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Benny Hill Explains the NRC Approach to Nuclear Safety

, director, Nuclear Safety Project

The Nuclear Regulatory Commission’s safety regulations require that nuclear reactors be designed to protect the public from postulated accidents, such as the rupture of pipes that would limit the flow of cooling water to the reactor. These regulations include General Design Criteria 34 and 35 in Appendix A to 10 CFR Part 50.

Emergency diesel generators (EDGs) are important safety systems since they provide electricity to emergency equipment if outside power is cut off to the plant—another postulated accident. This electricity, for example, would allow pumps to continue to send cooling water to the reactor vessel to prevent overheating damage to the core. So the NRC has requirements that limit how long a reactor can continue operating without one of its two EDGs under different conditions. The shortest period is 3 days while the longest period is 14 days. Read more >

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UCS to Nuclear Regulatory Commission: Big THANKS!

, director, Nuclear Safety Project

This spring, I ran into Mike Weber, Director of the Office of Nuclear Regulatory Research for the Nuclear Regulatory Commission (NRC), at a break during a Commission briefing. The Office of Research hosts a series of seminars which sometimes include presentations by external stakeholders. I asked Mike if it would be possible for me to make a presentation as part of that series. Read more >

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Nuclear Reactors and Flood Protection

, director, Nuclear Safety Project

Disaster by Design/ Safety by Intent #48

Safety by Intent

Oconee Flood Protection Issue

In August 2006, NRC inspectors identified a deficiency in a flood protection measure at the Oconee Nuclear Station in South Carolina. Specifically, the inspectors discovered that workers removed a 6-inch by 10-inch panel in the 5-foot tall flood wall around the Standby Shutdown Facility (SSF) to allow temporary cables to be used during a modification. When the work was completed and the cables removed, the panel was not re-installed.

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Nuclear Plant Containment Failure: Overpressure

, director, Nuclear Safety Project

Disaster by Design/Safety by Intent #30

Disaster by Design

Defense-in-depth is a primary element of the Nuclear Regulatory Commission’s approach to the safety of U.S. nuclear power plants. Many of the NRC’s regulatory requirements seek to reduce the chances of reactor core meltdowns to as low as achievable levels. But recognizing that the consequences of low probability events like meltdowns, sometimes called “black swans,” can be disastrous, the NRC also has regulatory requirements seeking to reduce the chances that radioactivity gets released in harmful amounts during an accident. This commentary describes the primary containments used in pressurized water reactors (PWRs) and boiling water reactors (BWRs) and how too much pressure can cause containment to fail. Read more >

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Spent Fuel Damage: Pool Criticality Accident

, director, Nuclear Safety Project

Disaster by Design/Safety by Intent #29

Disaster by Design

Disaster by Design/Safety by Intent #26 described a progression leading to overheating and damage to a reactor core, often labeled a meltdown. Disaster by Design/Safety by Intent #27 described the damage to a reactor core that can result from reactivity excursions. Disaster by Design/Safety by Intent #28 and #29 mirror those commentaries by describing how irradiated fuel stored in spent fuel pools can experience damage from overheating and reactivity excursions. Read more >

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