The following information was obtained from the licensee via facsimile:
In accordance with 10 CFR 50.72(b)(3)(v)(D) ['Any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident'], D.C. Cook Unit 2 is making an 8-hour non-emergency report.
At 00:20 [EDT] on 10-11-2004, it was discovered that neither train of the Containment Ventilation Isolation System would have automatically isolated containment purge on a high radiation signal within the containment. Also, a manual Phase A containment isolation actuation would not have isolated containment purge.
At all times, containment purge could have been isolated using individual control switches from the Unit 2 Control Room.
D.C. Cook Unit 2 Technical Specification 3.9.9 requires during core alterations or movement of irradiated fuel within the Containment that the Containment Purge and Exhaust Isolation System be operable. Technical Specification 3.9.4.c requires during core alterations or movement of irradiated fuel within the containment that each containment penetration providing direct access from the containment atmosphere to the outside atmosphere be closed by an isolation valve, blind flange, manual valve, or equivalent, OR be capable of being closed by an operable automatic Containment Purge and Exhaust isolation valve.
Technical Specification 3.0.4 requires when a Limited Condition of Operation is not met, entry into an operational mode or other specified condition in the applicability shall be made only in specified conditions. Core alterations and movement of irradiated fuel assemblies began at 14:41 on 10-09-2004, approximately 71 minutes after the Containment Ventilation Isolation System had been made inoperable.
At approximately 13:30 on 10-09-2004, breaker 2-CRID-1-7 (Reactor Protection and Safeguards Actuation Cabinet RPS-A Input Channel I & All RPS A Output) and 2-GRID-4-8 (Reactor Protection & Safeguards Actuation Cabinet RPS-B Input Channel IV & ALL RPS B) were opened and tagged as part of a clearance. This prevented the automatic actuation of both trains of the Containment Ventilation Isolation System and prevented a manual phase A containment isolation from isolating containment purge. Thereafter, at 14:41 on 10-09-04, fuel movement commenced from the reactor vessel to the Spent Fuel Pit.
At 23:25 on 10-10-2004, breakers 2-CRID-1-7 and 2-CRID-4-8 were re-closed.
At 0020 on 10-11-2004, it was discovered that during the time from approximately 13:30 on 10-09-2004 to 23:25 on 10-10-2004, the Containment Ventilation isolation system had been inoperable.
D.C. Cook Unit 2 is currently stable in Mode 6 during the Unit 2 Cycle 15 refueling outage with core offload to the Spent Fuel Pit in progress.
The licensee has notified the NRC Resident Inspector.
