Semantic search

The following information was provided by the licensee via phone and email: On November 10, 2024, at 0337 CST, Grand Gulf Nuclear Station (GGNS) was operating in mode 1 at 100 percent power when a manual scram was initiated due to degrading main condenser vacuum. The cause of the degrading main condenser vacuum is not known at this time and is being investigated. All control rods fully inserted and there were no complications. Reactor pressure was initially maintained with main turbine bypass valves. Reactor water level was initially maintained with main feedwater and condensate. At 0457, operators transitioned pressure control to safety relief valves and began using reactor core isolation cooling (RCIC) to maintain reactor water level. This was performed using plant procedures due to degrading vacuum. GGNS is currently in mode 3. Reactor level is being maintained with RCIC and pressure is being maintained using the safety relief valves. The manual reactor protection system (RPS) actuation is being reported in accordance with 10 CFR 50.72(b)(2)(iv)(B) and the RCIC actuation is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A). The NRC Senior Resident Inspector was notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: At the time of the notification, main steam isolation valves had shut on low vacuum.

• * * UPDATE ON 11/10/24 AT 1236 CST FROM MELISSA LIMBECK TO KERBY SCALES * * *

The following update was provided by the licensee via phone and email: This update is being made to report the following occurrences which took place after the scram reported in event number 57418. On November 10, 2024, at 0545 CST, a group 1 containment isolation signal resulted in the closure of all MSIVs. The signal was due to continued degradation of condenser vacuum post-trip. At 0620, an automatic RPS actuation occurred when reactor water level lowered to level 3. This RPS actuation occurred with all control rods fully inserted. Reactor water level lowered following closure of an open safety relief valve and was recovered to within the established band. The events are being reported as specified system actuations in accordance with 10 CFR 50.72(b)(3)(iv)(A). The NRC Senior Resident Inspector has been informed of the update. Notified R4DO (Dixon)

The following information was provided by the licensee via phone and email: On 9/23/2024 at 0720 EDT, with Unit 2 in mode 1 at 100 percent power, the reactor automatically scrammed due to turbine stop valve closure on a turbine trip. The scram was not complex. Due to the reactor protection system (RPS) actuation while critical, this event is being reported as a four hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Following the scram, reactor water level dropped below level 2 (108.8 inches), starting high pressure core spray (HPCS) and reactor core isolation cooling (RCIC); both injected into the reactor. RCIC is being used with turbine bypass valves to remove decay heat. Due to the emergency core cooling systems HPCS and RCIC discharging into the reactor coolant system, this event is being reported a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(A), and an eight hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A). In addition, with reactor water level below level 2 (108.8 inches), primary containment isolation signals actuated resulting in group 2 recirculation sample system isolation, group 3 traveling in-core probe (TIP) isolation valve isolation, group 6 and 7 reactor water cleanup isolation, group 8 containment isolations, and group 9 containment purge isolations. This event is being reported as an eight hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A). Operations responded using procedure N2-EOP-RPV (1-3) and stabilized the plant in mode 3. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector was informed. There was no impact on Unit 1.

• * * UPDATE ON 9/23/2024 AT 1550 EDT FROM RYAN LOOMIS TO IAN HOWARD * * *

On 9/23/2024 at 1156 EDT Constellation communications provided a media statement to Oswego area news media contacts summarizing the events that had occurred at Nine Mile Point Unit 2 and FitzPatrick Unit 1. This is a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(xi). The NRC Senior Resident Inspector has been notified. Notified R1DO (Dimitriadis), NRR EO (Felts), and IR MOC (Grant).

The following information was provided by the licensee via email: On September 18, 2024, Columbia Generating Station determined that lubricating oil was likely released into the plant service water system due to a failed heat exchanger on the reactor feed turbine alpha. Isolation of the heat exchanger from the plant service water system is in progress. The plant service water system returns water to a water basin that contains, at a minimum, 300,000 gallons of water. The water basin is connected to the Columbia River via a blowdown line. The blowdown line was secured at 0739 PDT on 9/18/2024. A visual inspection of the basin did not identify any oil sheen or film, but a sample downstream of the affected heat exchanger revealed an oily sheen in the sample bottle. It does not appear the oil released poses a threat to human health or the environment. However, there could have been a discharge of an unknown quantity of oil into the Columbia River. This matter is immediately reportable under Revised Code of Washington 90.56.280 to the U.S. Coast Guard National Response Center, Washington State Department of Ecology, and to the Energy Facility Site Evaluation Council per National Pollutant Discharge Elimination System (NPDES) permit section S3.F.2.b.i. This condition is being reported pursuant to 10 CFR 50.72(b)(2)(xi) for notification of other government agencies concerning an event related to the health and safety of the public or protection of the environment. Notifications to off-site agencies were performed at 0850 PDT on 9/18/2024. The NRC Resident Inspector has been notified. United States Coast Guard National Response Center Incident Report #141183 Washington State Department of Ecology #733853

• * * RETRACTION ON 10/10/24 AT 1513 EDT FROM CHASE WILLIAMS TO KAREN COTTON * * *

The following information was provided by the licensee via email: On September 18, 2024, Columbia Generating Station notified the NRC (event notification 57329) under 10 CFR 50.72(b)(2)(xi) of an offsite notification for potential oil release to the plant service water system and potentially the Columbia River. Further troubleshooting efforts refuted the possibility of leakage from the heat exchanger to the plant service water system. Engineering determined the most likely path of oil leakage was through a seal in the reactor feed turbine 'A' pump. This leakage would exit with seal water leak-off into the marine oil separator into collection barrels which are collected and processed. Since troubleshooting efforts determined oil leakage was not from the heat exchanger to the plant service water system, the offsite notification retractions were completed as of October 10, 2024, and therefore event notification 57329 is being retracted. The NRC Resident Inspector was notified. Notified R4DO (Gaddy).

The following information was provided by the licensee via fax and phone: On September 16, 2024, at 1240 EDT, with Unit 1 in mode 1 at 100 percent power and Unit 2 in mode 1 at 100 percent power, an Unusual Event was declared due to roads in the area leading to the plant being flooded and having the potential to prohibit plant staff from accessing the site via personal vehicles (Emergency Action Level HU3.4). Current onsite plant staff is sufficient for plant operation. This event is being reported in accordance with 10 CFR 50.72(a)(1)(i) due to the declaration of an emergency classification as specified in the approved Emergency Plan. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The NRC decided to remain in the Normal mode of operation at 1320 EDT. Notified DHS SWO, FEMA Ops Center, CISA Central Watch Officer, FEMA NWC (email), DHS Nuclear SSA (email), CWMD Watch Desk (email).

• * * UPDATE ON 9/17/2024 AT 1411 EDT FROM DAVID MACDONALD TO ROBERT THOMPSON * * *

The following information was provided by the licensee via phone and email: At approximately 1400 EDT on September 17, 2024, the Unusual Event at Brunswick was terminated due to the flood waters receding and roads to the plant becoming passable. The NRC resident inspector has been notified. Notified R2DO (Suber), NRR EO (Felts), IR MOC (Crouch), DHS SWO, FEMA Ops Center, CISA Central Watch Officer, FEMA NWC (email), DHS Nuclear SSA (email), CWMD Watch Desk (email).