unit 5_risk assessment and management

8/8/2019 Unit 5_Risk Assessment and Management

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Introduction

Any industrial activity involves some risk orhazard in terms of fire, explosion, toxic

releases etc. which lead to injuries, loss of life

& property ultimately adversely affecting the

environment as a whole if not managedcorrectly resulting

Truly speaking, any industrial installation

should have Zero risk situation, but, it isimpossible to achieve it.


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The potential causes for accidents are:

Increasing production.

Storage Volume.Competitive technology.

Use of hazardous substances.


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Risk Assessment & Risk Management

gives a framework for :

Setting regulatory priorities

Decision Makingthat cut across various

environmental areas.


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Environmental Risk Assessment may bebroadly defined as a scientific enterprise in

which facts and assumptions are used to

estimate the adverse effects on human

health or the environment that may resultfrom exposures to specific pollutants or

other toxic agents.


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Environmental Risk Management

refers to a decision making processinvolving risk assessment, technological

feasibility, economic information about

cost and benefits, statutory

requirements, public concerns etc.

Risk Communication is the exchange

of information about risk.


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RISK ASSESSMENT :

It is the systematic examination of anactual or proposed industrial installation:

(1) to identify potential hazard to occur

&

(2) to identify the possible consequences

from these hazards which would assist indecision making for reducing risk to anacceptable level.


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ALARP:

Mgmt. must take all measures to

reduce risks as low as reasonably

practicable. (ALARP) and this is achievedthrough a technique called Risk

Assessment orRisk Analysis.


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What is Hazard?

It is the property of a substance or a

situation which has the potential to

cause harm.

The potential hazards can be of fire,

explosion and release of toxic &harmful gases.


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HAZARD

By hazard we mean any physical activity,

situation or condition with the potential to causeharm, like:

Human injury or death

Damage to the environmentDamage to physical assets

Loss of production

The words threat and danger are sometimesused with a similar meaning as hazard.


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Hazard Categories

Hazards may generally be classified as:1. Natural hazards (e.g., Flooding, earthquake, storm,

lightning).

2. Technological hazards (e.g., industrial facilities,

structures, technical equipment, transportation systems,consumer products, pesticides, herbicides,

pharmaceuticals).

3. Societal hazards (e.g., assault, war, arson, terrorism,

sabotage, communicable disease).4.


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What is Risk?

It is related to the consequences of identified

hazard. It may also be defined as theunwanted consequences from a particular

activity.Risk has two variables:

(a) Magnitude of consequences

(b) Probability or frequency of the occurrence.

So, Risk = Frequency of the occurrence

Magnitude of consequences


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What Is Risk?

An expectation of loss

Always an element of uncertainty

Always refers to future

Usually covers both severity and likelihood of a loss

Usually refers to unwanted consequences


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The consequences of an accident may be

classified in different categories, as

1.P

ersonnel consequencesFatalities

Impairment

2. Environmental damage

3. Economic loss

Damage to material assets

Production/service loss

4. Information loss

4. Image loss(i.e., damage to reputation)


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Why Risk Assessment (Objectives ofRA):

(1) To prioritize safety investments : Allorganizations have limited resources.Risk assessment can be used toprioritize risks and ensure that

investment is directed to the greatestrisks.

(2) Risk estimates aids in decision making.

(3) Corporate Mgmt develops positive publicrelations with employees, communityand the Govt.


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RISK EVALUATION:

There are four steps in the evaluation of arisk.

(1) Hazard Identification

(2) Exposure Assessment

(3) Hazard Assessment

(4) Risk Characterization


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(1) HAZARD IDENTIFICATION:

It is an analysis to determine which of the

discharges from a process or an accidentalrelease will be a potential danger to public

health. E.g. Chemicals such as CO, HCl and

unburned organics would be established as

potential sources of risk for an incinerator.

The means of identifying hazard is complex.

Various methods are used to collect and

evaluate toxic properties ( properties that

indicate the potential to cause biological injury,

disease or death under certain exposure

conditions).


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HAZARD IDENTIFICATION:(Cont..)

Methods:(1) EPI-DEMIOLOGICAL STUDY: Use of

epidemiological studies deal with theincidence of disease among groups of people.

The study attempts to correlate incidence ofdisease like cancer from an emission by

evaluation of people with a particular disease

and people without the disease.


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HAZARD IDENTIFICATION: (Cont..)

Methods:(2) BIOASSAY: Long term animal bioassays

( an evaluation of disease in a laboratory animal)

is a very common method for hazard

identification. e.g. Increased tumor incidence inlaboratory animals is the primary health effect

considered in animal bioassay. Exposure testing

for a major portion of an animals lifetime (2 -3

years for rats and mice) provides information ondisease susceptibility, primarily for

carcinogenicity ( the development of cancer).


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(2) EXPOSURE ASSESSMENT:

This determines how much of an emission actually

reaches the receptor. Human exposure includesingestion (eating or drinking), dermal contact (

contact with the skin) & inhalation.

These means of exposure are pathways to the

human body. Thus, there is no risk withoutexposure.

The exposure assessment attempts to define the

route, amount, frequency and duration of

exposure of a given population to a toxic

substance. The principal pathways of exposure

generally considered in exposure assessment are

atmospheric transport, surface and ground water

trans ort in estion of food materials etc.


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(2) HAZARD ASSESSMENT :

A hazard assessment is a determination of the

relationship between the amount of exposure andthe risk to public health.

A person can drown in water, but that does not

mean that a glass of water is a danger to health.

Obviously, what defines a danger is not

necessarily the presence of a particular chemical

but rather the amount of that substance one is

exposed to. This amount is called dose.


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HAZARD ASSESSMENT : (Cont..)

Hazard assessment is also referred to as Dose

response assessment.

Dose is usually expressed as milligrams of

chemical received per kilogram of body weight per

day.For toxic substances other than carcinogens, a

threshold dose must be exceeded before a health

effect will occur. For many substances, there is a

dosage level below which there is no harm.However, at some given dosage, the threshold, a

health effect will occur ( or, at least be detected).


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(4) RISK CHARACTERIZATION:

It estimates the health risk associated withthe process under investigation.

This characterization gives a number that

represents the probability of adverse healtheffects from that process or from a

substance released in that process.


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RISK CHARACTERIZATION:(Cont)

Once a risk characterization is made, the

meaning of that risk must be evaluated.

Public health agencies generally only

considerrisk greater than 10 in 1 million

to be significant risks warranting action.


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MEASURE OF RISK

Though the risks to the people from

industrial hazards may be in the form of

injuries , exposure to harmful releases etc.,

risks are generally measured in terms of

deaths (since there is better accuracy indata pertaining to death).

Risks are generally expressed as(1) Individual risks

(2) Societal risks.


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(1) Individual Risk ( IR) :

This is the risk to an individualperson. It is the probability of death

occurring as a result of an accident at plant

or an installation or a transport route.A simple way to express an IR is the FATAL

ACCIDENT RATE (FAR).


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Individual Risk ( IR) : (Cont)

FATAL ACCIDENT RATE (FAR) is

the number of fatalities per 108 exposedhours.

One person works on average = 7.5 hrs /day

One person works on average= 7.55= 37.5hrs/wk

One person works on average = 37.552wks(yr) =

1950 hrs/year ( Say, 2000 hrs.)

Thus, 1000 persons in lifetime (50 yrs) would work

= 1000502000 = 100000000 i.e. 108 exposed hrs.

Exposed hours is the mean hrs. at work


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Individual Risk ( IR) : (Cont)

FATAL ACCIDENT RATE (FAR)

typically varies in the range of 1 - 30.

FAR of 1 means one fatal accident over

1000 working lifetimesor,

One fatal accident per 50 yrs. For a site

employing 1000 people.


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RISK CHARACTERIZATION:(Cont)

(2) Population Risk (PR) :

This is also known as group risk from

an activity.

It is the relationship between frequency of an

accident and total number of people harmed.The is often plotted as FN curve showing the

cumulative frequency (F) of accidents and Number

of fatalities( N).


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1.To prioritize safety investment (All organizations

have limited resources. RA can be used toprioritize risks and ensure that investments is

directed to the greatest risks).

2. To make planning & decision especially for

areas like plant design, plant safety reviews,

preparation of emergency / disaster plan etc.

3. To estimate financial risks.

4. To develop positive public relations withemployees, community and the Govt.

5. To get approval of projects.

Objectives of Risk Assessment


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6. To compare the estimated individual & societal

risks against acceptance criteria.

7. To identify major risk contributors and to

recommend remedial measures for risk reduction.

8. To carry out cost benefit analysis for the

implementation of the remedial measures.

9. To address land use planning issues includingsuitability of location, layout and design.

10. To develop appropriate contingency plan.

Objectives of Risk Assessment (Cont)


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Components of Risk Assessment:

Quantitative Risk Assessment ( QRA) includes:

(1) System Description

(2)H

azard Identification(3) Scenario Selection

(4) Consequence Estimation

(5) Likelihood Estimation

(6) Risk Estimation

(7) Utilization of Risk Estimates


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System Description:

It is the compiled process information that are neededfor the Risk Analysis. e.g.

(1) Site Location

(2)Weather Data

(3) Process Flow Diagrams (PFD)

(4) Piping & Instrument Diagram (P & ID)

(5) Layout Drawing(6) Effluent & Emission Summary

(7) Operating & Maintenance Procedures


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Hazard Identification:

It includes:

(1) Checklists

(2) Preliminary Hazard Analysis (PHA)

(3) Hazard & Operability (HAZOP) Studies It is a

methodology for identifying and dealing with potentialproblems in industrial processes, particularly thosewhich would create a hazardous situation or a severeimpairment of the process.

(4) Failure Mode and Effects (FMEA) -I

t prioritizespotential failures by looking into the probability ofoccurrence and likelihood of failure.

(5)What if Analysis


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Scenario Selection:

It is used to list out all accidental releasescenarios that have the potential to impact the

members of the public outside the installation

boundary. It considers:

(1) Nature of the hazardous substance released &

its operating T, P etc.

(2) Inventory of hazardous substance


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Consequence Estimation:

It is used to determine the potential for damageor injury from particular incidents.

By using this technique, the areas of the site

which would be affected in the event of anemergency is located.

Outcomes of an incident are analyzed using

source & dispersion models and Explosion & Fire

Models.


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Likelihood / Frequency Estimation:

It is used to estimate the frequency or

probability of occurrence of an incident.

Estimates may be obtained from historicalincident data.


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Risk Estimation:

It combines the consequences and likelihood ofall incident outcomes from all selected

incidents to provide a measure of risk. This

involves mapping the accident areas and risk

pattern.


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Utilization ofRisk Estimates:

It is the process by which the result from arisk analysis is used to make decisions.


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What is MaximumCredible Accident

(MCA) Analysis?It is a tool used to find the maximum potential

damage an accident can cause.

It helps in the identification of most vulnerablesections of the installation and facilities that

pose maximum possible risk if the hazardous

materials are released as a result of a failure.

This may be due to leakage from a crack or

fracture of the process vessel, vents, pump seals

or overflow of a tank or vessel.


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What is MaximumCredible Accident

(MCA) Analysis? ( Cont.)The extent of consequences arising from the

hazardous substances will largely depend on

quantity released, location, wind condition anddensity of population.


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Accident Scenarios ofRisk Potential

(1) BLEVE( Boiling Liquid Expanding Vapor Explosion):

This is a type of explosion that can occur when a vessel containing a

pressurized liquid is ruptured. Such explosions can be extremelyhazardous.

A BLEVE results from the rupture of a vessel containing a liquidsubstantially above its atmospheric boiling point. The substance isstored partly in liquid form, with a gaseous vapor above the liquid filling

the remainder of the container.

The primary cause is usually an external flame impinging on the shellof a vessel leading to sudden rupture of the shell.

The explosion is sufficient to cause fragments of the container to fly overlarge distances of few kms. The released liquid results into a fire ballhaving intense heat.

It causes intense damage to life and property.

LPG Storage vessels in petroleum installations can cause severe BLEVE.


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A BLEVE erupting from a tanker


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Accident Scenarios ofRisk Potential ( Cont)

(2) UCVE ( Unconfined Vapor Cloud Explosion):

When a flammable gas or liquid

escapes into the atmosphere and mixes

with air , an explosive gas or vaporcloud can form.

This flammable mixture will explode ifignited causing extensive damage to the

surroundings.


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Accident Scenarios ofRisk Potential ( Cont)

(3) Jet Fires:

Ejection of a flammable liquid from avessel, pipe etc. can give rise to a jet flameif the material ignites. It is not easy tohandle since a large jet flame has asubstantial reach ( sometimes 50 m ormore).

The jet flames from a pressure relief valvescan cause adjacent vessels to overheat andburst giving rise to BLEVE ( Boiling liquidexpanding vapor explosion).


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Accident Scenarios ofRisk Potential

Toxic Dispersion:

The hazard due to toxic chemical depends

on the condition of exposure and the type of

chemical. It can range from suddenexposure at high concentrations to

prolonged exposure at low concentrations.

A very large release of toxic chemical ( Cl orH2S) usually have greater disaster potential

than fires or explosion.


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Risk Management & Control

After assessing the risks , one recognizes the

courses of actions that would control and

minimize the risks to human health, property

and environment ( objective ofRisk Mgmt.)

Risk Mgmt. involves resource

allocation, cost benefit analysis,

acceptable risks etc.


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Risk Management & Control ( Cont.)

Risk Mgmt. involves:

(1) Reduction of risks to acceptable limits byjudicious investments.

(2) Relocating the activities on alternate sites /

routes

(3) Taking appropriate considerations whenbuying Insurance Policy of installations

with potential high risks.(4) Preparing Emergency / Disaster plans to

handle effectively any emergency situationswith minimum damages.


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Risk Management & Control ( Cont.)

Effective Risk Mgmt. Depends on:(1) Sound standards of engineering design

must be used.

(2) Quality control procedures must ensurethat all equipment conforms to designstandards and specifications.

(3) All equipment must be inspected,

maintained and tested at suitableintervals.

(4) Personnel must be experienced and

trained.


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Risk Acceptance / Tolerance

The result of a risk assessment is aquantification of risk.

It brings the level of risk that is acceptable to

public, authorities & the industry. But, thequestion is how much risk can be acceptable

or tolerable.

The risk from an activity should be judgedagainst the benefits from the activity, since no

activity can claim to be totally risk free.


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Risk Acceptance Criteria:

Since all industrial activities involve risks

including risks of fatality ( may be

employees engaged in the activity or,

common public outside).When an industrial activity imposes risk

common public, it especially becomes the

concern of regulators to assess the risk &evaluate it.


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Risk Acceptance Criteria: (Cont)

A good risk criteria should recognize:

(1) Level of risk which is so high that it isconsidered unacceptable/ intolerableregardless of the benefits derived from theactivity.

(2) Level of risk which is low enough to beconsidered negligible.

(3) Level of risk in between that is to beconsidered tolerable subject to their being

reduced to As Low As is ReasonablyPracticable (ALARP).

Risks become tolerable when all practicablemeasures are taken to reduce risk to ALARP.


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Risk Assessment Matrix

Risk Assessment Matrix is a tool for ranking

different activities / projects in terms of their

potential benefit and the likely risks/cost in

implementing them.

It is a tool that standardizes qualitative riskassessment and facilitates the

categorization of risk from threats to health,

safety, environment and companyreputation.I

Ri k A t M t i (C t )


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Risk Assessment Matrix (Cont..)

I

Likelihood Consequences

Catastro

phic

(5)

Major

(4)

Moderate

(3)

Minor

(2)

Insignific

ant

(1)

Almost

Certain (5)

10 9 8 7 6

Likely (4) 9 8 7 6 5

Possible (3) 8 7 6 5 4

Unlikely (2) 7 6 5 4 3

Rare (1) 6 5 4 3 2

Ri k A t M t i (C t )


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Risk Assessment Matrix (Cont..)

IRisk

Score

Risk Description What should be done?

9 - 10 Extreme Immediate action required

7 - 8 High Action plan required,

senior mgmt. attentionneeded

5 - 6 Moderate Specific monitoring or

procedures required,

mgmt. responsibility mustbe specified

2 - 4 Low Manage through routine

procedures

unit 5_risk assessment and management

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