Disaster by Design

Nuclear reactors use multiple safety systems to operate with low-risk. This series examines what happens when those systems fail—and explores what can be done to ensure better safety in the future.


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Nuclear Plant Containment Failure: Potpourri

, director, Nuclear Safety Project

Disaster by Design/Safety by Intent #33

Disaster by Design

Disaster by Design/Safety by Intent #30 discussed how containment structures can be adversely affected by high internal pressure experienced during an accident. Disaster by Design/Safety by Intent #31 discussed how containments can be adversely affected by damage/degradation that existed even before an accident started. Disaster by Design/Safety by Intent #32 covered times when isolation devices (e.g. doors, valves, dampers) failures created potential pathways for radioactivity to escape containment. This commentary follows that theme, describing a hodge-podge of ways containment performance capability was impaired. Read more >

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Nuclear Plant Containment Failure: Isolation Devices

, 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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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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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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