Edwin Lyman
@nucsafetyucs.bsky.social
Director of Nuclear Power Safety, Union of Concerned Scientists, Washington, DC.
On Friday the South #Texas Project-2 #nuclear reactor automatically scrammed at full power after the main transformer locked out. Around the same time the reactor also lost two offsite power sources, causing two emergency diesel generators to start up. The reactor is still down.
November 24, 2025 at 2:12 PM
My goodness. On Friday an Unusual Event was declared for more than 3 hours at the Clinton-1 #nuclear reactor in #Illinois after the emergency reserve aux transformer shorted out, causing a loss of offsite power. A worker was electrocuted and killed. A warning sign of the impact of reduced oversight?
November 17, 2025 at 2:43 PM
My goodness. On Friday an Unusual Event was declared for more than 3 hours at the Clinton-1 #nuclear reactor in #Illinois after the emergency reserve aux transformer shorted out, causing a loss of offsite power. A worker was electrocuted and killed. A warning sign of the impact of reduced oversight?
Yesterday an Unusual Event was declared for nearly two hours at the Oconee-1 #nuclear reactor in #SouthCarolina when the reactor coolant system developed a leak of 26 gallons per minute during maintenance of a letdown filter.
September 11, 2025 at 12:51 PM
Yesterday an Unusual Event was declared for nearly two hours at the Oconee-1 #nuclear reactor in #SouthCarolina when the reactor coolant system developed a leak of 26 gallons per minute during maintenance of a letdown filter.
On Tuesday the Susequehanna-1 #nuclear reactor in #Pennsylvania was manually scrammed at full power after the main transformer experienced a cooling loss. The reactor is still down today. Should be a warning to Amazon about the reliability of this plant to power its data center.
July 24, 2025 at 12:59 PM
On Tuesday the Susequehanna-1 #nuclear reactor in #Pennsylvania was manually scrammed at full power after the main transformer experienced a cooling loss. The reactor is still down today. Should be a warning to Amazon about the reliability of this plant to power its data center.
Yesterday the Watts Bar-2 #nuclear reactor in #Tennessee automatically scrammed at full power after a loss of secondary power caused both feedwater pumps to shut down and the turbine to trip. The reactor, which is on my "Terrible Thirteen," list, is still down this morning.
July 14, 2025 at 12:42 PM
Yesterday the Watts Bar-2 #nuclear reactor in #Tennessee automatically scrammed at full power after a loss of secondary power caused both feedwater pumps to shut down and the turbine to trip. The reactor, which is on my "Terrible Thirteen," list, is still down this morning.
This one is too close for comfort: Yesterday the 1.1 MW Armed Forces Radiobiology Research Institute research reactor (only a few miles from #WashingtonDC) experienced a rapid power excursion and scram during startup. The steady-state power limit was briefly exceeded.
May 23, 2025 at 4:56 PM
This one is too close for comfort: Yesterday the 1.1 MW Armed Forces Radiobiology Research Institute research reactor (only a few miles from #WashingtonDC) experienced a rapid power excursion and scram during startup. The steady-state power limit was briefly exceeded.
A serious contamination incident occurred on 4/8 at the Curium facility in #Indiana after two liquid radioactive waste lines broke when workers were repairing a strontium-82 production hot cell. Dose rates > 1000 rem/hr were detected and one worker exceeded the annual dose limit.
April 17, 2025 at 12:24 PM
A serious contamination incident occurred on 4/8 at the Curium facility in #Indiana after two liquid radioactive waste lines broke when workers were repairing a strontium-82 production hot cell. Dose rates > 1000 rem/hr were detected and one worker exceeded the annual dose limit.
Yesterday an Unusual Event was declared at the Palo Verde-1 #nuclear reactor in #Arizona after a forced shutdown of the single emergency diesel generator providing AC power at the time. The reactor is in a refueling outage and the core is in the spent fuel pool. I couldn't find any news accounts.
April 11, 2025 at 5:04 PM
Yesterday the River Bend #nuclear plant in #Louisiana was manually scrammed at 81 percent power after all normal service water pumps suddenly stopped operating. The reactor is still shut down this morning.
April 9, 2025 at 12:46 PM
Yesterday the River Bend #nuclear plant in #Louisiana was manually scrammed at 81 percent power after all normal service water pumps suddenly stopped operating. The reactor is still shut down this morning.
More problems with the safety of the NuScale small modular #nuclear reactor design. 11 (!) NRC staff members dispute management's acceptance of NuScale's claim that the DC power system does not need to be safety-related even though it is critical for maintaining reactor pressure boundary integrity.
April 1, 2025 at 6:01 PM
More problems with the safety of the NuScale small modular #nuclear reactor design. 11 (!) NRC staff members dispute management's acceptance of NuScale's claim that the DC power system does not need to be safety-related even though it is critical for maintaining reactor pressure boundary integrity.
Within the last 3 weeks 2 iridium-192 Category II radiography cameras were stolen from trucks in the United States: a 74-curie source in #NorthCarolina and a 95.4-curie source in #Texas. Both thefts are rated 2 on the International Atomic Energy Agency event system. Coincidence or conspiracy?
March 17, 2025 at 12:50 PM
Within the last 3 weeks 2 iridium-192 Category II radiography cameras were stolen from trucks in the United States: a 74-curie source in #NorthCarolina and a 95.4-curie source in #Texas. Both thefts are rated 2 on the International Atomic Energy Agency event system. Coincidence or conspiracy?
Yesterday an Unusual Event was declared at Turkey Point-4 in #Florida after the #nuclear reactor, which is down for refueling, lost offsite power to the one available electrical bus. An emergency diesel generator started up and the event was terminated after nearly 2 hours.
March 14, 2025 at 12:55 PM
Hot off the press: the Nuclear Regulatory Commission just issued a notice of violation to Holtec at the decommissioning Pilgrim #nuclear plant in #Massachusetts for a security problem at its spent nuclear fuel storage facility. Is this really a company that should be building new reactors?
February 28, 2025 at 4:06 PM
Hot off the press: the Nuclear Regulatory Commission just issued a notice of violation to Holtec at the decommissioning Pilgrim #nuclear plant in #Massachusetts for a security problem at its spent nuclear fuel storage facility. Is this really a company that should be building new reactors?
Eighteen force-on-force security inspections were conducted by the NRC in 2024. Additionally, two sites -- Watts Bar in #Tennessee and Vogtle in #Georgia -- were re-inspected following "ineffective" exercise outcomes in 2022. That means the bad guys won. www.nrc.gov/docs/ML2503/...
February 19, 2025 at 4:56 PM
Eighteen force-on-force security inspections were conducted by the NRC in 2024. Additionally, two sites -- Watts Bar in #Tennessee and Vogtle in #Georgia -- were re-inspected following "ineffective" exercise outcomes in 2022. That means the bad guys won. www.nrc.gov/docs/ML2503/...
Another day, another problem at Entergy Nuclear's Troubled Grand Gulf (TGG) #nuclear plant in #Mississippi. On Saturday the reactor was manually scrammed at 84 percent power after a loss of power to the steam seal controller.
February 18, 2025 at 1:44 PM
Another day, another problem at Entergy Nuclear's Troubled Grand Gulf (TGG) #nuclear plant in #Mississippi. On Saturday the reactor was manually scrammed at 84 percent power after a loss of power to the steam seal controller.
The #nuclear microreactor company Last Energy is hedging its bets. Last month it sued the Nuclear Regulatory Commission in federal court requesting an exemption from its utilization-facility licensing requirements. But it has also begun preapplication activities WITH NRC. www.nrc.gov/docs/ML2503/...
February 11, 2025 at 9:21 PM
The #nuclear microreactor company Last Energy is hedging its bets. Last month it sued the Nuclear Regulatory Commission in federal court requesting an exemption from its utilization-facility licensing requirements. But it has also begun preapplication activities WITH NRC. www.nrc.gov/docs/ML2503/...
On Saturday an Unusual Event was declared at the Browns Ferry-3 #nuclear plant in #Alabama after smoke was observed in multiple areas following a main generator fault and automatic scram. Both emergency diesel generators started up after power was lost to two shutdown boards.
February 10, 2025 at 1:51 PM
The Nuclear Regulatory Commission has granted a request by the Davis-Besse #nuclear plant in #Ohio to postpone its next force-on-force security inspection because of a "security project upgrade." I wonder if real terrorists would have been so accommodating. www.nrc.gov/docs/ML2435/...
February 1, 2025 at 4:07 PM
The Nuclear Regulatory Commission has granted a request by the Davis-Besse #nuclear plant in #Ohio to postpone its next force-on-force security inspection because of a "security project upgrade." I wonder if real terrorists would have been so accommodating. www.nrc.gov/docs/ML2435/...