societal risk mapping: a useful extension of qra … and risk analysis: sources other sources: ccps...

Societal Risk Mapping: A useful extension of QRA visualisation

Hans Boot

Contents

Background: History safety legislation in the Netherlands, coloured

books, TNO

Quantitative Risk Assessment: What, Why, How

Risk definitions: Criteria INDIVIDUAL / SOCIETAL risk

Usage of risk assessment criteria in Netherlands

Using criteria for urban development planning

The concepts of societal risk maps

Different types of SR maps

What do we see? / How are they constructed?

Practical applications: experiences in several cases

Conclusions & evaluation

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Societal Risk Mapping

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Safety legislation in the Netherlands

Densely populated areas close to

industrial sites:

requires strict regulation on safety !

Already in the eighties: development

of “coloured books”: How to perform

a consequence analysis, How to

do a QRA

The obligatory safety report for

SEVESO cat2+ companies should

contain a QRA !

Currently, risk criteria also used in

“urban development planning”:

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Does urban development

invoke a SOCIETAL RISK

problem here?

Scarce space: “Do we have problems with safety in this area?

TNO and “coloured books”

TNO is “Netherlands organization for Applied Scientific Research”

Semi-governmental contract research organisation

In the 80’s and 90’s: responsible for “Yellow book” and “Green book”

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1980’s

1990’s

2000’s

2010’s

2015If we want to use models we needed them in a

software tool: this evolved to a commercial spin-

off research

Describing typical methods to predict

“Consequences” (formula’s and overview of

existing modelling approaches)

Consequence and Risk modelling

Consequence analysis: first part of QRA

(an important first step !)

Risk = Chance * Consequence ??

Risk assessment includes failure frequencies,

event probabilities & weather statistics

Quantitative Risk Assessment aims at finding a

quantitative value for the risk that you can

judge against acceptance criteria

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Consequence

analysis

Define potential

accident

scenarios

Evaluate event

consequences

Estimate potential

accident

frequencies

Estimate the

impact of events

Estimate the risk

Evaluate the risk

Identify and

prioritize

potential risk

reducing

measures

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Consequence and Risk Analysis: sources

Other sources: CCPS Guideline books

HSE publications

Local regulations ?

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Identification of

accident scenario’s

Determining physical

effects

Determining the

damage

Consequence of risk

Chance effect

Chance scenario

Chance damage

Chance of risk

Consequence Chance

Quantification of risk

Red Book

(CPR-12)

Purple Book

(CPR-18)

Yellow Book (CPR-14)

Green Book (CPR-16)

Hazid, Hazop, FMEA

Risk Reducing proposals

(NL: Handleiding Risicoberekening BEVI)

Evaluate risk

Failure freq data:Orida database

HSE (hydrocarbon

release statistics)

DNV failure freq database

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Determine the risk of (fatal) injury to employees, the public or the

environment, due to accidental release of a hazardous material,

from production, storage, handling and transport.

Judge the risk against tolerance criteria, set by

the government or by the company internally

Determination of (absolute or relative) contribution

of the risk sources to the individual (aka locational)

and/or societal risk

Purpose of risk assessment

Purpose of risk assessment and – analysis (2)

Identification of opportunities of risk reduction and their effects

Modifications in process design or operation

Mitigating measures

Modification of plant layout

Alternative options for transportation

Change in land-use planning around plant

Implement / prioritize emergency preparation and response

In The Netherlands, nowadays: important instrument in land-use

decision making

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Risk definitions in a QRA

Risk = probability of undesired outcome

In QRA for hazardous materials:

Risk = probability of fatal injury due to exposure to release

of hazardous material

Risk is a QUANTIFIED VALUE (for probability of undesired

outcome)

Risk Assessment: Calculate such a risk

value for an activity / site / area

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Risk assessment procedure

A QRA requires to perform typical basic steps

1. Identify relevant activities / units / processes

2. Define Loss of Containment cases (which scenarios can happen)

3. Assess consequences (effects & damage) for all LoCs

4. Assess frequency and likelihood of LoCs and consequences

5. Calculate risk value for process / site / area

6. Present risk in IR-contours and/or SR-curve

7. Evaluate and analyse risk

Note: IR can be used on-site and off-site,

SR always offsite (“external” safety)

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Risk criteria 1 = Individual Risk (“Locational risk”)

The risk at a location outside the premises of an establishment,

expressed as the likelihood per year that a person that is continuously

and without protection at that location, is killed as a consequence of an

event inside the establishment leading to the release of a dangerous

chemical, dangerous waste or a pesticide.

Note:

‘Establishment’ also means ‘Activity’ like transport

‘Individual Risk’ is also being referred to as ‘Locational Risk’

A value associated with a coordinate, usually presented as Iso Risk Contours

The dimension is frequency: Hz . . . but expressed as “per year”

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Calculating Individual Risk (aka Locational risk)

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Source

location

Receiver X,Y: hit by

various

wind-directions

Start with a scenario consequence analysis: which phenomena ?

Provides a lethality footprint (ellipse, cone, circular)

Determine failure frequency for Loss of Containment

Combine with “probability of wind blowing in that direction”

A receiver at a specific spot, can be hit by wind from different angles,

each time with different lethality fractions !

Combine all events and all scenarios into

total chance of dying at THAT spot

A QRA= Book-keeping chances & lethality's

Presented on a MAP as ISO RISK CONTOURS

Risk criteria 2 = Societal Risk (“Group risk”)

Cumulative probability per year that at least 10, 100 of 1000 people

will be killed as a direct result of their presence within the impact area

of an establishment and the occurrence of an event in which a

dangerous chemical, dangerous waste or a pesticide is involved.

Presented as a log/log

graph: frequency vs

number of people

(at least N victims)

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Reduction

desired

Accceptable

Unaccceptable

Calculating Societal Risk (“Group risk”)

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Same input as IR: scenarios, failure frequencies, weather/wind

statistics but also POPULATION DISTRIBUTION (geographic info)

For Societal Risk

1. For every event (scenario,wind angle) count the total number of

people lethality injured (=size of group) and store chance of this

“event” (direction with weather class) : gives a F and N

2. Cumulate ALL wind-directions, ALL weather classes into FN curve

Source

location

Within

footprint:

number

of

victims50 Number killed

cumulative

frequency

10-7

10-6

10-5

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Scenario 1

Scenario 2

Scenario 1+2

Dutch Legislation on external safety : use of criteria

Individual (or Locational) risk

Presented on map: ISO Risk Contours

No “vulnerable objects“ within 10-6 contour

Based on unprotected situation, outside,

100% presence

Strict rule: authorities are drawing lines !

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Societal risk (Group risk):

A 2 dimensional graph

Indicative “guide” values:

stationary/transport

Motivation (measures) when exceeding

or increase due to developments

Dutch Legislation on external safety

“The Societal risk” = 2D graph

Calculated by using

“geographical oriented”

scenario’s & population

distribution !!

A measure for Social Disruption

Difficult to comprehend by local

authorities and land use

planners: Where ? Why ?

Which area’s still have

development space ?

Need for Societal Risk

visualisation, displayed on a

map

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Requirements for Societal Risk maps

Which population is contributing to the societal risk ?

Which area’s do already have a SR problem ?

What is the extend of the problem ?

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Which area’s are “safer” or “less

affected” : provide possibilities for

urban development or extension

industrial activities ?

No new criteria ! Just a visualization

method based on standard

calculation

Societal Risk Maps: SR Contribution map

What if we store SR calculation results per “population grid cell”

Use standardized (Purple Book) method for calculation of SR

• Scenario list: locations, frequencies, lethal inside/outside effect definitions

• Wind/weather definition: probabilities for occurring stability classes/wind

speeds and wind directions

• Population definition: day/night, inside/outside: cell based grid

Store intermediate results to obtain “geographic oriented” information

per grid cell

• Nr of victims / lethal “response” fraction per grid cell + Frequencies

• Stored for each cell and each (sub) event that hits the cell

• Event = Scenario + Wind direction + Stability class combination

Eventually provides full “FN curve” information for each cell

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For every scenario event: store cell victims N and frequency F

Eventually provides FN curve for that cell

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N=3N=1.5

F =

1e-9

N=1.7

N=2F = 1e-6

F = 0.3e-6

F=0.6e-10

AB

C

D

Societal Risk Contribution map: How ?

Gives an illustration of relative contribution to the Societal Risk

Illustrates “Hotspots”: possible problem causing habitation

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Societal Risk Contribution map: Result

Every cell with population gets a

colour, corresponding to FN curve

Translating FN curve to colour:

“Expected value”

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F =

1e -9

, N =

400

F = 1e-6, N = 150

F = 0.3e-6

N = 50

F=0.6e-10, N = 80

For every scenario event: store total victims N and frequency F

Eventually provides FN curve per cell = SR for scenario’s hitting cell

Societal Risk Area map: How ?

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Gives an presentation of magnitude and extent of Societal Risk

Illustrates IF there is a problem, WHERE there is a problem

Societal Risk Area map: Result

Every cell gets a colour,

corresponding to its FN (=SR

affecting events)

Translating FN curve to colour:

relative to “Guide value”

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Societal Risk “Area” mapGives an indication of which areas are affected and presents the level of the risk

Societal Risk “Contribution” map

Gives indication of amount that areas

contribute to risk

Geographic presentations of SR

Experiences IJmond study

Area with fertilizer plant, steel

industry, LPG filling stations, LPG

road transport, rail transport

flammables.

Using scale 6 colours : more

distinction problem or not

Emphases LPG risks causing

problems

Growing understanding spatial

distribution risks

Rerouting of LPG transport

considered

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Experiences Terneuzen study

Area with NH3 production site,

Bromide storage, many pipelines,

road an rail transport

Urban development plans: leisure

center and educational institute

Maps are created from “receivers

point of view”: which scenario’s

are affecting me ?

Legislation: responsibility creator

source risk

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Fascinating debates about justification “cumulating” of risks (Insight)

Possibilities with map visualisation:

Simply an additional view presented on a map !

Possible to include/exclude scenarios (maps for subsets)

Compare difference after change population / change of process

Because intermediate results are stored, fast interactive evaluation of

alternative urban development plans is possible:

1. Possibility to evaluate change population distribution → what

happens with risk maps and total fN

2. Possibility to include temporary population presence with specific

inside-outside distribution (festivals, sport events etc)

3. Possibility to evaluate change of transport intensity / failure

frequency

4. Possibility to evaluate change of route’s

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Evaluate risk contribution by source

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ACN production/storage (Large) Storage of Flammables

NH3 production/storage Loading-unloading rail tank wagons

Evaluate change in transport capacity

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Transport intensity liquefied

flammable gasses reduced with

factor 10

Ind. Value

FN curve selected scenarios

All scenarios ORIG

Cat A transporten gereduceerd met factor 10

Number of fatalities

1 10 100 1,000 10,000

Fre

quency [1/y

r]

-101.0 x10

-91.0 x10

-81.0 x10

-71.0 x10

-61.0 x10

-51.0 x10

-41.0 x10

-31.0 x10

-21.0 x10

EV = 5.53e-05

NormValue = 7.14e-04

Evaluation and conclusions

The SR maps have proven their value:

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SR contribution map shows cause of

SR bottlenecks

Typical SR contribution map applications:

• Guiding emergency response planning

• Pinpointing area’s for redevelopment

/reallocation of population

SR area map shows size and level of

SR bottlenecks

Typical SR area map applications:

• Guiding urban development planning

• Pinpointing safety problems to non-

specialist (risk communication)

Evaluation and conclusions

Looking from “point of receiver” appeals, but is not obligatory

Experience of “Experts” is still required to explain “red zones”

Spatial planners: which colour means a problem ?

Safety specialists: what is behind those colours ?

It is a visualization, not a criteria: traditional graphs also required

Visualization provides supplementary view, more insight

PR contours still provide the first step: where not to build ! (no

vulnerable objects inside the 10-6 contour)

BE CAREFULL when communicating with colours

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