Extended Abstract
Introduction
Passive defense refers to a set of non-armed actions and activities which reduces the vulnerability of buildings, manpower, facilities, equipment, funds and vital arteries of the country against destructive and hostile operations of the enemy as well as natural disasters such as earthquakes and floods. The Including passive defense policies in most countries of world and especially Iran is Building public shelters to protect and maintain of Citizens' lives, also minimizing possible damages in the human domain. But what is important in Proportion with the proposed policy, location and choice of place is suitable for the construction of urban shelters. That People can take refuge to these shelters during enemy attacks or during natural crises. For this end, the aim of doing this study is locating potential areas of urban shelters based on passive defense principles in Ilam city.             
Materials & Methods
Present research In terms of the purpose, is of the type applied research and in terms of the nature and method of investigation, is of the type descriptive-analytical. Also, in terms of the data collection method, is included in the category of documentary and field research. The statistical population studied is including experts, professors and experts working in academic centers and higher education institutions. Sample size for research based on pairwise comparisons it's limited According to Saati (2002) and are selected Minimum 5 and maximum 15 people for this type of studies. Therefore, in this research, 15 university professors and experts were selected by available sampling method. To weight to information layers used from Saati's 9-option spectrum (superiority of one criterion over another) in the form of a questionnaire and a plan of language expressions. In this Research selected 10 location index of urban shelters (Distance from densely populated places, Distance from the centers of population, Distance from the canal, river and surface water, slope of the land, Distance from vulnerable areas and worn tissue, Distance from main roads for access and movement, Distance from historical and cultural monuments, Distance from industrial centers and hazardous products, The distance from the target centers of enemy and Distance from centers with support functions in times of crisis) in the form of four general criteria (Demographic, functional, physical and natural-environmental). In the next step was determined Coefficients of importance of indicators and criteria using the network analysis process technique (ANP), Eventually has been identified the most preferred places In proportion to the purpose through overlapping layers of information and applying the obtained coefficients. Data analysis has been done in a descriptive-analytical way and Using Analytical Network Process (ANP) and also by using Excel, Super Decisions and GIS software.
Results & Discussion
The research results show that: Among the general criteria studied, two demographic and functional criteria in order with weights 0.427 and 0.305 and among the studied indicators, two indicators Proximity to densely populated places and Establishing at a suitable distance from the enemy's targets in order with weights 0.303 and 0.236 have been highest coefficients of importance. In the following Results of combined analysis GIS- ANP showed that: All four urban areas of Ilam (including Haniwan, Ostandari, Markazi, Banborz, Sabzi Abad, Nowruz Abad, Janbazan and Razmandegan districts) is prone to shelter construction, But is in priority Respectively Region 2 (Banborz and Sabzi Abad districts), Region 1 (Haniwan and Ostandari) and Region 3 (Nowruz Abad).
Conclusion
Examining the first question based on Current status of urban shelters in Ilam city show that, most urban shelters located in the average status from the aspect of spatial distribution. The result of second question based on identification most important indicators affecting on location of urban shelters show that, two demographic and natural-environmental criteria identified as the most important and least important effective criterion in Location of urban shelter respectively with weights of 0.427 and 0.056. Eventually the results of third question based on identification best places to build urban shelters in Ilam city show that, most suitable place to build urban shelter situated in Haniwan, Ostandari and central districts of region 1, Banborz and Sabzi Abad districts of region 2, Nowruz Abad district of region 3 and Janbazan and Razmandegan districts of region 4.