Event Notification Report for March 05, 2020

SECONDARY CONTAINMENT MOMENTARILY INOPERABLE

"On March 05, 2020, at 1235 EST, with the reactor at 100 percent core thermal power and steady state conditions, plant personnel notified the main control room that both doors in the secondary containment airlock on the reactor building fifth floor were opened simultaneously for a period of approximately three seconds (i.e., from 12:35:00 to 12:35:03 EST). The failure of this interlock, which is intended to prevent both doors from being opened simultaneously, resulted in the Technical Specification (TS) Surveillance Requirement (SR) 3 .6.4.1.3 not being met. The maximum secondary containment pressure observed during that time remained within TS limits. There were no radiological releases associated with this event.

"Declaring secondary containment inoperable as a result of not meeting TS SR 3.6.4.1.3 is reportable under 10 CFR 50.72(b)(3)(v)(C) as an event or condition that could have prevented the fulfillment of a safety function needed to control the release of radioactive material.

"The licensee has notified the NRC Resident Inspector."

PLANNED PLANT COMPUTER OUTAGE FOR SYSTEM UPGRADE

"On March 05, 2020, at 2100 EST, the site commenced a planned upgrade of the main plant computer system (MPCS). During this upgrade, the normal computer data will not be available to the emergency response facilities, but compensatory capabilities will be in place. The scheduled duration for the MPCS upgrade is 96 hours. Since the compensatory measures will be in place in excess of 72 hours, this condition is being reported pursuant to 10 CFR 50.72(b)(3)(xiii).

"The NRC Resident Inspector has been notified."

AGREEMENT STATE REPORT - STUCK OPEN SHUTTER ON DENSITY GAUGE

The following is a synopsis of information provided by the Nebraska, Department of Health & Human Services, via phone notification:

Licensee reported to the Nebraska Department of Health and Human Services on March, 24, 2020, that during their 6 month check of the shutter functionality on March 5, 2020, the shutter on a density gauge would not close all the way. The density gauge is an Ohmart/Vega Corporation model SH-F2 density gauge with a Cs-137 500 milliCurie source. The serial number for the gauge is 9103GK. The gauge is installed in a process system and provides no threat to personnel. The licensee has contacted the gauge manufacturer for repair.

Nebraska report number NE20004

60-DAY TELEPHONIC NOTIFICATION OF AN INVALID SPECIFIED SYSTEM ACTUATION

"This 60-day optional telephone notification is being made in lieu of an LER [licensee event report] submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B).

"At approximately 1025 Eastern Standard Time (EST) on March 5, 2020, with Unit 1 shutdown in Mode 5 for refueling, an invalid actuation of Group 6 Primary Containment Isolation Valves (PCIVs) (i.e., Containment Atmospheric Control/Monitoring and Post Accident Sampling isolation valves) occurred. The invalid actuation occurred when power was lost as a result of the Inboard Isolation Logic Fuse being removed per a planned clearance hang to support maintenance.

"The PCIVs functioned successfully and the actuation was complete. The actuation was not initiated in response to actual plant conditions, it was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation.

"This event did not result in any adverse impact to the health and safety of the public."

The licensee has notified the NRC Resident Inspector.