PWR Operator Manual · Open the simulator

04 — Normal Operating Procedures

Document: PWR-NOP-01
Plant: Pressurized Water Reactor (PWR)
Revision: 24

1.0 Purpose

Provide normal operating procedures (NOPs) for the Reactor⚛️Dynamics PWR in commercial plant format: purpose, applicability, prerequisites, precautions, steps with acceptance criteria, and outcome.

Master MODE paths (detail of each leg is in this chapter; path orchestration is in 05):

• PWR-T20 — Mode 5, Cold Shutdown → Mode 1, At Power
• PWR-T21 — Mode 1, At Power → Mode 5, Cold Shutdown
• PWR-T03 — Mode 3, Hot Standby → Mode 1, At Power (N03 → N04 → N05 → N06)

Commercial heatup practice (Westinghouse technology training outline) is subcritical heatup and pressurization from cold to Hot Standby, then a separate evolution from Mode 3 to power. PWR-N01 is that cold-to-hot leg on reactor coolant pump heat.

Related: 03 Controls and Indications · 05 Mode Transitions · 06 Alarm Response · 09 Setpoints and Limits · 12 Simulation Physics

2.0 Procedure index

Numbered in plant sequence.

A. Startup path (Mode 5 → Mode 1)

B. At-power maneuvers

C. Continuous control

D. Shutdown path (Mode 1 → Mode 5)

PWR-N01 — Heatup Mode 5, Cold Shutdown → Mode 3, Hot Standby (pump heat) [sim]

Purpose

Heat and pressurize the RCS from Mode 5, Cold Shutdown through Mode 4, Hot Shutdown to Mode 3, Hot Standby with the reactor subcritical throughout. Heat source is reactor coolant pump work (and pressurizer heaters), not fission.

Applicability

• Plant in Mode 5, Cold Shutdown.
• Master path: PWR-T20 Phase A.

Prerequisites

1. Plant in Mode 5, Cold Shutdown: subcritical, RCS 122 °F (50 °C), 363 psi (2.50 MPa), RHR in service, RCPs secured, both banks in, pressurizer heaters OFF and the spray in hand and shut (as PWR-N12 leaves them on the cooldown) — the cold_shutdown initial condition (09 §11.0; restored 2026-08-31; the pressure-control lineup added 2026-09-04). Starting from Mode 4, Hot Shutdown (hot_shutdown) works identically from step 2, and it arrives the same way — heaters off, spray in hand — so step 5b is an action from either start, not a check.
2. RHR aligned for shutdown cooling.
3. SI accumulators isolated (correct Mode 5 lineup — plant is below cover-gas pressure).
4. Generator off line.
5. Both rod banks fully inserted — control bank and shutdown bank. This is the Mode 5 lineup; the shutdown bank is withdrawn as step 2a below, not before.

Precautions and limitations

Procedure

Acceptance (Mode 3 declared)

• RCS at NOP T/P class: P ≈ 2235 psi (15.41 MPa), Tavg at no-load band ≈ 546.8 °F (286 °C) — measured on the shipped plant with the dumps in AUTO, 547.2 °F (286.2 °C).
• Heat sink is the condenser dumps, not a relief: STEAM DUMP status STM PRESS, dumps carrying 0.4–2.9 %, steam header on the 1020 psi (7.03 MPa) anchor (1005 psig), atmospheric dump valve shut. A plant sitting at 551.6 °F (288.7 °C) with that valve at 7–9 % is a plant that never got step 8b.
• Reactor subcritical (measured arrival on this plant: ρ = −3399 pcm on ~918 ppm, control bank still fully inserted at 0 of 627 steps; re-measured 2026-09-14, and re-confirmed by the 2026-09-18 end-to-end replay at −3400 pcm on 917.8 ppm. The −2772 pcm on 857 ppm printed here until then was wrong twice over — 857 ppm is the RETIRED engine’s cold-shutdown target, and −2772 is this plant at 857 ppm evaluated 10 °F above its no-load point. The shipped cold_shutdown boots at 917.8 ppm and PWR-N01 dilutes nothing, so ~918 ppm is what arrives).
• Shutdown bank fully withdrawn (step 2a) — this is the state every mode above Mode 5 assumes, and PWR-N03 cannot reach criticality without it.
• Accumulators aligned.
• Ready for PWR-N02 (lineup) then PWR-N03 (approach to criticality).

**You arrive at cold-shutdown boron, and it is NOT the boron the approach to criticality assumes. The heatup dilutes nothing — ~918 ppm in, ~918 ppm out**. That is ~199 ppm above the 719 ppm that puts criticality at the reference position, and measured it moves the critical rod position from 208 steps to 490 — far outside the ±750 pcm acceptance band (88–297) the estimate is checked against. **PWR-N02 step 15 is the dilution that closes it, and it takes ~88 plant-minutes**. Do not carry cold-shutdown boron into PWR-N03.

Expected heatup performance

Pump heat only — no rod motion, no dilution. Heat source is RCP work (about 0.55 % of rated core heat at full flow) plus pressurizer heaters.

Mode boundaries on this plant are by Tavg: Mode 5 ≤ 199.4 °F (93 °C), Mode 3 ≥ 350.6 °F (177 °C), Mode 4 between them — so on the way up 350 °F is the Mode 4 → 3 boundary, not the Mode 5 → 4 one.

Re-measured on the SHIPPED plant, 2026-09-18. Everything below replaces a table taken on the RETIRED engine on 2026-08-02, whose Mode 4 entry (18 plant-min) and steady rate (30 °F/hr) were both a different plant. Conditions, stamped: the **pwr_heatup walkthrough replayed END TO END** through RD.SimulationService on selectPlant('pwr2', 'cold_shutdown'), full stack (M4+M5+M6), free-play default lineup, seed 42, 10× acceleration (1.0 s of sim per tick), no settle — t = 0 is the first tick of step 1. All 31 of the replay's own acceptance and guard checks passed.

The clock below is the PLAYER'S route, not the replay's. The authored hold on the ride step is 40,000 s, so the replay went on holding for another 5.2 plant-hours after its own 542 °F acceptance was met; a player advances the moment the tile reads the target. Every row is the time the condition was first TRUE.

The pressurization is STAGED, and stage 1 needs no dial. The cold_shutdown plant boots with the Pressure SP box already on its floor, measured at 1700 psi (11.72 MPa) — the bottom of its own 1700–2501 psi (11.72–17.24 MPa) span — so putting the heaters in AUTO is stage 1. It has to stay there until the secondary is bottled on the 1020 psi (7.03 MPa) anchor, because crossing the **P-11 permissive (1972 psi / 13.60 MPa) with steam pressure still under the 327.7 psi (2.26 MPa)** low-steam-pressure SI setpoint auto-reinstates a STANDING safety-injection signal: SI actuates on a healthy plant, the heaters shed (157.8 kW → 0) and the pressurization parks at ~1922 psi (13.25 MPa) for good.

Rate. The pumps warm the cold plant fastest and then fade as the ΔT to the no-load anchor closes: measured per quarter plant-hour, 98.4 °F/hr (54.7 °C/hr) average over the first 15 minutes, 91.6 in the second quarter, 84.3 by 1 plant-h, 61.4 by 4, and 46.0 by 6. End to end, 122.0 → 541.4 °F in 5.83 plant-hours is 71.9 °F/hr (39.9 °C/hr) average. ⚠ The worst single minute of the run is the FIRST one, at 110.4 °F/hr (61.3 °C/hr) — over the sourced 100 °F/hr RCS limit (§5.0), for about a minute as the pumps come up on a 122 °F plant. Nothing else in the ride approaches it. The 567 °F (297.2 °C) endpoint printed in older revisions and in 05 §Phase A was the retired engine's Tavg-mode ride and is not this plant's.

To slow or hold the climb, secure the RCP — measured, the rate falls to 0.004 °F/hr. Do not use the steam dump as a fine throttle: at 5 % it reverses the heatup at −263 °F/hr (−146 °C/hr). That is a demanded dump position, which this plant does not offer anyway (03 §12.3) — it is not an argument against step 8b, where the dumps are in AUTO on a setpoint the secondary has already reached and carry only the 0.4–2.9 % the pumps are adding.

Outcome

Mode 3, Hot Standby — hot, pressurized, subcritical, zero rod motion.

PWR-N02 — Mode 3, Hot Standby — plant lineup [sim]

Purpose

Verify the unit is correctly lined up in Mode 3, Hot Standby before any approach to criticality. Commercial startups do not pull rods until the board is known.

Applicability

• After PWR-N01, or any plant already in Mode 3, Hot Standby.
• Post-trip recovery to hot, subcritical conditions (still Mode 3 by temperature class).

Prerequisites

• Plant in Mode 3 (or post-trip recovery still hot and subcritical).

Precautions and limitations

Procedure

Step 15 — the dilution, and why it is a step and not a note

Measured full stack. At the 719 ppm Hot Standby hold the reactor sits at ρ = −1137 pcm with the bank in, and withdrawing the control bank to about 208 steps brings it critical — that is the reference position. Diluting there from a PWR-N01 arrival (~918 ppm, ρ = −3399 pcm) takes ~88 plant-minutes: measured end to end, 850 ppm at +28 min, 800 at +50, 760 at +68, 740 at +78, 725 at +85. Boron differential worth over that span is 11.38 pcm/ppm, and the 719 ppm hold is path-independent — borate away from it and dilute back and the plant returns to −1141 pcm against the −1137 pcm it boots at, and the 918 → 719 dilution ends at −1138.8.

Why the old numbers here were wrong, and it was not a stale plant. This section printed criticality at 223 steps and ρ = −1257 pcm, and PWR-N03 printed a 226–238 band, a 111–310 acceptance band and 8.1 pcm/step. All of them came from one place: the reactivity calculation was evaluating this plant at the **BEAVRS / Watts Bar hot-zero-power physics-test anchor — 557.0 °F (291.67 °C) and 2248 psi (15.5 MPa)** — the benchmark the kinetics model is calibrated against, not an operating point. The plant's own no-load point is 547.0 °F (286.1 °C) / 2235 psi (15.41 MPa), ten degrees colder, and dρ/dT here is −11.6 pcm/°F. Evaluate at 557 °F and 223, −1257, −2772, 400, 111–310 and 8.06 all fall out to four figures; evaluate at the plant's own point and you get 207–208, −1136, −2707, 392, 88–297 and 7.76. The gate was real, tight, and pointed at the wrong temperature — and it stayed green while it published the answer. It now takes its temperature from the hottest row of the 09 §7.5 table it has just verified against the plant.

207 or 208 — both are this plant. Statically at the table's 546.8 °F anchor the crossing is at 207; measured full stack the plant settles ~0.25 °F above its boot T-avg and it is at 208. One control-bank step is 0.66 °F of T-avg here, so a step of spread is the honest width of the answer. ρ is −1.8 pcm at 207 and +5.8 pcm at 208 on the settled plant.

The instrument declaration lands on the same step. Rods held still for 900 s: the startup rate reaches 0.000 at 203, still decays (0.112 → 0.020) at 207, and settles positive at 0.033–0.043 with power climbing at 208. The live walkthrough's creep used to land on 226 (15 slow steps from 211) — eighteen steps past critical, and not a measurement of anything. Now it lands on 213, five steps past, and the burst that plotted a point at 211 is gone.

Skip the dilution and the numbers in PWR-N03 stop being true. Measured at the ~918 ppm you arrive with, the bank does not go critical until 490 of 627 steps (78 % withdrawn) — **282 steps above the reference position and 193 above the upper edge** of the ±750 pcm acceptance band (88–297 steps) that 09 §7.5.1 tells you to stop and re-work the estimate at. (At the 857 ppm this section assumed until 2026-09-14 — the retired engine's cold-shutdown target, not this plant's — it is 392 steps.) The 1/M burst sizes in PWR-N03 are sized for the 719 ppm plant and will walk you past the band without ever looking wrong.

Outcome

Mode 3 lineup complete, boron at the ECC — ready for PWR-N03.

PWR-N03 — Approach to criticality (Mode 3, Hot Standby → Mode 2, Startup) [sim]

Purpose

Take the reactor from Mode 3, Hot Standby to Mode 2, Startup (critical, power ≤ 5 %) by controlled rod withdrawal, using 1/M, SUR, and NIS handoff.

Applicability

• From Mode 3 after PWR-N02.
• Continues into PWR-N04 / PWR-N05 / PWR-N06 on master path PWR-T03.

Prerequisites

1. PWR-N02 complete — including step 15, the boron adjustment to the ECC. If you came from a PWR-N01 heatup and skipped it you are ~138 ppm high and every number below is wrong.
2. Estimated Critical Condition (ECC) worked for this Tavg and this boron — see 09 §7.5. Acceptance band for a good ECC is roughly ±750 pcm.
3. RCPs running; SR energized; SG level held on aux feed (the Mode 3 lineup: motor-driven aux feed pump RUNNING on its 33 % hold, main feed pumps secured).

**The worked example below is for the reference startup: 719 ppm, bank fully inserted, Tavg at the no-load band. There the core first goes critical at about 208 of 627 steps (33 % withdrawn)** — 207 statically, 208 on the settled plant, one step being 0.66 °F of T-avg — and the ±750 pcm band is 88–297 steps. **The board says so on the same step**: stop the rods at 208 and the startup rate settles positive with the count rate still climbing; stop one step lower and it decays. **These are not constants of the plant — they are the answer for one boron.** Re-work the ECC for the boron you actually sampled; the 1/M plot closes on your prediction, it does not replace it.

And read the position as the ANSWER, not the instruction. While the reactor is subcritical the source range count rate is the reactivity indication and the bank position is not; the position becomes the better indication only once you are critical (Ginna UFSAR §7.7.3.1, ML20339A027). The steps below are cued on the instruments for that reason, and the numbers in the burst table are what a correct approach lands on, not targets to drive to.

Precautions and limitations

Procedure

Typical 1/M burst sizes — the 719 ppm reference startup, bank starting fully inserted

The count rate is the cue; the step column is what the burst lands on. Withdraw, stop, let the counts settle to the value in the third column, then plot. The bursts shorten every time because the rods get more valuable as you go: 4.15 pcm/step off the bottom against 7.76 pcm/step in the critical band. At a different boron the whole ladder moves — re-scale it to your own ECC rather than reading it as the plant's burst pattern.

There used to be a fifth burst, and it went critical. It was 9 steps to bank 211, plotting the last 1/M point at ρ = +33 pcm — on a core that was already critical, which is the one thing a 1/CR approach exists to avoid — and the creep beyond it left 148 pcm, so it was removed. The prediction the panel reads at the end of the approach moves 213 → 211 against a true critical of 208 — two steps lower, two steps closer, and on the conservative side. The climb that follows is gentler for it: power arrests on its own near 4 % instead of running through Mode 1 to 10.7 %.

Outcome

Mode 2, Startup — critical, power ≤ 5 %. Ready for PWR-N04 / PWR-N05.

PWR-N04 — Mode 2, Startup — low-power operation and POAH [sim]

Purpose

Operate stably in Mode 2, Startup (critical, ≤ 5 %) and recognize the point of adding heat — when fission heat exceeds losses and Tavg begins to respond.

Applicability

After PWR-N03; before or during early turbine roll.

Prerequisites

• Mode 2 per N03.
• SG inventory available; Feed AUTO preferred.

Precautions and limitations

Procedure

Outcome

Stable Mode 2; operator recognizes POAH; ready to roll turbine.

PWR-N05 — Turbine roll and generator synchronization (Mode 2, Startup → Mode 1, At Power) [sim]

Purpose

Place the turbine-generator on the grid and establish electrical output coordinated with reactor power while entering Mode 1, At Power (power > 5 %).

Applicability

Reactor critical (Mode 2 or early Mode 1); condenser vacuum healthy; MSIV open.

ROLL AT 10–15 % POWER, NOT AT 2–5 %. *"To minimize primary plant transients, the turbine is rolled with reactor power between 10 and 15 percent"* — WTSM §19.3 (ADAMS ML11223A342); its App 19-1 sequences the same thing, raising power until the dumps pass 10–15 % of full-load steam flow (step 17), blocking the IR-high (25 %) and then the PR-low (35 %) trips above P-10 (steps 18–19), and then accelerating and synchronizing (step 21). The reason is the steam balance: at 10–15 % the dumps are already passing that flow, so as the governor valves open the dumps modulate shut and total steam flow barely changes — Tavg, SG heat transfer and feed flow all stay put. Synchronize at 2–5 % and there is no dump flow to trade away, so the load pickup is a step demand on the primary.

This chapter said "Mode 2, ≤ 5 %" until 2026-08-12, and the plant never did. The shipped pwr_startup walkthrough has always raised power to ~12 % and blocked both trips before pressing Connect Grid — gated by run_procedures_stack. The manual contradicted a passing gate; the manual was the wrong one.

Scope note — synchronization is ATOMIC here [sim, approx]

This plant has no turbine roll and no no-load speed hold. A real unit rolls the machine off the turning gear on no-load steam, holds rated speed off line, and synchronizes before the generator breaker closes. Here there is no no-load steam admission model, so an unloaded rotor with no steam coasts to rest, and one press of FOLLOW or MAN does the whole sequence at once.

What the real evolution actually looks like — worth knowing, because it is not the hand-throttled synchroscope drill it is often described as. On an EHC machine the operator selects a speed setpoint from a short list of pushbuttons — *Close Valves, 100, 800, 1500, 1800 RPM, Overspeed Test* — together with an acceleration rate; on the SLOW rate the roll to 1800 rpm takes about 30 minutes. As the machine approaches rated, the EHC's speed control section takes over and holds no-load speed automatically. Synchronizing may be done by the operator or, in coordinated control, initiated automatically; once the breaker closes the system shifts to load control on its own. So the operator's real job is *selecting a target speed and a rate and supervising the roll* — which is much closer to how this plant's **Pressure SP and Dump SP** boxes already work than to matching needles on a scope.

*(Sources: Westinghouse Technology Systems Manual §11.3 / §19.0, ADAMS ML11223A295 / ML11223A342; the speed-setpoint list is from GE EHC documentation, ML11258A318. These are search index extracts — the NRC document server refuses direct retrieval — so they are cited at this manual's weaker evidence class, per 12 §8.)*

The generator breaker is not a separate control: on/off line is the load-mode selector — FOLLOW and MAN are on line, OFF is the open breaker. Everything downstream of synchronization — motoring at zero load, planned offline vs. turbine trip, load rejection, the P-9 interlock — is modelled properly; it is the roll and the synchroscope that are not.

Prerequisites

• PWR-N04 complete or concurrent.
• Condenser available; MSIV open.

Precautions and limitations

Procedure

Outcome

Generator carrying load; plant in Mode 1, At Power.

PWR-N06 — Power ascension Mode 1, At Power to 100 % [sim]

Purpose

Raise reactor power and electrical output to full-power Mode 1 (~100 MWe) by coordinating rods, boron, and turbine load.

Applicability

Mode 1 (or completing entry via N05).

Prerequisites

• Turbine on line or Follow available.
• SG level control understood (PWR-N12).

Precautions and limitations

Procedure

Outcome

Full-power Mode 1, At Power equilibrium.

PWR-N07 — Power maneuvering — raise power (Mode 1, At Power) [sim]

Purpose

Increase power and MWe within Mode 1 from a partial-power plateau.

Prerequisites

Mode 1: critical, power > 5 %, turbine on line, stable.

Precautions

• Turbine leads up; rods follow: raise Turbine Load, then withdraw to bring Tavg back to program (01 §6.0).
• Avoid SUR alarms; let Tavg and xenon follow.
• A load INCREASE ramps at 5 % of rated per minute — 5 MWe/min (09 §10.0). What you dial

lands on the board at once; the machine takes a minute for every 5 MWe. Trim rods against the megawatts the generator is actually making, not against the number you typed, and expect a 20 MWe leg to be four minutes of walking. The ramp is there because a load increase delivered instantly shrinks the pressurizer onto its 17 % low-level isolation (12 §7.3).

• Above the P-9 interlock, a turbine trip is a reactor trip — not a ride-out. It arms at

power ≥ 50 % with the steam dumps available, ≥ 8 % if they are not — condenser lost, vacuum or MSIV shut (09 §2.0; engine P9 permissive, sourced Ginna TS Bases B 3.3.1). Below P-9 there is no reactor trip; the steam dump carries the transient instead. A turbine trip with the dumps also gone leaves nothing to hold power — watch condenser vacuum and MSIV status through the leg, not just MWe.

Procedure

Outcome

Stable higher power and MWe.

PWR-N08 — Power maneuvering — lower power (Mode 1, At Power) [sim]

Purpose

Reduce power and load within Mode 1 (or toward Mode 2 / Mode 3).

Prerequisites

Mode 1 (or Mode 2) with turbine on line.

Precautions and limitations

Procedure

Outcome

Stable lower plateau.

PWR-N09 — Boron and reactivity management (including xenon) [sim]

Purpose

Use CVCS boron and rods for long- and short-term reactivity control; manage xenon.

Prerequisites

Charging pump available.

Precautions and limitations

Procedure — routine boron adjust

Procedure — xenon awareness

Outcome

Operator balances rods (fast) vs boron (slow) and anticipates xenon.

PWR-N10 — Pressurizer pressure control [sim]

Purpose

Hold primary pressure near 2235 psi (15.41 MPa) with heaters (raise) and spray (lower).

Prerequisites

PZR in normal level band; RCP running for effective spray.

Precautions

• Low pressure erodes subcooling.
• High pressure approaches the PORV — which lifts 100 psi (0.69 MPa) above your setpoint, so 2335 psi (16.099 MPa) at the nominal 2235 psi (15.41 MPa) — and then the safeties at a fixed 2500 psi (17.24 MPa).

Procedure

Outcome

Pressure controllable; subcooling protected.

PWR-N11 — Pressurizer level control (CVCS) [sim]

Purpose

Control PZR level / primary inventory with charging and letdown.

Prerequisites

CVCS available.

Precautions

• Do not chase TMI-like false high level during a LOCA — see emergency procedures.
• AUTO make-up modulates charging; MANUAL for deliberate moves.

Procedure

Outcome

Level controllable under normal (non-voiding) conditions.

PWR-N12 — Steam generator level and feedwater control [sim]

Purpose

Control SG level with feed; use three-element AUTO as the normal driver.

Prerequisites

Main feed available; reactor at power preferred for three-element behavior.

Precautions and limitations

Procedure — manual skill

Procedure — normal automatic

Outcome

SG level controlled; MANUAL override semantics understood.

PWR-N13 — Reactor coolant pump (RCP) operation [sim, approx]

Purpose

Operate and recognize limits of the (lumped) RCP model.

Scope note

This plant models a single representative RCP. Multi-loop outage procedures are simplified.

Precautions and limitations

Procedure — verify running (normal)

Procedure — if RCP trips (see also PWR-E02)

Outcome

RCP treated as critical for at-power forced flow and for pump-heat heatup.

PWR-N14 — Normal shutdown Mode 1, At Power → Mode 3, Hot Standby [sim]

Purpose

Shut down from Mode 1 (or Mode 2) to Mode 3, Hot Standby; maintain decay-heat removal. First half of PWR-T21.

Prerequisites

Mode 1 or Mode 2.

Precautions and limitations

Procedure

Outcome

Mode 3, Hot Standby — shut down, hot. Continue to Mode 5 via PWR-N15.

PWR-N15 — Cooldown Mode 3 → Mode 5, Cold Shutdown (RHR) [sim]

Purpose

Cool and depressurize from Mode 3 through Mode 4 to Mode 5. Completes master path PWR-T21. Training time is accelerated; plant-time rates and endpoints apply.

Applicability

After PWR-N14 or any hot, subcritical plant.

Prerequisites

• Mode 3 (hot, subcritical).
• Heat sink available (SG / AFW).

Precautions and limitations

Procedure

Step 2 is one entry because a step on the setpoint itself is a burst — the primary follows the SG's boiling temperature down as fast as the dumps can carry the steam. Measured on this plant with the pacing deleted (Hot Standby, pressure mode, one entry 1020 → 814 psi / 7.03 → 5.61 MPa, 2026-09-28): the worst minute cools at −1686 °F/hr (−937 °C/hr). With the pacing, the same entry cools at 58–68 °F/hr (32.2–37.8 °C/hr) for its 27 plant-minutes and parks on the target. *(The retired engine's chase and staircase figures that stood here — −2340 and −1168 °F/hr — are superseded; they described the hand pacing this plant no longer asks for.)*

Expected cooldown performance

The cadence is part of the answer. The table below is read off the Shutdown Part 3 walkthrough for this procedure, replayed end to end. These are the times of one replay. Run it at a different rate and every row moves; that is the point of a programmed cooldown.

Re-measured on the SHIPPED plant, 2026-09-18. Everything below replaces a table taken on the RETIRED engine in 2026-08-02, which started at 566.6 °F on 683 ppm — neither of which is this plant. Conditions, stamped: the pwr_cooldown walkthrough replayed END TO END through RD.SimulationService on selectPlant('pwr2', 'hot_zero_power'), full stack (M4+M5+M6), free-play default lineup, seed 42, 10× acceleration (1.0 s of sim per tick), no settle — t = 0 is the first tick of step 1. All 32 of the replay's own acceptance and guard checks passed, so these are milestones of a route the player can actually walk. **The clock is the replay's authored holds, and on this leg that is close to but not identical to a player's: the boration step's acceptance (880 ppm) is met at 0.90 plant-h** while its hold runs to 1.08, so a player who advances on the tile arrives at every row below up to about 0.2 plant-h early. Unlike the heatup, no hold here overruns its acceptance by hours.

Measured rate, over 60-second windows binned by quarter plant-hour: −67 to −87 °F/hr (−37 to −48 °C/hr) through the secondary-led legs, with a worst single minute of −107.5 °F/hr (−59.7 °C/hr); and −53 to −81 °F/hr (−29 to −45 °C/hr) on the RHR leg, with a worst single minute of −133.3 °F/hr (−74.1 °C/hr) just after the suction opens. End to end, 547.2 °F to 199.4 °F in 5.50 plant-hours is −63.3 °F/hr (−35.2 °C/hr) average. Between the two there is a deliberate plateau — Tavg holds at ~341.6 °F (172.0 °C) from 4.11 to 5.03 plant-h while the pressure walk, the accumulator isolation and the RHR alignment happen with the secondary already stalled at its own saturation. The walkthrough's own runaway guard is −1080 °F/hr (−600 °C/hr): every known way to lose control of this evolution is far beyond it. If the accumulators are left open through 665 psi (4.585 MPa) they dump; if SI is left armed the pressurizer goes solid and trips the plant; if either reactor trip is left unblocked you scram in the first leg.

Outcome

Mode 5, Cold Shutdown — cold, depressurized, RHR in service. Accumulators remain isolated until PWR-N01 re-aligns on the next heatup.

3.0 Quick reference — Mode 1 full-power band (HFP)

4.0 Related documents

• 05 Mode Transition Procedures — master paths T20 / T21 / T03
• 03 Controls and Indications
• 06 Alarm Response Procedures
• 07 Abnormal and Emergency Operating Procedures
• 09 Setpoints, Limits, and Normal Values
• 12 Simulation Physics & Model Scope

5.0 References

These manuals are licensed CC BY 4.0 — see Legal. Training documents for an educational simulator, not licensing-basis documents for a real plant.