If the Nebraska Power Review Board determines that the statements in the petition filed pursuant to section 18-2427 are true and conform to public convenience and welfare and, so long as the plants, systems, and works, the operation of the same, the exercise of powers, and the assumption of duties and responsibilities of, or on the part of, such agency, do not nullify, conflict with, or materially affect those of a district or corporation organized under the provisions of Chapter 70, article 6 or 8 or the Electric Cooperative Corporation Act, the Nebraska Power Review Board or its successor shall, within thirty days after the receipt of such petition, execute a certificate in duplicate setting forth a true copy of the petition and declaring that the petition has been approved.