3 workers exposed to radiation at Cooper Nuclear Plant

Federal inspectors are trying to find out why three maintenance workers were exposed to higher than expected radiation levels at Cooper Nuclear Station near Brownville in southeast Nebraska.

The Nuclear Regulatory Commission says the workers were exposed to unplanned radiation on April 3 as part of maintenance work at the power plant run by the Nebraska Public Power District. NPPD spokesman Mark Becker says the level of radiation the workers were exposed to didn't exceed the commission's safety limits.

Cooper remains shut down while planned repair and refueling work is done. Regulators say the workers didn't follow the proper procedure for removing a long tube contaminated with radioactive material from the reactor because the tube was taken out of the bottom of the reactor vessel instead of the top.