Operational Accidents

DOE-STD-1027-92

undesired events. The following section discusses the range of events in

somewhat more detail.

Operational Accidents - Operational accidents are those that result from

processes and activities involved in operating the facility and generally

cover many diverse routine or non-routine events with potentially adverse

consequences to the workers or the public. Fires, explosions, spills,

process disturbances, and criticality events are included as operational

events. A reasonable set of operational events should be selected which

represents the accident release mechanisms identified. Explicit

consideration should be given to non-routine or unique events which

present significant risks to facility workers. These events should include

process explosions or criticalities which have the potential for serious

worker injury or death but would not necessarily cause significant releases

outside of the facility.

Design Basis Natural Phenomena Events - As currently defined by DOE,

design basis natural phenomena events include earthquakes, high winds,

tornados, floods, etc. for which the facility has been (or should have been)

designed. Explicit consideration should be given to such sequences and a

representative set of accidents described.

External Events - The effect of facility- or site-specific events such as

airplane crashes, transportation accidents, or collocated facility accidents on

the Category 2 facility should also be addressed.

Sequence Engineering Analysis

Engineering analysis concentrates on those structures, systems, and components

relevant to the accident scenarios developed. Although listed before actual

consequence determination, it will normally be conducted in an integrated fashion

with accident quantification. Engineering analysis is needed to determine the

amount of material which would be released in the scenario. For example, if an

accident scenario assumes that the High Efficiency Particulate Air (HEPA) filters

will work as designed, then an engineering analysis is needed to ensure that the

accident conditions experienced by the filters is within the filter design envelope.

However, for an event such as the explosion of an ion exchange column, where

there is sufficient energy to lift the charging lid on a dissolver, an elaborate

analysis of the structural strength of the vessel and its lid would be unwarranted if

the consequences are insignificant.

It should be noted that the detailed engineering analysis could be part of the

design documentation for the facility. Also, the engineering analysis will become a

significant part of the designation of safety class systems, structures, and

components and drive the Technical Safety Requirements for the facility.