The Administrative Review Board's (Board) review shall be based upon the hearing record. The findings of fact in the decision under review shall be conclusive if supported by substantial evidence in the record as a whole. The Board's review of conclusions of law shall be de novo. Upon review of the decision, the Board may affirm, reverse, modify, or vacate the decision, and may remand the case to the Office of Administrative Law Judges for further proceedings. The Board's decision shall be served upon all parties and the Chief Administrative Law Judge in accordance with 29 CFR part 26.