AB-PZR-0001                    Pressurizer Pressure Malfunction

Entry Conditions:

Any unexpected pressurizer pressure transient

Failure of pressurizer pressure controller

Pressurizer PORV or safety valve open or leaking

If RCS pressure drops to 2000 psig and lowering  – Trip | Confirm | EOP-TRIP-1 (prevent automatic OT∆T trip)

Basis for CAS - Scenarios were run on the simulator and determined the Reactor will trip between 1950 and 1975 psig on OT∆T. A failed open spray valve and a failed open PORV are the bases for establishing this value. The failed open spray valve resulted in an OT∆T Reactor Trip at 1985 psig at about the 5 minute mark. The failed open PORV resulted in an OT∆T Reactor Trip at 1950 psig at about the 30 second mark. Based on this testing the recommended Manual trip value is 2000 psig and decreasing.

Subsequent Actions:

If POPS is in service go to ATT 3 leaking PORV(remainder of procedure addresses NOP conditions)

If the PORV is open, verify it shuts less than 375 psig.  If the PORV fails to shut, place the affected channel in OFF and close the PORV and PORV Block Valve.  If the block valve fails to close, then send an operator to open the associated control power breakers for the PORV.

If a PORV is leaking and it is not known which one has leakby, shut PR6 & PR7 wait for tailpiece temperature to lower, open PR6, monitor tailpiece temperature.  If temperature is rising close PR6.  If temperature remains constant open PR7.  If temperature is rising shut PR7.  Place unisolated PORV in auto and rearm POPS.

If the controlling channel (I or III) has failed, place the master pressure controller in manual, adjust pressure to program, select the remaining control channel and return the master pressure controller to AUTO.  Remove the failed channel IAW SO.RPS-0003:

[image]      Select another recorder channel.

[image]      Select another ∆T recorder channel.

[image]      High Pressure Reactor Trip bistable.

[image]      Low Pressure Reactor Trip bistable.

[image]      Low Pressure Safety Injection bistable.

[image]      SI P-11 block bypass

[image]      OT∆T Trip bistable

[image]      OT∆T Turbine Runback & Block Automatic And Manual Rod Withdrawal bistable

If the master pressure controller has failed, place the controller in manual and restore pressure to program.  If unable to control pressure in manual, operate heaters and spray in manual to maintain pressure on program.

If the spray valves are not controlling pressure, place the valves in manual and restore pressure to program.

If the spray valve does not respond and pressure is dropping rapidly (> ~3 psi/min) then Trip | Confirm (prevent challenging RPS low pressure trip), and stop 23 and 21 RCPs (stopping pumps terminates or reduces the rate of pressure reduction and extends the time to SI initiation)

If the spray valve does not respond, and pressure is dropping slowly, commence a power reduction, place all heaters in MANUAL and ON (reduces rate of pressure reduction).  Attempt containment entry to isolate the spray valve.

If a PORV is failing to maintain RCS pressure, place the PORV in manual.  If the PORV fails to close, close the associated block valve (this step addressed PORVs not operating as designed – not leaking PORVs). If the block valve fails to close then send an operator to open the associated control power breakers for the PORV.

If a PORV is leaking and it is not known which one is leaking, shut PR6 & PR7 and wait for tailpiece temperature to lower, open PR6, monitor tailpiece temperature.  If temperature is rising, close PR6.  If temperature remains constant, open PR7.  If temperature is rising, shut PR7.  Place unisolated PORVs in AUTO (only a single tailpiece temperature instrument exists for the PORVs. This TE is not on P-250)

If Code Safety tailpiece temperatures are elevated and pressure is dropping in an uncontrolled manner, manually Trip | Confirm | SI | EOP-TRIP-1(If trip is not confirmed, go to EOP-TRIP-1)

If Pressurizer Heaters are not controlling pressure, place heaters in MANUAL and attempt to cycle heaters to control pressure.  If Backup Heaters are de-energized and unable to be controlled from the MCR, locally operate the heaters.  Shift to Emergency Power for Backup Heaters if required.