Fire Extinguishing Performance Assessment

10 Questions

What is the primary objective of Monte Carlo simulation in the context of risk assessment?

To realize a great number of histories and perform classical statistics on the results

What is the function of the transition T2 in the Petri Net model?

It is a deterministic transition with no delay

What is the purpose of the variable C_KO in the Petri Net model?

To indicate the failure of component C

What is the role of the weight of the input arc in the Petri Net model?

It enables the transition T1 to fire

What is the advantage of using Monte Carlo sampling in risk assessment?

It allows for the assessment of uncertainty associated with model parameters

What is the result of firing transition T1 in the Petri Net model?

The component C fails and waits for repair

What is the purpose of the delay δ1 in the Petri Net model?

It represents the time to failure of component C

What is the benefit of using Petri Net models in risk assessment?

They provide a quantitative approach to risk assessment

What is the primary goal of risk assessment in the context of domino effect prevention?

To assess the probability and impact of a domino effect

What is the role of uncertainty assessment in risk assessment?

It is used to assess the confidence that can be placed in model results

Study Notes

Performance Metrics

Time elapsed between the starting and extinguishing of a band fire is a key performance metric.
This performance is measured with respect to the probability (P2) that the duration is lower than 60 minutes.
Another performance metric is the probability (P3) of either fire extinction in due time (60 minutes) or the cooling system working.

Petri Nets (PNs) Models

PNs models are used to compute probabilistic quantities related to the described scenario.
The syntax of PNs models includes:
- # to indicate the marking of a place (e.g., #i is the marking of place i).
- jets to indicate the number of tokens.
- !! to introduce a list of variable assignments.
- ?? to specify a list of conditions that must be verified for the transition to be valid.
- drc d to indicate Dirac's law of duration d.
- @ (k) (e1, e2, …, en) to indicate a k out-of n logic (where ei are Boolean expressions).

PNs Models Construction

The interaction between PNs models is achieved through variables (guards and assertions).
Examples of PNs models are presented, including condensate LOC, gas detector 1 (GD1) behavior, and gas detection system.

Actions and Delays

Safety bounder establishment has an efficiency of 90% and is delayed by 3 minutes.
Ignition sources prevention has an efficiency of 91% and is also delayed by 3 minutes.
Foam film establishment depends on water pumps and emulsifier.

Water Pumps

There are 5 water pumps (3 on-site and 2 off-site).
The starting of water pumps can be performed in three ways:
- Instantaneously if the ESD push button works (probability of failure = 0.044) and the pumps work (with probability of failure for each pump = 0.019).
- After 3.50 minutes if the whole operational team (team 3) is available.
- After 7 minutes if the team is not available.

Monte Carlo Simulation

Monte Carlo simulation is used to assess performance parameters.
The principle of Monte Carlo simulation is to realize a great number of histories and perform classical statistics on the results.
Uncertainty assessment is achieved by means of Monte Carlo sampling, among other approaches.
Monte Carlo sampling method is used to handle uncertainty in model results.