The US Nuclear Regulatory Commission will conduct a special inspection at the single-unit Cooper nuclear power station in Nebraska to review the circumstances that contributed to a recent problem with one of the plant’s two service water systems.

The Cooper plant, operated by Nebraska Public Power District, was operating at full power on 6 December when the operators were unable to establish water flow through a large pipe that discharges water used to cool some of the plant’s safety-related equipment. A second service water system remained operable.

It was discovered that a large buildup of silt, which was later removed, from Missouri River flooding had blocked the pipe’s outlet.