ABSTRACT
The following silnplified example, constructed by Hendershot, will facilitate the transition to the case studies. 1 Suppose that a risk assessment is being conducted at a Che111ical plant to detennine the consequences of two incidents (the initiating events of the event tree shown in Fig. 21.1.1) defined as
I. an explosion resulting from detonation of an unstable chemical II. a release of a f131111nable toxic gas
Incident I has one possible outc0111e, an explosion, the consequences of which are asswned to be wIaffected by ,veather conditions. Incident II has several possible outcolnes which, for purposes of shnplification, are reduced to
IIA. vapor cloud explosion, caused by ignition of the gas released, centered at the release point, 31Id unaffected by ,veather conditions
lIB. toxic cloud extending downwind and affected by weather conditions
Again for purposes of simplification, only two weather conditions are envisioned, a northeast and a southwest wind. Associated with these two wind directions are events Im1 and 1m2.
