MODULE: QUANTITATIVE RISK ANALYSIS - Assignment.

MODULE: QUANTITATIVE RISK
ANALYSIS - Assignment

Objectives
The objectives of this case study are:
To determine the frequency or probability of a reactor
vessel explosion, resulting from an improper fuel-oxidant
mix, and;
To identify the consequences of that event, whilst
also commenting on risk acceptability, and mitigation.
Reactor Vessel Explosion

Process Schematic
Transmitter 1
Sol Valve 1
Controller 1
Sol Valve 2
Controller 2
Transmitter 2
FRC1
FRC2
Sensor
Sensor
Flow Trips
FT2
FT1

Process Brief
The process shown involves the mixing of fuel and
oxidant in a reactor vessel.
An explosive fuel-oxidant mixture will result if the fuel
feed is too high or if the oxidant feed is too low.
The design features include flow trips, sensors, flow rate
controllers, trip valves and transmitters, which are
numbered on the line diagram.
Situated about 1 mile North East from the process plant
there is a town with a population of around 70,000 people
and a very busy motorway, which connects the country
from south to north.

1. Examine potential failure modes of the operating system using
Failure Mode Effect Analysis (FMEA)
2. Construct a fault tree (FTA) starting with the top event “explosion”
3. Use the reliability data to calculate the expected frequency of the
explosion.
4. Using Event Tree Analysis (ETA) identify the consequences of the
top event.
5. Comment on the acceptability of the risk and recommend corrective
measures.
Questions

Essential Data
Failure / event or Faults/year or
Component/event Probability of failure minus FDT
Flow Trip 1 0.2
Alarm system 0.1
Flow Trip 2 0.01
Power Failure 0.01
Flow rate transmitter 1 0.5
Pipe rupture solid 0.05
Flow rate controller sensor 1 0.1
Flow rate controller 1 0.4
Flow rate transmitter 2 0.4
Flow rate controller 2 0.4
Flow rate controller sensor 2 0.2
Solenoid valves 0.02
Vessel defects 0.15
Wind from southwest 0.9
Wind stability ‘ good’ 0.8
Ignition source 0.75
• Assume any missing data

Assignment Format
Index
Introduction
Process description
Assumptions
Questions 1 to 5
References
Assignment word count (3500) - Graphs, Tables, Charts, Index
& Referencing do not constitute towards the word count.

Assessment Procedure
This element of assessment attracts 100% of the
final module mark. It will test all the learning
outcomes and will monitor development in all key
skills indicated.
Assessment