Hira Matrix 34313k

Safety Risk Severity Table

Severity of Occurrence Catastrophic

Hazardous

Major

Meaning -

Loss of life/lives A large reduction in safety margins, physical distress or a workload such that the operators cannot be relied upon to perform their tasks accurately or completely - Serious injury / illness

- Major equipment damage - A significant reduction in safety margin, a reduction in the ability of the operators to cope with adverse operating conditions as a result of increase in workload, or as a result of conditions impairing their efficiency - Serious incident -

Minor Negligible

Equipment destroyed

-

-

-

Injury to persons Nuisance Operating limitations Use of emergency procedures

Value A

B

C

D

Minor incident

Little consequence

E

Value 5 4 3 2 1

Safety Risk Probability Definitions Quantitative Numerical Likelihood Class Qualitative Definition Definition Likely to occur many times (has Frequent Ps > 10-4 occurred frequently) Likely to occur sometimes (has Occasional 10-4> Ps > 10-5 occurred infrequently) Unlikely to occur, but possible (has Remote 10-5> Ps > 10-6 occurred rarely) Very unlikely to occur (not known to Improbable 10-6> Ps > 10-7 have occurred) Almost inconceivable that the event Extremely Ps > 10-7 will occur improbable

Quantitative annual/daily equivalent (approximate) More than once per day More than once per month More than once per year More than once per 10 years More than once per 100 years

Safety Risk Assessment Matrix Safety Risk Severity Safety Risk Probability Frequent 5 Occasional 4 Remote 3 Improbable 2 Extremely Improbable 1

Catastrophic A

Hazardous B

Major C

Minor D

Negligible E

More than once per day

5A

5B

5C

5D

5E

More than once per month

4A

4B

4C

4D

4E

More than once per year

3A

3B

3C

3D

3E

More than once per 10 years

2A

2B

2C

2D

2E

More than once per 100 years

1A

1B

1C

1D

1E

Safety Risk Accepting Authority

Safety Risk Acceptability Unacceptable Undesirable Tolerable Acceptable

Suggested Criteria for Acceptability Unacceptable under existing circumstances. Major mitigation or redesign of the system may be necessary. May be accepted under exceptional circumstances under management decision. Requires risk control or mitigation. Risk acceptable. However, conscious efforts should be made to reduce the risk to ALARP. Risk acceptable. Still, reducing risk to ALARP is recommended.

Safety Risk Index

Risk Accepting Authority

5A 5B 5C 4A 4B 3A

Nil

4C 3B 2A 2B 1A

able Executive

5D 5E 4D 4E 3C 3D 2C 1B

Director – Ops

3E 2D 2E 1C 1D 1E

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