoints,"
and is therefore acceptable.
TS Table 3.3-4, "Table Notations,"
Item (3) change "In MODES 3-6" to "In MODES 3-4."
The purpose of Table Notation, Item (3) is to provide guidance on operation below the steam generator pressure trip setpoint in Modes 3-4.
However, Table
- Notation, Item (3) currently indicates Modes 3-6.
This is not consistent with the table notation in the Units 2 and 3 TS, and Table 3.3-3 indiates the MSIS engineered safety features actuation system instrumentation is not required'elow Mode 4.
Table 3.3-3, Notation b, also provides guidance on operation below the steam generator pressure trip setpoint in Modes 3-4.
Additionally,
II 0
steam generator operability is not required in Modes 5 and 6; hence, the typographical error needs to be corrected.
The proposed change to Unit 1
TS is purely administrative, correcting a
typographical error in Notation 3 of Table 3.3-4, "Engineered Safety Features Actuation System Instrumentation Trip Values."
The proposed change is therefore acceptable.
4.4 ~NT NN In accordance with the Commission's regulations, the Arizona State official was notified of the proposed issuance of the amendments.
The State official had no comments.
5.0 0
M CONSID RATIO The amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (61 FR 7544).
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth.in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the, issuance of the amendments.
4;4
~NI INN
,The Commission has concluded, based on the considerations discussed
- above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
C.
Thomas Date:.
April 5, 1996
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