Does this work?

Code:
SET serveroutput on size 1000000;

DECLARE
   CURSOR c1
   IS SELECT table_name
      FROM   cols
      WHERE  column_name = 'ID_CTLGRP' AND
             table_name LIKE 'TUA%';
BEGIN
   DBMS_OUTPUT.ENABLE(1000000);
--loop through tables with field CTLGRP
   FOR v_tabs IN c1
   LOOP
      DBMS_OUTPUT.put_line( 'Processing Table:' || v_tabs.table_name );

      EXECUTE IMMEDIATE 
         'Update ' || v_tabs.table_name ||
         ' SET ID_CTLGRP = REPLACE(ID_CTLGRP,chr(39),''_'')' ||
         ' WHERE ID_CTLGRP LIKE ''%''%''';
      COMMIT;
   END LOOP;

   DBMS_OUTPUT.PUT_LINE( 'Job Complete' );
END;
/