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Flashcards in Main Steam System Tech Specs Deck (8):
1

T.S. 3.3.1 Reactor Protective System (RPS) Instrumentation

T.S. 3.3.1 Reactor Protective System (RPS) Instrumentation

  • During Modes 1 and 2 or Mode 3 with more than one control rod capable of being withdrawn and < Refueling Boron Concentration
  • Mode 4 and 5: Bypass Restrictions

Requires four channels of Low SG Pressure trip Function per SG to be OPERABLE with a trip setting of ≥ 500psia.

Two separate Low Steam Generator Pressure trips, one for each SG.  Each Low SG Pressure trip monitors four measurement channels for the associated steam generator, one for each RPS channel.

LCO 3.3.1.A – One or more Functions with one RPS trip unit or associated instrument channel inoperable, place the trip unit in trip within 7 days.

LCO 3.3.1.D – One or more ZPM Bypass Removal channels inoperable, Remove the affected ZPM Bypasses Immediately OR Declare affected trip units inoperable Immediately

LCO 3.3.1.E – One or more Functions with two RPS trip units or associated instrument channel inoperable, Place one trip unit in trip within 1 hour AND restore one trip unit and associated instrument channel to OPERABLE status within 7 days

General Basis

The protection and monitoring systems are designed to ensure safe operation of the reactor.  The Low SG Pressure trip provides protection against an excessive rate of heat extraction from the steam generators, which would result in a rapid uncontrolled cooldown of the PCS.  This trip provides a mitigation function in the event of a MSLB.  The Low SG Pressure channels are shared with the Low SG Pressure signals which isolate the steam and feedwater lines.

2

T.S. 3.3.3 Engineered Safety Features (ESF) Instrumentation

T.S. 3.3.3 Engineered Safety Features (ESF) Instrumentation

APPLICABILITY: Modes 1, 2, and 3

  • Not required in Modes 2 and 3 to be OPERABLE if:
    • MSIVs are closed and deactivated, AND
    • MFRVs and MFRV Bypass valves either closed and deactivated, or isolated by manual valves

LCO 3.3.3.A – One or more Functions with one ESF bistable or associated instrument channel inoperable, place the bistable in trip within 7 days.

General Basis

This LCO applies to failures in the four sensor subsystems, including sensors, bistables, and associated equipment.  It requires a trip setting of ≥ 500psia.

Protects against violating core design limits and the PCS boundary and to mitigate accidents.  The ESF circuitry generates the signals when the monitored variables reach levels that are indicative of conditions requiring protective actions.

  • There are two separate Low Steam Generator Pressure (SGLP) actuation signals, one for each steam generator.
  • For each steam generator, four instruments (channels A through D) monitor pressure to develop the Steam Generator Low Pressure (SGLP) actuation.
    • Each of these instrument channels has two individually adjustable bistable trip devices, one for the bypass removal circuit (discussed below) and one for SGLP
    • The instrument channels associated with each Steam Generator Low Pressure Signal bistable include the pressure measurement loop, the SGLP actuation bistable, and the auxiliary relay associated with that bistable.
      • Each SGLP bistable trip device actuates an auxiliary relay.
        • The output contacts from these auxiliary relays form the SGLP logic circuits addressed in LCO 3.3.4

 

3

T.S. LCO 3.3.4 Engineered Safety Features (ESF) Logic and Manual Initiation

T.S. LCO 3.3.4 Engineered Safety Features (ESF) Logic and Manual Initiation

  • Two ESF Manual Initiation and two ESF Actuation Logic channels and associated bypass removal channels shall be OPERABLE for each ESF Function specified in Table 3.3.4-1

APPLICABILITY: Modes 1, 2, and 3

  • Not required in Mode 3 to be OPERABLE if:
    • MSIVs are closed and deactivated, AND
    • MFRVs and MFRV Bypass valves either closed and deactivated, or isolated by manual valves

General Basis

The ESF Instrumentation initiates necessary safety systems, based upon the values of selected plant parameters, to protect against violating core design limits and the PCS boundary and to mitigate accidents.  The ESF circuitry generates the signals when the monitored variables reach levels that are indicative of conditions requiring protective actions.

  • This LCO requires two channels of SGLP Manual Initiation to be OPERABLE.  As indicated by footnote (c) (Table 3.3.4-1), there is no manual control which actuates the SGLP logic circuits.  The actuated components must be individually actuated using control room manual controls.

Uses same measurement loops as the TS LCO 3.3.3 equipment with the additional relays and circuitry that actuates the actual isolation signal and the isolation signal block.

The bypass permissive is set low enough so as not to be enabled during normal plant operation, but high enough to allow bypassing prior to reaching the trip setpoint.

4

T.S. 3.3.7 Post Accident Monitoring (PAM) Instrumentation

T.S. 3.3.7 Post Accident Monitoring (PAM) Instrumentation

LCO 3.3.7 The PAM instrumentation for each Function in Table 3.3.7-1 shall be OPERABLE

APPLICABILITY: Modes 1, 2, and 3

LCO 3.3.7.A – One or more Functions with one required channel inoperable, restore required channel to OPERABLE status within 30 days.

General Bases

The primary purpose of the Post Accident Monitoring (PAM) instrumentation is to display plant variables that provide information required by the control room operators during accident situations.

  • Redundant monitoring capability is provided by two channels of instrumentation for each SG.
    • The steam generator level instrumentation covers a span extending from the tube sheet to the steam separators, with an indicated range of -140% to +150%.

5

T.S. 3.3.8 Alternate Shutdown System

T.S. 3.3.8 Alternate Shutdown System

LCO 3.3.8 The Alternate Shutdown System Functions in Table 3.3.8-1 shall be OPERABLE

APPLICABILITY: Modes 1, 2, and 3

LCO 3.3.8.A – One or more required Functions inoperable, Restore required Functions to OPERABLE status within 30 days

General Bases

The Alternate Shutdown System provides the control room operator with sufficient instrumentation and controls to maintain the plant in a safe shutdown condition from a location other than the control room.

SG pressure and instrumentation systems displayed on the Auxiliary Hot Shutdown Control Panel.

  • PT-0751A, PT-0752A

The Alternate Shutdown System instrumentation and control circuits covered by this LCO do not need to be energized to be considered OPERABLE

6

T.S. LCO 3.7.1 Main Steam Safety Valves (MSSVs)

T.S. LCO 3.7.1 Main Steam Safety Valves (MSSVs)

LCO 3.7.1 Twenty-three MSSVs shall be OPERABLE as specified in Table 3.7.1-1

APPLICABILITY: Modes 1, 2, and 3

LCO 3.7.1.A – One or more required MSSVs inoperable, restore required MSSVs to OPERABLE status within 4 hours.

General Bases

The primary purpose of the MSSVs is to provide overpressure protection for the secondary system. The MSSVs also provide protection against overpressurizing the Primary Coolant Pressure Boundary (PCPB) by providing a heat sink for the removal of energy from the Primary Coolant System (PCS) if the preferred heat sink, provided by the condenser and Circulating Water System, is not available.

  • Staggered lift settings reduce the potential for valve chattering because of insufficient steam pressure to fully open all valves following a turbine reactor trip.
  • The OPERABILITY of the S/G Code Safeties is defined as the ability to open within the lift setting tolerances and to relieve steam generator overpressure.

7

T.S. LCO 3.7.2 Main Steam Isolation Valves

T.S. LCO 3.7.2 Main Steam Isolation Valves

LCO 3.7.2 Two MSIVs shall be OPERABLE

APPLICABILITY: Mode 1

  • Modes 2 and 3 except when both MSIVs are closed and de-activated

LCO 3.7.2.A– One MSIV inoperable in Mode 1, restore MSIV to OPERABLE status within 8 hours.

LCO 3.7.2.C – One or more MSIVs inoperable in Mode 2 or 3, close MSIV within 8 hours AND verify MSIV is closed once per 7 days

The MSIVs are considered OPERABLE when the isolation times are within limits, and they close on an isolation signal

General Bases

The MSIVs isolate steam flow from the secondary side of the steam generators following a High Energy Line Break (HELB) downstream of the MSIV.  Closing the MSIVs isolates each steam generator from the other, and isolates the turbine, turbine bypass valve, and other auxiliary steam supplies from the steam generators, assuming the normally closed MSIV bypass valves are closed.  The MSIVs close on isolation signals generated by either Steam Generator Low Pressure or Containment High Pressure.

8

T.S. LCO 3.7.4 Atmospheric Dump Valves (ADVs)

T.S. LCO 3.7.4 Atmospheric Dump Valves (ADVs)

LCO 3.7.4 One ADV per Steam Generator shall be OPERABLE

APPLICABILITY: Modes 1, 2, and 3

  • Mode 4 when the steam generator is being relied upon for heat removal

LCO 3.7.4 A – one required ADV inoperable; restore ADV to OPERABLE status within 7 days.

General Bases

The ADVs provide a method for removing decay heat, should the preferred heat sink via the turbine bypass valve to the condenser not be available.  One ADV per steam generator is required to lower steam generator pressure to 885 psig in the event Auxiliary Feedwater Pump P-8C is needed to supply the steam generators for decay heat removal.

  • The design basis of the ADVs is to prevent lifting of the Main Steam Safety Valves (MSSVs) following a turbine and reactor trip and to provide the capability to cool the plant to SDC System entry conditions when condenser vacuum is lost, making the turbine bypass valve unavailable.

This LCO requires that one ADV is operable on each S/G.  An ADV is considered OPERABLE when it is capable of providing a controlled relief of the main steam flow, and is capable of fully opening and closing on demand from either the control room or Hot Shutdown Panel (C-33).

  • Closure of the manual isolation valve renders its ADV inoperable, since operator action time to open the manual isolation valve is not supported in the accident analysis.
  • Nitrogen Backup is not required by this LCO