Report to Congress on Abnormal Occurrences Fiscal Year 2025 (NUREG-0090, Volume 48)

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Publication Information

Manuscript Completed: June 2026
Date Published: June 2026

Office of Nuclear Regulatory Research
United States Nuclear Regulatory Commission
Washington, DC 20555-0001

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Abstract

Section 208 of the Energy Reorganization Act of 1974, as amended (Public Law 93-438), defines an abnormal occurrence (AO) as an unscheduled incident or event that the U.S. Nuclear Regulatory Commission (NRC) determines to be significant from the standpoint of public health or safety. The Federal Reports Elimination and Sunset Act of 1995 (Public Law 104-66) changed the AO reporting frequency from quarterly to annual. 

This report on AOs for fiscal year (FY) 2025 describes seven events involving Agreement State licensees and two events involving NRC licensees. These events were identified based on the criteria in the NRC policy statement, “Abnormal Occurrence Reporting,” published in the Federal Register (FR) on August 12, 2025 (90 FR 38828). Four AOs were medical events, as defined in Title 10 of the Code of Federal Regulations Part 35, “Medical Use of Byproduct Material.” The remaining five AOs consisted of one loss of an industrial radiography source, two events involving overexposure of declared pregnant radiation workers, one significant breakdown in radiological controls, and one unintended fetal/embryo exposure. No events at commercial nuclear power plants met the criteria for an AO. 

Appendix A, “Abnormal Occurrence Criteria,” to this report presents the NRC’s criteria for identifying AOs. The NRC identified no events during FY 2025 that met the guidelines for inclusion in Appendix B, “Other Events of Interest.” One event met the guidelines for inclusion in Appendix C, “Updates on Previously Reported Abnormal Occurrences.” Appendix D, “Glossary,” defines terms used throughout this report. Appendix E, “Conversion Table,” presents conversions commonly used when calculating doses.