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EOPs > EOP-LOPA-1 — Loss of All AC Power

EOP-LOPA-1 — Loss of All AC Power

⚠️ DRAFT

EOP-LOPA-1 — Loss of All AC Power

Purpose

Provides operator actions for responding to a loss of all AC power, including cooldown using MS10 atmospheric relief valves.

Key Actions / Information

Exam — 2022 Q77
Step 17.2: MS10 relief valves remain operable from the control room on loss of all control air because each MS10 has a bottle rack with four bottles of nitrogen (>= 2000 psig) providing backup air for control and operation. Bottle rack capacity is designed for a minimum of 72 hours of MS10 operation. Maximum cooldown rate in EOP-LOPA-1 is 100°F/hr. Do not confuse with 50°F/hr used in EOP-TRIP-6 (Natural Circulation Without RVLIS). The MS10s do NOT need to be operated locally — nitrogen backup keeps them available from the control room.
Scenario — 2020 #1
Entry on all three 4KV Vital Buses de-energized (2A Bus Differential, 2B EDG overspeed, 2C EDG C/T). Immediate actions: trip reactor, trip turbine, close 2CV2 and 2CV277. De-energize all SECs. Stop 2A EDG — running with no SW pumps (will overheat). Stop all loads in Table A. Reset SI. After maintenance returns 2C EDG from C/T: start 2C EDG, close output breaker to energize bus (CT-24), start one SW pump for EDG cooling (CT-25). Step 26: "When at least one 4kV vital bus is energized, THEN go to step 43."
JPM — 2019 Sim-g
EOP-LOPA-1 Step 13 CAUTION: 4KV VITAL BUS LOADING limits — DG 2000-HR LIMIT 2750 KW, 2-HR LIMIT 2860 KW, HALF-HR LIMIT 3100 KW. Step 14: start 2C EDG, verify FREQUENCY >= 60 Hz and VOLTS >= 4.15 KV, close output breaker via MIMIC PB for 2C DG 4KV BKR 2CDD (verify Yellow indication on both MIMIC PB and BUS INTLK CLOSE SELECTION bezel), then close 2C BREAKER CLOSE PB. Start one SW pump (25 or 26) for EDG cooling, close 23SW20. Step 17: start C bus loads — 22 Charging Pump, 23 CCW Pump, #2 ECAC.
Exam — 2018 Q59
Vital Power Restoration Steps: prior to restoring AC power, ALL SECs must be de-energized (not blocked and reset). Reason centrifugal charging pumps must not auto-start: preventing damage to the RCP seals. After prolonged loss of seal injection, injecting cold charging water into hot seals can cause thermal shock and seal damage. Trap: "blocked and reset" is an action performed in other EOPs (e.g., EOP-TRIP-1), not in EOP-LOPA-1 power restoration steps. Also: candidates may think preventing seal damage is NOT a concern because seal injection is normally beneficial.
JPM — 2018 IP-i
Shed non-essential DC loads per Checkoff Sheet 3 (COS 3-1 thru 3-3), 125VDC LOAD SHED LIST. Operator locates distribution panels at 64 ft elevation (2A 125VDC Bus, 2ADC, 2B 125VDC Bus, 2DDC, 2CDC panels) and 100 ft elevation switchgear room (2AADC, 2BBDC, 2CCDC panels). Opens ONLY breakers designated on the checkoff sheet (not all breakers in each panel). Checkoff Sheet 3 sections may be performed in any order.

Connections