Nuclear Cooling Water Flashcards
What’s the purpose of the NC Pumps ?
Circulates water for removal of heat from loads for transfer to PW system
Where are the NC pumps powered from ?
Powered from 4.16kv NBN-S01 & NBN-S02
What’s the GPM & discharge pressure for the NC pump ?
Pumps approx. 17500gpm at discharge pressure of 100-110psig
What kind of seals do the NC pumps use? Do you expect leakage from NC pump
They used mechanical Seals so shouldn’t expect any leakage from it
Where are the NC pumps normally started from? Where else can they be started ??
-They’re normally started from control room
-Can also be started locally at the breaker
How many NC pumps are usually running ?
-Normally one NC pump is running to supply system
-Other pump is in standby
What happens if operating NC Pump discharge pressure drops to it setpoint of 79psig ?
Standby pump will start
What happens if NC pump trips on electrical fault or physical degradation?
Local conditions may warrant quick actions by control room to prevent further equipment damage
What must be done for any auto start of a NC pump ?
Should be investigated locally and reported back to control room
What’s the purpose of the NC HEX ?
Used to transfer heat from NC system to PW system to be dissipated to atmosphere at CW Cooling Towers
What is installed on NC HEX for protection of over pressurizations ?
There is relief valves on shell & tube side to prevent over pressurization
Why is the PW pressure higher than NC system while going through NC HEX ?
-NC could have potential contamination from RC or Radwaste systems
-PW will leak into NC if a leak occurred inside NC HEX
-Used to prevent PW contamination and outside environment
How many NC HEX are normally in service ? What is the PW outlet valve normally throttled to on the inservice HEX ?
-Normally ONE HEX in service
-PW outlet valve throttled to 33% open for in service HEX
How is the standby NC HEX kept in standby ?
Both NC & PW outlet valves are closed with flow secured through it
How is NC temp controlled to maintain between 75-105F ?
Controlled manually by:
-Throttling HEX NC outlet valve
-Throttling bypass valve to maintain flow through & around HEXs
To maintain adequate system flow through NC HEX, what MUST be the position of the one valves when adjusting temperature of NC supply ?
-Either NC Outlet valve fully open or Bypass valve fully open
-Once one those valves is fully open you can use other valve to adjust temperature
In the summer instead of adjusting the NC HEX outlet valve or bypass valve, what other valve can you use to adjusted NC temperature ?
-PW outlet valve can be adjusted to lower NC temp
During summer why would you have to adjust PW outlet valve ?
Would have to be down when NC outlet valve is Fully Open & Bypass valve is Fully Closed & NC temperature is still high
What does the control room monitor as the primary means for adjusting NC temperature ?
Monitors flow through Letdown HEX
What is the Max. NC Flow through the Letdown HEX ?
-Max NC flow is 1500gpm
What happens to flow through Letdown HEX, when NC temperatures rise ?
Flow the Letdown HEX will rise to maintain Letdown Temp
What happens if Letdown HEX flow limit is reached & NC temperature continues to rise ?
Control room will direct AO to adjust NC temp generally maintained low in band
What is the purpose of NC Surge Tank ?
-Accommodate for volume changes in system due to temp changes
-Provide NPSH for NC Pumps
-Provides detection of leakage into or out of NC system
- Convenient place to add makeup water
What protection is in place for the surge tank to protect against a vacuum or over pressurization ?
-Pressure relief for over pressurization
-Vacuum breaker to prevent vacuum
What is the normal makeup source to the NC Surge Tank ? How is Demin. Water makeup controlled ?
-Demineralized water is used for makeup water
-Controlled by control valve in response to signals from level controller
Where is the backup makeup water to NC Surge Tank from ? How backup makeup water controlled ?
Backup makeup water is available from Cooling Water Holdup Tank by manual operation
What pressure is the Nitrogen cover gas at in the Surge Tank ?
Pressurized at 5psig to prevent oxygen intrusion
What could happen to surge tank if a RCP High Pressure Seal Cooler tube rupture happens ?
Could over pressure the NC system and eventually have a uncontrolled release through NC Surge Tank
Who must give permission to have chemical additions performed on NC system ?
-Must have approved Chemistry Control Instruction on file in control room
-SM/CRS gives permission
What does the Chemistry Control Instruction provide ?
Lists the chemical & quantity that’ll be added
Who is responsible to deliver the chemicals? Who is required to verify the chemicals ?
-Chemistry must deliver chemicals
-AO has to verify chemicals
What is the normal conditions of the Chemical Addition Tank ? What condition is it in during winter months ?
-Normal condition is isolated & depressurized
-Cold Weather Protection will have flow aligned through tank to prevent freezing
What does the Radiation monitor provide for NC system ?
Continuously monitors NC system for in-leakage from contaminated systems that it serves
Where does the NC RU monitor provide alarms & trending capabilities? What does a activity alarm indicate ?
-Does this via computer consoles in Effluent office & Control Room
-Indicates potential contaminated leakage
What drives flow through the NC RU-6 monitor?
-DP by NC pump, from the discharge to the NC HEX Inlet
What is the purpose of the Letdown HEX Temp Control Valve ?
(NCN-TV-223)
Used to automatically control NC flow through the Letdown HEX to maintain letdown temperature
What NCN-TV-223 normally controlled by?
Normally controlled by CHN-TIC-223, at the setpoint by control room
In event of inability of NCN-TV-223 being able to control letdown temp due to valve failure or loss of instrument air, what else can be used to control letdown temp ?
-Temperature can be controlled manually via a bypass around control valve
What must operators be aware if you have to manually control Letdown Temp ?
-To much NC flow makes letdown to cold causing resin to absorb more boron which causes positive reactivity
-Little NC flow makes letdown temp rise, resin gives off boron causing negative reactivity
-Also little NC flow will cause Ion Exchangers to be bypassed & letdown will be isolated
What’re NC priority heat loads ?
-Normal Chillers
-CEDM Coolers
-RCPs
-Nuclear Sample Coolers
What’re the Non-Priority Heat Loads ?
-SFP HEX
-Letdown HEX
-Radwaste Evap.
-BAC
-Non-Nuclear sample Coolers
-A/B Waste Gas Compressors
- Letdown HEX
-Gas Stripper
-Aux. Steam Vent Cond.
-RU-7 cooling coil
What is the EW to NC Crosstie Valve used for ?
-Used when NC is unavailable for its Priority Head Loads during normal operation or Loss Of Power
Which train of EW can be interconnected remotely to NC Priority Heat Loads ?
-‘A’ train can be interconnected to NC Priority Head Loads Remotely by MOV UV-145 & UV-65
-‘B’ train can be interconnected manually to NC Priority Heat Loads
Prior to opening the EW to NC Crosstie Valves what must be isolated ?
NC Non-Priority Heat Loads must be isolated to prevent transferring EW into the NC system
When the EW to NC Crosstie Valves are open, what happens during a SIAS or a Train ‘A’ EW Low Surge Tank ?
EW to NC CrossTie valves will automatically go closed
Is the EW system considered operable when the EW to NC CrossTie Valves are in service ?
NO, the EW system will be inoperable until the crosstie valves close
What is the purpose for the SFP EW to NC Crosstie valves used for?
-EW transfers decay heat loads from SFP to the Spray Pond under forced forced shutdown & accident conditions OR when NC is unavailable
What must be isolated to allow SFP EW to NC Crosstie Valves to be opened ?
-NC SFP HEX Inlet & Outlet Valve must be isolated
Once SFP HEX NC Inlet/Outlet valves are isolated, what can you do ?
The normally locked closed EW crosstie SFP HEX valves, can be unlocked and opened
When do the NC supply & return Containment Isolation Valves automatically close ?
They will automatically close on a CSAS
Why is there a Pressure Relief Valve(NCE-PSV-617) on the return line coming out of containment ?
-Used to prevent over-pressurization during a LOCA
-Water trapped in penetration line can expand during LOCA due to the water flashing
-Might rupture piping & cause loss of containment isolation
Why is there no relief protection on the supply line penetration going inside containment ?
There a check valve which would pass flow & won’t allow accumulation in piping
What’re the Pressure Relief Valves NCE-PSV-614 & NCE-PSV-615 used for ?
Used to protect piping inside containment against over pressurization & damage in event of leakage of RCP Seal Coolers into NC in conjunction with NC containment Isolation Valves closing
What’re the setpoints for pressure relief valves NCE-PSV-614 & NCE-PSV-615?
Setpoint is 135psig
What happens if you isolate NC containment return lines, while NC supply line is still open ?
It can cause a pressure surge in the NC system that will lift the reliefs
How do you prevent lifting of relief when placing containment section system in service ?
NC return isolation valves should be opened PRIOR to opening supply line
When removing containment NC system from service what containment valves do you close first ?
-Supply valve must be closed before either of the returns
When is NC system normally in service ? What is NC required for ?
-In service during all modes of plant operation
-Required for normal plant operation & normal shutdown
-Not required for emergency situation safe shutdown
What is the normal NC Pump discharge pressure ? When will standby pump start ?
-Discharge pressure is 100-110psig
-Standby Pumps will start if header pressure drops to 79psig
What NC temp maintained between ?
Maintained between 75-105F, but as low in the band as possible
How is the NC flow through the Normal Chillers controlled?
Automatically controlled by motor controlled valves which open in start sequence of chiller
During outages when PW system is secured, what is NC cooled by?
-Cooled by the PW T-Mod that’s tied into ‘B’ NC HEX PW supply & return
-T-Mod provides cooling NC from ‘A’ Spray Pond
-Provides cooling for a portion of normal loads
What does the PW T-Mod consist of ?
Consist of:
-portable water basin
-Pumps
-Piping
-Cooling Towers
What does the PW Temporary Cooling system was designed to cool NC system heat loads consist of what ?
-One SFP HEX
-TWO normal Chillers at 50% load
-BAC at 40% load
-LRS Evap at 50% load
-Aux. Steam Vent Cond.
What happens on a loss of NC to the RCPs ?
-With RCP Seal Injection in service cooling flow must be restored within 10 minutes
-If not restored in 10 mins reactor must trip & RCPs secured
When EW is cooling NC priority Heat Loads how would you clear RCP low flow alarms ?
You would have to unlock & throttle SDCHX EW outlet valve to force flow to RCPs
What Tech Spec are affected when Cross Tying EW to NC Priority Heat Loads ?
-Associated EW Train is inoperable
-Associated EC Train is inoperable
What Tech Spec are affected when cross tying EW to SFP HEX ?
-Associated EW Train will initially be inoperable
-Flow balance can restore operability of the EW Train
-Manual override of RHPCV will cause Essential Chiller to be inoperable during Flow Balance
-Be sure other Train is operable BEFORE manually overriding RHPCV
What happens to normal chillers if NC is lost ?
Normal Chillers will trip; If EW is supplying normal chillers than ONE chiller can be restarted
What chiller will continue running on a LOP ?
A chiller will continue running because it’s powered from PBA-S03
What happens to NC pumps if you lose NH ?
Will lose NC Pumo Motor space Heater which wouldn’t meet requirements to start standby NC Pump
What happens to NC system on a loss of NK ?
Would lose power to NC Surge Tank makeup solenoid valve failing closed which would causes loss of automatic makeup
What’re the Tech Specs related to the NC Containment Isolation Valves ?
-Each containment isolation valve must be operable in modes 1-4
-close in required time of 60seconds
