The ORACLE_DATAPUMP access driver is used for handling external tables in Oracle. It facilitates the reading of data from external tables and the insertion of this data into internal tables within the database. Additionally, it allows querying data from external tables. However, it does not support the execution of DML statements on external tables nor does it allow the creation of directory objects for flat files. Therefore, the three actions that can be performed using the ORACLE_DATAPUMP access driver are creating directory objects for external tables, reading data from an external table to load it into a database table, and querying data from an external table.