Except as specifically provided by this section, the Secretary of Energy shall fully cooperate with the Board and provide the Board with prompt and unfettered access to such facilities, personnel, and information as the Board considers necessary to carry out its responsibilities under this subchapter. Each contractor operating a Department of Energy defense nuclear facility under a contract awarded by the Secretary shall, to the extent provided in such contract or otherwise with the contractor’s consent, fully cooperate with the Board and provide the Board with prompt and unfettered access to such facilities, personnel, and information of the contractor as the Board considers necessary to carry out its responsibilities under this subchapter. The access provided to defense nuclear facilities, personnel, and information under this subsection shall be provided without regard to the hazard or risk category assigned to a facility by the Secretary.