10 CFR § 74.57 - Alarm resolution.
(b) Licensees shall resolve the nature and cause of any MC&A alarm within approved time periods.
(c) Each licensee shall notify the NRC Operations Center by telephone of any MC&A alarm that remains unresolved beyond the time period specified for its resolution in the licensee's fundamental nuclear material control plan. Notification must occur within 24 hours except when a holiday or weekend intervenes in which case the notification must occur on the next scheduled workday. The licensee may consider an alarm to be resolved if:
(1) Clerical or computational error is found that clearly was the cause for the alarm; or
(2) An assignable cause for the alarm is identified or it is substantiated that no material loss has occurred.
(d) If a material loss has occurred, the licensee shall determine the amount of SSNM lost and take corrective action to:
(1) Return out-of-place SSNM, if possible, to its appropriate place;
(2) Update and correct associated records; and
(3) Modify the MC&A system, if appropriate, to prevent similar future occurrences.
(e) The licensee shall provide an ability to rapidly assess the validity of alleged thefts.
(1) Material processing operations related to the alarm must be suspended until completion of planned alarm resolution activities, unless the suspension of operations will adversely affect the ability to resolve the alarm. Operation of continuous processes may continue for 24 hours from the time of the occurrence of the alarm during which time checks shall be made for mistakes in records or calculations that could have caused the alarm.