quadcities


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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Spent Fuel Damage: Pool Criticality Accident

, former 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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Fire at the Nuclear Plant

, former director, Nuclear Safety Project

Disaster by Design/Safety by Intent #2

Disaster by Design

The March 1975 near-miss at the Browns Ferry nuclear plant in Alabama involved a fire in the cable spreading room. This room is located directly below the control room for the Unit 1 and Unit 2 reactors. Electrical cables from switches, gauges, and alarms on the control panels are routed through the floor into the cable spreading room where they radiate out to equipment throughout the plant. The fire burned for over six hours, destroying thousands of electrical cables. All of the emergency core cooling systems were disabled for the Unit 1 reactor and the majority of those safety systems were disabled for the Unit 2 reactor. Only heroic actions by workers prevented core meltdowns that fateful day. Read more >

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An Electrical Cable Fire at the Quad Cities Nuclear Plant

, former director, Nuclear Safety Project

Fission Stories #178

On March 22, 1975, a worker using a lit candle to check for air leaks in the room directly below the control room for the Unit 1 and Unit 2 reactors at the Browns Ferry Nuclear Plant near Athens, Alabama accidentally ignited highly flammable material that had been used to seal openings in the wall where metal trays filled with electrical cables passed through. These cables connected switches, gauges, indicators, alarms, and other devices in the control room above to equipment throughout the plant. The fire burned for over six hours. As insulation burned away, exposed cables touched each other or the metal trays and shorted out. The extensive cable damage disabled all of the emergency core cooling systems for the Unit 1 reactor and most of these systems on Unit 2. Only heroic and ad hoc actions by workers prevented two core meltdowns. Read more >

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