Block used by undo not unfreezed on database 11.2.0.4 RAC

Hello Friends,

I need your help :

When  I  am checking  my undo space (Tablespace UNDOTBS1)  , it is taking  already 100 % of usage  and there are many block not released  on the system.

SQL> SELECT DISTINCT STATUS, SUM(BYTES)/1024/1024, COUNT(*) FROM DBA_UNDO_EXTENTS where tablespace_name = 'UNDOTBS1' GROUP BY STATUS;

STATUS    SUM(BYTES)/1024/1024   COUNT(*)

--------- -------------------- ----------

UNEXPIRED            94988.875      11289

EXPIRED                1429.25        315

ACTIVE                     248         10

Help me to   release the space that the status was   expired without  switch to another TBS undo.

Regards,

Six