The members of the panel shall not receive compensation for the performance of services for the panel, but shall be allowed travel expenses, including per diem in lieu of subsistence, at rates authorized for employees of agencies under subchapter
I of chapter
57 of title
5, while away from their homes or regular places of business in the performance of services for the panel. Notwithstanding section
1342 of title
31, the Secretary may accept the voluntary and uncompensated services of members of the panel.