10 CFR §110.89

1. (a)Hearing requests, intervention petitions, answers, replies and accompanying documents must be filed with the Commission by delivery or by mail to the Secretary, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, Attention: Rulemakings and Adjudications Staff or via the E-Filing system, following the procedure set forth in 10 CFR 2.302. Filing by mail is complete upon deposit in the mail. Filing via the E-Filing system is completed by following the requirements described in 10 CFR 2.302(d).
2. (b)All filing and Commission notices and orders must be served upon the applicant; the General Counsel, U.S. Nuclear Regulatory Commission, Washington, DC 20555; the Executive Secretary, Department of State, Washington, DC 20520; and participants if any. Hearing requests, intervention petitions, and answers and replies must be served by the person filing those pleadings.
3. (c)Service is completed by:
   1. (1)Delivering the paper to the person; or leaving it in his office with someone in charge; or, if there is no one in charge, leaving it in a conspicuous place in the office; or, if he has no office or it is closed, leaving it at his usual place of residence with some occupant of suitable age and discretion;
   2. (2)Following the requirements for E-Filing in 10 CFR 2.305;
   3. (3)Depositing it in the United States mail, express mail, or expedited delivery service, properly stamped and addressed; or
   4. (4)Any other manner authorized by law, when service cannot be made as provided in paragraphs (c)(1) through (3) of this section.
4. (d)Proof of service, stating the name and address of the person served and the manner and date of service, shall be shown, and may be made by:
   1. (1)Written acknowledgment of the person served or an authorized representative;
   2. (2)The certificate or affidavit of the person making the service; or
   3. (3)Following the requirements for E-Filing in 10 CFR 2.305.
5. (e)The Commission may make special provisions for service when circumstances warrant.