What Are the NRC Fatigue Management and Work Hour Limits?

Nuclear power plant licensees must manage worker fatigue under subpart I of 10 CFR part 26, the same part that sets up the NRC fitness-for-duty program. The NRC amended subpart I in its part 53 advanced reactor rule (91 FR 15696, March 30, 2026, effective April 29, 2026), which added parallel provisions for part 53 licensees and left the work hour numbers for operating reactor licensees unchanged.

Who is covered. The policy and fatigue assessment rules in 10 CFR 26.203 and 26.211 apply to individuals described in 10 CFR 26.4(a) through (c). The work hour limits in 26.205 through 26.209 apply to individuals in 26.4(a). Those are workers who perform certain operations duties, health physics or chemistry duties, fire brigade duties important to safety, maintenance of systems and components significant to public health and safety, and security duties.

Written policy and procedures. Under 10 CFR 26.203, the licensee's written fitness-for-duty policy must include a fatigue management policy. Procedures must cover self-declaration of fatigue, the work hour controls, fatigue assessments, and disciplinary actions.

Work hour limits. Section 26.205(d) caps covered work hours at:

• 16 work hours in any 24-hour period.
• 26 work hours in any 48-hour period.
• 72 work hours in any 7-day period.

Required breaks. Covered workers need a 10-hour break between successive work periods, or an 8-hour break when a break of less than 10 hours is needed for a crew shift transition. They also need a 34-hour break in any 9-day period.

Minimum days off or weekly average. Licensees must also either provide minimum days off, averaged over a shift cycle of up to 6 weeks, or keep each individual's weekly average at no more than 54 hours over an averaging period of up to 6 weeks (10 CFR 26.205(d)(3) and (d)(7)). The minimum is 1 day off per week for 8-hour shifts and 2 days per week for 10-hour shifts. For 12-hour shifts, operations, health physics, chemistry and fire brigade workers need 2.5 days per week, maintenance workers need 2, and security workers need 3.

Outages and waivers. During the first 60 days of a unit outage, different minimums apply, such as 3 days off in each 15-day period for operations, health physics, chemistry and fire brigade workers, and 1 day off in any 7 days for maintenance workers. Waivers from the limits are allowed only under the conditions in 10 CFR 26.207.

Fatigue assessments. Under 10 CFR 26.211, licensees must conduct fatigue assessments for cause, after a self-declaration (unless the worker receives a 10-hour break), after certain events, and as followup. Only supervisors or fitness-for-duty staff trained under part 26 may conduct them and the person who observed impaired alertness may not conduct a for-cause assessment. Work hours within the limits do not by themselves show that fatigue is absent. After an assessment, the licensee sets any controls and conditions, including a break, needed before the worker resumes duties, and documents the results. The reasoning resembles a reasonable suspicion determination.