LOCA EOP

Question 1

Given a LOCA condition, determine the MAJOR mitigating strategies in 40EP-9EO03, LOCA EOP:

• 7 Major strategies

Answer 1

1. Max SI flow and attempt to isolate leak
2. If leak isolated, control RCS pressure/inventory and maintain RCS Heat Removal
3. If isolated, perform controlled cooldown to SDC entry conditions
4. If Leak can’t be isolated, Rapid Cooldown using SG’s
5. If Leak can’t be isolated, commence post-LOCA long term cooling (Hot and Cold Leg inject)
6. If Leak can’t be isolated, determine whether SDC (small breaks) or Hot/Cold Leg inject in Recirculation (Large Breaks) should be continued
7. For Intersystem LOCA, RCP’s must be stopped, affected HPSC isolated after NC CIV’s closed

Question 2

Given a LOCA, how does the Plant respond to:
SMALL BREAKS vs
LARGE BREAKS

Answer 2

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%

Question 3

Given a LOCA, how does the Plant respond to:
LETDOWN LINE BREAK
INTERSYSTEM LOCA
PZR STEAM SPACE

Answer 3

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.

Question 4

When entering EOP’s from Modes 3 or 4, the reactor was already shutdown and the ___ may not be applicable to existing plant conditions.

Answer 4

…SPTA steps

Question 5

Given LOCA conditions, what are ENTRY conditions into the LOCA EOP:

Answer 5

1. SPTA’s have been performed or
   BOTH of following:
   * A LOCA initiated from M3 or M4
   * LTOP is NOT in service
   and
2. 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

Question 6

Given LOCA conditions, EXIT criteria:

Answer 6

LOCA EOP can be exited when ANY of following:

1. Diagnosis of LOCA is NOT confirmed
2. Any LOCA safety function acceptance criteria isn’t satisfied
3. 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

Question 7

Given LOCA conditions, analyze MVA for SFSC:

Answer 7

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

Question 8

Given ORP entry conditions, describe “Bus Plus” and if it’s met per Procedure:

Answer 8

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.

Question 9

Given LOCA conditions, analyze RCS inventory control, determine SFSC acceptance criteria:

Answer 9

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