Strategy Selection Process

This page describes Figures 6 and 7 of the ADS-IDAC manual: the Strategy Selection Process for the Action Taker (OAT) and the Decision Maker (ODM), respectively. Strategy selection is executed each time an operator performs the decision-making step. Its objective is to identify an appropriate problem-solving strategy based on the operator's current high-level goal and preferences.

Figure 6 from original manual: "Strategy Selection Process (Action Taker)"

Figure 7 from original manual: "Strategy Selection Process (Decision Maker)"

---

Action Taker Strategy Selection (Figure 6)

Available Strategies

The Action Taker uses only two strategies:

Strategy	Description
Wait and Monitor	Passive information gathering; also executes memorized mental procedures if queued
Follow Instruction	Executes actions ordered by the Decision Maker

Precedence Rules

The OAT strategy selection follows these precedence rules:

1. An ordered activity from the ODM (Follow Instruction) overrides Wait & Monitor whenever a queued ordered action exists.
2. The ODM's Follow Procedure strategy implies that ordered actions will be forthcoming — OAT transitions to Follow Instruction in anticipation.
3. The Maintain Global Safety Margin goal implies ODM will use Follow Procedure — OAT transitions to Follow Instruction.
4. Wait and Monitor is the default when no other conditions apply.

Flowchart

Block Descriptions

Block 1 — Start Strategy Selection Process

Strategy selection is executed each time the operator performs the decision-making step. The objective is to identify an appropriate problem-solving strategy based on the operator's high-level goal and preferences.

Block 2 — Is Goal Normal Operation or Monitoring?

If the goal is to maintain normal operation or to monitor an off-normal situation, the Wait & Monitor strategy is activated.

Block 3 — Wait and Monitor Strategy

Activates the Wait & Monitor problem-solving strategy: passive information gathering and, if applicable, execution of mental procedures.

Block 4 — Is Goal Troubleshooting?

The Troubleshooting goal means the ODM is using a knowledge-based reasoning strategy, which will generate ordered actions. Therefore, the OAT transitions to Follow Instruction in anticipation.

Block 5 — Is There a Waiting Ordered Activity?

If the ODM has issued an ordered activity through a mental procedure, the OAT must adopt the Follow Instruction strategy to perform it.

Block 6 — Follow Instruction Strategy

Activates the Follow Instruction strategy, enabling the OAT to implement any ordered activity directed by the ODM.

Block 7 — Decision Maker Using Follow Procedure Strategy?

If the ODM has activated the "Follow Procedure" strategy (activated by either: (1) activation of the Maintain Global Safety Margin goal, or (2) direct ODM implementation of a written procedure), the OAT transitions to Follow Instruction in anticipation of ordered actions.

Block 8 — Is Goal Maintain Global Safety Margin?

If the goal is Maintain Global Safety Margin, the ODM will implement the Follow Procedure strategy. In anticipation, the OAT adopts the Follow Instruction strategy to await ordered activities.

Block 9 — Invalid Option

If execution reaches Block 9, an error has occurred (the current goal does not match any allowed option). No strategy transition is permitted; the strategy selection process will be repeated during the next decision-making step.

---

Decision Maker Strategy Selection (Figure 7)

Available Strategies

The Decision Maker can choose from three possible problem-solving strategies:

Strategy	Description
Wait and Monitor	Passive and active information gathering to improve situational assessment; lowest precedence
Knowledge-Based Reasoning	Identifies mitigative actions based on imbalance diagnosis; mutually exclusive with Follow Procedure
Follow Written Procedure	Implements written emergency operating procedures; highest precedence (after instinctive response)

Order of Precedence

Instinctive Response (mental procedures)
      ↓
Follow Written Procedure
      ↓
Knowledge-Based Reasoning
      ↓
Wait & Monitor (default)

Mutual Exclusivity

Knowledge-Based Reasoning and Follow Written Procedure are mutually exclusive and cannot be activated simultaneously.

Instinctive Response Interruption

High-priority Instinctive Response strategy actions (skill-/rule-based mental procedures) will interrupt all other strategies. Lower-priority instinctive response actions may interrupt other strategies depending on the crew's high-level goal and individual operator profile. Once the instinctive response actions are complete, the operator returns to the previous strategy.

Flowchart

Block Descriptions

Block 1 — Start Strategy Selection Process

Strategy selection is executed each time the operator performs the decision-making step.

Block 2 — Is There a Queued Mental Procedure?

The operator's queue of mental procedures awaiting execution is checked. If any procedure is ready to execute, the Instinctive Response strategy is activated.

Block 3 — Instinctive Response Strategy

Executes the instinctive response strategy to follow a skill- or rule-based action. This strategy takes precedence over all other problem-solving strategies. Once the instinctive response actions are complete, the operator returns to the previous strategy.

Block 4 — Is a Procedure Ready for Execution?

Because a memorized mental procedure can trigger initiation of the emergency operating procedures, if the ODM has a queued written procedure awaiting execution, a transition to the "Follow Written Procedure" strategy is enabled.

Pre-emptive Procedure Activation

This criterion allows the ODM to initiate the emergency procedures before the Maintain Global Safety Margin goal is formally selected. For example, a memorized mental procedure might cause the reactor to trip and initiate the emergency procedures in advance of the VGMGSM goal transition.

Block 5 — Is Goal Maintain Global Safety Margin?

If the goal is Maintain Global Safety Margin, the ODM implements the Follow Procedure strategy to execute the written emergency operating procedures.

Block 6 — Follow Procedure Strategy

Activates the "Follow Written Procedure" strategy, enabling the ODM to initiate the emergency operating procedures. See the Procedure Following flowchart for details.

Block 7 — Is Goal Normal Operation or Monitoring?

If the high-level goal is Normal Operation or Monitoring, the Wait & Monitor strategy is activated.

Block 8 — Wait and Monitor Strategy

Activates the Wait & Monitor strategy, enabling:

• Passive information gathering (e.g., perception of alarms)
• Active information gathering from control panel scanning
• Performance of memorized mental procedures

Block 9 — Is Goal Troubleshooting?

If the goal is Troubleshooting, the Knowledge-Based Reasoning strategy is activated. This strategy can be used to either return the plant to normal power operation or mitigate an accident condition.

Block 10 — Knowledge-Based Reasoning Strategy

Activates the Knowledge-Based Reasoning strategy, enabling the ODM to identify mitigative actions based on the operator's current situational assessment. Diagnoses are linked to potential actions via:

• KB_ODM_Diagnosis_Actions.txt
• KB_ODM_Event_Matrix.txt
• KB_ODM_System_Decomposition.txt

See the Knowledge-Based Action Execution flowchart for details.

Block 11 — Invalid Option

If execution reaches Block 11, an error has occurred (the current goal does not match any allowed option). No strategy transition is permitted; the strategy selection process will be repeated during the next decision-making step.

---

Effect of Crew Goal on Problem-Solving Strategy

Goal	Passive Info Gathering & Panel Scanning	Skill-Based Memorized Actions	Written Procedure Following	Knowledge-Based Problem Solving
Normal Operation (VGNOP)	Yes	Yes	No	No
Monitoring (VGMON)	Yes	Yes	No	No
Troubleshooting (VGTS)	Yes	Yes	No	Yes
Maintain Global Safety Margin (VGMGSM)	Yes	Yes	Yes	No