There is hereby created the Legislative Council Retirement Study Fund. The fund shall consist of money appropriated to it by the Legislature and transfers made pursuant to subdivision (2)(f) of section 84-1503. Money in the fund shall only be used for a comprehensive study of the retirement systems listed in subdivision (1)(a) of section 84-1503. Any money remaining in the fund eighteen months after the date of transfer shall be transferred by the State Treasurer back to the retirement systems for credit to the various retirement funds. Any money in the Legislative Council Retirement Study Fund available for investment shall be invested by the state investment officer pursuant to the Nebraska Capital Expansion Act and the Nebraska State Funds Investment Act.