EXTERNAL PUBLICATIONS
HSE RR1165
Gas dispersion model DRIFT 3.6.14: evaluation and assessment
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SUMMARY
HSE uses gas dispersion modelling in its assessment of the hazards and risks posed by toxic and flammable substances stored at major hazards sites. To update its dispersion modelling capability, HSE commissioned ESR Technology to develop a new version of the gas dispersion model DRIFT. The new version, DRIFT 3, includes a significant number of modelling enhancements over the version previously used within HSE (DRIFT 2.31). These include the extension of the model to treat buoyant plumes and time varying releases. Before DRIFT 3 is adopted for use by HSE, it must undergo thorough evaluation and assessment for a range of release scenarios. The initial phases of the DRIFT 3 testing programme used DRIFT 3.6.4 and are described in reports RR1100 and RR1101. Further testing is described in four reports including this one: RR1165, RR1166, RR1167 and RR1168. The four reports cover the evaluation of the model and assessment for a range of scenarios using the enhanced version DRIFT 3.6.14.
Firstly, this report describes validation of DRIFT 3.6.14 against a Model Evaluation Protocol for dense gas dispersion models. It compares the DRIFT 3.6.14 outputs with those for the previous version, DRIFT 3.6.4 (see RR1100). This evaluation exercise finds DRIFT 3.6.14 to be fit for purpose. Secondly, the report describes an assessment of the performance of DRIFT 3.6.14 for modelling the dispersion of vapour from pools of toxic liquids. (See RR1101 for the assessment for the previous version DRIFT 3.6.4.) The enhancements to the model implemented between DRIFT 3.6.4 and DRIFT 3.6.14 have not significantly affected the dispersion predictions. As a result of this detailed evaluation and assessment, DRIFT 3.6.14 has been adopted by HSE to model the dispersion of vapour from pools of toxic liquids.
This Research Report and the work it describes were funded by the Health and Safety Executive. Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.
