## 2 FRAM and Decision Ladder Models' Development
### Decision ladder Models
** Through FRAM analysis, we observed seven functions that have a relatively higher workload, shown by the functions' higher number of aspects (F.2, F.7, F.11) and through systemic analysis (F.10, F.12, F13, and F.14). In the decision ladder model, however, only four of those functions are found to have many information processing steps, i.e., F.11, F.12, F.13, and F.14. In the following, we explain the remaining F.2, F.7, and F.10 mapping in the decision ladder model to support the same analysis result. Figure 4: An example of FRAM and decision ladder mapping: (**a**) A FRAM function (F.1) and (**b**) Mapping of the function into decision ladder, marked in yellow. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Activities** & **Activation** & **Observe Info.** & **Identify State** & **Predict** & - & **Evaluate** & **Predict** & **Predict** & **Define Task** & **Formulate** & **Execute** \\ \hline
**Knowledge** & **Alert** & **Info.** & **System State** & **Options** & **Goals** & **Chosen Goals** & **Target State** & **Task** & **Procedure** & **-** \\ \hline F1. Perform control guideline & & & & & & & & & & & & \\ desired mitigation strategy & & & & & & & & & & & & \\ \hline F2 Secure power & & & & & & & & & & & & & \\ F3 Monitor power plant’s & & & & & & & & & & & & & \\ \hline F4 Identity the available & & & & & & & & & & & & & \\ measures/methods & & & & & & & & & & & & \\ \hline F5 Identity and evaluate the devices/facilities recovery & & & & & & & & & & & & & \\ measures & & & & & & & & & & & & \\ F6 Identity the impacts of & & & & & & & & & & & & \\ \hline F7 Evaluation the possible negative & & & & & & & & & & & & & \\ impostons from mitigation strategy & & & & & & & & & & & & \\ F8 Deside whether to implement & & & & & & & & & & & & \\ the mitigation strategy & & & & & & & & & & & & \\ \hline F9 Decide the & & & & & & & & & & & & & \\ measures/methods to perform & & & & & & & & & & & & \\ mitigation strategy & & & & & & & & & & & & \\ \hline F10 Instrect for plant recovery & & & & & & & & & & & & & \\ measures & & & & & & & & & & & & \\ \hline F11 Evaluate the results of implementation & & & & & & & & & & & & \\ F12 Healthy and evaluate the measurements to multiple the & & & & & & & & & & & & \\ \hline F13 Evaluate the recovery & & & & & & & & & & & & \\ F14 Evaluate the alternative & & & & & & & & & & & & \\ strategies & & & & & & & & & & & \\ \hline \hline \end{tabular} Notes: Cells containing \({}^{\prime}\) represent the mapping of the functions from FRAM to the pairs of (information processing) activities and (states \(d\)) knowledge from the decision ladder.  
\end{table} 
Table 2: FRAM-Decision Ladder Matrix. Both 'F.2 Perform control guideline (select mitigation strategy)' and 'F.7 Decide whether to implement the mitigation strategy' do not have long information processing steps in the decision ladder, however, they include the 'Goals' state in the 'Evaluate performance' activity to decide the 'Chosen Goals' (marked 'o' in the Goals column in FRAM-Decision Ladder Matrix). The inclusion of 'Goals' implies that the goal is being identified or modified from the preceding state while its exclusion means that the goal remains the same (within the same workflow). Specifically, the 'Chosen Goals' in F.2 are to evaluate the selected mitigation strategy from the 'Goals' to mitigate the severe accident and the 'Chosen Goals' in F.7 are either to (1) implement the mitigation strategy or (2) cancel the strategy and proceed with devices/facilities recovery from the 'Goals' to evaluate the selected mitigation strategy. These states and activities on the top of the decision ladder deal with goal evaluation to choose a feasible chosen goal based on the perceived options and the desired goal's quality, which requires rigorous cognitive load [31]. Thus, even though F.2 and F.7 do not have long steps in the decision ladder, their complexities are reflected in the inclusion of the 'Goals' state.