05000346/LER-2002-003
| Docket Number | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3462002003R00 - NRC Website | |
FACILITY NAME (1) PAGE (3) LER NUMBER (6) DOCKET NUMBER (2)
DESCRIPTION OF OCCURRENCE:
On February 16, 2002, the Davis-Besse Nuclear Power Station (DBNPS) commenced the Thirteenth Refueling Outage. The plant entered Mode 6 on February 22, 2002, to perform refueling activities.
DBNPS Technical Specification (TS) 3.9.4, "Containment Penetrations" allows both doors of the containment personnel air lock to be open during core alterations provided that at least one personnel air lock door is capable of being closed and a designated individual is available immediately outside the personnel air lock to close the door. TS 3.9.4 also allows the containment equipment hatch to be open provided the requirements of TS 3.9.12 are satisfied. TS 3.9.12, "Storage Pool Ventilation" requires two independent Emergency Ventilation Systems (EVS) servicing the spent fuel pool area to be operable whenever irradiated fuel is in the spent fuel pool, or during core alterations or movement of irradiated fuel within the containment with the containment equipment hatch open. TS 3.9.12 permits the EVS to be considered operable with the equipment hatch and both doors of the personnel air lock open, provided that at least one personnel air lock door is capable of being closed and a designated individual is available immediately outside the personnel air lock to close the door. The EVS consists of two redundant, independent fan/filter trains, which can service the spent fuel pool area with the capability to maintain the spent fuel pool area at a negative pressure of greater than or equal to 1/8 inch water gauge relative to the outside atmosphere.
On March 11, 2002, at 0942 hours0.0109 days <br />0.262 hours <br />0.00156 weeks <br />3.58431e-4 months <br />, with the equipment hatch and both doors of the personnel air lock open, core alterations within containment were suspended. At 1603 hours0.0186 days <br />0.445 hours <br />0.00265 weeks <br />6.099415e-4 months <br />, the designated individual was released from their duties at the personnel air lock door so they could attend to other activities. At approximately 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br />, with the unit in Mode 6 at zero percent power, activities to repair a discharged fuel assembly in the spent fuel pool commenced. At approximately 2137 hours0.0247 days <br />0.594 hours <br />0.00353 weeks <br />8.131285e-4 months <br />, the fuel repair activities were suspended when it was discovered that the fuel rod being removed from the fuel assembly was broken. When the broken fuel rod was reported to the licensed operators on shift, it was realized that a designated individual was not available immediately outside the containment personnel air lock to close the airlock door as required by TS 3.9.12. Upon discovery, a designated individual was immediately dispatched to re-establish compliance with TS 3.9.12.
With the doors open and no designated individual immediately available outside the personnel air lock, the Limiting Conditions for Operation for TS 3.9.4 and TS 3.9.12 were no longer satisfied. The Action Requirement for TS 3.9.4 was met because core alterations in Containment had been suspended. However, the Action Requirement for TS 3.9.12 was not met because fuel movement occurred in the spent fuel pool during the fuel repair activities with no operable EVS servicing the spent fuel pool area. Therefore, this event represents a condition that was prohibited by the plant's Technical Specifications, which is being reported in accordance with 10CFR50.73(a)(2)(i)(B).
APPARENT CAUSE OF OCCURRENCE:
Operations personnel approved release of the designated individual on March 11, 2002, based on a review of TS 3.9.4, which provides requirements applicable to containment penetrations during core alterations or movement of fuel within containment. Core alterations within containment had been suspended, and review of the Technical Specifications prior to releasing the designated individual considered only the requirements of TS 3.9.4. The review did not consider the requirements of TS 3.9.12, which required the designated individual for EVS operability during operations involving movement of fuel in the spent fuel pool.
The Shift Engineer, who holds a Senior Reactor Operator's License, was interrupted multiple times during his review of Technical Specification requirements and did not focus on TS 3.9.4 intent and requirement.
Contributing to this event was that procedure DB-OP-06904, "Shutdown Operations," did not address the requirements of TS 3.9.4 or TS 3.9.12 for establishing/releasing the individual designated for airlock door closure when the containment equipment hatch and both personnel airlock doors are open.
ANALYSIS OF OCCURRENCE:
The EVS consists of two redundant, independent fan and filter trains of equipment. Each train contains prefilters, high efficiency particulate air (HEPA) filters, and charcoal adsorbers in series. The requirements for the EVS servicing the spent fuel pool area to be operable ensure that in the event of a fuel handling accident, radioactive material released from an irradiated fuel assembly will be filtered prior to discharge to the atmosphere. The operability of this system and the resulting iodine removal capacity are consistent with the assumptions of the safety analyses.
TS 3.9.12 permits an EVS train servicing the spent fuel pool area to be considered operable when the containment equipment hatch is open and both doors of the containment personnel air lock are open, provided at least one personnel air lock door is capable of being closed and a designated individual is available immediately outside the personnel air lock to close the door. When the containment equipment hatch is open and both doors of the containment personnel airlock are open, TS 3.9.12 Bases indicate that the EVS servicing the spent fuel pool area is incapable of maintaining a negative pressure of >/= 1/8 inches water gauge relative to the outside atmosphere during system operation, as required by Surveillance Requirement 4.9.12.1. The requirement that at least one personnel air lock door be capable of being closed and a designated individual be available immediately outside the personnel air lock to close the door ensures that the negative pressure boundary can be established in a timely manner following a fuel handling accident in the spent fuel pool area or containment. Once the negative pressure boundary is established, the EVS servicing the spent fuel pool area will be capable of establishing the required negative pressure relative to the outside atmosphere.
ANALYSIS OF OCCURRENCE: (Continued) In the event of a fuel handling accident, radiation detectors provide signals to isolate the normally operating fuel handling area ventilation system and automatically start the EVS fans. Radiation detectors also provide for shutdown of Containment Purge System fans. Results of Surveillance Requirement 4.9.12.1 completed on February 18, 2002 indicate that with one EVS fan in operation, there is sufficient margin to ensure that air would be exhausted from the fuel handling area at a rate greater than supplied with the airlock door open. This would maintain the area under a negative pressure and thus ensure that leakage is into the fuel handling area. In addition, procedure DB-OP-02530 "Fuel Handling Accident," provides specific instructions for response to a fuel handling accident in containment or the fuel handling area with the equipment hatch off. The procedure directs evacuation of personnel from containment prior to closure of the personnel airlock door, and specifically requires verification that at least one containment personnel airlock door is closed. The time required to evacuate containment would provide sufficient time to dispatch an individual to close the containment airlock door. Since both EVS trains were available and the EVS remained capable of exhausting air from the fuel handling area during the time required to dispatch an individual to close the airlock door, the lack of a designated individual at the airlock door did not result in a loss of safety function to control the release of radioactive material or mitigate the consequences of an accident. Therefore, this event had low safety significance.
CORRECTIVE ACTIONS:
Upon discovery that a designated individual was not available immediately outside the personnel air lock to close the door per the requirements of TS 3.9.12, a designated individual was immediately dispatched to re-establish compliance with the Technical Specification.
Actions were taken to address personnel performance issues, with emphasis on expectations and standards. Additionally, an Operations Department stand-down was immediately conducted following the event with Senior Reactor Operators to review the requirements and applicability of TS 3.9.4, TS 3.9.12 and DB-OP-06904, and to ensure understanding of the associated requirements for an individual designated for airlock closure.
Procedure DB-OP-06904 was changed on April 17, 2002 to clearly address the requirements of TS 3.9.4 and TS 3.9.12 for establishing/releasing the designated individual when the containment equipment hatch and both personnel airlock doors are open.
FAILURE DATA:
The TS provision for EVS servicing the spent fuel area to be considered operable when the containment equipment hatch is open and both doors of the containment personnel air lock are open was recently approved by amendment dated February 14, 2002. There have been no LERs in the previous two years involving inoperability of the spent fuel pool ventilation system during refueling.
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
NP-33-02-003-00 � CR 2002-01199