I got it. See an example below

> create table abc (a varchar2(20));

Table created.

> insert into abc values ('Varchar2');

1 row created.

> /

1 row created.

> create table bcd (a nvarchar2(20));

Table created.

> insert into bcd select translate(a using NCHAR_CS) from abc;

2 rows created.


Thanks
MS Reddy