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Fish Or Cut Bait

Still a Dangerous Business, But Not for the Reasons You Expect
by Bob Ciminel


August 10, 2004

An accident at the Mihama-3 nuclear power plant in Japan resulted in the deaths of four workers and severe injuries to seven others. The story only made the headlines because the accident happened at a nuclear power plant. Had the accident happened at a fossil power plant, we probably would not know about it.

photo turibne-generator

"Turbine-Generator at a U.S. Nuclear Power Plant."
Photo by Bob Ciminel

Mihama Unit 3 went into commercial operation in 1976. Westinghouse Electric Corporation designed the plant, which is similar to several pressurized water nuclear power plants built in the United States during the same period. In a pressurized water reactor, heat from uranium fission in the reactor core heats water in the primary coolant system pressurized to 2,235 psi. The primary coolant then circulates through tubes in heat exchangers called steam generators where it heats the secondary water and creates steam. After passing through the turbine-generator, the steam condenses back into water and returns to the steam generators. Before the water enters the steam generators, it a series of six to eight heaters, called feedwater heaters, heat the water using small amounts of excess steam from the turbine-generator. This improves the overall plant efficiency. One of these pipes ruptured at Mihama -3.

The accident had absolutely nothing to do with the type of power plant involved. Once you get beyond the reactor side of the plant, everything is essentially the same. The pipes, pumps, valves, and heat exchangers are no different, whether the plant burns coal, oil, natural gas, or uranium.

In this case, a pipe ruptured, sending 300-degree Fahrenheit steam into an enclosed area where workers were making preparations for the plant's upcoming maintenance outage. Shortly before a power plant shuts down for maintenance, worker swarm like ants throughout the plant erecting scaffolding around equipment that will be worked on during the shutdown. It is normal for this work to begin while the plant continues generating electricity. Today's economic environment, both here and overseas, demands that power plants keep their outages to an absolute minimum. There are 8,760 hours in a year, and customers, investors, and regulators want the plants making electricity 7,800 of those hours.

I expect more of the Japanese workers to die. Remember the last time you lifted the cover on a dish you took out of the microwave oven, or lifted the lid on a pot on the stove. Steam obeys the laws of thermodynamics; at 212 degrees Fahrenheit, steam has 500 times more energy than water at the same temperature. When it touches your skin or clothing, it releases that energy as heat. Personally, I will take my chances with radiation. At worse, it may shorten my life by five or 10 years; there are other hazards in a power plant that will end it much quicker.

As one who has talked the talk and walked the walk, my prayers go out to the Japanese workers and their families.


Bob Ciminel ©2004
All Rights Reserved

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