LOSCM Flashcards
What are entry conditions for LOSCM?
1) LOSCM following RX trip
2) LOSCM following ESAS and RCS pressure > 150 psig
What are the first 3 steps of LOSCM?
1) If < 2 min, Trip all RCPs. (> 2 min, leave RCPs running and go to step 34 to perform rapid cooldown)
2) Initiate full HPI (RT-3). (If HPI < full flow from one HPI pump and RV head voids then perform rapid c/d per step 34)
What actions are taken for EFW per RT-5 and what other FW sources are addressed in the contingencies?
Depress PBs for reflux boiling
IF EFW not in service, start Aux FW Pump, MFW or CFW and establish 370 - 410” within 25 minutes of SCM Loss using SU Valves.
What transition occurs during LOSCM when RCS pressure gets < 150 psig?
Transition to ESAS to establish LPI Flow
What actions are taken to address potential RCS leak paths?
Isolate PZR spray line, Isolate ERV Isolation (Only if HPI Cooling NOT in progress AND ERV was not opened by procedure to intentionally depressurize RCS), and isolate ICW via LD cooler outlets and if not isolated and SI not available then isolate seal bleedoff, secure seal cooling pumps and isolate ICW to RB.
When is transition made to Tube Rupture?
RT-18 is performed and if SCM is adequate or no other indication of LOCA exist (RB/Aux bldg sump levels stable) then go to tube rupture.
What actions are taken if SG Levels aren’t approaching 370 - 410”?
Re-perform RT-5, Start CFW if EFW not available.
If all sources of FW NOT available and SCM adequate, go to overheating.
What contingency steps are taken if primary to secondary heat transfer not indicated (step 19)?
1) If RCS pressure 2400# or NDTT Limits, then cycle ERV until pressure less than 1650 psig if SCM not adequate or cycle ERV to minimum SCM value if SCM adequate.
2) Raise primary to secondary delta T to 40 - 60 deg F by bypassing MSLI and opening TBV/ADV per figure 5.
What actions are taken once SCM is adequate (Step 20)?
Restore RCPs per RT-7/11 and return 1 per loop, PZR level 180” and unisolate PZR spray and stabilize temps using TBV/ADVs.
What steps are taken if SCM is not adequate per step 20?
Check prim to sec heat transfer adequate
If its not, RCPs not in service and SCM adequate then open hi point vents and vent hot legs to establish prim to sec heat transfer.
If RCPs not in service and SCM inadequate, raise prim to sec delta T to 90 - 110 deg F using Figure 6.
What actions are performed if SCM remains inadequate, prim to sec heat transfer cannot be established or cannot correct LOSCM?
1) If uncontrolled CD due to HPI/break flow go to small break LOCA cooldown.
2) If RCS leak un-isolable and RCS pressure remains greater than or equal to 150 psig then if all RCPs off start one in each loop and go to forced flow cooldown. If RCPs not available go to natural circ cooldown.
When is a rapid plant cooldown performed and what actions are taken?
Rapid Plant Cooldown performed if LOSCM and either HPI flow less than full flow from one HPI pump and head voids indicated or RCPs not tripped within 2 minutes. (C/D rate limits do not apply)
Using feed source other than P-7A, fully open TBVs/ADVs, feed to 370 - 410”, If one SG and one LPI train available then open ERV.
If rapid cooldown due to HPI flow inadequate, perform RT-3, close ERV.
