The Vermont Yankee power plant has been at reduced power for the past two days because of a with a pilot valve on the main valve on the B turbine. Smith said that plant personnel were performing scheduled maintenance surveillance of the turbine valves when the problem occurred. He said the valve closed properly, but would not “respond as expected” and reopen.
Turbine stop valves are swing disc-type valves on the lines carrying steam from the reactor to the turbine, he said, and they are designed to abruptly close when the reactor trips, or shuts down, causing the turbine to slow down and eventually stop.
“Problems involving the turbine can force a shutdown, which can challenge plant operators,” he added.
Sheehan said that Entergy employees used the reduced power time to clean the water box of the plant’s condenser. He said the water box, at the base of the condenser, is cleaned out periodically.
On Tuesday, the Vernon reactor was at 20 percent, and earlier Wednesday, it was at 34 percent, according to the morning report posted by the Nuclear Regulatory Commission on its website. Entergy Nuclear spokesman Laurence Smith said late Wednesday afternoon that Yankee was at 43 percent power, but was increasing power production.
Source: Times Argus
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