In 1996, the IAEA published the Guidebook to Accompany IAEA Map: World distribution of Uranium Deposits (the ‘Guidebook’). This publication, which was the culmination of a process that began in 1990, introduced a descriptive deposit classification that expanded upon the classification used in the OECD/NEA-IAEA Red Book. Experts from six countries and from the IAEA collaborated on establishing the deposit classification. They also contributed information on a total of 582 deposits worldwide, and provided summary information on these deposits that became part of the Guidebook including their location, status (operating, dormant, depleted, etc.), resources (within a specific resource range — e.g. 1 500 to 5 000 t U), average grade (within a grade range — e.g. 0.03–0.10% U), geologic age, host rocks and tectonic setting.

Provision is also made in the database to record references relating to the deposits and to include maps and photos of deposits. To have been included in the database, a deposit must have minimum resources of >500 t U at an average of 0.03% U or greater (note: exceptions to these guidelines have been allowed in a small number of cases where small deposits occur near operating or proposed production centres). The deposit-specific information, a map showing deposit locations and a discussion of the new deposit classification were published in the 1996 Guidebook . The Guidebook and the database on which it is based have come to be known collectively as UDEPO. The database was created on a computer based system to allow publishing above mentioned product easily.

Major modification has been implemented on UDEPO database in 2004. The database has been moved to MS SQL relational database server to allow building client/server architecture applications so that multiple users are able to access to the database at the same time. Another advantage of having database on the server is ability to update continuously. This has also allowed publishing the database through the internet. A web application has been developed and made available to the public access in 2004. The UDEPO database and its web site have been continuously updated and improved since then.

In 2002, the IAEA began an effort to integrate all nuclear fuel cycle related databases and computer simulations to make them more readily accessible to the Member States. A consultants meeting was held in 2003 to establish guidelines for restructuring UDEPO to ensure that it would be compatible with the integrated database approach. Assembling UDEPO data into a new structure began in 2003. A website, which was developed to publish the database, became available to the public in February 2004. The site has been periodically revised based on feedback from users and recommendations from consultants. Presently deposits have resources more 300 tU are included in the database. Thus,  most of the deposits that resulted from past exploration are included in the UDEPO database.