Procedures.txt

Purpose

The Procedures.txt input file serves two main functions:

1. Master procedure index — provides a list of all modeled procedure steps, which is used during input file processing to identify the corresponding ZProcedure_procedure_name_step_name.txt files for the project.
2. Step skipping model parameters — specifies global time transfer values and a set of static multipliers that determine the probability of a crew skipping a procedure step.

Step Skipping Model

ADS-IDAC models omission of procedure actions to simulate step skipping behavior. Step skipping is applied at the sub-step level. The likelihood of skipping a sub-step is calculated by adjusting a base "skip step" probability by dynamic and static multipliers.

Static Factors

Static factors reflect the properties of the procedure and do not change during the simulation. They include:

• Procedure type — reflects how strictly operators adhere to different procedure categories (e.g., mental procedures are skipped more often than EOPs).
• Step objective — reflects how likely operators are to skip steps based on the step's purpose.
• Step complexity — reflects the structural complexity of the step; more complex steps have a higher likelihood of being skipped.

The three static factors are multiplied together to yield the overall static factor $f_{\text{static}}$.

Dynamic Factors

Two types of dynamic factors adjust the base skip probability:

• PIF_TimeConstraint — time constraint loading performance influencing factor (PIF), ranging from 1 to 10, with higher values indicating increased time pressure.
• Step relevance ($R_{\text{action}}$) — determined from the operator's situational assessment via the diagnostic engine. Calculated as (Equation 12):

$$R_{\text{action}}={10}^{(1-2d)}$$

Where $d$ is the maximum membership value of all functional imbalances associated with the action (range: 0.0 to 1.0). The relevance factor $R$ varies from 0.1 for highly relevant actions to 10.0 for irrelevant actions. Actions not associated with a specific component (e.g., procedure transfers) are assigned $R_{\text{action}}=1.0$.

The action relevance factor is multiplied by the time constraint load PIF to yield the overall dynamic factor $f_{\text{dynamic}}$.

Skip Probability Calculation (Equation 13)

The adjusted step skipping probability is:

$$P_{\text{skip}}=\frac{P_{\text{base}}\cdot f_{\text{static}}\cdot f_{\text{dynamic}}}{1+(P_{\text{base}}\cdot f_{\text{static}}\cdot f_{\text{dynamic}}-1)\cdot P_{\text{base}}\cdot f_{\text{static}}\cdot f_{\text{dynamic}}}$$

Where $P_{\text{base}}$ is the basic step skipping probability sampled from the Beta distribution (specified per substep in the ZProcedure files) and $P_{\text{skip}}$ is the adjusted probability.

Input File Format

Step_Transfer_Time                  step_transfer_time
Procedure_Transfer_Time             procedure_transfer_time

normal_procedure_multiplier         skip_multiplier_normal
abnormal_procedure_multiplier       skip_multiplier_abnormal
alarm_response_procedure_multiplier skip_multiplier_alarm
optimal_recovery_procedure_multiplier  skip_multiplier_EOP
functional_recovery_procedure_multiplier  skip_multiplier_FRG
mental_procedure_multiplier         skip_multiplier_mental

verification_step_multiplier        skip_multiplier_verification
monitoring_step_multiplier          skip_multiplier_monitoring
prerequisite_step_multiplier        skip_multiplier_prerequisite
objective_step_multiplier           skip_multiplier_objective
diagnosis_step_multiplier           skip_multiplier_diagnosis

Coded_Steps                         number_of_coded_steps
procedure_name_1
step_name_1
.
.
procedure_name_n
step_name_n

Parameter Descriptions

Global Time Parameters

Parameter	Type	Description	Example Value
step_transfer_time	Double, > 0.0	Nominal time delay (seconds) to transition between steps within the same procedure.	0.5
procedure_transfer_time	Double, > 0.0	Nominal time delay (seconds) to transition between different procedures.	5.0

Procedure Type Skip Multipliers

Higher values indicate a greater likelihood of skipping. Typical range: 1.0 to 10.0.

Keyword	Procedure Type	Description	Typical Value
normal_procedure_multiplier	Normal Operating Procedure	Routine power changes and plant evolutions	2.0
abnormal_procedure_multiplier	Abnormal Operating Procedure	Non-routine non-emergency events	1.0
alarm_response_procedure_multiplier	Alarm Response Procedure	Follow-up actions after control panel alarm activation	5.0
optimal_recovery_procedure_multiplier	Emergency Operating Procedure (EOP)	Accident mitigation procedures	1.0
functional_recovery_procedure_multiplier	Functional Recovery Guideline (FRG)	Addresses degradations of critical safety functions	5.0
mental_procedure_multiplier	Mental (Memorized) Procedure	Skill-based actions without reference to written procedures	10.0

Step Objective Skip Multipliers

Higher values indicate a greater likelihood of skipping. Typical range: 1.0 to 10.0.

Keyword	Step Objective	Description	Typical Value
verification_step_multiplier	Verification	Checking status of parameters or components where no recovery action is normally expected	5.0
monitoring_step_multiplier	Monitoring	Observing status of a changing parameter in order to initiate action at a threshold	7.0
prerequisite_step_multiplier	Prerequisite	Actions that support later activities but do not directly address the event cause	3.0
objective_step_multiplier	Objective-related	Actions directly addressing the cause or symptoms of the ongoing event	1.0
diagnosis_step_multiplier	Diagnosis	Identifying root causes of abnormal or emergency events	3.0

Coded Steps Index

Parameter	Type	Description	Example Value
number_of_coded_steps	Integer, > 0	Number of procedure steps listed in the index. Only the first number_of_coded_steps entries are read.	3
procedure_name_i	String	Procedure name. Must be associated with a valid ZProcedure_procedure_name_step_name.txt file. No spaces (use _). Reserved prefixes: FRG_ and MPBG_.	E_0
step_name_i	String	Step name paired with procedure_name_i. Must be associated with a valid ZProcedure file. No spaces (use _).	Step_1

INFO

Because mental procedures and functional recovery guidelines require special handling, the procedure name prefixes FRG_ and MPBG_ are reserved. The prefixes ECA_, E_, and ES_ are recommended for emergency contingency actions, emergency procedures, and supplemental procedures respectively.

Sample Input

Step_Transfer_Time                     0.5
Procedure_Transfer_Time                5.0

normal_procedure_multiplier            2.0
abnormal_procedure_multiplier          1.0
alarm_response_procedure_multiplier    5.0
optimal_recovery_procedure_multiplier  1.0
functional_recovery_procedure_multiplier  5.0
mental_procedure_multiplier            10.0

verification_step_multiplier           5.0
monitoring_step_multiplier             7.0
prerequisite_step_multiplier           3.0
objective_step_multiplier              1.0
diagnosis_step_multiplier              3.0

Coded_Steps    3
E_0
Step_1
E_0
Step_2
E_0
Step_3

Sample Explanation

• The step transfer time (0.5 s) is significantly shorter than the procedure transfer time (5.0 s), reflecting the greater ease crews have in transitioning between steps within the same procedure compared to starting a new procedure.
• The skip multipliers reflect crew tendencies: mental procedures have the highest skip multiplier (10.0), while EOPs have the lowest (1.0), consistent with operators following emergency procedures most carefully.
• Three procedure steps are indexed: E_0 steps 1, 2, and 3. Each must have an associated ZProcedure_E_0_Step_N.txt input file.