(a) This section provides for the payment of the balance in a retired member's account to paid in the manner described in this section in the event that all claims to benefits payable to, or on behalf of, a member expire before his or her member account has been fully exhausted. The expiration of the rights to benefits would be on the later of either the death of the retired member drawing benefits under a straight life annuity, or the death of a survivor annuitant drawing benefits under any optional form of benefit selected by the retired member.

(b) In the event that all claims to benefits payable to, or on behalf of, a retired member expire, and the accumulated contributions exceed the accumulated net benefit payments paid to or on behalf of the retired member, the balance in the retired member's account shall be paid to the person or persons as the retired member has nominated by written designation duly executed and filed with the board of trustees. If there is no designated person or persons surviving the retired member following the expiration of the claims, the excess of the accumulated contributions over the accumulated net benefit, if any, shall be paid to the retired member's estate: Provided, That the provisions of this section are retroactive to all members who entered retirement status on or after June 9, 2000.