Analysis Procedure - DOE-HDBK-1100-20040043

DOE-HDBK-1100-2004

The what-if analysis encourages a PrHA team to think of questions that begin with

"What-if." Through this questioning process, an experienced group of individuals

identify possible accident events, their consequences, and existing safety levels, then

suggest alternatives for risk reduction. The potential accidents identified are neither

ranked nor given quantitative implications.

The what-if analysis method may simply generate a list of questions and answers about

the process. However, it usually results in a tabular listing of hazardous situations, their

consequences, safety levels, and possible options for risk reduction.

4.2.2 Analysis Procedure

PREPARING FOR THE ANALYSIS.

The information needed for a what-if analysis includes

process descriptions, operating parameters, drawings, and operating procedures. All

information must be available to the PrHA team, if possible, in advance of the team

meetings.

For analysis of an existing plant, the PrHA team may want to interview personnel

responsible for operations, maintenance, utilities, or other services, if they are not on the

PrHA team. In addition, if the analysis is performed offsite, the PrHA team should walk

through the facility to better understand its layout, construction, and operation. Thus,

visits and interviews should be scheduled before the analysis begins. Finally, some

preliminary what-if questions should be prepared to "seed" the team meetings. If the

analysis is an update of a previous PrHA, then questions listed in previous reports can be

used. For a new process or a first-time application, preliminary questions should be

developed by team members before the meetings, although additional questions

formulated during the meetings are essential. The cause-and-effect thought process used

in other types of analyses described in this section, such as HAZOP studies and FMEAs,

can help formulate questions.

PERFORMING THE ANALYSIS.

The scope of the study should be agreed upon by the team

members. The analysis meetings should begin with a basic explanation of the process by

operations staff who have overall facility and process knowledge, plus expertise relevant

to the team's area of investigation. The presentation should also describe the facility's

safety precautions, safety equipment, and health control procedures.

The meetings then revolve around potential safety issues identified by the analysts. The

analysts are encouraged to voice any potential safety concern in terms of questions that

begin with "what-if." However, any process safety concern can be voiced, even if it is

not phrased as a question. For example:

"I wonder what would happen if the wrong material was delivered."

"What if Pump Y seals begin to leak?"

"What if valve X fails open?"