The Demon Hot Atom -- Control Room

Control Room: A place where mistakes happen quickly.

The Control Room is the place where they try to control the reactor. Shown below is the Control Room of Three Mile Island Unit Two:

-- Above image is from: Report of the President's Commission on the Accident at Three Mile Island: The Need for Change: The Legacy of TMI, John G. Kemeny, Chairman, (Bruce Babbitt also signed the document, with 10 others), page 112, October, 1979.

Controlling a reactor, especially one that is being powered up or powered down, and/or one that has been damaged, can be a very demanding task, and the indicators and controls available to the operator are frequently inadequate. To make matters worse, when things start going wrong, they can do so in fractions of a second.

Because of the complexity, even in hindsight, the operators frequently can't figure out, for example, why valves open, then close, then open again, etc. etc.. And sometimes things happens so fast, that even if the Control Room's indicators keep up with the actual events inside the reactor, the operators won't know what's going on anyway, because they can't assimilate the incoming data stream quickly enough.

In an emergency, plant supervisors meet in a separate room, usually adjacent to the control room.

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But there's another endemic problem in the control room:

Maintenance Tags

Maintenance Tags? What are maintenance tags?

Maintenance Tags are used to indicate problems with equipment, and they are placed on controls which should not be used, or should be used in an unusual way.

The close-up below is of the control panel of TMI-2, from a government report. According to the caption, it shows "maintenance tags that operators testified covered one of the closed emergency feedwater valve indicator lights during the first 8 minutes of the accident".

-- Above image is from: Report of the President's Commission on the Accident at Three Mile Island, page 117

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If you're thinking the nuclear industry has learned anything, or has modernized their Control Rooms so much that they are now "foolproof" from even the most determined fools, THINK AGAIN! The following photograph is of the control room at Prarie Island Nuclear Power Station. Looks pretty similar, doesn't it?

-- Above image is from: Powerhouse: Inside a Nuclear Power Plant, by Charlotte Wilcox, page 22, Carolrhoda Books, Inc., 1996.

Now, look at this close-up, seen on the following page of the same 1996 book:

-- Above image is from: Powerhouse: Inside a Nuclear Power Plant, by Charlotte Wilcox, page 23, Carolrhoda Books, Inc., 1996.

See the large tag? I wonder what it's covering up. The bold print on the tag reads "NO ONE ALLOWED IN CONTAINMENT", which sounds like an excellent idea, generally.

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