Phast Risk Release Notes

Phast Risk Release Notes for V6.7

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Phast Risk v6.7 Release Notes 2

Phast Risk v6.7 Release Notes Contents New Features and Major Enhancements...................................................... 4

Workflow for transferring data from Phast Risk v6.7 into Extended Reporting........................... 4 Default Mode ........................................................................................................................... 4 Advanced Mode....................................................................................................................... 5

Added output for toxics mixtures................................................................................................ 13 Warehouse Fire Model................................................................................................................ 13

Not enough material model enhancement.............................................................................. 14 Mixture lethality contours enhancement................................................................................ 16 ERPG equivalent mixture concentration contours enhancement........................................... 18 Rename K1/K2 liquids to ADR Class 3................................................................................. 20 Removal of ADR Class 3 from some fire fighting systems................................................... 21 User defined reaction rate for non PGS15 extinction systems............................................... 23

In-Building model improvements ............................................................................................... 25 Improved output report for discharge results .............................................................................. 26 New numerical solver for UDM outdoor dispersion model........................................................ 27 Improved correlation for initial droplet size ............................................................................... 28 Modelling of solid effects for CO2 .............................................................................................. 29 Materials Property update ........................................................................................................... 30

Update to toxic Probit values................................................................................................. 30 Pools on Water....................................................................................................................... 30

Modified Pool Fire Location in case of bunds ............................................................................ 31 New Indoor/Outdoor Method for Population.............................................................................. 32 3D Cloud ME/Purple Book Explosion........................................................................................ 35

Comparison of the Wiekema and 3D Cloud ME/Purple Book explosion methods............... 35 External CAD connection wizard ............................................................................................... 37 Help menu additions ................................................................................................................... 41

Minor enhancements..................................................................................... 42 Workarounds and Bug Fixes........................................................................ 43

Known Issues, Alerts and Workarounds for v6.7 ....................................................................... 43 Bug Fixes for v6.7....................................................................................................................... 46

Discharge ............................................................................................................................... 46 Dispersion .............................................................................................................................. 47 Risk ........................................................................................................................................ 47 GUI ........................................................................................................................................ 47

Making the Most of the Documentation...................................................... 49 Phast Risk v6.7 Compiled Help .................................................................................................. 49 Phast Risk v6.7 Release Notes .................................................................................................... 49 Technical Reference.................................................................................................................... 49


For System Administrators: Technical Notes ............................................ 50 System Requirements.................................................................................................................. 50 Internet Protocol v6 (IPv6).......................................................................................................... 50 Temporary folders....................................................................................................................... 50

Managing Study Folders............................................................................... 51 Memory Management................................................................................... 52


New Features and Major Enhancements This section describes the main new features in Phast Risk v6.7

Workflow for transferring data from Phast Risk v6.7 into Extended Reporting In order to use the Extended Reporting Extension with v6.7 it is necessary to transfer risk data from Phast Risk to Extended Reporting. The program uses a database and generates database files. There is no need to get involved in the detail of how the database works unless larger more complex studies are required.

Default Mode Phast Risk v6.7 is designed by default to make transfer of data between Phast Risk and Extended Reporting happen without any further intervention or specialist knowledge from the user. Default mode is used for small to medium sized studies where long term storage of the data is not required and where the generation of Risk data takes a relatively small amount of time. The workflow is simple:

Select Run Rows and calculate Consequence and Risk. When Risk results have been created the sigma button will become activated Click on the sigma button and Extended Risk Reporting will open using the current risk

results


If after examining the risk results in Extended Reporting you wish to edit the input data in the study and re-run the Consequence and Risk calculations you can click the sigma button again to generate the new risk results database. When you click the sigma button Phast Risk will offer you the option to Overwrite previous data, Save as or Cancel the database creation. If you overwrite the results database, previous results are lost. If you choose to Save as you can rename the new risk database file and therefore store both the old and new results for analysis.

If you leave extended reporting open, then return to Phast Risk, make further edits and then click the sigma button you are effectively trying to open a second instance of the Extended Reporting tool. Because the first instance of Extended Reporting is reading from the original data file then Phast Risk will not allow you to overwrite the original data file whilst it is in use.

Advanced Mode Working in advanced mode may be necessary to support working with larger, more complex studies which are time consuming to run. There are methods for selectively running calculations of only some aspects of the study. This reduces storage needs and calculation times and methods for automatically saving the data at the end of lengthy calculation runs. This way, the program can be left to perform calculations and data saving unattended.


Setting up to automated data saving at the end of a calculation run. If a long calculation time is predicted then it is useful to be able to automatically save risk results at the end of the calculation so that it is ready to be examined in Extended Reporting. The process of saving the potentially large amounts of results generated by Phast Risk can be a lengthy operation for very large studies so it can be useful to include this in an unattended process. Navigate to Options Preferences Risk Extended Risk Reporting (tab)

Set the file name for the data using the File field (as shown above), or by browsing to the desired location using the button.

Check Write Extended Risk Results after Risk Calculations Click OK on the Risk Preferences dialog and choose Run Models to begin the calculation and

data writing process

If you want to Launch Extended Reporting so that it is ready for use at the end of the calculation and data writing run, then check Launch Extended Risk Reporting

Please note it is not possible to save a data file to a compressed drive, or networked drive or to a drive where the current user of the machine does not have the necessary read/write permissions.

Important facts about the results data file: At the end of the calculation and data writing process a Microsoft SQL Server (*.mdf) data file will be generated. This is a self contained set of results data which contain the risk results generated by the study at the time of its calculation. It has an audit number and a creation time which are visible in the Extended Reporting application.


Please be aware that if you intend to save variations and versions that it is necessary to reset the file name for each MDF file that you wish to Save. The file name can be defined via Options Preferences Risk Extended Risk Reporting (tab)

It is not possible to double click on an MDF file to open it. It must be opened using the File menu of Extended Reporting. The datafile is transferrable if the installed version of SQL Server on the original PC is the same as the installed version on the destination PC. The default version of SQL Server installed with Phast Risk v6.7 is SQL Sever Express 2008 R1 The maximum size of the datafile is finite and determined by the particular version of SQL Server which is installed with Phast Risk. If the size of your studys database exceeds the limit set on it then the data writing will fail for the current run row and there will be incomplete data, accompanied by a warning. It is near impossible to reliably predict how large a data file will become ahead of performing the calculations. However, we have produced a set of example studies which will give approximate sizes of data files when using various configurations of run rows, models, weathers, etc. These should help in the planning of a study which might exceed the data limit. Whilst it is always preferable to deal with the problems of large amounts of data through design there may be some instances where you find it necessary to produce extremely large studies which exceed or nearly exceed the 4GB storage constraints imposed by the SQL Server Express R1 version. There are a number of steps which can be taken to maximise storage capacity and to create smaller subsets of the risk data, details of each option follow.

Upgrading SQL Server Version: It is possible to increase the storage capacity of the data files by upgrading the SQL Server version

Selecting a subset of Run Rows Using preferences to limit results produced: It is possible to set preferences so that only

particular aspects of the risk calculations generate results. For example. It is possible to switch off all societal risk results and only produce results for individual risk.

Using preferences to limit which precompiled tables are produced: Similarly, by default, a number of precompiled views are created by the data writing process. By switching these off space may be saved at the expense of speed of access in Extended Reporting.

Upgrading SQL Server Version By default Phast Risk uses SQL Server Express R1. The size of individual data files is limited to 4GB. A newer version of SQL Server Express exists called SQL Server 2008 R2 Express. This version expands the limit of the datafile to 10GB. SQL Server Express R2 can be downloaded at no cost from: http://www.microsoft.com/express/Database/ Please follow the instructions which have been provided with the technical documentation which will guide you through installing the database so that it will communicate with Phast Risk. Both SQL Server Express R1 and R2 are free to use but have fixed data limits set and will only use one processor and up to 1GB of RAM . It is possible to purchase a full version of SQL Server where the data file size is limited only by the hardware constraints of the machine on which it is installed.


Selecting a subset of Run Rows A straightforward method to reduce the overall size of the data file produced by a study is to deselect Run Rows for calculation.

In this way you can use the Extended Reporting to examine the details of the risk results in stages rather than having to write the entire study results to a single, large database. This will keep the database size down. Sometimes it is necessary to write results from every run row to the database: for instance to obtain combined contours for the whole study or an overall FN curve. For very large studies, if all the risk results are written to the database at one time then this operation may exceed the allowed database size so a reduced set of risk results must be obtained by running the risk again to obtain only these results. This is explained in the next section.


Using preferences to limit results produced By default when Risk calculations are run all types of Risk Results are produced by the models regardless of what you might specifically be interested in. If you are only interested in particular categories of risk then the types which are not of interest may be switched off. Options Preferences Risk Run Control (tab)

For example, if you have a study which you know will exceed the data file size if all risk results were generated then it would still be possible to get an overview of risk across the entire study by changing the Calculation scheme to Contours & F/N Curve only. This effectively tells the calculation run to not generate data for Risk Ranking Points, Risk Ranking Results and Building Category Results. Another example would be, if you wanted to generate an overview of Risk Ranking Points for an entire, large study then you could switch off results generation for all but Risk Ranking Points. The technique of limiting the results produced and saved by models can be combined with other techniques for limiting the size of the data files for very large studies.

Using preferences to limit which pre-compiled results tables are produced: At the end of the calculation and data writing process Phast Risk compiles the data into a format that is designed to enhance the speed with which you can interact with the risk data in Extended Reporting.


Pre-compiled results preparation can also be turned off if you are not interested in a particular type of results in order to reduce the data file size.

There are two types of precompiled data tables: Summary tables and Details. Summary tables

Risk Dashboard

RIByN (Risk Integral By Number of statistical fatalities), Bar Chart and Pie Chart Category PLL/FAR (Potential Loss of Life/Fatal Accident Rate) Individual Risk

Details tables

FN Totals and Raw FN Chart

FN Details

Individual Risk Details

Explosion Details


The summary tables occupy a relatively small amount of storage space within the data file. However, the detail tables can potentially occupy a large amount of space and will provide a significant space saving if they are not required and can be switched off. Turning off the generation of either summary tables or details tables does not preclude you from seeing those results in Extended Reporting: the results views are simply not pre-prepared for faster viewing. However, in the case of a large study, turning of their creation will impact significantly on the speed at which various data views in Extended Reporting can be loaded and navigated.

Data Size Limits of studies which use Extended Reporting The log window in Phast Risk will tell you which version of SQL Server that is installed and what the storage capacity of the data file is: The writing process will warn you at 90% of the capacity of the limit and will stop writing at 95% of the capacity of the limit.

08:20:00 Creating storage for Extended Risk Reporting data...

08:20:00 SQL server version is Express Edition with Advanced Services

08:20:00 Max allowed storage size is 10.00Gb. Writing will stop at 95.00% full.

08:20:06 Results data written to C:\dnvuser\PHAST_6_7_0_334\Examples\Extended Explosions\Explosion Example.mdf.

08:20:06 Creating Summary Data...

08:20:08 Extended Risk Reporting data writing complete. 0.0781% full.

08:20:09 Opening Extended Risk Reporting Tool...


It is not possible to predict the size of a studys risk results as it depends on whether consequences impact populations and risk ranking points, etc. However, here are a set of input parameters for a range of studies which offer guidelines about approximate sizes of risk result data files.

Study Size in GigaBytes 1.219 1.007 2.376 5.093 9.926 8.204 9.926

Study Inputs

Number of Run Rows 4 7 130 15 40 90 45

Avg Events per Run Row 194 437 24 170 78 192 266

Avg Weathers per Run Row 4 6 2 2 4 2 2

Avg Weather Directions per Run Row 32 96 32 40 64 40 40

Avg BuildingTypes per Run Row 17 17 2 6 5 6 6

Avg Buildings per Run Row 18 2 2 58 2 56 56

Avg PopulationCategories per Run Row 10 10 14 10 10 10 10

Avg Areas per Run Row 3 1 1 4 1 4 4

Avg Obstructed Regions per Run Row 13 86 1 24 2 20 20

Avg Risk Ranking Points per Run Row 10 260 0 9 8 9 9

Percentage of storage size occupied by Summary Tables

RIByN, Bar Chart, Pie Chart 0.02 0 0.09


Added output for toxics mixtures Phast Risk v6.7 now generates additional output for mixtures containing toxic components:

- Graphs: o ERPG concentration contours o Mixture lethality contours in addition to component lethality contours

- Report: component probit/lethality versus distance and mixture lethality versus distance

These new additional results are available for the Vessel/Pipe Source, User-defined Source and the Warehouse Fire Model scenarios. These enhancements are further detailed below for the specific case of the warehouse scenario.

Warehouse Fire Model Phast Risk v6.7 includes a number of modifications and enhancements to the Warehouse Fire Model. The enhancements include

Extension to the model for instances when there is not enough material present for the specified fire duration,

Enabling mixture lethality contours for warehouse fire models,

Enabling ERPG equivalent mixture concentration contours.

The modifications include

Renaming K1/K2 liquids to ADR Class 3,

Removing ADR Class 3 materials from appropriate fire extinction systems,

Enabling user specified reaction rate for non-PGS15 fire extinction systems.

The sections below describe these modifications and enhancements in further detail.


Not enough material model enhancement In previous versions of Phast Risk if there was not enough material present the warehouse scenario would fail and a message was displayed in the Message Log window as follows:

15:43:14 ----- Calculating Model Doors Open- 900 m2/1800 s for Weather Deelen, nacht:Deelen - F 1.5m/s... 15:43:14 ***Error: WHFIRE 4: Specified fire duration is larger than time 1031.11 s at which all warehouse materials are burned

15:43:14 *******Run Failed*******

In Phast Risk v6.7 the model has been enhanced to reset the fire duration time to the actual duration it takes for all materials to be burnt and the model will now run successfully.

15:47:39 ----- Calculating Model Doors Open- 900 m2/1800 s for Weather Deelen, dag:Deelen - D 9.0m/s...

15:47:39 ---Info: WHFIRE 2001: Specified fire duration is larger than time 1031.11 s at which all warehouse materials are burned. So fire duration is reset to the time 1031.11 s at which all warehouse materials are burned


The message displayed will only be seen if display information messages and display warning messages are selected in the Miscellaneous tab from the Options>Preferences>General Preferences menu.


Mixture lethality contours enhancement For each warehouse fire scenario, the warehouse fire model predicts the dispersion of the combustion mixture released from the warehouse. This mixture is modelled as a mixture of the toxic components NO2,, SO2 and HCl. It is labelled in the materials tab as the Warehouse Reference material. In previous versions, the following toxic graphs were produced:

NO2,SO2,HCl separate probits versus distance NO2/SO2/HCl mixture dose/lethality versus distance NO2,SO2,HCl separate footprint contours for probit/dose/lethality

In v6.7 additional toxic graphs are produced, so all the following combinations are now available: NO2,SO2,HCl separate probits/lethality versus distance NO2/SO2/HCl mixture dose/lethality versus distance NO2/SO2/HCl mixture footprint contours for probit/dose/lethality NO2,SO2,HCl separate footprint contours for probit/dose/lethality

An example can be seen in the Outdoor Toxic Lethality Footprint below where version v6.54 displays the NO2 & HCl lethality footprint.


The v6.7 plot displays the Warehouse Reference mixture footprint in addition to the NO2 & HCl lethality

Please note that in the above screen shot the formatting of the plots has been adjusted from the default (right-click on legend and choose Properties) to help distinguish between overlapping lines.


ERPG equivalent mixture concentration contours enhancement In Phast Risk v6.7, users now have the option of specifying ERPG averaging time for the warehouse fire model. A new tab has been introduced to the Warehouse Fire model, the Location tab. This tab is analogous to the Location tab in the Vessel/Pipe source model.


The Dispersion stop criterion in the Dispersion Parameter group set in the Other tab (seen below) is defaulted to Risk based.

The above default option should always be chosen for risk calculations, i.e. to determine the individual and societal risk. However, with this option chosen the toxicity calculations will not proceed beyond the minimum probability of death (default 1% in Phast Risk) and therefore all ERPG concentration values may not be reached. To ensure that all equivalent ERPG concentration values are reached, the user should change the above option from Risk based to Mixed Basis (in addition to selection of ERPG averaging time in Location tab of the Warehouse Fire model.

Please note that regardless of the option chosen dispersion calculations will always stop when the cloud reaches the Maximum distance for dispersion set in the System Parameters (defaulted at 50 km), even if the other criteria have not all been met.


Rename K1/K2 liquids to ADR Class 3 In previous versions of Phast Risk the labels read K1/K2 liquids in the fire extinction systems. These have been renamed to ADR Class 3 all throughout the product. This has been carried out to be consistent with the PGS15 terminology as described in the Reference Manual BEVI Risk Assessments (formerly the Purple Book) The screen below shows the input dialog for the warehouse fire model. The help file has also been updated.


Removal of ADR Class 3 from some fire fighting systems In previous versions of Phast Risk, there was no logic preventing users from selecting synthetic packaging for K1/K2 liquids even though the Fire-fighting system would not involve these, according to the PGS15 methodology. This can be seen in the following screen where Fire-fighting system 2.1b Fire brigade mobilization


PGS15 logic for allowing ADR Class 3 liquids has now been fully implemented. This logic is as follows:

None allowed is only to be selected for system 3.1 Both synthetic and other packaging allowed are available for all systems except

2.1a,2.1b,2.2a,2.2b and 3.1 Synthetic Packaging allowed only is available for systems 2.1a, and 2.2a Other packaging allowed only is available for systems 2.1b, and 2.2b

The screen below shows that for Fire-fighting system 2.1b, the not stored & Stored in other packaging are now the only available options, as expected from the details above.


User defined reaction rate for non PGS15 extinction systems

In previous versions of Phast Risk user defined reactions rates are only available to PGS-15 Fire-fighting systems. Once the PGS-15 option is unticked the option of user defined reaction rates is no longer available as can be seen in the Phast Risk v6.54 image below.

In Phast Risk v6.7, users now have availability of the user-defined reaction rate when PGS-15 Fire-fighting systems are not selected.


Users need to select either Stored in Other Packaging or Stored in Synthetic Packaging in order for the Reaction rate calculation field to be enabled. Then, the user defined calculation can be selected and the desired value may be entered, as can be seen below.


In-Building model improvements

The following enhancements have been implemented in Phast Risk v6.7 to the in-building release model:

In v6.7, the release duration is set so all liquid will eventually evaporate from the building for both instantaneous and continuous releases. This corrects an inconsistency previously present where liquid would not always evaporate for instantaneous releases.

For continuous releases the release duration from a building can never be less than one air change.

The release duration can never be more than the maximum release duration as set in the parameters (currently 1800 seconds).

For indoor releases, the vapor fraction multiplication factor remains in use (current default value of 3) and the material remaining is presumed to be trapped as liquid in the building. This multiplication factor determines the fraction of vapor that can be released from the building and can be modified in the Discharge parameters group. In addition to dispersion calculations, the in-building model also carries out explosion calculations, (which are not included in the risk calculations). Previous to v6.7, the venting parameter of the indoor confined explosion model was a constant. The venting parameter is now a variable based on the laminar burning velocity. Please note this correlation is only applicable for low-strength enclosures which cannot withhold an overpressure higher than 0.1 bar (National Fire Protection Association -NFPA 68) for laminar burning velocity not higher than 0.6m/s. Currently, there is no implementation for high-strength enclosures; this is listed as a potential enhancement for a future version. For further information on the in-building release model theory, please refer to the technical documentation which is available with the Phast Risk installation


Improved output report for discharge results The layout of the discharge report produced a by Vessel or pipe source has been improved in order to produce a more clear overview of the output results. A clear distinction is made between stagnation data (data at upstream end for long pipe), orifice or pipe exit data before atmospheric expansion, and final data (after atmospheric expansion). See the screen dumps below for the case of a chlorine leak.

Old 6.54/6.6 discharge report


Improved 6.7 discharge report

New numerical solver for UDM outdoor dispersion model The UDM Version 1 model is the model available in v6.54 and earlier versions, and the UDM Version 2 model is an enhanced model, introduced as an option in v6.6. The default in Phast Risk v6.7 has changed to the UDM Version 2 model. The UDM Version 1 model was based on synchronised solution of two separate sets of differential equations for droplet and plume-dispersion variables. The UDM Version 2 model adopts a more rigorous approach by solving simultaneously a single set of droplet and plume-dispersion variables using a differential-algebraic solver. This eliminates previous erroneous droplet oscillations and allows accurate location of cloud transitions. For further information on the UDM Version 2 model theory, validation and verification, please refer to the technical documentation which is available with the installation


Improved correlation for initial droplet size The Phast Risk outdoor dispersion model (Unified Dispersion Model, UDM) requires as input an initial value of the averaged droplet size (Sauter Mean Diameter, SMD) to perform dispersion calculations. This initial droplet size is the droplet size following expansion of the release to the atmospheric pressure. Phast Risk v6.54 made use of the 1994 CCPS droplet correlation to estimate this initial droplet size for continuous and instantaneous releases. The 1994 CCPS correlation involves both a mechanical and flashing break-up prediction of which the minimum is chosen as the droplet diameter. When compared with experimental data, obtained through a series of joint industry research projects where DNV was involved, the results showed that the 1994 CCPS model tended to under predict liquid droplet size for a range of materials, as shown in the figure below.

1994 CCPS Correlation

10

100

1000

10000

10 100 1000 10000Measured SMD [microns]

Pre

dic

ted

SMD

[m

icro

ns

]

Cardiff_Cyclo-HexaneCardiff_WaterCardiff_GasolineCardiff_ButaneCardiff_PropaneINERIS_ButaneVKI - R134-ASTEP - PropaneHSL - PropaneINERIS - ButaneEcole de Mines - Water+30%-deviation-30%-deviation

A modified CCPS droplet correlation has been developed and implemented in Phast Risk v6.7 as the default choice for non-instantaneous releases. This modified CCPS correlation chooses the mechanical break-up droplet size for sub-cooled releases and the flashing droplet size for superheated releases, instead of choosing the minimum size as in the original CCPS correlation. Better predictions compared to experiments are obtained with the modified CCPS droplet correlation, as shown in the figure below.


Modified CCPS Correlation

10

100

1000

10000

10 100 1000 10000Measured SMD [microns]

Pred

icte

d SM

D [m

icro

ns]

Cardiff_Cyclo-HexaneCardiff_WaterCardiff_GasolineCardiff_ButaneCardiff_PropaneINERIS_ButaneVKI - R134-ASTEP - PropaneHSL - PropaneINERIS - ButaneEcole de Mines - Water+30%-deviation-30%-deviation

Please note the modified CCPS droplet correlation is intended to be used in conjunction with the Unified Dispersion Model (UDM) Version 2, which is the new default UDM model in Phast Risk v6.7. Additionally, it was also shown that the modified CCPS droplet correlation resulted in the most accurate UDM predictions of rainout. For further details, see the document Dropsize_theory_validation.pdf included as part of the Phast Risk technical documentation.

Modelling of solid effects for CO2 For the most accurate CO2 atmospheric-expansion and dispersion calculations the UDM Version 2 contains a flag whereby it automatically switches to the equilibrium, no rainout dispersion parameter option for droplet modelling. There is a warning to this effect in the message log window and in the commentary report when this takes place, as shown below.

13:45:47 +++Warning: UDMA 1106: Solid CO2 modelling enabled, but droplet

modelling not handled. Dispersion modelling will use equilibrium no rainout

The inclusion of CO2 as a Hazardous Substance in the Seveso Directive has been described in a HSE paper available from the HSE's web site (http://www.hse.gov.uk/seveso/co2-hazardous-substance.pdf). This paper states that the Phast CO2 model currently has the greatest potential to accurately model the release of CO2. For further information on the modelling, see also the files Thrm_theory.pdf and Xprp_Theory.pdf included as part of the technical documentation on the release DVD.


Materials Property update In v6.7, there have been a number of updates to the property system. For further details than provided in this section, please refer to the Property_Database_Property_List.pdf document provided with the technical documentation The updates can be grouped as follows:

Update to toxic Probit values In Phast Risk v6.7 the A, B & N values for nitrogen (N2) and carbon dioxide (CO2) have been updated as shown on the table below.

Component A B N

Nitrogen (N2) -65.7 1 5.2 Carbon Dioxide (CO2) -90.778 1.01 8

The above values for nitrogen correspond to the probit function recommended in the Reference Manual BEVI Risk Assessments (formerly Purple Book) for inert gases such as nitrogen. The above values for carbon dioxide are derived from values recommended by the HSE for SLOT (1% probability of death), SLOD (50% probability of death) and N. The HSE SLOT DTL and SLOD DTL values for carbon dioxide are 1.5 x 1040 and 1.5 x 1041 respectively (units ppm for concentration c and minutes for time t), where the dangerous toxic load DTL is defined by = dtcDTL N

Please note that the above values are not used by default, since both nitrogen and carbon dioxide are flagged as inert materials. The materials Flammable/Toxic physical property setting needs to be set to Toxic to enable toxicity calculations (and associated risk). Previously, if using dangerous toxic load values greater than 3.4 x 1038 you receive an error during toxic effect calculations. The SLOT DTL and SLOD DTL values for Carbon Dioxide are 1.5 x 1040 and 1.5 x 1041 respectively. The dangerous toxic load model currently uses single precision floating point values which have a maximum definable positive value of 3.4 x 1038. Over time all of the DNV Software models are being updated to use double precision floating point numerical values but at this time the dangerous toxic load calculation is awaiting update. It is worth noting that this problem tends to exist for materials which are not strictly classified as toxic but are considered harmful at relatively large concentrations and exposure times based on their asphyxiation potential. Please note that when calculating toxic load using these toxic coefficients changes should be made to the model inputs as follow:

1. Change the Toxic parameters > Toxic Tab > Probit Calculation Method to 'Use Probit' 2. For SLOT use 1% lethality, for SLOD 50%

Pools on Water The table below lists the material properties used in Phast Risk for pools on water. These are all non-DIPPR physical properties. The last two properties in the table concern ammonia only, and for this case the properties are obtained from Raj and Reid as described in the PVAP theory manual. For the remaining first four properties a thorough literature search has been done and new values have been


implemented in Phast Risk v6.7. For further details on the actual values please refer to the Property_Database_Property_List.pdf document provided with the software.

Property Affected Pool Scenarios

Material-water interfacial tension, Lw (N/m) Spreading of instantaneous releases on water Heat of solution, Hsol (J/kg) Dissolution in water Solubility in water, fs (kg/kg) Dissolution in water Heat transfer coefficient, hs (W/m2K) Boiling on water Reaction with water (0, none, 1=Raj and Reid) Reaction with water (=1, for ammonia only) Liquid-water enthalpy coefficients AL,w , BL,w, CL,w, DL,w Reaction with water (ammonia only)

Modified Pool Fire Location in case of bunds Phast Risk v6.6 applies circular pools centered at the rain-out point, as seen in the image below. In reality the release location may be anywhere within the bund; if the release location is outside the bund, no bund should be specified. Modifications to Pool Fire and UDM bund modelling

bund

Bund radius

vapour-plume centre-line (always unaffected by bund)

Bund wall = point of rainout = pool centre

If the release location is indeed at the centre of the bund, the formulation in previous versions of Phast Risk may have given too conservative results; particularly for the cases of a large bund, rainout locations at or near the bund wall and formation of a large pool filling the entire bund. Phast Risk v6.7 provides a modified less conservative method, which applies the assumption that the release point is at the centre of the bund both for the rainout criterion and the subsequent pool fire calculations.

vapour-plume centre-line (always unaffected by bund)

Bund wall = point of rainout (pool spreads towards upwind edge of bund)

bund

Bund radius

If rainout occurs outside the bund, this enhancement will have no effect.

If the droplets hit the bund wall, rainout is assumed to occur inside the bund and the resulting pool is assumed to have spread back, in the upwind direction

If rainout occurs within the bund, without hitting the wall, it is assumed that the pool will spread without bund effects until the downwind radius of the pool reaches the downwind radius of the bund and then spread back upwind, ultimately with the pool constrained by the bund centered at the release point.


The previous versions of Phast Risk assumed the pool centre to be equal to the rainout location. This simplistic latter assumption has been maintained in Phast Risk v6.7 for the purpose of the pool evaporation calculations and the pool vapour added back to the UDM cloud. However the early and late pool fires will apply the new, more correct location of the pool fire, with the downwind edge of the pool fires moved to the downwind bund wall (but reduction of radiation due to shielding by the bund wall is not considered).

New Indoor/Outdoor Method for Population In v6.6 of Phast Risk and before all the population in a given run row was split between indoors and outdoors according to the setting of the parameter Fraction of population outdoors (Societal Risk) found in the General Risk Parameters. This split between indoors and outdoors is important because of the different probability of death indoors versus outdoors. Phast Risk v6.7 introduces a significant change in the way population is split between indoors and outdoors and allows specific populations to have indoor/outdoor fractions that differ from the parameter setting for the run row.


The first change is that the parameter is now set as an indoor fraction instead of an outdoor fraction in order to make the input consistent with the data in the population database; hence it is renamed to Fraction of population indoors (Societal Risk), and the default values have been changed to 0.9


Each population now has an indoor fraction attribute, shown below. This parameter is used as the default setting for each population defined in the population set and the value will be surrounded by a green border. This value can be set individually for each population as needed.


3D Cloud ME/Purple Book Explosion A new explosion modeling method has been developed and introduced for use in risk calculations. This new explosion is provided in addition to the previous Wiekema explosion model (the original explosion method used in Phast Risk) and the Extended Explosion method (introduced as an extension available to Phast Risk 6.6). The new 3D Cloud ME/Purple Book method uses the Multi Energy explosion method and a 3 dimensional cloud shape derived from the UDM dispersion results rather than the equivalent approximate ellipses for the LFL contours as used by the Wiekema method. Users can switch between the pre-v6.7 method (2D) and the new method in v6.7 by double-clicking the highest level in the study tree (root node) and choosing the appropriate method in the dialog, as shown below

In Phast Risk v6.7, the 3D/ME Purple Book method requires an Unconfined Explosion Strength and this can be used together with an efficiency factor in such a way to represent a cloud where a fixed proportion of the cloud is ignited within assumed but unspecified obstructed regions in all delayed ignition locations. The Unobstructed explosion strength and Explosion Efficiency parameters are located in the General Risk Parameters, ME and BST tab. Please note that the Unconfined Explosion Strength can be set to any value between 0 and 10 and therefore possibly represents unconfined or confined explosion source strengths, depending on your preferred input value. The default value is 2.

Comparison of the Wiekema and 3D Cloud ME/Purple Book explosion methods To obtain equivalent results to the former Wiekema method when using the new 3D ME/Purple Book method the following settings would be used:

The Multi Energy curve used is 10 (Unobstructed strength parameter value 10) 12.5% of the flammable mass is considered to be in obstructed regions (12.5% Unobstructed

explosion efficiency) Heavy explosion damage corresponds to an overpressure of 0.3 bar (Indoor and outdoor

fatality = 1) Lighter explosion damage corresponds to an overpressure of 0.1 bar (Indoor fatality only

0.025)


0.001

0.01

0.1

1

10

100

0.1 1 10 100

Scaled distance r'

Scal

ed

peak

si

de-o

n o

verp

ress

ure

Ps

'

0.3

0.1

Use of Multi Energy Curve 10 to obtain radii R1 (0.1bar) and R2 (0.3bar) Reading from Multi Energy curve 10 gives values of 1.3 and 2.8 respectively for scaled distances r1 and r2. This gives a ratio between the heavy and lighter damage radii of 2.16 by using 0.3 and 0.1 bar as the overpressure criteria. This compares with the ratio of 2 using the previous Wiekema method. To derive an obstruction factor, , the expression for the Wiekema radius may be substituted in the Multi-energy equation for scaled distance.

( ) 3/1exp ls ECR = ( 1 )

31

=

aPE

Rr

( 2 )

3

=

rCP sa

( 3 )

Given a Wiekema explosion efficiency of 10% and atmospheric pressure of 101550 Pa efficiencies for R1 and R2 may be calculated as 12.5% and 10% respectively. In order to match the dimension of the heavy damage zone and be slightly conservative for the lighter damage zone the 12.5% efficiency is recommended. Where the two methods differ significantly is the treatment of the cloud shape and combination of the flash fire effect with the overpressure effects. The Wiekema method depends on ellipses to represent the cloud shape while the 3D method uses the LFL fraction envelope directly. So the risk calculations reflect the results of the dispersion calculations directly, rather than via the intermediate step of fitted


ellipses so the new method removes one of the approximations in the risk calculations. There are some further significant differences;

When applying the free-field logic (only normally used in SAFETI-NL) this means that the risk model knows how far the cloud travels along the centreline. In the 2D method it knows only how far the ellipses go downwind at the flammable effect height (1m in SAFETI-NL, 0m in Phast Risk). So the free-field decision algorithm can use the cloud centreline distance to determine whether the cloud crosses the plant boundary at any height. If the explosion fails to generate overpressures because the energy available is below the minimum parameter value then in the 2D method there are limited mechanisms to ensure that the flash fire zone still does generate risk. In reality if there is ignition then the flash fire hazard (possibly with pool fire too) will be present even if no overpressures are generated. However the 2D modeling has limitations as listed in the following table;

Type of risk result 2D 3D

Risk grid Explosion effect only; no effect if below minimum explosion energy

Risk ranking points Combination of explosion, flash fire and pool fire effects

Societal risk grid Maximum value of N corresponding to either the Flash and pool fire combined effects or the N corresponding to the explosion effects

Combination of explosion, flash fire and pool fire effects

Treatment of the Explosion Combined with the Flash Fire and Pool Fire Effects In the 3D method the flash fire hazard is always present so users can expect that the new method will give more consistent results between the different types of result. Also the results on the risk grid (ie contours) may show higher risk in the case of the new modelling. Again the new modelling removes some of the approximations in the risk calculations.

External CAD connection wizard In earlier versions of Phast Risk users who wished to import CAD files had to go through a lengthy process to create a CAD Server Schema file (CSD file). Phast Risk v6.7 has a new wizard that will create the CSD file in fewer steps. The CAD wizard can be accessed from the root node of the study file while on the map tab, then selecting the Input option and the CAD option will then be available, as shown in the following image


This will then bring up the wizard where you can select the type of CAD connection to be used and the file to be used.

Once the file is selected the wizard will create the CSD file and will include all layers available. As you can see below the location of the CSD file is displayed


Once the Finish button is pressed, the tree will show the new connection created.


Help menu additions The Help menu now includes links to the Release Notes as well as the Technical Documentation for Phast Risk as shown on the image below


Minor enhancements

Specification of breach location larger than the total pipe length will produce a fatal error, resulting in a red bordered Vessel/Pipe Source and no consequence results in v6.7 whereas the previous behavior was to automatically relocate the break location to the end of the pipe. This change applies to both long pipeline models: the vapor phase long pipeline scenarios and 2-phase long pipeline scenarios.

In calculation of ambient temperature, now dry air specific heat instead of wet air is used in the code in line with UDM theory (Appendix A.3 in UDM theory manual). Particularly in cases which experience large elevation changes this may have some effect. This has less effect if UDM version 2 (default) is in use for dispersion calculations

The default value for the parameter for maximum step size for instantaneous releases has been reduced from 1000s to 100s. This will affect results for instantaneous releases for step sizes larger than 100 seconds. This will also result in more smooth results in the far-field.

Modified pool fire maximum burn rate mixing rule - incorrect mixing rule is applied in case a mixture contains both components with defined maximum burn rate and undefined maximum burn rate. In Phast Risk v6.7 a mixtures maximum burn rate is now set to undefined when any of the components are undefined. An undefined mixing rate as input to the pool fire model POLF, means that POLF will calculate the burn rate itself.

Corrected density calculations for jet fires. The saturated vapour density at atmospheric pressure is required for two-phase jet fire calculation. For some materials, particularly mixtures, liquid density could previously be erroneously returned as vapour density by the property calculation if the saturation temperature at atmospheric pressure is very low and this would subsequently lead to under-predictions of jet fire radiation. This is prevented now by using ideal gas density if no valid vapour density is found by the property calculation for a 2-phase discharge. If this occurs, the JFSH warning 1050 is given. Thus if this warning is given in Phast Risk v6.7, increased risk may occur for the jet fire compared to v6.6.

Warehouse fires, with warehouse material including Br and F. The modelled combustion product released to the atmosphere consist of HCl, HBr and HF. Prior to v6.7, HBr and HF were classed together with HCl to conserve mass in line with previous CPR-15 regulations. To obtain more accurate toxicity calculations it is however more appropriate to conserve number of moles instead of mass. Thus in Phast Risk v6.7, HBr and HF are classed together with HCl such as to conserve moles in line in more recent PGS-15 regulations. In case Br and/or F are present in the stored warehouse material, this will affect the mass fraction of HCl per unit mass of active warehouse material, the mass fraction of HCl in the modelled released combustion product (HCl, NO2, SO2 mixture), and the mass release rate of HCl/NO2/SO2 mixture.


Workarounds and Bug Fixes Known Issues, Alerts and Workarounds for v6.7 Please find below a list of known issues, alerts and workarounds for v6.7. These comprise items that are behaving as designed though it is not necessarily intuitive as well as issues related to external components and we have been able to obtain a solution for.

Feature Description Alert/Workaround

SI10489: In some instances it is possible to have errors (as shown below) in risk calculations and still have risk results: 13:24:05 Generating population data using Population analysis 13:24:30 ***Error: MPACT 59: Number of toxic clouds 0 out of range 13:24:30 ***Error: MPACT 59: Number of toxic clouds 0 out of range 13:24:30 ***Error: MPACT 59: Number of toxic clouds 0 out of range 13:24:30 Population Risk calculations for Run Row 1 completed

The latest UDM can lead to a higher fraction of liquid rainout than in previous versions. This can mean that there is no toxic cloud at all. The result is the Mpact 59 message. If this is a pure toxic case then deselect it since there is no risk. If it is a both case then change it to a flammable only case.

SI10384: When a file created in versions previous to v6.7 is opened and the map is viewed there may be a GIS error on the message log and the map may be invisible

This can be remedied by saving the PSU file in v6.7, closing the file and then reopening the file.

SI10311: When exporting a report, the save as dialog does not show a field to enter a name in Vista

The workaround is to click the save button and then rename the saved file to the desired name

SI10150: When using external connections, the data complete check does not spot if an External Connection has moved from its original location. This means that you can have an External Connection with Feature Classes showing as complete in the node tree, but not displaying in the GIS views. On opening a map or risk contour plot you get the following message in the log window: "GIS Error: Unable to connect to the database. Please verify that your warehouse-connection parameters are correct and try again."

If you get this message in the log window, please check the locations for the external connections and modify accordingly

When inserting a building type, the geometry is mandatory but there is no warning if you do not enter the data and the program does not run the risk calculations. An error similar to the one below will appear: *** Error: Cannot execute run row 'Flammables Night ME' because Building Type 'Building Set\Building Type' has incomplete data

The workaround is to fill in the building type geometry. Values of 10, 10, 10 may be suitable if there are no known values.



SI10525: It has been discovered at a late stage of the Phast 6.7 development project that a bug is present in the area of producing graphs of radiation lethality from a jet fire resulting from a vessel/pipe and user defined source release when using Case Lists.

The problem arises if the Vessel/Pipe or User Defined Source has a case list in use and you choose to calculate lethality results.

Unfortunately, for the above situation lethality ellipses are not plotted when graphs are generated.

This problem does not occur for Vessel/Pipe and User defined sources which do not use case lists.

There are two possible workarounds for this issue:

The first workaround is to convert sources that use caselists into a set of independent sources. This can be done by right clicking a case list and choosing "Convert all caselists to models". From the resulting models, it is possible to produce lethality graphs.

If you also switch on the calculation of Dose and Probit, this overcomes the issue and lethality plots can be viewed from caselist results.

SI10536: Import of certain AutoCAD files results in undesirable display of vectors zig zagging the object. An example of such a drawing is:

The example.dwg import was created using the new CAD import wizard (see page 37). This method imports all layers. To workaround the problem, use the manual CAD import method and exclude the problematic layer when defining feature classes. Alternatively, remove the layer in AutoCAD.



An issue has been discovered relating to the use of WMS GIS data sources in the map in Phast and Phast Risk. Import of some map imagery can result in illegible images. For example, a map which should appear in this way:

Can only be displayed in the following unusable style:

There is no workaround to this issue at this time but will be addressed in an update of the 3rd part GIS mapping software Geomedia by Integraph in a future release of Phast and Phast Risk.



SI10538: Initial societal frequency value very large leading to incorrect societal risk results. If a study is set up to use the following conditions, a problematic graph will be displayed:

- 3D Obstructed Region method or 3D ME/Purple Book method in use

- Free field method in use - No ignition sources and population Omega

Factor value =0 - Residual Pool Fire event probability >0

Or

To workaround this problem, a dummy ignition source can be introduced within the plant boundary. The ignition probability of this source can be set to zero, therefore not impacting the risk results undesirably, whilst still fixing the problem.

Bug Fixes for v6.7 There are several bug fixes to the modelling and the user-interface for Phast Risk v6.7. For the most up-to-date list of known bugs and other issues, see the Technical Support area of the DNV Software website: http://www.dnvsoftware.com. In order to access the support information, you must enter a valid user name and password, which you can obtain from your local DNV Software office.

Discharge 10044 Premature termination for time-varying vapour line ruptures In earlier versions there were cases

of premature termination of time-varying line rupture cases. In v6.7 this has now been largely addressed for cases where the storage state is pure vapour. For cases that did not depressurize fully, the release duration, expelled mass and hence risk may increase in v6.7. However, results are not expected to change for cases which previously depressurized successfully.


J415 Discharge from vessels and short pipes (leak, line rupture, relief valve scenarios) DISC warning 1005 converted to DISC error 32. The error is now provided in case entropy is not conserved for property calculations associated with choked orifice flow. This appears to be mostly caused by picking up incorrect vapour density instead of liquid density and vice versa. This is now an error because previous results were shown to be physically incorrect by a large margin. To model cases which show this error it will be necessary to adjust inputs and/or use the user-defined source model.

Dispersion 2110 UDM instantaneous dispersion taking excessively large downwind steps Very large steps taken

by instantaneous dispersion model results in discontinuities in the toxic and concentration results. This has been resolved in reducing the default maximum step size for instantaneous dispersion calculations from 1000 seconds to 100 seconds.

10365 Droplet trajectories for pressurised instantaneous releases These were incorrectly calculated, resulting in rainout too far downwind. This would result in clouds leaving the pool behind too soon.

Risk 9964 Zero length route segments It was possible to enter a route geometry with successive identical

points. This resulted in a route model error and the associated model group being left out of the risk calculations. The error message could be missed in the log window by the user. So, the identical points are now eliminated and the model can process them.

10285 Delayed Ignition Probability for K2, K3 and K4 liquids should be zero. Previously, the delayed ignition probability for K2, K3 and K4 liquids was set to 1-Immediate ignition probability and not zero as prescribed by the Purple Book. Thus did lead to erroneous inclusion of delayed explosions and delayed flash fires and too high risk. This is fixed in v6.7, i.e. in v6.7 the delayed ignition probability is set equal to 0 for K2,K3,K4 liquids. This therefore results in a risk reduction.

10408 Toxic risk can be too high This could occur when subsequent toxic clouds have the property such that the clouds have a high width/length ratio (>1) and decreasing length between clouds. Resolution of this incident can only reduce risk results.

10239, 10283

Vertical refrigerated releases missing the jet fire effects This could result in not including the jet fire for the risk calculations. In v6.7 the jet fire will be vertical and will be included in the risk calculations. Thus this change may increase the risk but normally the jet fire effects from such a release are not significant.

GUI 8812 Problems connecting to some GIS database formats

Previously there were problems connecting to GML, WCS and WMS sources.

9128 Warehouse can be deselected when changing stop criterion In v6.54 if you switch the dispersion stop criterion from 'mixed basis' to 'risk based' then it can change the model selection. This can result in changes in the risk results and may not be noticed by the user so they finish with incorrect results.

9343 Warehouse model - Coordinates do not change after "move" button Previously, if a user tries to move the warehouse model in the graph by using the "move" button, it visually changes location on the map, but when opening the model > geometry tab, the coordinates are still the same original values. Results are also given with the old location so the risk results may be wrong without the use noticing.


9838 Not possible to import multiple materials into a PSU Previously multiple weathers and models can be exported and re-imported into a different PSU, but this is not possible with materials (each has to be imported as a separate PSU file). Thus it is not possible to transfer multiple materials defined in a study (not in the matls.xpu file) to another study: they need to be transferred one at a time and this can be a slow process if there are many materials.

10030 Red-boxed risk inputs do not stop risk calculations Previously some risk inputs could be incomplete and the behaviour was to leave out the items with the incomplete data ignition sources for instance. The risk calculations proceeded but without the incomplete items. This behaviour is inconsistent for other types of input, so to be consistent it is not necessary to either remove the incomplete items or satisfy the input requirements.

10225 Flammable Mass in earlier fireball report is not the mass actually used in the model For v6.7, in the Fireball report there are now two fields: Potential Fireball Mass (total mass in vessel), and Actual Flammable Mass (mass used for fire-ball calculations, three times vapour fraction (if < 100%).

10227 Negative areas for dose, probit, lethality contours The area calculation could result in a ve or +ve value in the legend depending on the order of the points. Now only +ve values are calculated and reported.

10235 The Arcview DLL doesn't work in v6.54 (or v6.6) Corrected in v6.7

10290 The flammable lethality zone on the Map tab in graphs is incorrectly calculated. Changing the lethality on the jetfire reporting levels grid had no effect on the jetfire lethality Effect zone on the map.

10379 The Pool fire report included the radiative fraction for general fires even if not used Now the correct radiative fraction is reported (as output by the pool fire calculations) for all types of fires (general, luminous, smoky fires). This only affects the pool fire report and does not otherwise affect the results.

10440 Save as with results not working properly with psc format with memory saving on The supplementary results files we not being written the results folder as required by the minimise memory option.

10469 Warehouse fire scenario remains blue while copying to other study Because the parameters may vary between studies then the results must be regenerated in the new study and not copied from the existing run of the model.

10513 Save as overwrites existing file on Vista and Windows 7 with file extensions on It was easy to think you were saving to a new file and instead the existing file was being overwritten so your original data was lost. The problem only occurred on Windows Vista and version 7 when the user had activated the display of file extensions (non-default).


Making the Most of the Documentation The Documentation folder on the Phast Risk v6.7 CD contains a wide range of information on the program, and should enable you to find answers to most of the questions you may have about Phast Risk. Most of the information is supplied in the form of password-protected *.PDF files. You can obtain the password for these files by contacting DNV Software Technical Support at [email protected] The contents of the folder are described below, in the order in which they appear inside the folder.

Phast Risk v6.7 Compiled Help The Online Help for Phast Risk v6.7 is in the form of a *.chm filea compiled HTML Help file. The file will be installed with the rest of the Phast Risk files when you install the program, and you will normally access it using the Help menu, but you can also open and read the file directly. There is a separate version of the Help for each product. In order to read the files, you must have Microsoft Internet Explorer Version 5 or later installed on your PC, although it does not have to be your default browser. You must also have some additional files that are specific to Microsoft HTML Help; these are installed automatically during the Phast Risk setup process, so you should be able to read the files directly if you have already installed Phast Risk.

Phast Risk v6.7 Release Notes These Release Notes are supplied in *.PDF form, for future reference.

Technical Reference The Technical Reference subfolder contains *.PDF documents which give details of several aspects of the modelling. These details include verification and validation of the models.


For System Administrators: Technical Notes These notes give technical details to help you improve the performance of Phast Risk v6.7 on your system. They are aimed mainly at secondary support personnel (e.g. IT professionals), but may be useful for expert users.

System Requirements Operating system

Windows XP SP3, Windows Server 2003, Windows Server 2008, Microsoft Vista, Windows7

Internet Browser

IE 5.0x. This does not have to be set as your default browser, but you must have at least this version installed in order to run the program.

Display 800x600 resolution

Screen color depth

65536 (16-bit) and higher

CPU 32 or 64 bit multi-core CPU from Intel or ADM like Intel Core2 Duo Media DVD-ROM drive or internet connection

Pointing device MS Mouse or compatible

Disk Space The installation requires 285 MB of disk space Spreadsheet The program is capable of using Excel spreadsheets for input/output of

data

.

CPU Speed Recommended Memory (minimum)

Phast Risk 2.8+GHz 3GB (2GB) Phast Risk (large study) 3.2+GHz 6GB (4GB)

These values are based on the user experiencing acceptable performance. Depending on your needs you may consider to select a more powerful machine. The indicated required disk space is very dependent on the existing system. Our values are based on a clean operating system with no additional software.

Internet Protocol v6 (IPv6) Testing of v6.7 has shown that network licenses set up with client machines using IPv6 are not supported when remotely connecting to the network. A new version built with IPv6 libraries can be made available on request.

Temporary folders The program uses hard disk space to write temporary, or scratch files which are subsequently deleted once the run has completed or in some cases when the program has been closed down. By default the program uses the subfolder C:\DNVUser\Temp to write temporary files during the calculation of results, and also to write temporary files that are used during the reporting of results. For large Study Folders, these temporary files can require a lot of hard disk space. Phast Risk will crash if there is insufficient hard disk space for it to create the temporary files, so you should save your


Study Folder before running calculations or viewing results, and avoid running Phast Risk if the free space on your hard disk is low Phast Risk uses a third party product called Seagate Crystal Reports to produce text reports. Crystal Reports always uses the temporary folder set up by your operating system for its own scratch file space, and by default this is generally the C:\Temp folder.

Managing Study Folders Some general points:

You should always save your Study Folder before you run any calculations. This will ensure that you do not lose any changes that you have made to the input data in the unlikely event that a condition emerges in the calculations that means that the program must be terminated.

It is unwise to give the same name to more than one Model in a given Study Folder, Phast Risk will allow you to do this, but you will find it difficult to distinguish between the results for the Models in Reports and Graphs, and it is not good practice.

You should use only letters, numbers and underscores (_) in the names of Study Folder files, and should not use special characters such as commas or quotation marks.


Memory Management Phast Risk can use a lot of memory (RAM) when running very large studies/study folders, and also when viewing large combinations of text reports and graphs. You should follow these simple rules to avoid problems with memory:

Close all out-of-date Reports and Graphs if you are no longer using them. You can always reopen the Report or Graph for the Model if you need to view it again; if the name of the Model is displayed in blue in the Study Tree, then that Model has results that are available for viewing.

Use the option in the Results tab of the General Preferences to save results to files instead of storing them in memory. Reports and Graphs will take longer to generate if you choose this option, but it will reduce the memory requirements considerably.

For very large studies (for example those containing more than 100 models and 3 associated weathers) ensure before you run that you have sufficient hard disk space for temporary file storage and also for runtime memory requirements.

Runtime memory is memory which will be used by Phast Risk for storing results as it performs its calculations; it is a combination of fixed RAM plus virtual (hard disk substitute) memory. You can adjust the total available memory size using the System option in the Control Panel. Consult your IT professional before altering any of these settings. During calculations for a very large study, you may see an "out of memory" message (or similar) appear on the screen. If this occurs it is important you stop the calculations immediately and save your work. If you do not stop the calculations, Phast Risk may crash, and you will lose any changes you made to your Study Folder since the last time you saved your work. The process of generating Graphs can sometimes require a large amount of memory (especially graphics memory). Models which involve the rainout and evaporation of a flammable material can produce a particularly large number of data points that need to be plotted, with large demands on the Graphing function. If you use the data culling option (on the Graphs tab section of the Preferences dialog, which is under the Options menu), then the Graphing function will ignore unnecessary data points (i.e. data points which do not describe significant changes in the behavior), and will therefore save memory and time. See the online Help for more details of data culling. It has not been explicitly mentioned that the application is single-thread software and increasing cores or CPUs will not improve calculation. However, multi-cores would benefit the overall user experience as the OS, Outlook, SQL Server or other applications can use the other system capacities. In this case, the bottleneck may be the RAM or disk read/write speed (local or remote).

Phast Risk Release Notes

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Transcript of Phast Risk Release Notes