A guard at the Oak Ridge National Laboratory in Tennessee was wounded during a mock terrorist attack on the nuclear reactor there when live ammunition was mixed with blanks mistakenly.

Allen P. Ellis was injured on June 13 as he and six other guards stormed the facility while five other guards playing the parts of terrorists barricaded themselves inside.

According to Ed Aebischer, a spokesman for the Energy Department facility, a live cartridge passed through the blank firing adapter on a "terrorist's" M16 rifle, shattering the adapter and flinging metal fragments that lodged in Ellis' hand, arm and side. He is recovering.

Aebischer said the mock exercise, which took place in the Health Physics Research Reactor, was one of many conducted by the department at various reactors to train guards to respond to terrorist attacks. Each rifle was equipped with a special laser device so participants could record hits and misses.

An investigation into the Oak Ridge incident found four other live cartridges in ammunition that was scheduled to be used in the exercises, Aebischer said. He added that active cartridges will not normally fit into firing magazines intended for blank rounds, blanks being considerably shorter than live rounds. But in this case, Aebischer said, because of a manufacturing error the live rounds looked about the same as the blanks.

Aebischer said that the Energy Department plans to look into requiring an improvement in quality-control assurances made by the manufacturer. In future exercises, he said, a more careful inspection of ammo is planned.