Sections8-36-109(b)(1)(C) and8-36-123(a)(2) shall not apply in determining the retirement allowance payable under §8-36-109(b) or under §8-36-123(a) to a deceased participant's surviving spouse, if any. Instead, the retirement allowance payable under such sections shall be reduced by an actuarially determined factor as set by the board from time to time.