(a) A member who has 5 years of credited service shall have a vested right to a service pension.
(b) If a member who has less than 5 years of credited service ceases to be an employee, the service credits to the date of termination shall be cancelled unless:
(1) The member again becomes an employee within 4 months after such cessation of employment; or
(2) The member subsequently acquires 5 years of credited service; or
(3) The member has joined a state pension plan which provides for a unified state service pension and subsequently acquires 5 years of credited service; and provided that, if the member has withdrawn that member's own contributions, the member repays them with interest at a rate determined by the Board.
(c) For purposes of this section, credited service shall include any period during which a member is receiving a disability pension as provided by this chapter.
(d) A former employee's vested right shall be forfeited upon application for a refund of accumulated contribution.