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The “Race” to Resolve the Boiling Water Reactor Safety Limit Problem

, director, Nuclear Safety Project

General Electric (GE) informed the Nuclear Regulatory Commission (NRC) in March 2005 that its computer analyses of a depressurization event for boiling water reactors (BWRs) non-conservatively assumed the transient would be terminated by the automatic trips of the main turbine and reactor on high water level in the reactor vessel. GE’s updated computer studies revealed that one of four BWR safety limits could be violated before another automatic response terminated the event.

Over the ensuring decade-plus, owners of 28 of the 34 BWRs operating in the US applied for and received the NRC’s permission to fix the problem. But it’s not clear why the NRC allowed this known safety problem, which could allow nuclear fuel to become damaged, to linger for so long or why the other six BWRs have yet to resolve the problem. UCS has asked the NRC’s Inspector General to look into why and how the NRC tolerated this safety problem affecting so many reactors for so long. Read more >

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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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Friendly Answers Following Blowing of the Winds

, director, Nuclear Safety Project

Disaster by Design/ Safety by Intent #59

Safety by Intent

With ample warning, Hurricane Matthew made landfall in South Carolina coast on October 8, 2016, bringing along its heavy rainfall and high winds.

The Federal Emergency Management Agency conducted Disaster Initiated Reviews for nuclear plants in South Carolina, North Carolina and Florida to determine whether Hurricane Matthew adversely affected emergency planning measures within a 10-mile radius of each site. Read more >

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Nuclear Plant Containment Failure: Pre-Existing Damage

, director, Nuclear Safety Project

Disaster by Design/Safety by Intent #31

Disaster by Design

Federal regulations require that nuclear plant containments withstand the temperature, pressure, hydrodynamic forces, humidity, and other consequences from design basis accidents and limit the amount of radioactivity to the atmosphere. By limiting the radioactivity release, containments minimize the harm to nearby populations and the environment.

The surest way for a containment to be damaged after an accident and be unable to fulfill this safety function is for it to be damaged before the accident starts. Read more >

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The Importance of Nuclear Training

, director, Nuclear Safety Project

Disaster by Design/Safety by Intent #20

Disaster by Design
In nuclear power safety, training has nothing to do with steam engines, diesel engines, passenger cars, freight cars, and cabooses. In nuclear power safety, training encompasses education, experience, and qualifications seeking to ensure that workers know what to do, and what not to do. Training is not just a good idea, it’s the law. Read more >

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