During the first week of August 2025, the U.S. Nuclear Regulatory Commission (NRC) published Event Notification Reports documenting a wide range of nuclear-related incidents nationwide. The following events were published between August 1 and August 8, including equipment malfunctions, unplanned reactor trips, radioactive material mishandling, and security barrier issues.
August 1 Report
- Medical Underdose – Rush University Medical Center, Illinois
A patient prescribed 47.42 mCi of Y-90 Theraspheres received 36.81 mCi (22.4% below prescription) due to the use of a smaller catheter for targeted delivery. No adverse health effects are expected. The Illinois Emergency Management Agency is investigating, and both patient and physician were notified. - Potential Overexposure – Tanner Health System, Georgia
During a high dose rate Ir-192 brachytherapy procedure, a nurse was inadvertently in the treatment vault behind lead shielding. The facility is analyzing dosimetry results and conducting a pregnancy test as precautionary measures. - Damaged Portable Nuclear Gauge – Frederick, Maryland
A Troxler Model 3440 moisture-density gauge was struck by a reversing roller at a construction site. Housing damage was noted, but no radioactive release was detected. Leak test results are pending, and the device has been removed from service for evaluation. - Automatic Reactor Trip – Braidwood Unit 1, Illinois
On July 30, the reactor automatically tripped from full power due to an over-temperature delta-T reactor protection system actuation during a lightning storm. Auxiliary feedwater pumps started as designed, and the unit was stabilized in hot standby. - Potential Residual Heat Removal System Inoperability – Dresden Station, Illinois
On July 30, grass buildup in the ultimate heat sink crib house temporarily rendered the single-train RHR system inoperable. Operators cleared the blockage within eight minutes, restoring operability. No public or personnel safety impact was reported.
August 4 Report
- TheraSphere Device Failure – Northwestern Memorial Healthcare, Illinois
During a Y-90 TheraSpheres liver cancer treatment on September 23, 2024, infusion was halted after excessive air bubbles and possible microsphere leakage were observed. The patient received 42.18 Gy of the prescribed 45.48 Gy. No contamination or medical follow-up was required. Manufacturer analysis later suggested low flow rate, possibly due to kinks in the microcatheter. - Unanalyzed Condition – Urenco USA, Eunice, New Mexico
Three end-of-life uranium hexafluoride traps were moved to a location where flooding is a credible event, a scenario not analyzed in the facility’s nuclear criticality safety assessment. The area was secured pending evaluation. - Medical Event – Adventist Health, Daytona, Florida
A patient receiving Y-90 TheraSphere treatment for the liver had one treatment segment delivered as prescribed, but the second segment received only 51% of the intended dose, exceeding the ±20% reporting threshold. The cause was excess residual activity in the equipment. The provider was informed; patient notification status is unknown. - Potential Inoperability of Residual Heat Removal System – Dresden Station, Illinois
On July 30, 2025, grass buildup in the river crib house intake rendered the single-train ultimate heat sink inoperable. Operators cleared the blockage within eight minutes, restoring operability. No public safety impact occurred. - Control Room Ventilation System Inoperable – Calvert Cliffs, Maryland
On July 31, 2025, both trains of the control room emergency ventilation and temperature systems were inoperable for less than one minute due to a damper malfunction. Systems returned to normal automatically. - Automatic Reactor Scram – Browns Ferry Unit 1, Alabama
On August 1, 2025, the reactor automatically scrammed due to low water level, triggering containment isolation and actuation of high pressure coolant injection and core isolation cooling. All safety systems functioned as designed, and the unit was stabilized without public safety impact.
August 5 Report
- Overexposure to Declared Pregnant Worker – Johns Hopkins Imaging, Maryland
Between March and June 2025, a PET technician at the Bethesda facility received a fetal dose of 14.79 rem, whole-body dose of 29.966 rem, and extremity dose of 6,329 rem—above investigation thresholds. The worker was removed from duties involving radioactive materials. No contamination was detected; investigation is ongoing. - Medical Event – Adventist Health, Daytona, Florida
A patient receiving Y-90 TheraSphere liver treatment on July 25, 2025, received only 51% of the intended dose in one of two treatment segments, exceeding the ±20% deviation threshold. Residual activity remained in the administration equipment. The provider was informed; patient notification status is unknown. - Damaged Portable Nuclear Gauge – Somat Engineering, Michigan
On July 7, 2025, construction equipment struck an InstroTek Explorer 3500 gauge (10 mCi Cs-137, 40 mCi Am-241) during density measurements. The source remained intact, radiation surveys were below background, and the gauge was secured for disposal. - Lost Cs-137 Sources – Central Diagnostic Imaging Network, California
Two Cs-137 attenuation correction sources (~13 mCi each) were found missing during a March 2025 inventory. A facility search was unsuccessful. Material is “less than IAEA Category 3” but still requires secure handling. - Lost Am-241 X-ray Analyzers – Bar Resource International, Illinois
Three portable X-ray fluorescence analyzers (30 mCi Am-241 each) from a company that ceased operations after March 2020 are missing. The Illinois Emergency Management Agency is investigating. Material is “less than IAEA Category 3.” - Lost Tritium Exit Signs – AMC Westminster Promenade 24, Colorado
Two self-luminous exit signs containing 10 Ci of tritium (H-3) each were reported lost. Manufactured by Isolite Corporation, these devices are “less than IAEA Category 3” but regulated for safety and security.
August 6 Report
- Damaged Portable Nuclear Gauge – Somat Engineering, Michigan
On July 7, 2025, a density technician was struck by construction equipment while taking measurements, damaging an InstroTek Explorer 3500 gauge containing 10 mCi Cs-137 and 40 mCi Am-241. The source remained intact, surveys showed readings below background, and no additional exposures occurred. The gauge was secured in a sand-filled drum and prepared for disposal. - Lost Cs-137 Sources – Central Diagnostic Imaging Network, California
In March 2025, two Cs-137 attenuation correction sources (~13 mCi each) were found missing during inventory. A facility search was unsuccessful. The material is considered “less than IAEA Category 3,” unlikely to cause permanent injury, but still reportable. - Lost Am-241 X-ray Analyzers – Bar Resource International, Illinois
Following investigation into an unresponsive general licensee, three portable X-ray fluorescence analyzers (30 mCi Am-241 each) were determined lost or missing. The company ceased operations after March 2020 and has been unresponsive. Material is “less than IAEA Category 3.” - Lost Tritium Exit Signs – AMC Westminster Promenade 24, Colorado
Two self-luminous exit signs containing 10 Ci of tritium (H-3) each were reported lost. Manufactured by Isolite Corporation, these devices are also “less than IAEA Category 3” but require secure handling and reporting when lost.
August 7 Report
- Medical Event – Aspirus Wausau Hospital, Wisconsin
On July 31, 2025, during the third of five HDR gynecological cylinder fractions, the treatment cylinder shifted by up to 1 cm, possibly reducing the delivered dose to the cervix from 6 Gy to 2.6 Gy. No dose limits to other organs were exceeded, and the patient was notified. State investigation is underway. - Lost Radioactive Source – Adventist Health Systems, Florida
A Gd-153 rod source (0.04 mCi) in a lead sleeve was lost in transit to a manufacturer. The package arrived empty on July 7, 2025. Carrier and facility investigations are ongoing. The quantity is less than IAEA Category 3, posing minimal safety risk. - Automatic Reactor Trip – Surry Unit 1, Virginia
On August 6, 2025, the reactor tripped automatically due to a false high containment pressure signal, leading to actuation of safeguards and auxiliary feedwater systems. All safety systems responded correctly, and the trip was uncomplicated. Offsite power remained available, with no effect on Unit 2.
August 8 Report
- Potential Overexposure – High Mountain Inspection, Texas (Retracted)
Initially reported as a 7.7 rem exposure in February 2025 to an assistant radiographer. Investigation found the dose reading was a dosimeter processing anomaly. Actual assigned dose was 285 mrem; event retracted. - Medical Event – Aspirus Wausau Hospital, Wisconsin
During an HDR gynecological cylinder treatment on July 31, 2025, the cylinder shifted up to 1 cm, potentially reducing the dose to the cervix from 6 Gy to 2.6 Gy. No other organs exceeded dose limits. The patient was informed, and the state is investigating. - Lost Source – Adventist Health Systems, Florida
A Gd-153 rod source (0.04 mCi) in a lead sleeve was lost in transit to a manufacturer. Package arrived empty on July 7, 2025. Common carrier and licensee investigations are ongoing. Material is “less than IAEA Category 3.” - Medical Event – Doctors Hospital, Georgia
On July 7, 2025, a Y-90 therapy underdose occurred due to a kinked catheter, delivering 40% less than prescribed. Two similar underdosing events in 2024 were also identified, both involving catheter kinking. A formal report is pending. - Damaged Portable Nuclear Gauge – Earth Strata Geotechnical Services, California
A CPN MC-3 moisture-density gauge (10 mCi Cs-137, 50 mCi Am-241/Be) was run over by a bulldozer, breaking the source rod and damaging housing. Surveys showed no significant radiation above background. Gauge will be disposed of; investigation ongoing. - Automatic Reactor Trip Update– Surry Unit 1, Virginia
On August 6, 2025, the reactor tripped automatically due to a false high containment pressure signal. All safety systems actuated as designed, including containment isolation and auxiliary feedwater. Trip was uncomplicated; Unit 2 unaffected.
Why This Matters
While most NRC event notifications do not pose an immediate hazard to public health, they reveal important lessons for the nuclear industry, emergency planners, and policymakers. These reports cover a broad range of nuclear safety domains—operational reliability, radiation protection, medical safety, security protocols, and transport controls. Transparent reporting supports public confidence, enhances emergency preparedness, and strengthens national resilience against both accidental and intentional threats.
For a detailed review of each incident, including technical and corrective action specifics, visit the NRC’s daily event report page.