Good News: Workers removed a valve from the piping of a cooling water system at the Indian Point nuclear plant in New York on August 13, 1984, for maintenance. The cooling water system had two redundant loops of pumps, pipes, and heat exchangers. The loop the workers removed the valve from had been shut down for maintenance and inspections. The other loop remained in service. A pipe cross-connected the two loops, but three separate valves within the connecting pipe prevented water from the running loop from entering the idle loop.
Bad News: Other workers discovered the room containing the cooling water system pumps filling with water that poured from the ends of the pipe where the valve had been removed. The water leaked from the pipe faster than it left via drains in the floor. It was later determined that all three valves in the cross-connect pipe had failed, allowing water from the running loop to reach the idle loop’s piping and from there reach the floor. The workers could not stop the room’s flooding.
Good News: The rising water levels submerged the electric motors for the cooling water system pumps. The motors shorted out and the pumps stopped running. Leakage of water into the room stopped and the floor drains slowly emptied water from the room.
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