Sec. 21. (a) If benefits are not payable to the survivors of a participant who dies, and if a withdrawal application is filed with the board by the survivors or the participant's estate, the total of the participant's contributions, plus interest at a rate specified by rule by the board and minus any payments made to the participant, shall be paid to:
(1) the surviving spouse of the participant or the children of the participant, as designated by the participant;
(2) any dependents of the participant, if a spouse or designated child does not survive; or
(3) the participant's estate, if a spouse, designated child, or other dependent does not survive.
(b) The amount owed a spouse, designated children, other dependents, or estate under subsection (a) is payable not later than sixty (60) days after the date of receipt of the withdrawal application, or in monthly installments, as the recipient elects.