Simulator Operating Procedures and Procedure-Use Standards

Why Procedures Are Central to Nuclear Plant Safety

In a nuclear power plant, procedures are not suggestions—they are the primary defense against human error. The U.S. Nuclear Regulatory Commission (NRC) and the Institute of Nuclear Power Operations (INPO) both support the principle that procedures must be followed exactly as written. This expectation is a cornerstone of nuclear safety culture. Deviating from a procedure without authorization, even with good intentions, has contributed to real plant transients and, in the broader history of the industry, to serious events. Your job as a technician or operator is to execute procedures precisely, verify the expected response, and stop to get guidance if something does not match.

The Hierarchy of Plant Procedures

Plant procedures are organized in a clear hierarchy based on the plant condition they address.

Normal Operating Procedures (NOPs) govern routine plant activities—startup, power ascension, steady-state operation, and planned shutdown. They are used when the plant is behaving as expected. NOPs are typically the most detailed and the most frequently revised, because normal operations are refined continuously.

Abnormal Operating Procedures (AOPs) are entered when a system or parameter moves outside its normal band but no immediate safety threat exists. An AOP guides the operator to diagnose the deviation, stabilize the plant, and restore normal conditions or transition to the appropriate emergency procedure if conditions worsen. AOPs are symptom-based or event-based depending on the plant's procedure philosophy.

Emergency Operating Procedures (EOPs) are used when plant safety systems have actuated or when key parameters reach emergency action levels. EOPs take priority over all other procedures. Most modern EOPs are symptom-based—meaning you respond to what you observe on the instruments, not to what you think caused the problem. This approach was widely adopted in the U.S. nuclear industry following the Three Mile Island accident in 1979.

Understanding the hierarchy means knowing which procedure governs at any moment and being ready to transition between levels when plant conditions change.

Procedure Revision Control

Every procedure is a controlled document. Controlled means there is only one authorized version in use at any time, and it carries a revision number and an effective date. Before you use a procedure, you confirm you have the current revision. Using a superseded revision is a procedure use error—even if the steps happen to be identical. Plants maintain strict configuration control over their procedure libraries, and the simulator training environment mirrors this practice so that habits formed in training carry directly to the plant floor.

Anatomy of a Procedure Step

Procedures contain several distinct elements you must recognize:

• Action steps — numbered or lettered items that direct you to perform a specific task (open a valve, verify a reading, place a switch).
• Cautions (CAUTION) — statements placed immediately before a step to warn of a condition that could cause equipment damage or plant problems if the step is performed incorrectly. A caution must be read and understood before you take the action below it.
• Notes (NOTE) — informational statements that clarify why a step is written a certain way or describe what to expect. Notes do not require action but provide important context.
• Warnings (WARNING) — statements alerting you to conditions that could cause personal injury or radiological hazard. Like cautions, warnings appear directly before the related step.

Cautions, notes, and warnings are not optional reading. They are integral parts of the procedure.

The Continuous-Use Technique

Continuous-use procedure technique is the standard method for executing safety-significant procedures, including all AOPs and EOPs, and many NOPs. The method requires:

1. Read the step aloud — verbalize the exact text of the step.

2. Perform the action — operate the component or verify the reading.

3. Verify the expected response — confirm the plant (or simulator) responded as the procedure states; verbalize what you observe.

4. Initial or check off the step — mark the step complete only after verification.

5. Do not skip ahead — complete each step in the sequence written unless the procedure explicitly directs branching.

Reading aloud serves two purposes: it keeps you focused on the exact words rather than your memory of what the step says, and it allows a second person (a supervisor or peer checker) to verify you are performing the correct step. This is a human performance tool with direct backing from INPO procedure-use standards.

Lockout/Tagout and PPE During Procedure Execution

Many procedure steps involve equipment isolation. Before performing any maintenance-related step, confirm that lockout/tagout (LOTO) has been applied in accordance with your plant's energy control program and applicable OSHA standards. The procedure will typically reference the clearance order number. Verify the clearance is in place before proceeding. Similarly, if a step involves a radiation work permit (RWP), don required dosimetry and PPE before entering the controlled area. Never use a procedure step as authorization to skip a required permit or clearance.

Lessons from Industry Events

Two recurring themes emerge when procedure deviations contribute to plant transients: workers convinced they already knew the correct lineup and therefore skipped verification steps, and workers who encountered an unexpected condition and improvised rather than stopping and getting supervision. Both behaviors violate the continuous-use standard. The corrective practice in both cases is identical—follow the procedure as written, verify each expected response, and when conditions differ from what the procedure anticipates, stop, notify your supervisor, and do not proceed until the discrepancy is resolved or the procedure is formally revised.

Simulator Practice

The non-powered simulator panel gives you a realistic environment to build correct habits before you reach a licensed facility. Practice reading every step aloud even when the action feels obvious. Instructors evaluate not just whether you complete the procedure but whether you demonstrate the continuous-use technique on every step. Forming that habit now makes it automatic on the plant floor.