Event Notification Report for October 11, 2021

EN Revision Imported Date: 11/10/2021

EN Revision Text: AUTOMATIC REACTOR SCRAM AFTER MAIN TURBINE TRIP

"At 1321 EDT on October 11, 2021, Susquehanna Steam Electric Station Unit 2 reactor automatically scrammed due to a trip of the Main Turbine.

"Unit 2 reactor was being operated at approximately 95 percent RTP [rated thermal power] with no evolutions in progress. The Control Room received indication of a Main Turbine trip with both divisions of RPS [Reactor Protection System] actuated and all control rods inserted. Turbine bypass valves opened automatically to control reactor pressure and subsequently failed open causing the reactor to depressurize. When reactor pressure reached approximately 560 psig, the operations crew manually closed the Main Steam Isolation Valves (MISVs) to stop the depressurization. Reactor water level lowered to -31 inches causing Level 3 (+13 inches) isolations. No [automatic] ECCS [Emergency Core Cooling System] actuations occurred. HPCI [High Pressure Coolant Injection] and RCIC [Reactor Core Isolation Cooling] were manually initiated to control reactor water level. The Operations crew subsequently maintained reactor water level at the normal operating band using RCIC and reactor pressure was controlled with HPCI in pressure control mode and main steam line drains. The Reactor Recirculation Pumps tripped as designed on EOC-RPT [end of cycle recirculation pump trip].

"The reactor is currently stable in Mode 3. An investigation into the cause of the turbine trip is underway.

"The NRC Resident Inspector was notified. A voluntary notification to PEMA will be made.

"This event requires a 4 hour ENS notification in accordance with 10 CFR 50.72(b)(2)(iv)(A), 10 CFR 50.72(b)(2)(iv)(B) and an 8 hour ENS notification in accordance with 10 CFR 50.72(b)(3)(iv)(A)."

EN Revision Imported Date: 11/12/2021

EN Revision Text: ONE PRIMARY COOLANT LOW PRESSURE INSTRUMENT CHANNEL SCRAM SETPOINT FOUND BELOW TECHNICAL SPECIFICATION REQUIRED MINIMUM

"[This notification is required] per University Of Missouri Research Reactor (MURR) Technical Specification (TS) 6.6.c(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, had occurred. MURR was not in compliance with one (1) Limiting Conditions of Operations (LCO). TS 3.2.g. which states, 'The reactor safety system and the number (N) of associated instrument channels necessary to provide the following scrams shall be operable whenever the reactor is in operation..' TS 3.2.g.6 requires four (4) Primary Coolant Low Pressure reactor safety system instrument channels provide a reactor scram when the primary coolant pressure corresponding to the pressurizer during normal flow drops below 75 psia. Surveillance testing on 10/11/2021 revealed that one (1) of the four (4) channels was not operable.

"On 10/11/21 while the reactor was shutdown for maintenance and conducting surveillance testing on the reactor core outlet pressure channels, the surveillance testing revealed that the reactor core outlet pressure channel associated with pressure transmitter 944B did not provide a reactor scram at an appropriate TS low pressure setpoint. On 10/11/21, the Primary Coolant Low Pressure reactor safety instrument channel 944B scram setpoint was calculated to be 74.43 psia which is slightly below the required 75 psia minimum. Previously on 4/12/2021, the Primary Coolant Low Pressure reactor safety instrument channel 944B scram setpoint was calculated to be 76.94 psia which is within the TS-required setpoint range. So, sometime between 4/12/2021 and 10/11/2021, the reactor possibly operated while one (1) of the four (4) instrument channels deviated from TS 3.2.g.6.

"Troubleshooting revealed the component in instrument channel 944B that caused the setpoint deviation. That component was replaced with an exact spare, and the instrument channel was retested and documented to be back in compliance with TS 3.2.g.6. In accordance with TS 6.6.c(4), permission from the Reactor Facility Director was obtained prior to the reactor returning to operation later on 10/11/21. Currently, MURR is operating at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c(3)."

EN Revision Imported Date: 1/21/2022

EN Revision Text: AGREEMENT STATE REPORT - LOST TRITIUM EXIT SIGNS

The following information was provided by the Nebraska Department of Health and Human Services via email:

"During annual inventory inspection, two devices were found missing and new non-radioactive exit lights had been installed. Further investigation found that on October 11, 2021, Slater Electric of Grand Island, NE was hired to install the devices. Removal of the tritium [23 curies] devices was not part of the scope of work, but Slater took it upon themselves to remove the old devices and disposed of them in the garbage at their shop in Grand Island, NE which has since went to the landfill. To avoid future instances, Aurora Cooperative discussed with Slater Electric the importance of proper disposal of the signs containing radioactive material and steps to take if hired to do such work again. No further follow up is needed.

"Item Number: NE210004"

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