ML17312A702
| ML17312A702 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 04/05/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17312A701 | List: |
| References | |
| NUDOCS 9604230295 | |
| Download: ML17312A702 (2) | |
Text
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 2919 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 2890 psia, which provides an additional 24 psi 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 The proposed technical specification (TS) changes to the instrumentation setpoint for the reactor trip and HSIS actuation on low steam generator pressure are as follows:
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Item I.A.S, "Steam Generator Pressure Low" change the trip setpoint from
~919 psia to h895 psia and change the allowable values from h911 psia to
~890 psia.
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- At tt Eyt I
t Trip Setpoint Values,"
Item IV.A.1, "Steam Generator Pressure Low" - change the trip setpoint" from 2919 psia to ~895 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.
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IIPIIEE P-E' MODES 3-4."
The purpose of Table Notation, Item (3) is to provide guidance on operation below the steam generator pressure trip setpoint in Hodes 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 HSIS engineered safety features actuation system instrumentation is not required below 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,
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