10 CFR §13.47

1. (a)A notice to the person alleged to be liable under this part with respect to a claim or statement shall be served in the manner specified in § 13.8 not later than the later of:
   1. (1)6 years after the date on which the violation is committed; or
   2. (2)3 years after the date on which facts material to the action are known or reasonably should have been known by the authority head, but in no event more than 10 years after the date on which the violation is committed.
2. (b)A civil action to recover a penalty or assessment under this part shall be commenced within 3 years after the date on which the determination of liability for such penalty or assessment becomes final.
3. (c)The statute of limitations may be extended by agreement of the parties.