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Exams > 2023 Scenario 1 — Load Reduction / LBLOCA

2023 Scenario 1 — Load Reduction / LBLOCA

⚠️ DRAFT
Scenario 1 — Load Reduction / LBLOCA Simulator | 8 Events | 2 Critical Tasks
Initial Conditions: Salem Unit 2 is at 100% power BOL

Turnover: The crew is directed to reduce power to 89% power at 10% per hour IAW S2.OP-IO.ZZ-0004 using boration, control rods and turbine load control in preparation for Main Turbine Valve testing.
Major Events:
  1. Planned Load Reduction to 89% at 10%/hour
  2. 24 Vacuum Pump trips
  3. 2N41 Power Range Channel Fails High (TS)
  4. RCS Leak — 20 gpm (TS)
  5. Large Break LOCA (leak worsens to 350 gpm)
  6. Auto SI fails to actuate on both trains
  7. #2 ECAC Fails to Start on SEC Signal
  8. Two Phase A valves (2CV116 and 284) fail to close
▶ Show Event Sequence & Expected Responses
# Event Expected Crew Response
1 Planned Load Reduction to 89% CRS briefs crew on power reduction. RO initiates boration IAW S2.OP-SO.CVC-0006. PO initiates turbine load reduction IAW S2.OP-SO.TRB-0002 — adjust ramp rate to 10%/hr, set to 89%, select GO.
2 24 Vacuum Pump trips PO reports trip. CRS enters S2.OP-AB.COND-0001, Loss of Condenser Vacuum. PO initiates Att 1 CAS, dispatches operator for Att 2 local checks. PO starts 22 and 25 vacuum pumps — 22 trips after start, 25AR25 fails to open. Backpressure stabilizes below trip setpoint.
3 2N41 Power Range Channel fails high RO reports rods stepping in, no runback. RO places rod control in Manual. CRS enters S2.OP-AB.NIS-0001, NIS Malfunction. CRS directs removal of 2N41 from service IAW S2.OP-SO.RPS-0001 (place in Tripped Condition). CRS evaluates TS 3.3.1.1 — one PR channel inoperable.
4 RCS Leak — 20 gpm inside containment RO reports 2R11A containment radiation rising, PZR level lowering, RCS pressure lowering. CRS enters S2.OP-AB.RC-0001, RCS Leak. RO determines leak rate. RO swaps to centrifugal charging pump. CRS evaluates TS 3.4.7.2 for identified/unidentified leakage.
5 Large Break LOCA — leak worsens to 350 gpm RO reports leak exceeds makeup capability. CRS implements Att 1 CAS — Trip the reactor. RO manually trips reactor, verifies trip. CRS enters EOP-TRIP-1.
6 Auto SI fails to actuate on both trains RO manually actuates SI on one train, verifies other train actuated. Continues EOP-TRIP-1 immediate actions: backs up turbine trip, verifies 4KV vital buses energized, verifies SI initiated.
7 #2 ECAC fails to start on SEC signal PO reports #2 ECAC failed. PO blocks and resets 2C SEC. RO starts #2 ECAC. PO throttles AFW flow. RO reports containment pressure >15 psig — Phase B and Spray auto-initiated. MSLI auto-initiated.
8 Two Phase A valves (2CV116, 284) fail to close PO reports 2CV116 and 284 NOT in required position. CRS directs manual closure. At least one valve on each penetration must be closed before transitioning out of TRIP-1. (Critical Task #1)
Critical Tasks:
CT#1 (CT-11): Close containment isolation valves such that at least one valve is closed on each Phase A penetration before transition out of TRIP-1. Safety significance: preserves containment boundary to minimize fission product release following LOCA.

CT#2 (CT-36): Transfer to cold leg recirculation before RWST Lo-Lo level (1.2 feet) is reached or ECCS pump cavitation. Includes time-critical operator actions: (1) Close 2SJ69 within 3.7 min of RWST Lo Level, (2) Stop 22 CS pump within 5.5 min, (3) ECCS pumps verified in recirculation within 11.2 min. Safety significance: failure to transfer before RWST empties results in loss of all pumped safety injection and containment spray.
EOP Pathway:
S2.OP-AB.COND-0001 (vacuum pump trip) → S2.OP-AB.NIS-0001 (PR channel fail) → S2.OP-AB.RC-0001 (RCS leak) → EOP-TRIP-1 (reactor trip/SI) → EOP-LOCA-1 (RCS leak identified, SI termination criteria, RWST Lo Level) → EOP-FRTS-1 (possible Purple path on Thermal Shock — enter/exit, no actions) → EOP-LOCA-3 (transfer to cold leg recirculation) → Scenario terminated after ECCS aligned to recirculation
Source: 20-01 ESG-1 | View Scenario PDF

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