waterford


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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Command and Control

, director, Nuclear Safety Project

Disaster by Design/Safety by Intent #17

Disaster by Design

Command and control is often used to describe the authority of military leaders in directing armed forces in battle. It can also refer to senior managers at nuclear power plants and the resources they command and control to fend off safety challenges.

Faulty intelligence, or flawed situational awareness, undermines command and control when leaders have the wrong understanding of hazards and/or response capabilities. Read more >

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Nuclear Power(less) Plants

, director, Nuclear Safety Project

Disaster by Design/Safety by Intent #3

Disaster by Design

The primary purpose of commercial nuclear power plants in the U.S. is to generate electricity. When not fulfilling that role, nuclear power plants that are shut down require electricity to run the equipment needed to prevent the irradiated fuel in the reactor core and spent fuel pool from damage by overheating. The March 2011 accident at Fukushima Daiichi in Japan graphically illustrated what can happen when nuclear plants do not get the electricity they require. 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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Fission Stories #21: The Dirt on Two Cleaning Tales

, director, Nuclear Safety Project

#21a: Nuclear Power’s Dirty Little Secret

One June 17, 1970, an operator at the LaCrosse nuclear plant near Genoa, Wisconsin, used a dust cloth to clean a console in the control room. The cloth snagged the identification tag attached to one of the key switches and caused it to move around to the OFF position. The repositioning of this single switch caused the reactor to automatically shut down.

To prevent this unfortunate event from happening again, the plant’s owner directed control room operators to use a feather duster when cleaning control room consoles.

The training program for operators consists of more than a year’s worth of classroom instruction and simulator exercises. Proper dusting techniques–whether dust cloth or feather duster–are not covered during this otherwise comprehensive training.

#21b: Safety SWISHed at Waterford

An operator at the Waterford nuclear plant near New Orleans, Louisiana used a commercial cleanser called SWISH to clean a control room panel on October 25, 1992. In less than two hours, “the cleaner solvent caused the plastic parts of 16 safety-related control switches to bond together, making the switches inoperable” according to the NRC. The broken switches included those for valves on both the high-pressure and low-pressure systems needed to supply makeup water to the reactor core in case of an accident.

Had an accident occurred with these switches cleaned but busted, things in Louisiana may have gotten dirty and stayed dirty a long time.

Our Takeaway

Fission Stories #20 described the importance of asking all the right questions to ensure safe outcomes. These events further illustrate the necessity of asking all the right questions. The seemingly innocuous task of cleaning a control room panel undermined safety levels. Such events are as important tribal knowledge as the lessons from the Three Mile Island accident because they help calibrate questioning attitudes to the level of detail needed to flush out subtle but significant issues.

“Fission Stories” is a weekly feature by Dave Lochbaum. For more information on nuclear power safety, see the nuclear safety section of UCS’s website and our interactive map, the Nuclear Power Information Tracker.

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