Overheating Flashcards
What are entry conditions for Overheating?
What thresholds must be met to perform RT-4 (HPI Cooling)?
What is order of preference for restoring primary to secondary heat transfer?
1) EFW
2) MFW/AFW
3) CFW
What actions are taken if RT-4 conditions met, but HPI not available?
1) If SCM adequate, trip running RCP
2) Cycle ERV to 1650 psig to 2400# if SCM not adequate or Cycle to minimum SCM if adequate
3) If ERV cannot be opened, throttle HPI if NDTTs limits will be violated, if not then allow PZR safeties to lift.
At what SG tube to shell delta T are RCPs secured? At what value can RCPs be restarted?
60 deg F (Tubes Hotter)
RCPs cannot be restarted unless delta T is less than 50 deg F (Tubes Hotter)
What conditions are required to restore letdown?
1) No fuel damage
2) RCS to ICW leak not suspected
3) SCM adequate
What actions are taken if CET temps are not stable or dropping and HPI is less than full flow from one pump or greater than 120 minutes on HPI cooling have elapsed and CETs still rising?
Go to step 35, and if CETs are not subcooled to to ICC.
Restore EFW is possible, if not use Main, aux or CFW. If all unavailable attempt to use Condensate pumps and then SW pumps.
If all options fail then go to HPI cooldown.
What actions are taken once CETs are stable and dropping?
1) Use applicable feed source to begin feeding using RT-16.
2) Maintain RCS pressure per fig 3 by balancing MU and LD
3) Secure HPI cooling
4) Establish PZR steam bubble by firing PZR heaters, reducing makeup flow and raising letdown (maintaining SCM 5 deg F greater than minimum SCM)
5) Establish force flow in both loops using RT-7/RT-11
6) Return to Rx Trip
What temperatures are characterized for PZR temperature adequate?
What SG pressure is lowered to for condensate pump? SW pumps?
Condensate Pumps - < 580 psig (Feed rate is less than 0.2 E6 lbm/hr if SCM adequate and 25 minutes to reach 370 - 410” if SCM inadequate)
SW Pumps - Fully depressurize
What are recovery strategies for overheating?
