Condenser Air Removal - 1.0 Flashcards
At what power must the mechanical vacuum pump be removed from service, why?
Concerns if MVP operating when > 5%:
Significant Hydrogen presence in MC, potential for detonations
High rad levels at the South Plant Vent
What are the trips of the mechanical vacuum pump?
1) “OVLD/PWR FAIL” - illuminates when a phase overcurrent or bus power failure condition exists.
2) “High Radiation Trip” - illuminates when ‘A’ or ‘B’ main steam lines sense a high radiation condition (3 x NFPBG).(single coincidence) - closes recirc pump sample lines
3) “Low Seal Flow” - illuminates when a low seal flow condition (<18gpm) exists 20 seconds after the initial starting of the mechanical vacuum pumps.
What is the process to start he mechanical vacuum pump?
The start pushbutton closes the associated breaker which causes the following automatic actions:
* Opens Suction Valve
* Starts seal water pump
What is the process to stop he mechanical vacuum pump?
The stop pushbutton causes the following automatic actions:
* Closes Suction Valve
* Stops the seal water pump
When are the SJAE placed in service?
The vacuum pumps are used to draw the initial vacuum and are removed from service at approximately 300 psig; at which time the SJAE is placed in service.
What cools the Mechanical vacuum pump?
TB Chill Water cools via the seal water cooler.
what is the tech spec basis for tripping the mechanical vacuum pump?
Tripping of the MVP limits the offsite and control room doses in the event of a control rod drop accident. (On MSL Rad Monitors)
What actions must you take for mechanical vacuum pump operations with suspected fuel damage?
try to maintain SPV RMS < alert level. However, if condenser vacuum cannot be maintained, flow may be increased not to exceed the SPV RMS High (RED) alarm. (ensures that ODCM release rate limits are not exceeded)
What provides steam to the SJAE during times when steam from the RX Vessel is not available?
- Closing the Aux steam isolation valve closes both aux steam distribution valves.
- Only one Aux steam distribution valve can be opened at a time. (Alternate distribution valve will automatically close when the other is opened).
What are the automatic actions associated with the Main steam distribution valves and the SJAEs? What is the purpose of this closure?
Each main steam distribution valve will auto close on low dilution steam flow when its associated third stage air ejector senses a low dilution steam flow (5,700 lbm/hr) if any of the first stage suction isolation valves indicate open [not 100% closed]. There is a 30s TD for starting SJAE
To prevent excess hydrogen from being sent to the offgas system
When are you allowed to break vacuum?
Vacuum should not be broken with turbine speed >1200RPM except in an emergency
What pressure should recirc back to the main condenser maintain discharge pressure?
11 psig to prevent excess flow to offgas.
What should be done prior to 5% power?
- Take MVP OOS.
- Place SJAE I/S.
