Social Risk & F-N Curve

Model Fatalities — For each scenario, FatalityUtils.js integrates the death probability over concentric rings of 5 m width (up to 10 km), computing $E[F(A_s)] = \sum_i F_i$ using the applicable Probit function.

Exposed Population $N_g$ — ng-calculator.ts computes $N_g$ using the 1% Probit radius for thermal/overpressure models, the LFL polygon area for Flash Fire, or the weighted wind-rose sum for multi-directional scenarios.

F-N Curve Construction — calculateFnCurve() collects all $(f_s, N_s)$ pairs and computes $F(N_k) = \sum_{s:\,N_s \geq N_k} f_s$ for each unique $N$ value, producing a decreasing log-log step function.

ALARP Evaluation — analyzeUnacceptableScenarios() compares each curve point against the upper limit $F_{lim}(N) = C_1/N^{|n|}$, computes excess frequency $\Delta F$, and generates frequency reduction recommendations per scenario.

Collect all scenarios with their pairs $(f_s, N_s)$: frequency and fatalities for each

Extract the unique set of $N$ values, sorted in descending order

For each $N_k$: compute $F(N_k) = \sum f_s$ where $N_s \geq N_k$

Plot the pairs $(N_k,\, F(N_k))$ as a decreasing step function on log-log axes

Identify unacceptable point — Find all $(N_k, F(N_k))$ where $F(N_k) > F_{upper}(N_k)$

Apply ALARP target — Set objective with 10% safety margin below upper limit: $F_{target}(N) = F_{upper}(N) \cdot (1 - m), \quad m = 0.10$

Compute excess frequency: $\Delta F(N) = F(N) - F_{target}(N)$

Required reduction per scenario — For contributing scenario $s$: $f_{required,s} = f_{current,s} - \Delta F(N), \quad RF_s = \frac{f_{current,s}}{f_{required,s}}$ If $f_{required,s} \leq 0$, the scenario alone cannot fix the problem — combined reductions are required.

Define scenarios — For each source, create RiskModels with event type (PoolFire, JetFire, FlashFire, VCE, FireBall) and assign frequency $P(A_s)$.

Run consequence calculations — Execute each model to obtain fatalidades.sumaFatalidades and fatalidades.resultados.

Configure criteria — In Project Settings → Social Risk Criteria, select the international standard or enter custom $C_1$, $C_2$, and $n$ values.

Visualize the F-N Curve — In the Social Risk tab → F-N Curve sub-tab, the table automatically computes $N$ and $F(N)$ for each scenario and plots them.

Interpret zones — Points above the upper line ($F > C_1/N^{|n|}$) are unacceptable. The system generates automatic frequency reduction recommendations.

Individual Risk — In the Individual Risk sub-tab, enter $N_g$ or let the system calculate it automatically, then verify $RI_g$ against the country criterion.