Event Notification Report for February 10, 2012

MAINTENANCE ACTIVITIES CAUSE AN INADVERTENT EMERGENCY DIESEL GENERATOR START

"On February 10, 2012, with Unit 1 in Mode 5, while performing scheduled maintenance, a technician inadvertently made contact with a component that caused an undervoltage condition on an essential bus, resulting in the automatic start and loading of the 1B Emergency Diesel Generator (EDG). Prior to the event the 1B EDG was inoperable and not required by Technical Specifications; however, the 1B EDG was available. All equipment responded as expected. Currently maintaining the plant in Mode 5. Decay heat removal is being supplied by the 1A Shutdown Cooling train and was never interrupted. There was no impact on the Shutdown Safety Assessment.

"Unit 2 was unaffected and remains in Mode 1 at 100% power.

"This event is reportable pursuant to 10CFR 50.72(b)(3)(iv(A)."

The licensee notified the NRC Resident Inspector.

UNANALYZED CONDITION - GUIDANCE NOT ADEQUATE TO MITIGATE A DESIGN BASIS FLOOD

"During a review of the station's procedures for responding to external flooding conditions, it was determined that the guidance is not adequate to mitigate a design basis flood event (1014 feet mean sea level [msl]).

"Compensatory actions have been identified and are being implemented. Additional corrective actions are being evaluated.

"The plant is currently in Mode 5, Cold Shutdown, with a river level of 986 feet 2 inches msl with no predictions for river level to pose a threat to safety related components."

NRC inspectors identified procedural inadequacies relating to the mitigation of flooding. The licensee is addressing the procedural inadequacies.

The NRC Resident Inspector has been notified.

AGREEMENT STATE REPORT - MEDICAL OVERDOSE

The following report was received via e-mail:

"During a routine inspection, an Agency [Massachusetts Radiation Control Program] inspector identified a past possible gamma stereotactic radiosurgery (GSR also known as gamma knife) medical event that occurred on February 10, 2012 and had not been reported by the licensee.

"The licensee's written directive was incomplete. Page three of the written directive that described plug placement in the helmet used for treatment was not printed. As a result of the missing information, sixteen gamma knife plugs were not placed in position as intended and instead collimators were placed, the same size collimators used for the remaining plug pattern. Consequently, the patient received an 8.8% overdose to the treatment site. Based on the initial exposure determination to the treatment site by the licensee, the licensee concluded this was not a reportable medical event.

"However, the dose to tissue other than the treatment site exceeded 0.5 Sv (50 rem) and 50% of the dose expected from the administration defined in the written directive. This is a reportable medical event in accordance with 105 CMR 120.594(A)(1)(c).

"The dose to tissue other than the treatment site, tissue located beneath the skin and each of the sixteen collimators was calculated to be 71 rem, and greater than 50% of the dose expected from the administration. The dose expected to the tissue, tissue beneath the skin other than the treatment site from the administration defined in the written directive was expected to be less than 710 mrem.

"The gamma knife, a Leksell Gamma System model 24001 Type C device contained 201 Elekta model 43685 sealed sources totaling approximately 2,519 total curies of cobalt-60 on the date of the event, February 10, 2012.

"The licensee reported that the authorized user determined that the plug omission error would have no significant detrimental effect on the outcome of the treatment or patient condition and that no further action was necessary in the care of the patient. The licensee reported that that the authorized user reported the event in detail to the patient and provided a written description to the referring physician.

"The Agency issued notice of violations to the licensee and the licensee described its corrective actions in its response to the notice of violations.

"Corrective action: The licensee reported that following the omission of the plugs, the Radiation Oncologist Authorized User would designate on page 1 of the written directive if plugs were used and that this would alert the treatment team to identify and implement the appropriate plug pattern; that the licensee replaced the model 24001 Type C gamma knife with a model Perfexion gamma knife that does not use plugs; and that written directive printouts now contain both the individual page number and the total number of pages in the written directive."

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.