Final refueling at Pilgrim
- Apr 16, 2017 5:46 pm GMT
An army of 1,400 plant workers and outside system specialists are at
The process takes great precision, as 168 highly radioactive fuel assemblies -- about one-third of those in the reactor -- are taken out. The assemblies are moved by crane, one by one, through a water-filled canal and into the adjacent spent fuel pool, where about 3,000 spent assemblies are currently cooling.
The assemblies, 12 to14 feet long, must be kept upright and under water throughout the moving process, since water provides a shield from the intense radiation they would give off.
The new fuel assemblies, which arrived in
By Thursday, the containment vessel had been opened and the head of the reactor vessel removed by contractors from
"We raised water in the reactor up to the level on the refueling floor so we can remove spent fuel to the pool," said
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The reactor temperature must be maintained a little above 90 degrees to keep it from fracturing, Noyes said.
The fuel pool is kept between 80-90 degrees. Lower temperatures would raise the radioactivity of the fuel assemblies, Noyes said.
The refueling process is required every two years and takes approximately 30 days. Noyes had denied a request from the
"We are focusing on this last outage, and the leadership wanted no distractions," Noyes explained.
While a reporter had recently been allowed to tour
"The performance of the plant through the recovery process has not been what we want or expect it to be," Noyes said of the plant's performance over the past 18 months. "We're applying resources and effort -- not just Pilgrim but the whole
Preparation for the spent fuel transfer actually began in January,
An evaluation in December projected about 900 of the panels will be in danger of deterioration by September. Noyes said that projection is proving to be accurate.
"We moved about 1,600 assemblies in January," O'Brien said -- more than half of those now in the pool. The assemblies that had been in the pool the longest were put in areas where deterioration may be occurring.
Meanwhile, workers are being carefully monitored for radiation levels during refueling. "Because of the nature of the work, more radiation dose is received by workers who will be accessing areas not usually accessed," Noyes said. "We manage the dose and minimize it by using robots."
While the reactor is shut down, the level of radiation outside the plant is even lower than it normally is, Noyes said.
In addition to replacing spent fuel assemblies, systems that have been plagued with problems over the past two years will be overhauled, Noyes said.
On the list are improvements to feedwater regulator valves, which caused a shutdown in September; replacement of all eight main steam isolation valves, which were the cause of a recent shutdown; testing and several improvements to the troubled switchyard, where on-site and off-site electricity is transferred (related to Pilgrim's downgrade to Column 4); replacement of two of the four massive screens that filter out marine life from seawater drawn into the plant.
"With the reactor shut down, we can also do internal inspections like piping components to make sure metal integrity is sound," Noyes said.
Public pressure had been applied to prevent this final refueling, but following an intense three-week inspection federal regulators said the long list of system snafus and shortcomings they had found didn't pose enough danger to warrant an ordered shutdown.
The cost of the refueling has been estimated at
Federal legislators from
The vent would have to be installed during the current refueling outage if no extension is granted, Sheehan wrote in an email, "or the plant would not be allowed to restart."
Based on Sheehan's final comment, it likely won't come to that. "We will likely have a decision on the extension request some time soon," he said.
(c)2017 Cape Cod Times, Hyannis, Mass.
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