U shouldn't any prombem with UNICODE, because:
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FROM ORACLE DOC:

The Export utility always exports user data, including Unicode data, in the character sets of the Export server. The character sets are specified at database creation.

The Import utility automatically converts the data to the character sets of the Import server.

Some 8-bit characters can be lost (that is, converted to 7-bit equivalents) when you import an 8-bit character set export file. This occurs if the client system has a native 7-bit character set or if the NLS_LANG operating system environment variable is set to a 7-bit character set. Most often, you notice that accented characters lose their accent mark.

Both Export and Import provide descriptions of any required character set conversion before exporting or importing the data.