10 C.F.R. § 712.37

If DOE determines that an HRP candidate or HRP-certified individual has used any hallucinogen, the individual is not eligible for certification or recertification unless:

(a) Five years have passed since the last use of the hallucinogen;

(b) There is no evidence of any flashback within the last five years from the previous hallucinogen use; and

(c) The individual has a record of acceptable job performance and observed behavior.