Event Notification Report for October 06, 2010

UNAVAILABILITY OF TSC VENTILATION SYSTEM DUE TO SCHEDULED MAINTENANCE

"At 0700 on Wednesday, October 6, 2010, the Cook Nuclear Plant (CNP) Technical Support Center (TSC) air conditioning and charcoal filtration systems have been removed from service for scheduled maintenance.

"Under certain accident conditions the TSC may become unavailable due to the inability of the air conditioning and charcoal filtration systems to maintain a habitable atmosphere. Compensatory measures exist to relocate TSC personnel to the unaffected unit's control room if necessary.

"TSC ventilation system maintenance is scheduled to be completed by 1600 on Wednesday, October 6, 2010.

"The licensee has notified the NRC Resident Inspector."

"This notification is being made in accordance with 10 CFR 50.72 (b)(3)(xiii) due to the loss of an emergency response facility."

* * * UPDATE AT 1738 ON 10/6/2010 FROM BRADDOCK LEWIS TO BILL HUFFMAN * * *

TSC ventilation was returned to service at 1645 EDT. The licensee notified the NRC Resident Inspector.

Notified the R3DO (Passehl).

VALID ACTUATION OF AUXILIARY FEEDWATER SYSTEM IN RESPONSE TO VALID STEAM GENERATOR LOW-LOW LEVEL SIGNALS

"At 0008 on Wednesday, October 6, 2010, Cook Nuclear Plant (CNP) Unit 2 had a Valid Automatic Actuation of the Unit 2 Turbine Driven Auxiliary Feedwater Pump. Cook Nuclear Plant Unit 2 Reactor had been manually tripped at 0001 from 14% power per normal operating procedures in preparation for the Unit 2 refueling outage.

"Following the reactor trip, water level in steam generators 23 and 24 lowered to 21% causing an automatic start of the Unit 2 Turbine Driven Auxiliary Feedwater Pump. Manual operator actions were in progress to restore steam generator water levels at the time of the actuation. The Turbine Driven Auxiliary Feedwater Pump operated normally to provide auxiliary feedwater flow to all four Unit 2 steam generators, and steam generator levels were restored to normal post trip values. Prior to the trip of Unit 2 reactor, the Unit 2 East and West Motor Driven Auxiliary Feedwater Pumps were manually started per procedure, as part of the pre-planned reactor trip, to control steam generator water levels. The cause of the low steam generator levels is still under investigation."

The licensee has notified the NRC Resident Inspector.

24 HOUR NOTIFICATION UNDER BULLETIN 91-01 CONCERNING COOLDOWN VERIFICATION OF UF6 CYLINDERS

"At 1106 CDT, on 10/06/2010 the Plant Shift Superintendent was notified that the independent verification of cylinder cool down time had not been completed on the following Uranium Hexafluoride (UF6) Cylinders: PP5436, PP5453, PP5389, PP5435, PP5388, PP5424, PP5459, and PP5443 in accordance with NCSA GEN-003.

"NCSA GEN-003 requires that prior to movement of a cylinder from a liquid UF6 cylinder handling area it shall be determined, independently verified, and documented that the required cooling time has passed. The purpose of this requirement is to ensure the cylinder does not contain liquid UF6 before it is moved from a liquid handling area. Upon discovery of the violation, it was determined that the cylinders had, in fact, met the required cool down period prior to movement; however, the independent verification had not been completed.

"Since this independent verification was not completed, double contingency was not maintained. Therefore, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC BL 91-01 Supplement 1.

SAFETY SIGNIFICANCE OF EVENTS
"Although an NCSA control was violated, cylinder integrity was maintained.

POTENTIAL CRITICALITY PATHWAYS (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR)
"A solid UF6 cylinder would have to have been breached and sufficient moderator entered the cylinder in order to support a criticality.

ESTIMATED AMOUNT, ENRICHMENT, FORM OF MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS)
"The assay of any material involved is less than or equal to 5.5 wt. % U235. The cylinders involved were 10 ton cylinders.

NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES
"Double contingency is maintained by implementing two independent controls on one parameter (moderation).

"The first leg of double contingency relies on it being unlikely that industrial grade cranes, forklifts, and cylinder haulers would drop an ANSI N14.1 designed cylinder in such a way that it would be breached. This moderation control was maintained.

"The second leg of double contingency relies on independent verification that the required cool down time has passed, prior to moving a cylinder from a liquid cylinder handling area. This control helps ensure that the cylinder does not contain liquid UF6 prior to movement. The independent verification was not performed or documented. Therefore, this moderation control was violated. Upon discovery of the violation, it was determined that the cylinders had, in fact, met the required cool down period prior to movement.

"Double contingency relies on two independent controls on the same parameter. Since one of the two independent controls on moderation was violated, double contingency was not maintained; however, the moderation parameter was maintained.

CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED
"The cool down times for the identified cylinders have been independently verified thus bringing them back into compliance with double contingency."

The NRC Resident Inspector has been notified of this event.

DELIVERED DOSE POTENTIALLY DIFFERENT THAN THE PRESCRIBED DOSE

During a brachytherapy treatment, the patient breast received an incorrect entry of the catheter position from a treatment planning system. Because of this, the prescribed dose was 340 centi-Gray at 1 centimeter from the tumor cavity while the actual dose received was 680 centi-Gray at 1 centimeter from the tumor cavity.

The physician notified the patient of the potential dose difference. Based on physician review, it was determined that there was no affect on the patient.

The reason for the potential dose difference was due to a missed change of a program default in the software program of the radiation treatment planning system. A new check step has been added to the Community Hospital procedure in order to correct the issue.

* * * UPDATE AT 1550 EDT ON 10/26/10 FROM ANDREA BROWNE TO S. SANDIN * * *

The licensee is updating this report to confirm that upon further evaluation this is a medical event.

Notified R3DO (Skokowski) and FSME (Burgess).

A Medical Event may indicate potential problems in a medical facility's use of radioactive materials. It does not necessarily result in harm to the patient.

DELIVERED DOSE POTENTIALLY DIFFERENT THAN THE PRESCRIBED DOSE

During a brachytherapy, a patient was prescribed a dose of 125 Gray to the prostrate. The delivered dose resulted in about 11 percent of the prescribed dose. The physician notified the patient and his guardian and also determined there was no radiation impact on the patient.

A Medical Event may indicate potential problems in a medical facility's use of radioactive materials. It does not necessarily result in harm to the patient.

IMPROPERLY DISPOSED OF TRITIUM SIGNS

Notified by the licensee that two tritium exit signs were improperly disposed of as trash. The signs were manufactured on April/1999 and the tritium gas was in sealed tubes. The sign manufacturer was NRD-LLC\Penteco and the original source strength was 25 Ci for each sign.

THIS MATERIAL EVENT CONTAINS A "LESS THAN CAT 3" LEVEL OF RADIOACTIVE MATERIAL

Sources that are "Less than IAEA Category 3 sources," are either sources that are very unlikely to cause permanent injury to individuals or contain a very small amount of radioactive material that would not cause any permanent injury. Some of these sources, such as moisture density gauges or thickness gauges that are Category 4, the amount of unshielded radioactive material, if not safely managed or securely protected, could possibly - although it is unlikely - temporarily injure someone who handled it or were otherwise in contact with it, or who were close to it for a period of many weeks. For additional information go to http://www-pub.iaea.org/MTCD/publications/PDF/Pub1227_web.pdf

This source is not amongst those sources or devices identified by the IAEA Code of Conduct for the Safety & Security of Radioactive Sources to be of concern from a radiological standpoint. Therefore is it being categorized as a less than Category 3 source