Recirc Flashcards
What is the purpose of the Reactor Recirculating System?
Provides forced circulation of water through the reactor core to achieve a higher power than it would through natural circulation.
Why are Reactor Pump Flows required to match?
Ensure assumptions of DBA LOCA analasis are maintainted.
What provides the cooling to the RR Pump Motor? to what component?
RBCCW to the Oil COoler
What happens to the RR Pump if RBCCW Cooling is lost?
Trip within 1 minute or pump bearings will get destroyed
RR Pump Seal Purge: what is its purpose?
What provides it? What is flow rate?
Seal purge provided by CRD flow to seal assemblies to remove dirt and prevent damage - approximately 2gpm
What must be done to RR when the pump is off and seal purge is lined up, and why?
must Leave RR discharge or suction valve open to prevent destroying seal.
What is the pressure of RR Seal 1 and 2? Alarm?
Seal 1 is 1000psig
Seal 2 is 500psig
Computer Alarm on Lo and HI pressure - 400/600
What happens to RR on a failure of Seal 1?
Seal 2 would approach seal 1 pressure and get hi pressure COMPUTER alarm
What happens to RR on a failure of Seal 2?
Seal 2 pressure will drop. get a seal 2 leak MCR annunciator alarm (0.25gpm) and lo press. computer alarm
THIS IS THE ONLY MCR ALARM - OTHERs are ONLY COMPUTER
What happens to RR on a failure of both seals?
Seal leakage limited to 60gpm by breakdown bushing. leak to DWFDS
What happens to RR on a plugging of Orifice 1?
Seal pressure 2 drops - no leakage alarm
What happens to RR on a plugging of orifice 2?
Seal 2 pressure increases. Computer alarm hi. Input to DWEDS increases No MCR Alarm
What is the power source for the RR Suction and Discharge vavles?
MMC 28-7/29-7
Will the RR Suction and Discharge Valves cause a RR Pump Trip?
Yes - if either is <90% open, the pump will trip
What will cause a RR Pump Anti-Cav Run Back? What happens?
If the Discharge valve is not full open (if it is between 90% and 100%) the RR pump will run back to min speed (30%) at a rate of 2.5%/second
What does the RR Run back protect against?
Axial thrust and cavitation issues
What is the normal leakage from RR Seal? to where?
0.75gpm to DWEDS
What is the minimum speed of the RR Pump and why? Rated flow?
Minimum speed of 30%, core rated flow of 98Mlbm/hr (with both pump). low speed limit based on ensuring adequate flow in lower head to prevent stratification of cool CRD water - preventing failure of CRD stube tube welds
What is the limitation for rasing RR speed above 30%?
Cannot be done until feedwater flow >2Mlbm/hr and RR discharge valve full open.
What other systems use the RR Suction and Discharge lines?
LPCI - EIther RR discharge depending on loop select
SDC - suction from eitehr or both RR Suction and returns to Recirc
RWCU - Suction from B Loop for U2; A Loop for U3
ISO condenser returns to vessel via A RR suction
What is the purpose ofthe RR Sample flowpath?
Exists to continuously monitor pH, conductivity and O2
When is the RR discharge valve “not full open” bypassed?
during start up - before it reaches “full open” position
What positions exist for the RR Discharge Valve Jog Switch?
1/2 second, neutral, 1 second - opens for that amount of tiem then cuts out. Allows for better control of recirc flow
What indication of the RR Suction and Discharge valves are required, what happens if not received?
Must have dual indication within 2 minutes or Pump must be tripped.
What is the basic logic of the RR LOCA LOOP SELECT LOGIC?
Initiate on HI DW Pressure or Lo Rx Level - Uses Pp DP to determine if both Pps are in same running condition - then uses Riser DP to determine if there is a loop broken.
Chooses B unless B is broken
What could happen with a failed jet pump?
Indicaitons of condition?
May not ensure 2/3rd core height during LOCA. Indicated by: Decrease in Core Thermal Power Decrease in MWe Decrease in Core Plate D/P
What Rx parameters indicate a trip of a SINGLE RR Pump?
increase flow in running loop jet pumps due to reduced back pressure.
What must be done on a single RR Pump Trip? Why?
Close discharge valve to prevent pump spining backward
Reduce running pp to 60% on U3 and 43% on U3 to prevent excessive vibrations of jetpumps on subsequent Pp start
What is the required Feedwater condition for RR Pump?
Feedwater flow must be >2Mlbm/hr before RR Pump allowed above 30%.
Are the RR Seals and Gaskets considered part of the RCS Pressure Boundary?
NO
