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Control of Industrial Major Accident Hazards (CIMAH) Report Page 51
Ranhill SAJ Sdn. Bhd. Revision 01
Part D: Information on the Potential Major Accident Date Aug 2019

The failure frequency (F f) is calculated for each scenario and presented in
APPENDIX D2

D.6.2.2 Location Specific Individual Risk (LSIR) & Iso-Risk Contour

The quantitative individual risk is calculated and transferred to the location map as
an iso-risk contour for the major accidents modelled in this report.
In constructing iso-risk contours, the following assumptions are made:
• Risk contour map starts at the center of the hazardous area and moves
outwards radially; and

• Risk contour defines the probabilistic of individual risk at location of the given
major accident scenario.

The quantitative risk acceptance criteria are adopted from the Malaysia Department
of Environment (i.e. EIA Guidelines on Risk Assessment) as follows:
-5
• 1 x 10 per year for a fatality (industrial)
-6
• 1 x 10 per year for a fatality (residential)

Based on the vulnerability model formula, the quantitative risk number of exposure to
a “fatality concentration level” at a maximum consequence distance from the source,
under a specific combination of wind speed, direction and atmospheric stability, is
given in Table D.6.2.2a / Table D.6.2.2b and graphically presented as iso-risk
contours in APPENDIX D3, and further described in Figure 6.2.2.

From the analysis, all event scenarios modelled has the individual risk number in an
acceptable level.

For all the event scenario, the maximum consequence distance generated from the
physical effect modeling are within the boundary or perimeter of the plant/facility, and
it could be inferred that the quantitative risk number for community at the outside of
the plant boundary will be lesser and within the criterion of 1x10-6.