South Jersey nuclear reactor remains on ‘alert’
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Plant operators "started to see water pile up in the intake structure," he said. When the water reaches a level of 4.5 feet, Sheehan said, federal regulations require the plant to declare an "unusual event." That happened at about 4 in the afternoon on Monday. By about 8:45 p.m., waters had risen to above 6 feet, the threshold for triggering an "alert." At 6.5 feet, Sheehan said, pump operations begin to be affected. Waters reached a peak of 7.4 feet at 12:45 a.m. Tuesday.
Sheehan said that if pumps are affected, backup portable generators can be used, but he is not sure if they were deployed. One reason may be that the first pumps affected by rising water would be those used to cool the condenser, cooling steam generated by an operating plant, but the plant was not operating. By 6:12 a.m., the waters had receded to 6.5 feet and levels were still dropping.
Even though the reactor generates power, it also uses power from the grid for operations. When the storm knocked out the reactor's power, the diesel operated backup generator kicked in, Sheehan said. But because the plant was in shutdown mode, not as much power was required, he said.