Given a LOCA condition, determine the MAJOR mitigating strategies in 40EP-9EO03, LOCA EOP:
- 7 Major strategies
- Max SI flow and attempt to isolate leak
- If leak isolated, control RCS pressure/inventory and maintain RCS Heat Removal
- If isolated, perform controlled cooldown to SDC entry conditions
- If Leak can’t be isolated, Rapid Cooldown using SG’s
- If Leak can’t be isolated, commence post-LOCA long term cooling (Hot and Cold Leg inject)
- If Leak can’t be isolated, determine whether SDC (small breaks) or Hot/Cold Leg inject in Recirculation (Large Breaks) should be continued
- For Intersystem LOCA, RCP’s must be stopped, affected HPSC isolated after NC CIV’s closed
Given a LOCA, how does the Plant respond to:
SMALL BREAKS vs
LARGE BREAKS
Small: Loss of inventory with gradual pressure drop. Operator will rapidly depressurize to ensure SI flow covers core. Uses SG’s only
Large: Rapid depressurization, LPSI < 200#. Core cool by SI and break flow (not SG’s, actual heat source), shift to RAS at 9.4%
Given a LOCA, how does the Plant respond to:
LETDOWN LINE BREAK
INTERSYSTEM LOCA
PZR STEAM SPACE
LD line: Gradual depressurization of RCS. Aux Bldg rad alarms
IS LOCA: NC or EW. RU-6, RU-2/3 alarms. Expansion tank rise. Small leaks, gradual PZR level drop.
PZR Space: Initial drop in PZR level with RCS # drop. Bubble somewhere else in RCS (PZR Level up). Less inventory loss than liquid source due to density.
When entering EOP’s from Modes 3 or 4, the reactor was already shutdown and the ___ may not be applicable to existing plant conditions.
…SPTA steps
Given LOCA conditions, what are ENTRY conditions into the LOCA EOP:
- SPTA’s have been performed or
BOTH of following:
* A LOCA initiated from M3 or M4
* LTOP is NOT in service
and - Plant conditions indicate a LOCA has occurred. ANY or all of following may be present:
* PZR Level Low (break in PZR, may be High)
* SIAS auto actuated
* Rise in CTMT pressure, temp, rad, humidity, level
* High RDT level, temp, or pressure
Given LOCA conditions, EXIT criteria:
LOCA EOP can be exited when ANY of following:
- Diagnosis of LOCA is NOT confirmed
- Any LOCA safety function acceptance criteria isn’t satisfied
- LOCA EOP has satisfied ALL of following:
* All SFSC criteria satisfied
* SDC entry conditions satisfied, or break isolated or RCS is in long term cooling
* Appropriate procedure to implement has been provided and admin approved
Given LOCA conditions, analyze MVA for SFSC:
a. At least 1 vital 4.16kV AC bus energized
b. At least 1 of following PK/PN trains available and on same train as powered 4.16kV AC bus:
* PKA-M41, PKC-M43 and PNA-D25
* PKB-M42, PKD-M44 and PNB-D26
c. No jeopardized safety functions require restoration of electrical power to vital AC or DC bus
Given ORP entry conditions, describe “Bus Plus” and if it’s met per Procedure:
Minimum: 1 vital 4.26kV, 1 vital 120 VAC, 1 vital 125 VDC
MVA is NOT MET if any vital equipment needed to maintain safety functions is NOT available and recovery depends on restoring electrical power to a vital AC or DC bus.
Given LOCA conditions, analyze RCS inventory control, determine SFSC acceptance criteria:
Condition 1: LOCA Isolated (meet all)
a. PZR Level >10% [15%]
b. RCS is 24F [44F] or more subcooled
c. RVLMS indicates that RVUH plenum is 16% or more
Condition 2: LOCA NOT Isolated (meet all)
a. SI Flow adequate (Appendix 2, Figures)
b. CET Subcool < 44F (60F) superheat and not rising
c. RCS Subcool < 44F (60F) superheat and not rising
