Quick start: Create a new project

The first step in performing a QRA with RISKCURVES is creating a project.

Start RISKCURVES (see “Installing the software and starting RISKCURVES”) and choose File | “New” from the main menu or press the “New project” toolbar button. The user is asked for a project name, and an empty project tree will be created.

To create and run a QRA calculation, the following steps need to be taken:

1.Add a background map 2.Verify Calculation settings 3.Define meteorological conditions 4.Define population distribution

5.Define Stationary or Transport equipment locations 6.Add Scenarios to equipment location

7.Entering consequence model set data 8.Performing the risk calculation

9.Evaluate results of the calculation

10.Optionally, define Cumulation sets , to make a subset of scenarios

11.Optionally, define Comparison sets , to compare different calculations or cumulations 12.Optionally, define Analysis points, to compare risk at specific locations

2.3.1 1 Add a background map

The use of a topographic background maps is very useful and highly recommended. Got to the background node and select < Right mouse> < Add background>. A new (Red) node will be created. Select the node and use the browse button in the input panel to select a background file. Currently supported formats are: JPG, PNG, BMP, TIF and TIF as pixel oriented files, and DXF and SHP as vector formats.

Note that pixel formats require the use of a ESRI worldfile to be able to determine scale and location of the image, whereas the vector formats SHP and DWG already include scale and position information.

RISKCURVES supports the use of multiple backgrounds, so a background can be composed of adjacent or overlapping images.

2.3.2 2 Verify calculation settings

Without any additional user input, RISKCURVES will perform calculation with default settings for “Accuracy” “Vulnerability” and “Environment” parameters.

The “Environment” block is most likely to be modified since it describes typical environmental conditions applicable for the region were the QRA is to be performed: parameters like ambient temperature, water temperature, humidity, surface roughness, solar radiation flux, latitude and cloud cover are country and even location dependent.

The values that are entered here will be "pushed" into each modelset that will perform a consequence calculation.

One can define or alter default environment to be used when creating a new project by using menu “Edit” “Options” “Default environment”.

2.3.3 3 Define meteorological conditions

The probability of a risk occurring at a specific location is highly influenced by the probability of the wind blowing from the accident location towards that location. In order to take this into account, a meteorological definition has to be supplied. Meteo data consists of the definition of typical Pasquill stability class with a wind speed (e.g. D5 or F2), the probability of that class occurring, and the probability for the wind-directions for that class and is applicable for the region where the scenario’s are to be defined. This data is usually supplied by meteorological station at airports etc. and can be predefined for met-stations at your country.

A new meteo-station definition can be added under menu “Edit”, “Option” “default meteo distribution” and the browse button:

All definitions that are provided in “Options” can be selected in the combobox in the input panel of the Meteo data node:

Once a meteo station location has been entered, the red label will turn to black, illustrating that acceptable input has been provided.

Note that the provided (Dutch) meteo station definitions all contain 6 weather classes, but it is also possible to use only two any other number of different Pasquill classes. Using only two classes imply that calculation time will be reduced since the consequence models need to perform two calculations.

The spatial distribution of occurance of specific wind directions can be visualised in a windrose view

2.3.4 4 Define population distribution

This step is only required if a user wants to calculate societal risk, which includes risk of actual exposed population. Population always distinguishes separate population during day and population at night definitions.

To add population, select the <Total population> node and use < Right mouse> <Import Population> or < Add Population Polygon>.

Note that as of version 9, it is possible to combine multiple grids or polygons; the resulting end population will be created on the base of ALL grids an polygons defined in the yotal population node, using the defined population grid cell size.

Population import Wizard

A population grid can be imported from an ASCII based grid, ESRI grid format (provided by local authorities) or the previous RISKCURVES Vs 7 .POP file.

Apart from grid based input files, population can be also created from polygons loaded a shape file.

To import an external grid, select the "import population" from the popup menu at a population node.

Follow the suggestions by either selecting a Population Grid (cell based distribution) or select Population Polygons, which are separate area definitions that can be edited separately after importing. When using highly detailed shape files, containing real "building"

descriptions, it is advised to translate this into a grid (because of the huge number of shapes these files can contain), when using "region based" shapes, it can be useful to import these as separate polygons.

For grids, the type of file to import needs to be defined: it can be an ESRI grid , ASCII / CSV table, RISKCURVES Vs 7 POP file or created from a Shape file.

An ESRI grid file contains a header, describing the dimensions (number of rows, columns and cell size) and location (position of lower left corner) of the grid, followed by the grid values themselves. The header also contains a <NoData> value, which is treated as empty cell, this value is often defined as as -999 or -9999.

A version 7 POP file also contains the complete grid definition including location and dimensions.

An ASCII table assumes the data to be available as separate lines, containing X coordinate, Y coordinate, Population, possibly separated by spaces or other delimiting characters. The import screen offer the possibility to define the decimal separator, and a field separator character, and to skip one or more header lines.

A SHAPE file contains descriptions of polygons with population info about those regions:

When using a shape file as a grid, all shapes will be combined into one grid based definition.

This requires the definition of a grid cell size and selection of fields for daytime / nighttime population.

After importing the file, the boundary definitions of the grid can be provided by defining lower left and upper right corner of the grid:

Population Polygons

A population polygon is a definition of areas with specific population information, they can be created by drawing a shape on the background map or importing a shapes from a SHAPE file.

Importing polygons from SHAPE file

When importing a shape file as polygons, all shapes will be added separately as population polygons.When defining by means of a shape file, the fields containing relevant info in the shape tables need to be defined. Select the name of the field containing the description of the region, and the field that contains the number of people (day/night). Furthermore, the population value provided can contain a density (value is population per area: select the corresponding unit by using the right mouse button on the units description) or an absolute number of people.

After importing polygons, it is possible to edit the shapes, and potentially define specific areas as "temporary population", which implies that a specific utilization fraction can be entered.

These “Temporary populations” are intended for usage in special situations like festivals, sport events or other situations where non-permanent presence of large amounts of people can occur during a FRACTION of the time. This is particular relevant if large crowds are outside and have no protection by houses.

The usage of multiple "temporary" population polygons also implies that that multiple areas can be affected by an event, leading to the situation of combination of victims. The current calculation procedure also checks for potential occurrence of MULTIPLE “Temporary” (even if they have 100% presence) populations, and accounts for the potential PROBABILITY of multiple polygons being exposed, with potential COMBINED NUMBER OF VICTIMS.

Note: When using many (say more than 10) temporary polygons that can be exposed to the same event (when they are close to one another, so within the potential lethality footprint of a single event), this procedure can get time consuming because all potential combinations of these areas need to be evaluated !!!. As an example, just for three temporary population area’s we need to evaluate: A and B and C exposed, A and B exposed, A and C exposed, B and C exposed, only A, only B , only C, and no area (just base population) exposed, where every combination has its own probability of occurrence!!

Manual definition:

Zoom in on the area of interest (use mouse wheel for zooming, right mouse drag for moving the map) and select the edit button. Start pinpointing coordinates on the map, thus defining the shape (polygon) of the habituated area. Select the edit button when definition is finished and enter the number of people within this area during day and during night. For standard usage select “is temporary” as NO.

Give the polygon or grid a specific and recognizable name: select the population polygon, and click on the text “population polygon” or press <F2> to be able to modify the name of the branch.

Note: Renaming a tree node can also be used on Calculation Set, Equipment or Scenario ! 2.3.5 5 Define Stationary or Transport equipment locations

Select the Stationary equipment branch and use < Right mouse> <Add Equipment> . Rename the “Equipment” using <F2> or selecting the string and provide a useful descriptive name.

Select the map view, zoom in to the location where the equipment is placed, hover the mouse to the exact location and select <Right Mouse> < Set Release point> . The current world coordinates of the mouse will be entered in the input fields “X coordinate”and “Y-coordinate” of release. Select the “Show release point” toolbar button to illustrate the location with a label and cross on the map.

Transport equipment: Select the Transport equipment branch and press <Right Mouse><Add equipment> and again rename the “Equipment” using <F2> or selecting the string and provide a useful descriptive name.

. Select the map view and zoom in to the area where the route is to be defined. Press the

“Edit” button in the transport equipment input panel and start pinpointing route points on the map. Watch all route coordinates being added to the table when selecting route points on the map.

Finish the route definition by pressing “End Edit” again. Note that it is still possible to manually modify the coordinates. The “correction factor” column can be used for switches on railroad tracks or locations where a local altered failure frequency needs to be applied.

2.3.6 6 Add Scenarios to equipment location

Once stationary equipment locations or transport equipment routes have been defined, typical LOC (Loss Of Containment) scenarios belonging to the equipment can be added.

Select the equipment and press <Right Mouse><Add scenario> and select the type of scenario to be added from the branch of models:

EFFECTS models are consequence calculations performed by single phenomena consequence models. They can either be based on atmospheric dispersion of toxic or flammable gasses or based on heat radiation (Bleve , poolfire of jetfire phenomena).

Combined models support multiple phenomena; if a material is both flammable and toxic, or direct and delayed iginition can occur, these combined LOC model chains will distinguish several phenomena.

The combined models are supplied for Gaseous, Liquid and Two phase materials, and are available for specific release cases. A release can be either an instantaneous release (called G1 scenario in the Purple Book), a release within 10 minutes (G2 scenario) or a leak scenario with a specific hole size (G3 scenario). If the user doesn’t know the state of , one can select the Unified LOC model, which determines the state itself, and provides a choice to evaluate Damage definition s can be used to enter pre-calculated consequence areas. The damage models are also dedicated to a specific phenomenon.

Another possibility to add scenario is by using the floating panel: Select an equipment node, and hover the mouse over the white line on the left border of the RISKCURVES window. A model selection panel will unfold, illustrating different possibilities by family name:

After the scenario has been added, the definition itself needs to be provided.

A scenario definition consists of two elements: a frequency part and a consequence part.

The tree visualises this as two nodes of the scenario: the scenario node and the corresponding (consequence) modelset. For a scenario, main parameters are base frequency (expressed as chance of occurrence per year), a possible correction factor (which can be used to represent risk reduction actions), and a daytime fraction. The daytime fraction can be used to express the situation that an activity only takes place during day or night time.

By default, this fraction should be the average occurrence of daytime situation, according to the meteorological data definition (e.g. for Netherlands 44% is daytime). If another fraction is used, this implies that the activity is predominantly shifted into day or night time.

Combined models also require entering a fraction for direct ignition, delayed ignition, BLEVE and explosion phenomenon. For single phenomenon models, is it assumed that this fraction is already included in the base frequency. Pressing the < Defaults> button will quickly enter feasible frequency / probability values here, but is not advised because failure frequencies tend to be very specific for the typical situation.

2.3.7 7 Entering consequence model set data

Dependent on the type of model (single phenomenon model, combined model or damage definition) a dedicated input parameter list will be presented. An first example is provided for a BLEVE damage definition:

This input is defined by a fireball radius (100% lethality inside and outside), a 35 kW/m2 radius (same lethality as within fireball), and a lethality versus distance response table which defines unprotected outside lethality.

This lethality table needs to be entered in a logical ascending distance / descending lethality order.

If input is invalid, the table caption will turn red.

Note that the weatherclass combobox can be used to define either ALL (default) or ONE specific meteorological condition. Start with entering all (Default), and IF specific damage distances occur (such as expected in case of toxic dispersion phenomenon), select distinguished weather classes and enter dedicated distances.

Note: If a weather class specific parameter is displayed in a blue color, it means that it is identical to the default situation. This illustrates the fact that in the background this parameter is linked to the default model (see EFFECTS for details about model linking)

A consequence model definition is basically identical to an EFFECTS model definition: the input panel displays all relevant input parameters. In fact, it is also possible to copy/paste EFFECT end models into RISKCURVES. (An end models implies that the model ends up with any lethality information, eg. a single outflow model is no end model)

The number of required input parameters for an EFFECTS model can be changed depending of the setting of complexity: Simple, Normal or Expert. The three toolbar buttons on top of the main window will define this state. It is advised to start using “Simple mode”, which only requires main parameters (Chemical, amount of material released) to be entered, and only use “Normal” or “Expert” if one wants to divert from standard method. In “Expert”

mode, all parameters that influence the result of the calculation are shown, providing the possibility to alter parameters like ambient temperatures or other default value parameters defined in “System Settings”.

If an EFFECTS model has been selected as scenario type, this consequence model will be calculated for a number of weather conditions, equal to the typical Pasquill classes defines in the meteo data node. This results in a Set of models in which every model can have specific input. The weather class dedicated input can be accessed by selecting the appropriate weather class from the combobox.

Note that the way the scenario node is displayed, reflects the current state:

- a red scenario means data is incomplete or incorrect

- an italic presentation means that input has changed and the node needs to be (re) calculated

- a blue presentation of a specific weather class model implies that the data is linked to the default weather class model

2.3.8 8 Performing the risk calculation

After defining scenarios a calculation can be performed. The calculation can be started by

pressing the <Calculate> button on the bottom of the screen. Dependent of the number of (modified or uncalculated) scenarios, a calculation can take seconds, minutes or hours for large (hundreds) scenario sets.

Note that consequence (EFFECTS) models will not be recalculated if only a location or frequency has been changed, a scenario will not be recalculated if only location changed, and equipment is skipped if nothing has changed etc. Only modified input needs to be redone, where the calculation of a societal risk, which is a accumulation of several scenario/

equipment contributions, will always be redone.

During calculation, several progress bars will be presented, to give an idea about the current progress status. If for some reason, a scenario or equipment is skipped, the calculation will proceed with the next scenario, and store the result of previous calculation!

2.3.9 9 Evaluate results of the calculation

After the calculation is finished, the Log tab will display any abnormalities, using a Yellow color for warnings, and Red for errors. The severity will also be represented by the LED icon on top of the log window.

Note that the contents of the Log window reflects the current active node. If a calculation set is active, all Logs of underlying nodes will be included. To see dedicated results for one equipment, or even one scenario, this node has to be activated (selected).

The same selection method applies for all other results: specific results from equipments (Individual risk contours and FN curve) can be evaluated by selecting the equipment, a scenario has results in terms of individual risk per wind-direction (FX graphs) or even calculated consequence distances can be evaluated by selecting the required weather class.

Main results of course can be found on “Calculation Set” level: The complete set of scenarios and equipments will result in a Individual Risk Contour map, and Societal Risk curves.

The Societal risk of transport scenarios is depicted in transport FN cuvres, applicable for a section of the route. These graphs are part of the results of individual transport equipments (per route).

2.3.10 10 The use of Cumulation sets

Very often one is not interested in the fully accumulated results of all scenario’s, but want to know the contribution of a specific subset of scenario, e.g. only flammable scenario’s or accumulation of specific vessels or equipments. Such a subset can be made using a Cumulation Set. Define a new set by selecting the “Cumulation sets” node and selecting

<Right Mouse> <Add cumulation set>. Give it a descriptive name (e.g. “Only Flammables”) and use the checkboxes to select which equipments or separate scenarios should be incorporated within this accumulation. After pressing the <Calculate> button, which only takes a few seconds, the subset results will be presented.

It is important to realise that a Cumulation set can also be used to ADD different calculation

It is important to realise that a Cumulation set can also be used to ADD different calculation