(1) Upon retirement, a member shall receive a nonduty disability retirement allowance equal to two percent of average final compensation for each service credit year of service: PROVIDED, That this allowance shall be reduced by two percent of itself for each year or fraction thereof that his or her age is less than fifty-five years: PROVIDED FURTHER, That in no case may the allowance provided by this section exceed sixty percent of average final compensation.
(2) If the recipient of a retirement allowance under this section dies before the total of the retirement allowance paid to the recipient equals the amount of the accumulated contributions at the date of retirement, then the balance shall be paid to the member's estate, or the person or persons, trust, or organization as the recipient has nominated by written designation duly executed and filed with the director or, if there is no designated person or persons still living at the time of the recipient's death, then to the surviving spouse or, if there is neither a designated person or persons still living at the time of his or her death nor a surviving spouse, then to his or her legal representative.