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EOPs > EOP-LOCA-5 — Loss of Emergency Coolant Recirculation

EOP-LOCA-5 — Loss of Emergency Coolant Recirculation

⚠️ DRAFT

EOP-LOCA-5 — Loss of Emergency Coolant Recirculation

Purpose

Provides operator actions when emergency coolant recirculation capability is lost, including RCS depressurization guidance and monitoring for upper head voiding.

Key Actions / Information

Exam — 2020 Q42
Step 9 — Table C determines required number of containment spray pumps based on RWST level, containment pressure, and number of CFCUs operating. With RWST > 15.24 ft, containment pressure 18 psig, and 4 CFCUs operating → 0 CS pumps required. Must correctly identify which bus is lost to calculate ECCS flow rate and RWST depletion. 2A Vital Bus lost = "A" bus loads lost (lower depletion rate, 4350 gpm). Assuming "B" bus loads lost gives incorrectly high depletion rate.
Exam — 2023 Q17
Step 23 — during RCS depressurization, upper head voiding IS expected with no RCPs running. Monitor pressurizer level — rapidly rising PZR level indicates upper head voiding. Stop depressurization before the pressurizer goes solid.
JPM — 2019 SRO-A1
Step 19.2 minimum ECCS flow from Figure A: at 50 minutes post-trip (0550 - 0500 = 50 min), minimum flow is 390 gpm (+/- 10 gpm). With 21 SI Pump at 420 gpm and 22 Charging Pump at 360 gpm: 22 Charging pump CAN be stopped (360 gpm alone < 390 gpm minimum), but 21 SI pump must remain (420 gpm alone > 390 gpm minimum). Contrast with 2023 SRO-A1.a where neither pump could be stopped.
JPM — 2023 SRO-A1.a
Step 16.1 minimum ECCS flow from Figure 1: at 100 minutes post-trip, minimum flow is 290 gpm (acceptable band 280-320 gpm). With 21 SI Pump at 160 gpm and 22 Charging Pump at 220 gpm, NONE can be stopped — neither alone meets the 290 gpm minimum. Both must remain in service (combined 380 gpm).
Exam — 2022 Q80
Caution C3-1 in EOP-FRCE: if LOCA-5 is in effect, operation of containment spray pumps should be IAW LOCA-5 (not FRCE-1). LOCA-5 has less restrictive criteria allowing reduction of operating CS pumps based on RWST level and CFCUs to conserve RWST inventory. The CRS can transition to EOP-FRCE-1 for containment pressure concerns but follows LOCA-5 direction for CS pump operation. FRCE-1 establishes maximum available heat removal (more spray), which conflicts with LOCA-5 priority to conserve RWST inventory.
Scenario — 2022 #1
Entered from LOCA-1 when 22 RHR pump trips — no RHR pumps available (21 RHR C/T). CT#3 (CT-29) has four parts: (1) Stop CS pumps — CRS determines no CS pumps required per Table C, RO resets Spray actuation, stops 21 and 22 CS pumps. (2) RWST makeup — RO initiates makeup IAW S2.OP-SO.CVC-0006: places 2CV179 in Manual (full open), 2CV172 in Manual, starts 22 Primary Water pump, locally opens 2CV182 and 2CV184, starts 22 BA pump, adjusts BA flow ≥20 gpm, adjusts 2CV179 to 50 gpm. (3) Reduce SI to one train — stop all but one charging pump, run only one SI pump. (4) If RWST Lo-Lo alarm received, stop ALL pumps taking suction from RWST prior to cavitation.
Scenario — 2020 #2
Entered from LOCA-1 when 22 RHR pump trips (overcurrent) — no RHR pumps available (21 RHR C/T for motor bearing replacement). CT#3 (CT-29) in three parts: (1) Stop CS pumps — CRS determines 0 CS pumps required per Table C (RWST ~14.2 ft, containment pressure ~17 psig, 4 CFCUs running), resets Spray actuation, stops 21 and 22 CS pumps. (2) RWST makeup — initiates makeup IAW S2.OP-SO.CVC-0006 Section 5.8 (starts RWST heater pump, 22 Primary Water pump, locally opens 2CV182 and 2CV184, starts 22 BA pump, adjusts 2CV172 and 2CV179). (3) Reduce SI to one train — stops all but one charging pump, runs only one SI pump. RCS cooldown at 100 F/hr using intact MS10s.
Exam — 2018 Q65
Step 24 — RCS depressurization with all RCPs stopped: normal spray NOT available → use a PZR PORV to depressurize (not AUX SPRAY). Upper head voiding indication: PZR level rising from 10% to 45% in 30 seconds = rapidly rising PZR level. AUX SPRAY maintains RCS inventory but is not the procedure-directed depressurization method. PORV depressurization loses inventory but is what EOP-LOCA-5 directs.
Exam — 2019 Q65
Step 24 — RCS depressurization to minimize subcooling: with normal spray not available (all RCPs stopped), the crew depressurizes using a PZR PORV (not AUX SPRAY). Upper head voiding indication: rapidly rising PZR level (35% rise in 30 seconds in this example). Do not confuse AUX SPRAY (which maintains RCS inventory) with PORV depressurization (which loses inventory). With no RCPs running, normal spray is NOT available. Also: rapidly rising PZR level IS an indication of upper head voiding — the steam in the upper head collapses, pushing water into the PZR.
Exam — 2019 Q15
Step 6 Table B/C analysis with 2B 4KV Vital Bus de-energized: Table B determines NO TRAINS of Emergency Recirculation available (both SJ44 sump valves closed). Table C determines CS pumps required: with Containment Pressure = 19 psig, RWST Level = 10 feet, and only 3 CFCUs in slow speed (2B bus loss → 22 and 24 CFCUs unavailable) → 0 CS Pumps required. Crew stops BOTH CS pumps per Step 9, then proceeds to Step 10 (add makeup to RWST). Correct CFCU count depends on knowing which CFCUs are powered from the 2B bus. With 2B lost: only 21 (A bus), 23 (C bus), and 25 (C bus) remain — 3 CFCUs total.
Exam — 2020 Q17
LOCA-5 mitigation strategies include: (1) Run all CFCUs in high speed, (2) Minimize SI flow, (3) Depressurize RCS to minimize subcooling, (4) Make up to RWST. During a DBA LBLOCA with loss of one EDG (2B EDG), only strategies 2 and 4 are applicable because: 22 and 24 CFCUs are powered from the 2B EDG bus and are NOT available (eliminates strategy 1), and a DBA LOCA has already completely depressurized the RCS so no RCS subcooling exists to minimize (eliminates strategy 3).
Exam — 2018 Q81
RWST makeup procedure selection: IAW EOP-LOCA-5, crew adds makeup to RWST per S2.OP-SO.CVC-0006 Section 5.8 (Makeup to RWST Using CVCS Makeup System) — NOT S2.OP-SO.SF-0001 Section 5.6 (Transferring Spent Fuel Pool Water to RWST). SG NR Level feed flow target depends on containment conditions: ADVERSE containment (≥ 4 psig): maintain total feed flow > 22E04 LB/HR until at least one SG NR Level > 15%. NORMAL containment: > 9%. At 12.0 psig containment pressure = adverse conditions apply. Trap: S2.OP-SO.SF-0001 Section 5.6 IS an approved RWST makeup procedure, but EOP-LOCA-5 specifically directs CVC-0006 Section 5.8.

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