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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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Special Inspections: Safety Relief Valve Problems at Perry and Hatch

, director, Nuclear Safety Project

Near-Miss Summary

The Near-Miss

The Nuclear Regulatory Commission (NRC) sent special inspection teams to the Perry Nuclear Power Plant in Perry, Ohio and to the Edwin I. Hatch Nuclear Plant near Baxley, Georgia early this year. Both plants feature boiling water reactors (BWRs) and both experienced problems with safety relief valves that prompted the NRC’s reactions. 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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Remote Control at Nuclear Power Plants

, director, Nuclear Safety Project

Disaster by Design: Safety by Intent #18

Disaster by Design

Disaster by Design/Safety by Intent #17 covered command and control problems at nuclear power plants that undermined safety. Remote control is required at nuclear power plants to provide capabilities when the control room has to be abandoned. This commentary covers remote control and some of its problems. Read more >

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Fire at the Nuclear Plant

, 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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