Term
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Definition
The purpose of the Pressurizer System is to:
§Control RCS pressure during normal operation and accommodate RCS volume changes during plant transients.
The purpose of the PRT System is to:
§Collect, condense and contain a release of steam from the Pressurizer Relief and Safety Valves, as a result of an RCS design basis transient.
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Term
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Definition
Pressurizer (PZR) Surge Line:
§Limit pressure drop between RCS and the safety valves with design discharge flow from the safety valves.
§Withstand thermal stresses that result from volume surges occurring during operation.
Pressurizer:
§Combined saturated water and steam expansion volume is sufficient to provide the desired pressure response to system volume changes.
§Water volume is sufficient to prevent the heaters from being uncovered during a step load increase of 10% full power.
§Steam volume is large enough to accommodate the surge resulting from a 50% load reduction from full load with automatic rod control and steam dumps w/o reaching high level reactor trip setpoint.
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Term
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Definition
Pressurizer:
§Steam volume is large enough to prevent water relief through the safety valves following a loss of load with the high water level initiating a reactor trip.
§PZR does not empty following a reactor and turbine trip.
§
The Safety Injection signal is not activated during a reactor and
turbine trip.
Pressurizer Relief Tank (PRT):
§Condense and cool a discharge of PZR steam equal to 110% of the volume above the full power PZR water level setpoint.
§The tank is NOT designed to accept continuous discharge from the PZR.
Pressurizer Safety and Relief Valves:
§The capacity of the PZR safety valves accommodates the maximum surge resulting from a complete loss of load.
§The PZR PORVs are designed to limit PZR pressure to a value below the high pressure reactor trip setpoint.
•PORVs are NOT required to open to prevent overpressurization of the RCS.
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Term
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Definition
§§~125 gallons / % level (cold)
§
~ 75 gallons / % level (hot)
1% Level / Deg. F
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Term
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Definition
§Heater Support Plates:
•Support heaters and distribute incoming surge flow.
§
Three Heater Groups
•One Control group
–415 KW
–Used during steady state to compensate for ambient heat loss and continuous bypass spray
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Sized to provide 2x the heat input required for ambient losses
•Two Backup groups
–Aid Control Group
–21 – 415 KW
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22 – 969 KW
Silicone controlled rectifier (SCR)
§Located between circuit breaker and heaters
§Controlled by Master Pressure Controller
§SCR controls how long the heaters are energized.
§Pressure < 2250 psig heaters modulate
§Pressure < 2220 psig heaters are full on
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Term
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Definition
§< 2210 psig the breakers for 21 and 22 group will close if in Auto.
> 2218 psig the breakers open if in Auto and the alarm clears
Heaters also energize on a PZR level increase 5% above programmed level.
At < 17% pressurizer level the breakers for all heaters are opened (Auto or Man)
Prevents heater damage in the event of uncovery.
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Term
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Definition
21 Group from “C” bus
22 Group from “A” bus
Note: Manually aligned to Vital buses and only 3 breakers closed (9 heaters) T/S Requirement 150 mw.
select MCR Bezel Press Local Manual |
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