Spray Pond Week Flashcards
What is the purpose of the spray pond system?
a) Remove heat from EW during normal or emergency shutdown
b) Remove heat from the Diesels when they are running
c) Reject heat to the essential spray ponds which dissipate heat to atmosphere
Draw the spray pond system.
make sure the drawing included:
DG fuel oil cooler, jacket water cooler, air after cooler, & lube oil cooler; EW HX; filtration equipment; Chem injection system components and injection lines; SP cross tie valves; major system isolation valves
What is meant by the term Ultimate Heat Sink?
Both A & B spray ponds cross tied together
Where does the essential spray pond pump take a suction from?
Its associated pond and discharges through its associated train heat loads.
What are the major heat loads on the spray pond system?
a) EWHX
b) coolers and heat exchangers on one DG
How does the spray pond maximize cooling of the water returned to it from its loads?
by spraying the water into the air through nozzles, allowing part to evaporate and the rest to fall back into the pond.
Why is pressure on the tube side of the EWHX maintained higher than the shell side?
so that if there is a leak, EW system water won’t enter the spray pond and contaminate the environment
Where does makeup water for the spray pond come from?
either DS (domestic water), or TB (Tower makeup and Blowdown)
What are the 6 chemicals added to the spray pond for chemistry control?
a) Hypochlorite (biologics)
b) Biocide (biologics)
c) sulfuric acid (pH control)
d) Copper Corrosion Inhibitor (corrosion)
e) Mild steel corrosion inhibitor (corrosion)
f) dispersant (scale and deposit control)
Where do the filter backwash pumps discharge to?
circ water intake structure
How long can either train maintain shutdown cooling conditions without makup for the ponds with them cross connected?
26 days
How long can the diesels run loaded and unloaded without spray ponds available?
15 minutes unloaded
2.6 minutes loaded
Where does the Hypo header originate?
WRF
What happens to the spray pond system on a loss of instrument air?
loss of remote level indication & level will need to be obtained locally
Which pumps in the spray pond system are powered by class power?
the spray pond pumps (PB)
Can the spray ponds with unit 1 be cross connected with unit 2 or 3?
no
How many headers and risers are there in the spray pond?
4 headers with 20 risers each.
How many nozzles are there per spray pond?
320
How is the source of makeup water determined?
Chemistry department via CCI and it depends on current spray pond chemistry conditions.
What are the differences between DS and TB as far as makeup water quality is concerned?
DS has more calcium and less biologics, but TB has less calcium and more biologics.
What is a last resort source of makeup water for the spray ponds?
Fire protection system
Where can the spray pond pumps be manually started from?
Control room or supply breaker
What automatically starts spray pond pumps?
Diesel start signal
SIAS, CSAS, AFAS (1 or 2), LOP
CRVIAS (control room ventilation isolation actuation signal) or CREFAS (CR essential filtration activation signal)
Does any equipment start when the spray pond pump starts?
Yes, the pump house exhaust fan starts
What is the automatic function on the spray pond filter pump?
it will auto stop on a low level in the associated spray pond
Why is the spray pond filter pump normally ran?
for feed and bleed as directed by chemistry. the pump takes a suction on the spray pond and discharges to the circ water intake canal at a rate determined by chemistry dept.
What will start the backwash sump pump if it’s in auto?
High level in the backwash sump and it will stop once the low level signal is received.
What are the spray pond corrosion test racks?
racks that are installed to monitor the corrosive effects of the spray pond water on piping and the HX.
Where are the spray pond cross tie valves actually located?
in the spray ponds approximately 6” off the bottom of the spray ponds
What two actions must take place within 24 hours of a loss of makeup water to the spray ponds?
a) if 2 trains of shutdown cooling are in service, secure one of them
b) open at least one cross tie valve
When is the spray pond normally operating?
When its associated diesel is running or when shutdown cooling is in operation.
Describe the spent fuel pool.
Stainless steel lined, concrete walled, 206,700 gallon pool
Where can makeup to the spent fuel pool come from?
RWT, LRS/RMT, CST, or in an emergency fire protection or DW via hoses.
What is the minimum boron concentration in the SFP?
Tech spec says 2150ppm, but we keep it between 4000-4400ppm
What is the high temperature alarm set point for the SFP?
High - 125F
Hi-hi - 145F
What is the low level alarm set point for the SFP?
137’6” low level
137’ low low level alarm
High level is at 138’2”
How are the fuel assemblies arranged in the SFP?
Checkerboard array in order to preclude inadvertent criticality
How can level in the SFP be determined?
1) by using the yard stick measuring device inside the fuel pool
2) the ultrasonic transceiver system
Why don’t you want the level in the SFP to be over 138.16’?
You could flood the fuel elevator cable tray and damage the motor or you could introduce water into the in core instrument tubing.
Why can’t the underwater lights be uncovered?
because without the water, they would burn out due to insufficient cooling
What is the PC (pool cooling and cleanup) system used for?
a) remove heat from the SFP, cask pit, fuel transfer canal, upper guide structure pit, and refueling pool
b) maintain water cleanliness and clarity in above areas
c) maintain water level above spent fuel in the SFP to provide adequate shielding during fuel handling operations
d) Provide clean up capability for the RWT
e) provide alternate source of borated water to CVCS
Where does the PC system take a suction from and discharge to in the SFP?
suction from the upper part, discharge to the lower part
Draw PC system.
verify you have:
2 PC cooling pumps, suction sources, discharge paths, 2 PCHX, cooling sources for HXs, and makeup sources
Describe the PC Cooling pumps.
Qty 2 of them, horizontal, centrifugal, 2000gpm, driven by 100HP class powered motor.
Where can the discharge pressure for the PC Cooling pumps be read?
From PCN-E02 above the hand switches for the PC Clean up pumps.
What will automatically stop the PC Cooling pumps?
A load shed signal or an electrical protection trip. Pump must be manually restarted after a load shed once power has been restored.
What cools the PC cooling HX?
NC on the shell side.
Why are siphon breakers installed in the SFP cooling and cleanup system?
To limit drain down of the SFP if a line should break or a vent or drain valve is accidentally left open in the piping.
What do the siphon breakers limit drain down to?
132.5’
Draw PC Cleanup.
Verify that your drawing has:
PC Cleanup pump, filter, IX, suction sources, and discharge paths.
Are there any automatic functions for the PC cleanup pumps?
no. they are start or stop only.
What are the power supplies for the PC Cooling and PC Clean up pumps?
Cooling - PGA, PGB
Cleanup- NHN
Where are the filters in the PC clean up system?
between the pumps and the IX
What type of resin is in the PC Cleanup IX?
mixed bed, disposable resin
Is the PC system required for safe shutdown?
No. It is used to cool and clean the SFP during normal plant operations including shutdown and power generation
How many trains are typically needed to keep the SFP in temperature band?
One, so the other is in standby
What system can be used as a back up to the PC Cooling HX if NC isn’t available?
EW
What is the cleanup pump typically running on ?
The RWT
What system is used to transfer water between the RWT and the refueling pool?
The SI system.
How is the fuel transfer tube isolated when not in use?
by PCN-V118 on the spent fuel pool side (manually operated valve) and by the quick operating closure device (QOCD) on the containment building side.
Why should an operator be cautious about ventilation shifts in the fuel building or in containment when PCN-V118 is open?
the refueling pool and the transfer canal become a large manometer and pressure changes translate into level changes in the fuel building or containment. you could possible overflow the transfer canal into the new fuel elevator cable tray.
What is the advantage of the QOCD over a flange?
it can be removed or installed remotely from the operating floor so no personnel are required to enter the refuel cavity.
How many seals are provided for the cask pit and decon pit gates?
two class seals with two unisolated back up nitrogen bottles in case of failure
How many seals are on the SFP transfer gate?
one with one isolated backup nitrogen bottle
On a loss of Instrument Air, which gate’s seal(s) will fail?
The SFP transfer gate seal will fail until the nitrogen bottle can be unisolated
What would be the water supply if the cask loading pit needed to be filled?
RWT using BAMPS via the cask loading pit drain line. You would move about 82k gallons of water
Where does the cask pit drain to and what should the AO be watching as it is drained?
Drains to the fuel building sump.
The AO would need to be watching the SFP level, SFP/Cask Pit Gate for leaks, and/or the Spent fuel transfer canal level.
What can EW supply if NC is not available?
fuel pool cooling HX, RCPs, CEDM normal air cooling units, nuclear sample coolers, and normal chillers
How does the EW system aid in preventing a radioactive release?
It acts as a barrier between the RCS and the spray pond to reduce the possibility of release
Draw EW
verify the drawing has:
Surge tank, EW pump, heat loads, EW HX, chem add tank, piping and valves including cross tie valves
What are the normal loads for the EW system?
an essential chiller and a SDCHX.
Is the EW system at a higher or lower pressure than the SP system and why?
lower to protect against leakage into the spray pond in case of a tube leak
Describe cross connecting EW to NC.
Method 1:
cross connect 1 train (ex., “A” EW) with the same fuel pool HX (“A”) with the same essential chiller (“A”) in parallel.
Method 2:
cross tie to supply the NC priority loads. Only one train may be cross tied to the priority loads at any time. The associated train is rendered inoperable while cross tied.
What systems can provide makeup water to EW?
DW (normal source)
CT (safety related backup)
FP (emergency/last resort)
What is used to prevent corrosion in the EW surge tanks?
Nitrogen
What is the power supply to the EW pumps?
PBA and PBB
What is the larges load for the EW system?
The SDCHX
What will cause the EW pumps to automatically start?
LOP (20 seconds after DG output bkr closes) CSAS SIAS CREFAS or CRVIAS AFAS 1 or 2
What cools the EWHXs?
Spray pond
What is the purpose of the EW surge tanks?
a) allow for adding makup water
b) accommodate changes in system volume due to temp changes
c) means of leak detection into the system
d) NPSH for EW pumps
How is makeup water provided to the surge tanks?
Demin water is provided via a solenoid valve that responds to level transmitter signals from the tank
What will cause the train A EW to NC cross tie valves to close?
EW "A" surge tank low level (17") or a SIAS this ensures the EW system can perform its class function
What will cause the surge tank makeup solenoid valve to automatically close?
High level or Low low level (14”) Low low level is to prevent feeding a leak
Why do we add chemicals to the EW system?
To maintain ph and maintain nitrite concentration for proper water quality and corrosion prevention
How do the chemicals get into the system?
They are added to the tank and then flushed into the system using a portion of the flow off the discharge of the EW pump.
What is the difference between train “A” cross tie valves and train “B” cross tie valves in the EW system?
“A” train valves are motor operated and can be operated from the control room, while “B” train valves are manual.
Is EW operating during power generation?
no, it is in standby
What is “stacking” in relation to the Essential Chiller?
During winter months low cooling load and low EW temperature can cause liquid refrigerant to remain in the condenser due to there not being enough refrigerant pressure to drive the liquid through the flash economizer to the cooler. Temperature and pressure drop and the chiller trips on low temp.
How is stacking prevented?
Refrigerant head pressure control valves (RHPCVs) are installed in the EW lines downstream of the condensers. The valves close at low pressures and open at higher pressures to reduce EW flow rate at lower EW temperatures.
When should the bypass valve around the RHPCVs be opened?
If EW pump performance is degraded and EW aligned to the fuel pool cooling loads.
How are the RHPCVs over ridden?
hydraulically using the pilot bypass stem located on top of the valve (preferred) or the manual override screw located on the bottom of the valve (the pilot bypass stem must be backed off first).
What are the loads off EC?
LPSI, HPSI, and CS pump rooms
Control room ventilation, ESF switchgear room, DC equipment room
AFWP room, EW pump room, electrical pen. Room
What are the normal and backup supplies for makeup water to EC?
DW (normal), CT , and FP
What is the Nitrogen pressure on the EC expansion tank?
28 psig
Added to minimize corrosion, due to its location in the building it’s also needed to maintain the surge volume, and it maintains the system full should a leak occur in an upper portion of the system
What is the power supply to the compressor on the chiller pkg?
PB
What makes up the “thermal economizer” section of the chiller condenser and what is it for?
The 12% of the condenser tubes that are at the bottom of the condenser that are isolated from the main tube bundle by a partition. It sub cools refrigerant before it gets to the flash economizer to add efficiency
What is the purpose of the EC expansion tank?
Location for adding makeup water
Accommodate for temp changes
Allow for a means of detecting leakage in or out of the system via level changes
What will isolate makeup from the EC expansion tank?
Lo lo level
What will auto start an essential chiller?
SLAC CC
Following what trip will the chiller auto restart and when will it restart?
Low chill water temp (auto load recycle).
It will restart when chilled water temp returns to normal range
What are the power supplies to the EC?
PB for compressors, PH for water pumps
What happens to the EC chiller on a loss of spray ponds or EW?
Chillers trip on high refrigerant pressure in the condenser
Where will the fuel building HVAC system shift suction to in the event of a LOCA?
The area below the 100’ level of the aux building
What will actuate the essential exhaust air filtration units and dampers that are located on the 100’ level of the fuel building?
A FBEVAS will align the two suction dampers to the fuel building and a SIAS will align them to the aux building. If there is a FBEVAS in and we get a SIAS, the SIAS will take priority and align to the aux bldg.
What tanks vent to the HF system?
RWT & HUT
What will cause a FBEVAS?
Bop-ESFAS provides the signal on a high rad signal from the fuel building HVAC effluent or SFP area rad monitors
What is the purpose of the air washers in the AHUs?
DS water is sprayed into the incoming air inside the AHU when air temp >80F to cool it. Mist eliminators then remove entrained water from the air before it gets to the fans.
What will cause the normal supply and exhaust dampers to close?
FBEVAS
Where do the spray pond chem injection pumps discharge to?
A “quill” that creates turbulent flow to mix with the recirc flow and dispense to the spray ponds.
What do the recirc pumps do?
Circulate water through the injection quill and back to the spray ponds. Any pump can go to either pond
Where does hypo come from?
Water rec
