Information Processing
This page describes Figure 2 of the ADS-IDAC manual: the Information Processing flowchart. The flowchart applies to both the Action Taker (OAT) and the Decision Maker (ODM); the diagram is shown for the Action Taker, with a note that the Decision Maker follows a similar process.
Figure 2 from original manual: "Information Processing"
Overview: The Blackboard Architecture
ADS-IDAC employs a central communication clearinghouse called the blackboard to handle all information interchange between control room crew members and the reactor plant. Each communication packet posted to the blackboard carries:
- Identity of the sender
- Identity of the intended recipient(s)
- Type of communication
- Content of the message
Each time step, operators and the reactor plant scan the blackboard to retrieve their messages. For example:
- The reactor plant may post an alarm actuation with all operators as intended recipients.
- When an operator opens a valve or starts a pump, a message to the reactor plant is posted to the blackboard.
Because the blackboard serves as a centralized dispatcher of all information exchange, it provides a convenient location for assessing the average information load for each operator.
Flowchart
Block Descriptions
Block 1 — Start Information Processing
The IDAC cognitive model consists of three main activities: information processing, decision-making, and action execution. Information processing is the first activity in this sequence.
In ADS-IDAC, an operator can only act upon perceived information. Raw information from the reactor plant model must first be gathered and memorized before it can support decision-making. Two information processing filters are applied:
- Control panel scanning queue — governs which parameters the operator actively scans (see
KB_OAT(ODM)_Scanned_Parameters.txt) - Bias factors — can adjust perceived parameter values (see
KB_OAT(ODM)_Bias_Factors.txt)
Block 2 — Retrieve Data from Communication Board
Each time step, the operator retrieves all pending communication packets from the blackboard. The blackboard centralizes all information exchange between crew members and the reactor plant.
Block 3 — Is Data Related to a Paused Activity?
Certain operator activities cause the decision-making process to be temporarily suspended until the activity is completed. For example:
- If the Decision Maker requests the Action Taker to read a plant indicator, the Decision Maker will not proceed until the result is reported.
Decision-making suspension is implemented via two Boolean pause activity flags per operator:
| Pause Flag | Suspends |
|---|---|
| Mental procedure flag | Decision-making activities associated with memorized mental procedure execution |
| General activity flag | All other operator activities (written procedures, knowledge-based actions, goal and strategy selection) |
A pause flag is set to true when an operator begins an activity that involves either a time delay or crew coordination. When the operator receives a communication packet indicating the paused activity is complete, the flag is reset to false.
Block 4 — Clear Appropriate Pause Flags
If the received communication packet is associated with a pause activity, the appropriate pause flag is set to false to re-enable the operator's decision-making process.
Block 5 — Identify Data Sender / Originator
Communication packets originate from three possible sources:
| Source | Description |
|---|---|
| Internal | Transfers of cognitive decisions within the operator's own memory (goals, strategies, mental beliefs) |
| External crew | Communication from other operators |
| Reactor plant | Control panel status information |
The source determines how further information processing proceeds.
Internal Communications (Blocks 6–17)
Block 6 — Internal Communications
Internal communication transfers information related to cognitive decisions within the operator's own memory. Goals, strategies, and mental beliefs are communicated only internally.
Block 7 — Identify Type of Data (Internal)
Internal communication is associated with four possible data types:
- Goal
- Mental belief
- Procedure
- Strategy
Block 8 — Goal-Related Information
Goals represent high-level operator objectives. Four goals are currently implemented in ADS-IDAC:
- Normal Operation
- Troubleshooting
- Monitoring Abnormal Conditions
- Maintain Global Safety Margin
When the current goal changes, an internal communication packet is generated to update the goal in the operator's memory.
Block 9 — Update Goal
The operator updates perceived information memory to reflect the new goal. Depending on branching options, the new goal may either be implemented or bypassed. If bypassed, the updating process is omitted and the new goal has no effect.
Block 10 — Mental Belief-Related Information
When a mental belief is activated (see KB_OAT(ODM)_HardWired_Diagnosis.txt), a communication packet is generated to add the belief to the operator's perceived information memory. Mental beliefs serve two main functions:
- Activation of associated memorized mental procedures
- Serving as prerequisite conditions for other mental beliefs
As with goals, branching options can either permit or bypass perception of a mental belief.
Block 11 — Does Mental Belief Reference a Procedure?
If the mental belief is associated with a memorized mental procedure, that procedure must be added to the operator's procedure queue.
Block 12 — Add Mental Procedure to Queue
The procedure name, step number, priority level, and timing parameters are added to the mental queue. During the decision-making process, the operator checks this queue; if a mental procedure is found, a procedure-related communication packet is generated to activate it.
Block 13 — Procedure-Related Information
A communication packet identifying the procedure name and step number activates the associated procedure. Two procedure types are supported:
| Type | Description |
|---|---|
| Memorized mental procedure | Generally associated with skill-based memorized actions |
| Written procedure | Conventional written procedure (e.g., emergency operating procedure) |
Procedure Status Categories
Procedures can be placed in any of five status categories:
| Status | Meaning |
|---|---|
NONE | Inactive and awaiting execution |
ACTIVE | In progress |
PAUSE | Temporarily suspended |
INTERRUPTED | Permanently suspended |
DONE | Completed |
If a new procedure is activated while an earlier procedure is in progress, the earlier procedure is placed in PAUSE status (most recently activated procedure takes precedence).
Block 14 — Activate Procedure
The procedure status is set to ACTIVE, enabling the operator to begin implementation during the decision-making process.
Block 15 — Update Hard Wired Diagnoses
Activation conditions for mental beliefs can include other mental beliefs and procedure status. Each mental belief in the operator knowledge base is updated based on currently perceived mental belief and procedure information. See KB_OAT(ODM)_HardWired_Diagnosis.txt.
Block 16 — Strategy-Related Information
A strategy communication packet is generated when the operator changes the current problem-solving strategy. ADS-IDAC strategies are:
| Operator | Available Strategies |
|---|---|
| Action Taker (OAT) | Wait and Monitor; Follow Instruction |
| Decision Maker (ODM) | Wait and Monitor; Knowledge-Based Reasoning; Follow Written Procedure |
Block 17 — Update Strategy
The operator updates perceived information memory to reflect the new strategy. The current strategy establishes the problem-solving methods used by the crew.
Ordered Activities from Decision Maker (Blocks 18–19)
Block 18 — Ordered Activity from Decision Maker to Action Taker?
In the ADS-IDAC crew model, only the Action Taker may manipulate reactor plant controls. During execution of either a mental or written procedure, the Decision Maker may request the Action Taker to provide control panel information.
A communication packet is classified as an ordered action if all three of the following are true:
- The packet is associated with a control panel parameter, component state, alarm, or action
- The sender is the Decision Maker
- The recipient is the Action Taker
INFO
This step applies only to the Action Taker and is not applicable to the Decision Maker.
Block 19 — Add Ordered Activity to Queue
Ordered actions received from the Decision Maker are placed in the Action Taker's ordered action queue (first-in, first-out). During the decision-making process, the Action Taker checks this queue and performs the requested action or obtains the needed information.
Reactor Plant Communications (Blocks 20–29)
Block 20 — Data Sent from Reactor Plant Control Panel
When an operator executes an interaction with the control panel, a communication packet is sent to the reactor plant. The reactor plant executes the interaction and returns a confirmation packet to the operator. Control panel interactions include:
- Control manipulations (opening a valve, stopping a pump)
- Checking plant parameters
- Verification of component or alarm states
Block 21 — Identify Type of Information (Control Panel)
The reactor plant control panel can send four types of information:
| Type | Description |
|---|---|
| Action confirmation | Confirms that a requested control manipulation has been executed |
| Component state | Provides requested component state information |
| Indicator (parameter value) | Provides requested parameter value; may be adjusted by bias factors |
| Alarm | Provides alarm actuation or clearance information (self-initiated by the control panel) |
Block 22 — Action Confirmation
A confirmation packet is sent back to the operator who initiated the control manipulation, confirming that the action has been completed.
Block 23 — Component State Information
The packet provides the operator with requested component state information.
Block 24 — Indicator Information
The packet provides the operator with a requested parameter value. The value may be subsequently adjusted by a bias factor (Block 25).
Block 25 — Apply Bias Factors
If bias factors are specified in KB_OAT(ODM)_Bias_Factors.txt, the parameter value is adjusted by the bias factor. The operator perceives the biased value rather than the raw value from the control panel.
Modeling Instrument Failures
Bias factors can be used to model certain types of instrument failures by systematically offsetting the parameter value perceived by the operator.
Blackboard Item Types
The following communication item types are used on the ADS-IDAC blackboard:
| Type Identifier | Description |
|---|---|
VALARM_STATE | Alarm status (activated or cleared) |
VCOMPONENT_STATE | Component state information |
VPARAMETER_VALUE | Numeric parameter value from control panel indicator |
VPARAMETER_TREND | Trend direction for a parameter value |
VPARAMETER_STATE | Qualitative state of a parameter (e.g., high/normal/low) |
VPARAMETER_DIFFERENCE | Computed difference between a parameter value and a reference |
VCONTROL_COMMAND | Command to manipulate a control (issued to reactor plant) |
VCONTROL_REPORT | Confirmation of a control action completion (returned by reactor plant) |
Block 26 — Alarm Information
The packet provides the operator with alarm information. New alarms are self-initiated by the control panel and include both actuation and clearance of alarm conditions.
Block 27 — Update Hard Wired Diagnoses
Activation conditions for mental beliefs can include control manipulations, alarms, component states, and parameter values. Each mental belief in the operator knowledge base is updated based on newly perceived information. See KB_OAT(ODM)_HardWired_Diagnosis.txt.
Block 28 — Was Information from Reactor Plant Associated with an Ordered Activity?
The ordered action queue is checked to determine if the perceived information is associated with an activity previously ordered by the Decision Maker.
INFO
This step applies only to the Action Taker.
Block 29 — Send Ordered Activity Confirmation to Decision Maker
A communication packet is sent from the Action Taker to the Decision Maker to confirm completion of the ordered action. When the Decision Maker initiated the ordered action, further Decision Maker decision-making was paused; this confirmation packet clears that pause.
Block 30 — Proceed to Decision-Making Process
After information processing is complete, the operator initiates the decision-making process.