ActionTaker.txt

Purpose

ActionTaker.txt specifies the static behavior factors that shape Operator Action Taker (OAT) behavior throughout a simulation run. These factors govern:

• Proportional scaling of all operator activity execution times.
• Whether the operator uses previously memorized (cached) plant information or always retrieves current readings from the control panel.
• The maximum size of the operator's scan queue and the information load thresholds that feed the Information Load PIF.
• Weibull-distributed recency criteria for alarm, component, support system, and parameter information.
• Minimum probability thresholds for generating step-skipping branch points.
• The diagnostic threshold for declaring an abnormal condition and the priority threshold for suspending low-priority mental procedures.
• Inter-crew communication delay times.
• Branching probabilities for the troubleshooting goal and the procedure-use goal transition (Decision Maker only; dummy values for OAT).

Parameters

Parameter	Type	Description	Example Value
number	Integer	Dummy count of operator behavior factors included in file; not used by the current version of ADS-IDAC. Enter any integer (e.g., 1).	16
action_time_multiplier	Double (> 0.0)	Uniformly scales execution time for all operator activities (communication, action, and decision-making). A value of 2.0 doubles all activity times; 0.5 halves them. No dynamic event tree branches are generated.	1.0
confidence_level_for_acting_HWKB	Double (0.0 – 1.0)	Not used in the current version of ADS-IDAC. Enter a dummy double (e.g., 0.0). Activation confidence for hard-wired diagnoses is set in KB_OAT_HardWired_Diagnosis.txt.	0.80
use_memorized_info (information_branch_probability)	Double (0.0 – 1.0)	Branching probability for enabling the operator's use of previously perceived (memorized) plant data. Values > 0.999999 always enable memorized information; values < 0.000001 always block it. Intermediate values generate a branch point early in the simulation.	0.0
initial_scan_queue_limit	Integer (> 0)	Maximum number of parameters that may be placed in the operator's periodic scan queue. The effective limit is dynamically reduced during simulation by information-load PIFs; low-priority parameters are evicted when the limit is exceeded.	30
lower_info_load_threshold	Double (≥ 0.0)	Lower bound of the information processing rate range used to calculate the Information Load PIF. When the operator's average information processing rate is below this threshold, the PIF is set to 0.0. See Figure 15.	0.0
upper_info_load_threshold	Double (> lower threshold)	Upper bound of the information processing rate range. When the rate exceeds this threshold the PIF is set to 10.0. Intermediate rates are linearly interpolated. See Figure 15.	250.0
alarm_update_time	Double, Double, Double (all > 0.0)	Three-parameter Weibull distribution (minimum u, alpha α, beta β) defining the recency criterion for memorized alarm state information. If the age of a perceived alarm exceeds the Monte Carlo draw from this distribution, the operator obtains a fresh reading from the control panel.	100.0 1.0 1.0
component_update_time	Double, Double, Double (all > 0.0)	Three-parameter Weibull distribution (u, α, β) for the recency criterion for memorized component state information.	100.0 1.0 1.0
support_system_update_time	Double, Double, Double (all > 0.0)	Three-parameter Weibull distribution (u, α, β) for the recency criterion for memorized support system state information. The parser expects this line; see the warning below — the shipped BV4 files omit it.	100.0 1.0 1.0
parameter_update_time	Double, Double, Double (all > 0.0)	Three-parameter Weibull distribution (u, α, β) for the recency criterion for memorized parameter value information.	100.0 1.0 1.0
skip_action_threshold	Double (0.0 – 1.0)	Minimum dynamically calculated probability required to generate a branch point for skipping a procedure step's initial action activity. If the calculated skip probability is below this threshold the action is always executed. Setting to 1.0 prevents all initial-action skipping.	1.0
skip_non_response_threshold	Double (0.0 – 1.0)	Minimum dynamically calculated probability required to generate a branch point for skipping a procedure step's non-response action. If the calculated skip probability is below this threshold the non-response action is always executed when expectations are not met. Setting to 1.0 prevents all non-response-action skipping.	1.0
abnormal_signal_threshold	Double (0.0 – 1.0)	Diagnostic membership value threshold for declaring an abnormal condition. The fuzzy logic engine calculates a membership value for each AOO and DBA event category at each time step; if the maximum exceeds this threshold the operator concludes an abnormal condition exists. Lower values increase sensitivity (risk of false positives); higher values require more evidence.	0.4
mental_procedure_priority_threshold	Integer (> 0)	Following detection of an abnormal condition or a reactor trip, all mental procedures with a priority value numerically greater than this threshold are suspended. Lower priority integers correspond to higher-importance procedures (priority 1 is highest).	2
nominal_communication_time	Double (> 0.0)	Baseline inter-crew communication delay in seconds. Controls the time required for the Decision Maker to direct the Action Taker and for the Action Taker to report completion. Applied by the sender of each communication.	1.0
troubleshooting_probability	Double (0.0 – 1.0)	Branching probability for activating the troubleshooting goal when the normal operation goal is no longer appropriate. Currently implemented for the Decision Maker only; enter a dummy value for the OAT.	0.0
procedure_use_probability	Double (0.0 – 1.0)	Branching probability for transitioning from the troubleshooting goal to the "maintain global safety margin" goal after a reactor trip is identified. Currently implemented for the Decision Maker only; enter a dummy value for the OAT.	0.5

Weibull Parameter Triple Format

The three Weibull parameters are always entered on a single line in the order: minimum_time alpha beta (i.e., u α β). The cumulative distribution function is:

F(t) = 1 - exp( -((t - u) / alpha)^beta )

All three values must be greater than 0.0.

Figure 15 — Information Load PIF

The lower_info_load_threshold and upper_info_load_threshold parameters define the two breakpoints of the piecewise-linear Information Load PIF curve (Figure 15 in the manual). The PIF value is 0.0 at or below the lower threshold, 10.0 at or above the upper threshold, and linearly interpolated for intermediate processing rates. A higher PIF value represents a greater cognitive information load on the operator.

Dummy Values

confidence_level_for_acting_HWKB, troubleshooting_branch_probability, and procedure_use_branch_probability are not used by the OAT. Always enter syntactically valid dummy values to avoid input file processing errors.

File Format

The file begins with the keyword Action_Taker followed by an integer count (not used by the parser). Each subsequent line contains a field-name label followed by its value(s) on the same line, separated by whitespace (spaces or tabs). The labels themselves are read into placeholders and not validated — the line order is what matters. Weibull triples are three numbers on the same line (u alpha beta).

The parser reads 17 labeled lines in this order:

Action_Taker 17
action_time_multiplier              <action_time_multiplier value>
confidence_level_for_acting_HWKB    <confidence_level_for_acting_HWKB value>
use_memorized_info                  <use_memorized_info value>
initial_scan_queue_limit            <initial_scan_queue_limit value>
lower_info_load_threshold           <lower_info_load_threshold value>
upper_info_load_threshold           <upper_info_load_threshold value>
alarm_update_time                   <u> <alpha> <beta>
component_update_time               <u> <alpha> <beta>
support_system_update_time          <u> <alpha> <beta>
parameter_update_time               <u> <alpha> <beta>
skip_action_threshold               <skip_action_threshold value>
skip_non_response_threshold         <skip_non_response_threshold value>
abnormal_signal_threshold           <abnormal_signal_threshold value>
mental_procedure_priority_threshold <mental_procedure_priority_threshold value>
nominal_communication_time          <nominal_communication_time value>
troubleshooting_probability         <troubleshooting_probability value>
procedure_use_probability           <procedure_use_probability value>

Shipped BV4 files omit support_system_update_time — tail of the file is silently ignored

The reference files tests/BV4/Input/Crew/ActionTaker/ActionTaker.txt and DecisionMaker.txt still use the legacy 16-line layout without support_system_update_time. Because parsing is positional, the read then misaligns at line 10 and fails partway through, with these effects:

• support_system_update_time absorbs the values of the file's parameter_update_time line;
• parameter_update_time gets the skip_action_threshold value as its minimum time, with α = 0 and an indeterminate β (uninitialized);
• everything after that — skip_action_threshold, skip_non_response_threshold, abnormal_signal_threshold, mental_procedure_priority_threshold, nominal_communication_time, troubleshooting_probability, procedure_use_probability — keeps the built-in defaults (all zero), and the values written in the file are never applied.

There is no error message. The BV4 validation baselines were produced with this effective configuration, so adding the missing line to the shipped files changes simulated behavior and invalidates byte-comparison baselines — treat any migration as a deliberate, validated model change. For new plant models, use the full 17-line layout above so every value in your file actually takes effect.

Sample Input

Action_Taker 17
action_time_multiplier              1.0
confidence_level_for_acting_HWKB    0.80
use_memorized_info                  1.0
initial_scan_queue_limit            250
lower_info_load_threshold           0.0
upper_info_load_threshold           250.0
alarm_update_time                   100.0 1.0 1.0
component_update_time               100.0 1.0 1.0
support_system_update_time          100.0 1.0 1.0
parameter_update_time               100.0 1.0 1.0
skip_action_threshold               1.0
skip_non_response_threshold         1.0
abnormal_signal_threshold           0.4
mental_procedure_priority_threshold 2
nominal_communication_time          1.0
troubleshooting_probability         0.0
procedure_use_probability           1.0

TIP

Setting skip_action_threshold and skip_non_response_threshold both to 1.0 (as shown above) is the conservative baseline: no procedural steps are ever skipped. Lower these values only when explicitly modeling operator error modes such as step omission.