SALEM
SALEM STUDY SYSTEM
Systems > Main Turbine

Main Turbine

⚠️ DRAFT

Main Turbine

Function

Converts steam energy from the steam generators into electrical energy. (UFSAR 10.2)

Design

  • Tandem compound, six-flow exhaust, 1800 RPM
  • Westinghouse design
  • Electro-hydraulic control system (UFSAR 10.2)

Turbine Trips

TripSource
Low auto stop oil pressureUFSAR 10.2
Thrust bearing failureUFSAR 10.2
Low bearing oil pressureUFSAR 10.2
Generator protectionUFSAR 10.2
ManualUFSAR 10.2
Reactor trip (P-4)UFSAR T7.2-2

Reactor Trip on Turbine Trip

  • Turbine trip generates reactor trip on 2/3 low auto stop oil pressure
  • Interlocked with P-9: reactor trip on turbine trip is blocked below ~50% RTP (UFSAR T7.2-1)
Exam — 2020 Q1
OHA F-36 (TURB TRIP & P-9) confirms turbine trip above P-9: either 4/4 Turbine Stop Valves ≤ 85% open OR 2/3 Auto Stop Oil Pressures ≤ 50 psig. On 2RP4, turbine stop valve closed lights: LIT solid = both SSPS trains agree valve closed; FLASHING = train disagreement. Redundant trip solenoids: 20-ET, 20-AST-1, 20-AST-2. 45 psig is the Tech Spec value for auto stop oil — the actual setpoint is ≤ 50 psig.
Exam — 2023 Q15
Grid disturbance — loss of a Salem unit causes 500KV switchyard voltage to lower. As grid voltage drops, remaining generating units share reactive load: Unit 2 MVARs rise to compensate for the lost reactive support from the tripped unit. (Ref: S2.OP-AB.GRID-0001)
Exam — 2023 Q20
Rising condenser backpressure reduces LP turbine efficiency, confirmed by lowering generator MWe output. The primary operational concern is overpressurization and damage to the LP turbine/main condenser, not condensate pump cavitation.
Exam — 2022 Q17
When one unit trips, reactive load (MVARs) is shared among remaining generators on the grid — the operating unit picks up LESS than the full amount (grid absorbs the rest). The voltage regulator senses terminal voltage drop from increased MVAR loading and increases generator field current to restore terminal voltage to setpoint.

Tech Spec LCOs

Exam — 2023 Q66
Stator Water Cooling: Unit 2 (GE SCW) is the ONLY unit with an automatic turbine runback feature — triggered by low flow, low pressure, or high temperature. If runback fails to lower amps to specified value within the time delay, a turbine trip occurs. Unit 1 (Westinghouse SCW): low flow inputs into a 45-second time-delayed turbine TRIP circuit — no runback feature. Unit 1 does not have a SLMS System.
Exam — 2023 Q80
ATWS turbine trip verification (EOP-FRSM-1 Step 6): confirmed by ALL turbine stop valve closed bi-stables LIT on 2RP4. Auto Stop Oil low pressure bi-stables (2/3) on 2RP4 indicate a turbine trip demand, NOT confirmation the turbine actually tripped (stop valves may not have closed). If turbine trip is not confirmed, dispatch operator to locally trip at the front standard.
Scenario — 2020 #5
Main turbine fails to auto trip following reactor trip (23BF19 failure). Pistol grip manual trip also fails. RO must trip turbine using turbine trip bezel pushbutton (CT-13). If crew isolates main turbine by actuating MSLI, this also satisfies CT#1. Safety significance: failure to trip turbine after reactor trip causes continued steam demand → excessive RCS cooldown → challenge to subcriticality (return to power) and integrity (PTS) CFSTs, or transition to EOP-LOSC-1. Auto SI actuates following reactor trip due to turbine failing to trip and high steam flow conditions.
JPM — 2019 Sim-e
Main Turbine Stop Valve retest at 89% power IAW S2.OP-PT.TRB-0003. Navigate DEHC HMI to STOP/GOV TEST screen. Test permissives: TURBINE INLET PRESSURE OK and NO OTHER TESTS IN PROGRESS (both GREEN). P&L 3.4.3: operate at <=75% turbine load with any one HP inlet valve closed. 22MS29 (Governor Valve) closes first (~2 min), then 22MS28 (Stop Valve) strokes closed and open (~25 sec). OHA G-12 TURB STM STOP VLV CLSD expected during test. Alternate path: field operator misses valve stroke → select RESTROKE on HMI to re-verify.
JPM — 2018 Sim-e
S2.OP-SO.TRB-0001 Section 4.5 — Synchronizing the Generator: at 16% power starting up, turbine at 1800 rpm with excitation applied. Key steps: scope test (synchroscope at 12 o'clock, voltmeters upscale), verify SYNC PERM BYPASS in NORMAL. Select 1-9 Mimic Bus and SYNCH POT ON. INCOM KV must be 3-5 KV above RUN KV (as-found both ~498-499 KV — must raise via Voltage Regulator). Turbine speed must produce synchroscope rotation every 25-30 sec in FAST direction (raise SETTER from 1801 to 1802-1803 rpm). Close 500 KV 1-9 breaker when synchroscope 1-2 minutes before 12 o'clock. Verify 40-60 MW load pickup within 15 seconds.
Exam — 2018 Q91
Turbine runback from 100% power can cause control rods to insert below the Rod Insertion Limit (ROD INSERT LIMIT LO-LO alarm). Raising turbine power to counter the runback is NOT permitted per the alarm response procedure — the ONLY allowed action to restore rods above the RIL is performing S2.OP-SO.CVC-0008 (Rapid Boration).

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