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This project is funded by the European Union Projekat finansira Evropska Unija

This project is funded by the European Union Projekat finansira Evropska Unija. EFFECTS TO PEOPLE AND STRUCTURES, DOMINO EFFECTS ANALYSIS Antony Thanos Ph.D. Chem. Eng. antony.thanos@gmail.com. Project implemented by Human Dynamics Consortium Projekat realizuje Human Dynamics Konzorcijum.

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This project is funded by the European Union Projekat finansira Evropska Unija

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  1. This project is funded by the European Union Projekat finansira Evropska Unija EFFECTS TO PEOPLE AND STRUCTURES, DOMINO EFFECTS ANALYSISAntony ThanosPh.D. Chem. Eng.antony.thanos@gmail.com Project implemented by Human Dynamics Consortium Projekat realizuje Human Dynamics Konzorcijum

  2. Main top event categories Initial event Top event Consequences Fire Fire Fire Thermal Radiation Thermal Radiation Thermal Radiation Hazardous substance release Explosion Overpressure Toxic dispersion Toxic dispersion Toxic effects Toxic effects

  3. Probit functions • Relation of probability for a certain effect level to a cause level • Probit function defined per type of effect expected • For thermal radiation, example of effects : • death • 1st degree burns • For toxic substance, example of effects : • death • irreversible effects

  4. Probit functions (cont.) • Origin from toxicology. Extension to thermal radiation, overpressure effects • Basic assumption: cause and effects follow Gaussian distribution. • Why Gaussian distribution ? • Population members are not identical : • age • sex, • health status • etc.

  5. Probit functions (cont.)

  6. Probit functions (cont.) • Transformation to probit results in close to linear relationship of cause (dose) and probit parameter

  7. Probit functions (cont.) • Relation of ammonia dose vs probability of lethality and probit function for lethality

  8. Probit functions (cont.) • P = (Pr), • P : probability value • Pr : probit value •  : standard function of probability with probit value • function  calculated by numerical approximations using error function (erf), for probit value Pr such as : use this for Excel

  9. Probit functions (cont.) • error function (erf) definition: • erf calculated readily, even in spreadsheets (excel) • Polynomial approximations of error function also are available:

  10. Probit functions and cause levels • Generally : • Pr = A + B ln(D), • Pr : probit value • A, B : probit constants for a specific harm • D : cause value for specific harm • Cause value in many cases relates also with exposure time

  11. Toxic substance effects (cont.) • Toxic effects via inhalation • Dose concept : Dose = Cn t • C, concentration • t, exposure time • n, exponent depending on substance : • available on literature for several toxics, • usually in the range 1-2 • even higher values (NO2 : 3.7, SO2 : 2.4), • if not known, or no suitable data are available, n=2

  12. ToxicEffects (cont.) • Exposure time : • Usually 30-60 min (assumed time for escape time to shelter) • Probit constants available in literature for several toxics • Toxic endpoints definitions must include exposure time, e.g. LC50 (30 min)

  13. ToxicEffects (cont.) • Toxicity data vs species and exposure time : • Literature toxicity data must be adjusted to humans and for the required exposure time, e.g. literature data for LC1 (2 hours) on rats must be adjusted to LC50 (30 min) for humans • Adaptation for exposure time : via exponent n for same dose, example for exposure time ta, tb, e.g. :

  14. ToxicEffects (cont.) • Conversion of data between species (TNO Green Book) : • In general, safety factors taken for conversion of animal data to human : • 5 for locally acting substances (lung damage), different breathing rate and lung surface taken also into account • 10 for systemic damage (damage to other organs via blood circulation), different body weight taken also into account • In emergencies, additional safety factor (2) is encountered, due to increased breathing rate

  15. ToxicEffects (cont.) • Conversion of data between species (TNO Green Book) : (cont.) • Finally, extrapolation factors (fd) are calculated (0.2-0.5) • Toxicity parameter such as LC50, LC1 etc.

  16. ToxicEffects (cont.) • Conversion of data between species (TNO Green Book) : (cont.) • Example results for extrapolation factors (Green Book)

  17. ToxicEffects (cont.) • Endpoints used • LC50, concentration of toxic in air for lethal effect to 50% of exposed people (usually provided for 30 min) • LC1, concentration of toxic in air for lethal effect to 1% of exposed people (usually provided for 30 min) • LDx, dose for lethal effect to x% of exposed people, dose defined as toxic load per body mass (kg of toxic/kg of body weight) • LD cannot be directly be used in Seveso application, as consequence analysis results in estimation of toxic in air concentration. Conversions are required for exposure time, breathing rate, body mass

  18. ToxicEffects (cont.) • Endpoints used : (cont.) • IDLH (Immediately Dangerous to Life and Health), concentration threshold of airborne toxic likely to cause death or immediate or delayed permanent adverse health effects or prevent escape. • Maximum exposure time of healthy worker 30 min • Damage affecting escape action (irritation of eyes or lungs) are taken also into account. • Threshold for high reliable breathing apparatus requirement .

  19. ToxicEffects (cont.) • Endpoints used : (cont.) • IDLH source : NIOSH • IDLH available for limited number of substances • If not available and required, approximations are used : • IDLH= 0.1 LC50 (EPA)

  20. ToxicEffects (cont.) • Other endpoints used : (cont). • ERPG 1/2/3 (Emergency Response Planning Guidelines, USA). Exposure time up to 1 hour, general population. • AEGP 1/2/3 (Acute Exposure Guideline Levels, USA). General population, exposure times 10 min, 30 min, 1 hour, 4 hour, 8 hours) • ……. • Safety report must not be a collection of toxicity parameters

  21. ToxicEffects (cont.) • Endpoints used in legislation, risk acceptance criteria • Usually up to 3 different endpoints required • France : LC50/LC1/Irreversible effects • Greece : LC50/LC1/IDLH • Italy : LC50/IDLH • Portugal : AEGL 3/AEGL 2

  22. ToxicEffects (cont.) • Endpoints used in legislation, risk acceptance criteria • Common characteristics in most cases : • Inner endpoint : LC50 • Outer endpoint : irreversible effects • Tables with values of required toxicity endpoint provided in Guidance documents (NO REQUIREMENT FOR TOXICITY ENDPOINT CALCULATION FOR MOST COMMON TOXICS)

  23. ToxicEffects (cont.) • Mixed Toxics (e.g. pesticide warehouse) • Toxics in same category (e.g. organophosphates) • act via the same route in organism (e.g. respiratory system damage, depletion of oxygen) • concentrations in air can be aggregated and treated as one substance, via weighted average using toxicological endpoints (LC50, LC1, IDLH etc.) for each one: Aggregated (equivalent) concentration relates to category member with maximum endpoint

  24. ToxicEffects (cont.) • Mixed Toxics (e.g. pesticide warehouse) • Toxics in different category (e.g. organophoshates, carbamides, organochlorides) • act via the different route in organism • concentrations cannot be aggregated

  25. Thermal radiation effects • Impacts depend on both thermal radiation flux and exposure time, e.g. • Thermal radiation flux 37,5 kW/m2 : • damage to equipment after 20 minutes • 100% lethality in 1 minute • 1% lethality for 10 seconds

  26. Thermal radiation effects to people • Best practice the use of Thermal Dose : • TDU = Q4/3 t • Q (W/m2), emissive power (thermal radiation flux) from flame/fireball surface at point in interest • t (sec), exposure time

  27. Thermal radiation effects to people (cont.) Pr = A + B ln(D), D : Thermal Dose • Probit constants A, B available in literature for several levels of harm from thermal radiation • lethal effects probit function • where : Q (W/m2), t (sec) • Q calculated by consequence analysis

  28. Thermal radiation effects to people (cont.) • Exposure time : • Short time period phenomena, e.g. • BLEVE/fireball : duration of BLEVE (appr. up to 30 sec, even for very big tanks) • Longer period phenomena : assumed escape time (time to shelter), as for : • pool fires • jet flame

  29. Thermal radiation effects to people (cont.) • Exposure time : (cont.) • Estimation of exposure time required • HSE GRAG for LPGs, flammables: • Escape speed for average public 2.5 m/sec • Escape speed for elderly, children 1 m/sec • Distance to shelter in suburban areas 50 m • Distance to shelter in rural areas 78 m

  30. Thermal radiation effects to people (cont.) • Exposure time : (cont.) • In most cases, exposure time is defined in guidance documents (usually in the order of 0.5-1 min) • Netherlands : 20 sec • Greece : 40 sec • UK : 60 sec • Flash fire case : • death expected within flammable cloud section limits (UFL/LFL) due to ignition of clothes • no effects expected outside flammable cloud

  31. Thermal radiation effects to people (cont.) • Endpoints for thermal radiation to be reported in Safety Report defined usually for effects to humans (e.g. lethal effects, irreversible damage), inline with acceptance criteria • Be careful !!!!! • Thermal Dose in endpoints could require Q expressed in kW/m2 • Typical case when thermal dose is expressed with TDU units ((kW/m2)4/3 sec)

  32. Thermal radiation effects to people (cont.) • Endpoints in Greece : • 1500 TDU : 3rd degree burns (lethal effects) in 50% of exposed people • 450 TDU : 3rd degree burns in 1% of exposed people • 170 TDU : 1st degree burns in significant part of exposed people • Endpoints in France : • 1800 TDU : Significant lethal effects • 1000 TDU: Lethal effects threshold • 600 TDU : Irreversible effects threshold

  33. Thermal radiation effects to people(cont.) • Endpoints in UK : • 1800 TDU : Significant likehood of death (12.8 kW/m2 for 1 min) • 1000 TDU : Dangerous dose for average people (8.2 kW/m2 for 1 min) • 500 TDU : Dangerous dose for vulnerable people (4.9 kW/m2 for 1 min)

  34. Thermal radiation effects to structures • Damage type : • Level 1. Ignition of surfaces, breakage of structure elements • Level 2. Optical deterioration of material (discoloration, paint peeling off), structural element deformation • For Safety Reports, effects to structure elements are in primary interest, as no combustible (wood) buildings are expected

  35. Thermal radiation effects to structures (cont.) • Parameters affecting effects : • Thermal radiation flux on exposed surface • Material of construction and shape • Exposure time • Surface and bulk material temperature rises • Deterioration of material properties (e.g. yield strength) • Potential to exceed the capability of material to carry the structural loads present

  36. Thermal radiation effects to structures (cont.) • For buildings, severe damage referred in literature for 12.6 kW/m2 and 20 min. For which buildings ??? • TNO Green Book clarifies : • 25 kW/m2, wood ignition for prolonged exposure • 12.5 kW/m2, piloted ignition of wood, plastics melt • 4 kW/m2, glass breakage

  37. Thermal radiation effects to structures (cont.) • France : 16 kW/m2 generic for structures (excluding reinforced concrete) • UK, SRAG documents: • 25.6 kW/m2, spontaneous ignition threshold • 14.7 kW/m2, piloted ignition threshold • What about steel/equipment ??

  38. Thermal radiation effects to structures (cont.) • Generic threshold for equipment : 37.5 kW/m2 and 20 min exposure time • TNO Green Book for beam profiles : • Level 1 damage expected for 100 kW/m2 • Level 2 damage expected for 25 kW/m2 • Exposure time for critical temperature to be reached, depends strongly on beam (geometry and orientation to heat source) • Level 2 damage for exposure time in the range of 10-50 min, depending on beam type.

  39. Overpressure effects to structures (cont.) • Some examples for equipment damage (note that 100 kPa=1000 mbar) : • Destruction of sphere support structure : 100 kPa • Movement of cylindrical tank, failure of connecting piping : 50 –100 kPa • Damage in distillation column : 35 – 80 kPa • Rail tank turnover: 50 kPa • Piperack destruction : 40 – 55 kPa • Crack in empty oil tank : 20 –30 kPa • Destruction of tank roof : 7 kPa

  40. Overpressure effects to structures (cont.) • Some examples for buildings : • Total destruction : 70-83 kPa • Partial destruction : 35-50 kPa • Severe and repairable damage (partial collapse of walls and roofs): 15-20 kPa • Partial demolition, made inhabitable : 8 kPa • Limited damage (windows break, small cracks in walls) : 3-5kPa

  41. Overpressure effects to structures (cont.) • Apparently effect to buildings are strongly related with building elements construction characteristics, as for example: • shape • dimensions • material of construction (brick wall, reinforced concrete wall etc.), • type of window used (old type-single ones versus modern-double ones) • Effects are related also with probit functions for damage to both human and structures

  42. Pa t+ • Overpressure effects to structures (cont.) • Effects are related also with probit functions for damage to either human and structures • Some probit functions use in addition to overpressure, the impulse parameter (is)

  43. Overpressure endpoints in Safety Reports • Usually, impulse parameters is not taken into account for endpoints defined in legislation, guidance for Safety Reports (especially for non-probabilistic approach) • Common characteristic : endpoints defined for effects only to structures

  44. Overpressure endpoints in Safety Reports (cont.) • France : • 200 mbar : significant lethal effects • 140 mbar : lethal effects threshold • 50/20 mbar : irreversible effects (direct/indirect) • Greece : • 350 mbar, severe and not repairable damage to bearing structure and walls • 140 mbar, damage to bearing structure and walls • 50 mbar, simple cracks in walls, damage to doors, windows

  45. Overpressure endpoints in Safety Reports (cont.) • Italy : • 300 mbar, high lethal effects • 140 mbar, lethal effects threshold • 70 mbar, irreversible effects • 30 mbar, reversible effects • Portugal : • 140 mbar : lethal effects • 50 mbar : irreversible effects

  46. Overpressure endpoints in Safety Reports (cont.) • UK : • 500 mbar, house completely demolished • 200 mbar, severely damaged housed • 100 mbar, house inhabitable but repairable • 40 mbar, window breakage

  47. Overpressure effects. What about people ? • Effects to humans are present at similar or higher overpressures than for effects to structures. Examples : • 1000 mbar : Probability of death due to lung hemorrhage 0.5%. Fatality to people expected for extremely high overpressures • 350 mbar : Probability of 5% of ear drum rupture • More severe effects expected to people due to building collapse, window fragments injuries (indirect effects)

  48. Overpressure effects. What about people ? • No benefit for requesting definition of zones for direct effects of overpressure to human

  49. Domino effects • Evaluation of secondary accidents expected due to initial accident (internal primary accident, or known external accident)

  50. Domino effects (cont.) • Example case : PEMEX Mexico City 1984 • Initial LPG pipeline rupture lead to 19 successive BLEVEs

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