In any proceeding upon an application for an operating license for a utilization facility required to be licensed under section
2133 or
2134
(b) of this title, in which a hearing is otherwise required pursuant to section
2239
(a) of this title, the applicant may petition the Commission for a temporary operating license for such facility authorizing fuel loading, testing, and operation at a specific power level to be determined by the Commission, pending final action by the Commission on the application. The initial petition for a temporary operating license for each such facility, and any temporary operating license issued for such facility based upon the initial petition, shall be limited to power levels not to exceed 5 percent of rated full thermal power. Following issuance by the Commission of the temporary operating license for each such facility, the licensee may file petitions with the Commission to amend the license to allow facility operation in staged increases at specific power levels, to be determined by the Commission, exceeding 5 percent of rated full thermal power. The initial petition for a temporary operating license for each such facility may be filed at any time after the filing of: