E-1 Series EOP's Flashcards
What is an RCS Leak?
The mass loss rate is within the capacity of the charging system.
- AOP directs operator to trip the RX if PZR level cannot be maintained with two charging pumps and letdown isolated.
What is a Small Break LOCA? (SBLOCA)
- Pressure stabilizes at some value < than the shutoff head of the RHR pumps AND RHR flow is < 400 gpm
OR - RCS pressure stabilizes at some pressure > shutoff head of the RHR pumps
- UFSAR: Break with an area < 1 sq. ft. but > 3/8th inch and normal charging is unable to maintain PZR level and pressure.
What is a Large Break LOCA? (LBLOCA)
- Pressure stabilizes at some value < shutoff head of the RHR pumps AND RHR flow is > 400gpm.
- UFSAR: A break with an area >1 sq. ft. and during depressurization the RCS pressure equals containment pressure.
What are the phases of a LBLOCA?
- Blowdown Phase: Starts at initiation of LOCA and ends when RCS equalizes containment #.
- Refill Phase: Starts at end of blowdown phase and ends when addition of ECCS water fills to bottom of the vessel and reaches bottom of fuel.
- Reflood Phase: Starts at end of refill phase and ends when the vessel has been completely filled with water and core temps reduced to long term decay heat levels.
- Long Term Recirc Phase: Starts when RHR and CTS suction aligned to Recirc Sump.
What are the sub-phases of the Blowdown Phase?
- Subcooled Blowdown
- Saturated Blowdown
- Superheated Blowdown
Why are RCP’s tripped during a LBLOCA?
- To prevent damaging the pumps.
- Phase B isolates CCW from the RCP’s.
- Pressure below 1300# does NOT provide adequate NPSH.
What are the phases of a SBLOCA?
- Blowdown Phase: Starts at the LOCA and ends when vessel level stops lowering before the bottom of the core uncovers.
- Reflood Phase: Starts at end of blowdown phase and ends when vessel has been filled with water and core temps have lowered to long term decay heat levels.
- Long Term Recirc Phase: RHR and CTS aligned to recirc sump AND CCP/SI pump suction aligned from RHR.
Why are RCP’s secured during a SBLOCA?
- The longer the RCP’s are left running, the more two-phase flow is lost through the break
Why aren’t RCP’s secured unless ECCS flow is verified?
- RCP’s must remain running to ensure adequate core cooling.
- If RCP’s were secured (with no ECCS flow) natural circulation would be the only method of heat removal. This requires higher delta T’s to get flow, therefore PCT’s must be higher.
When do the RCP trip criteria NOT apply?
- Anytime an operator induced cooldown has been commenced.
- SI is actuated from cold shutdown, hot standby, or start-up.
- Following RCP restart that is directed by EOP’s.
- EOP specifically states they don’t apply.
What are the FOP Criteria for E-1? (Loss of Reactor or Secondary Coolant)
- RCP Trip Criteria: Trip all RCP’s if CTS phase B actuated OR, RCS pressure < 1300# AND at least on CCP or SI pump running.
- SI Reinitiation: Manually establish ECCS flow as necessary to restore conditions if subcooling is < 40F OR PZR level cannot be maintained > 16% (28%) adverse.
- Secondary Integrity: Go to E-2 if any S/G pressure is lowering uncontrollably OR has completely depressurized, AND the affected S/G has NOT been isolated.
- E-3 Transition: Manually establish ECCS as necessary and go to E-3 if any S/G level rises uncontrollably OR any S/G has abnormal radiation.
- Cold Leg Recirc: Go to ES-1.3 if RWST level < 30%
- AFW Switchover: Switch to alternate AFW supply if CST < 15%.
- RHR pump restart: Manually start RHR pumps if RCS pressure lowers to < 300#.
- Control Room Pressurization System: Maintain one pressurization fan running during subsequent recovery actions.
- Sump Blockage: Go to ECA-1.3 if Recirc Sump level low LIT with one train of RHR and CTS operating OR Recirc Sump level low RED light LIT with one train of RHR and CTS operating OR air entrainment of either or both trains of RHR or CTS.
What conditions will require transition to E-2 (Faulted S/G Isolation) from E-1?
Either:
- S/G(s) pressure lowering in an uncontrolled manner
- S/G(s) completely depressurized
What conditions will require transition to E-3 (SGTR) from E-1?
- NR level in any S/G continues to rise in an uncontrolled manner.
- Secondary radiation monitors NOT normal.
- S/G Blowdown sampling or treatment NOT normal.
While performing E-1 why is there a caution about aligning control air to containment with containment pressure > 6# when isolating accumulators?
If accumulators need to be isolated and the operator has to do it by venting the accumulators to containment, with 6# in containment integrity may be violated when accumulators are vented AND when the pressure spike happens after the ice melts.
While performing E-1 at what pressure are the accumulators isolated and why?
- 150#
- Prevent Nitrogen injection
What conditions are required to transition to ES-1.2 (Post LOCA Cooldown and Depressurization) from E-1?
- Checks to see if RCP’s should be stopped are complete.
- Checks to see if transition to E-2 or E-3 are complete.
- Checks to see if leakage is from the PORV’s complete.
- Checks to see if SI termination criteria met are complete.
- Cold leg recirc available.
- Lastly, RCS pressure > 300#
While performing E-1 what are the hydrogen concentration bands and actions taken for each when checking containment hydrogen concentration?
- > 4%: Consult the PET for further recovery actions.
- High probability of burn.
- Between 0.5% and 4%: If 6 hours have elapsed, start the hydrogen recombiners. If 6 hours have not elapsed, wait until they have.
- 6 hour wait ensures additional heat from recombiners does not overpressurize
containment.
- 6 hour wait ensures additional heat from recombiners does not overpressurize
- < 0.5%: Monitor hydrogen concentration.
- No threat of burn.
What is the time band requirement for transitioning to Hot Leg Recirc, the reason for it, and when does E-1 direct the operator to transition?
- 5.5 to 7.5 hours following the LOCA
- 5.5 hours is based on precluding core uncovery for all break sizes, while 7.5 hours is the minimum time when boric acid concentration could approach precipitation concentrations.
- E-1 directs transfer at 7 hours following the LOCA.
What are the FOP criteria for ES-1.1? (SI Termination)
- SI Reinitiation: Manually establish ECCS flow as necessary to restore conditions AND go to E-1 if subcooling < 40F OR PRZ level cannot be maintained > 16% (28% adverse)
- Secondary Integrity: Go to E-2 if any S/G pressure is lowering in an uncontrolled manner or has completely depressurized AND affected S/G has not been isolated.
- Cold Leg Recirc: Go to ES-1.3 if RWST level < 30%.
- AFW Switchover: Switch to alternate AFW supply if CST < 15%
What are the SI Termination Criteria?
- Subcooling > 40F
- Secondary Heat Sink Established:
- Feed flow > 240K lbm/hr -OR-
- NR level in one S/G > 13%
- RCS # stable or rising
- PZR level >16%
While performing ES-1.1, what is the time requirement for stopping all but one CCP?
15 minutes
While performing ES-1.1, what conditions will require transition to ES-1.2? (Post LOCA Cooldown and Depressurization)
- All but one CCP secured
- Charging flow is through the BIT
- RCS # lowering (One CCP is NOT adequate ECCS flow)
While performing ES-1.1, what is the time requirement for isolating the BIT?
17 minutes
After securing ECCS flow in ES-1.1, why is it important to maintain RCS hot leg temp stable?
Makes PZR pressure and level control much easier, particularly since ECCS has most likely forced a large amount of colder water into the RCS.