Upon the death of any person after retirement and while receiving a retirement allowance from this system, or any superseded system, there shall be paid to his estate, or to such beneficiary as he shall nominate by written designation duly executed and filed with the board, the sum of seven hundred fifty dollars ($750). This

section applies to every member who dies after this

section becomes operative whether he has retired before or after the operative date or effective date of this section. The death benefit provided by this

section shall be paid in lieu of a payment under

Section or 31789.1 and may be paid in part, from contributions of the county or district in accordance with

Section 31789, and in part, from surplus earnings of the retirement system in accordance with

Section 31789.1. This

section shall not be operative in any county until such time as the board of supervisors shall, by resolution adopted by a majority vote, make the provisions of this

section applicable in such county and until such time as the board of retirement, by resolution adopted by a majority vote, determines that its portion of the benefits may be financed from surplus earnings of the retirement fund. Upon adoption by any county providing benefits pursuant to this section, of

Article 5.5 (commencing with

Section 31510) of this chapter, only that portion of those benefits which is paid from surplus earnings described in

Section 31592.2 shall be paid, instead, from the Supplemental Retiree Benefits Reserve established pursuant to

Section 31510.8.