Type with nested table in oracle
I managed to create an array of size one instead of using a object type. Through thorough reading I found no mention of whether a nested table within a type was possible, although  varrays of nested tables are; Nested tables of varrays are also allowed.

CREATE TYPE correction_info_objtyp AS OBJECT
(
   correction_date   DATE,
   raised_by         VARCHAR(50), 
   problem           VARCHAR(255)
);

CREATE TYPE correction_info_ntabtyp AS TABLE OF correction_info_objtyp;

CREATE TYPE assignment_status_info_objtyp UNDER status_info_obj
(
   corrections     correction_info_ntabtyp
);

CREATE TYPE assignement_status_info_v AS VARRAY(1) OF assignment_status_info_objtyp

CREATE table assignement_tbl
(
    assignment_id       NUMBER(6),
    assignment_title    VARCHAR(40),
    elements            elements_v,
    assignment_status   assignement_status_info_v
)VARRAY assignment_status STORE AS LOB assignement_status_store; -- contains the nested table