monticello


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

, former 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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Nuclear Plant Containment Failure: Isolation Devices

, former director, Nuclear Safety Project

Disaster by Design/Safety by Intent #32

Disaster by Design

Containment structures at nuclear power plants have multiple purposes. Containments protect vital safety equipment from damage caused from external events like high winds and the debris they can fling. And containments protect nearby communities against radiation released from reactor cores damaged during accidents. Read more >

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ROSS

, former director, Nuclear Safety Project

Disaster by Design/Safety by Intent #15

Disaster by Design

You probably have noticed by now there’s no shortage of acronyms and abbreviations in the nuclear industry. There are so many that the Nuclear Regulatory Commission (sometimes called the NRC) published a report chock-a-block with many of them. Because one can never have too many acronyms, I’ll unveil another one: ROSS, for Race of Safety Snails. Read more >

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Nuclear Maintenance: If It Ain’t Broke, Let’s Break It

, former director, Nuclear Safety Project

Disaster by Design: Safety by Intent #5

Disaster by Design

Thirty years ago, the average annual capacity factor of U.S. nuclear power reactors—the fraction of electricity generated compared to what could be generated by operating at 100% power over the entire year—was between 55 and 60%.

Over the past decade, the average annual capacity factor has steadily been around 90%. Read more >

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Fission Stories #128: Monticello’s Radioactive Steam Dryer

, former director, Nuclear Safety Project

On March 5, 2011, operators at the Monticello nuclear plant in Minnesota shut down the reactor to enter its 25th refueling outage. Monticello has a boiling water reactor with a Mark I containment design like the Unit 2 reactor at Fukushima Daiichi. Read more >

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