10 U.S.C. § 8587

(a) At the time of his retirement, a civilian member retiring under this chapter may elect to receive instead of the amount payable annually by the Secretary of the Navy under section 8585 or 8586 of this title a reduced annuity for his life and an annuity payable after his death to his beneficiary in either— (1) an amount equal to his reduced annuity; or (2) an amount equal to 50 percent of his reduced annuity. The annuities payable to principal and beneficiary, under either election, shall be in amounts that have, on the date of the retirement of the civilian member, a combined actuarial value equal to the actuarial value of the annuity payable by the Secretary under section 8585 or 8586 of this title, as determined under actuarial tables prepared by the Director of the Office of Personnel Management. (b) If the civilian member elects to take a reduced annuity under this section, he shall, at the time of his retirement, designate the beneficiary in writing and file the designation with the Secretary. (c) The annuity payable under this section to the beneficiary of a deceased civilian member shall be terminated upon the death of the beneficiary.