with t1 as (
select 1 as acode, '100,00' as avalue from dual union all 
select 2 as acode, '100.00' as avalue from dual union all 
select 3 as acode, '100.00%' as avalue from dual union all 
select 4 as acode, '100.00perc' as avalue from dual 
           )
select acode, 
nvl(abs(regexp_replace(replace(avalue,',','.'),'[^1,2,3,4,5,6,7,8,9,0,.,]')),0) as avalue 
from t1

SQL> with t1 as (
  2  select 1 as acode, '100,00' as avalue from dual union all 
  3  select 2 as acode, '100.00' as avalue from dual union all 
  4  select 3 as acode, '100.00%' as avalue from dual union all 
  5  select 4 as acode, '100.00perc' as avalue from dual 
  6             )
  7  select acode, 
  8         nvl(to_number(translate(avalue,
  9                                 ','||translate(avalue,'%.,0123456789','%'),
 10                                 '.')),0) avalue
 11  from t1
 12  /
     ACODE     AVALUE
---------- ----------
         1        100
         2        100
         3        100
         4        100